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Jin G, Zou M, Li L, Liu Z, Young C, Qi H, Zheng D. Corneal biomechanics and their association with severity of lens dislocation in Marfan syndrome. Int Ophthalmol 2024; 44:148. [PMID: 38502381 DOI: 10.1007/s10792-024-03079-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 02/16/2024] [Indexed: 03/21/2024]
Abstract
PURPOSE To investigate corneal biomechanical properties and its associations with the severity of lens dislocation in patients with Marfan syndrome. METHODS A total of 30 patients with Marfan syndrome and 30 age-, sex- and axial length (AL)-matched controls were recruited. Corneal biomechanical parameters of both groups were measured by CorVis ST and were compared between groups. Potential associations between corneal biomechanical parameters and severity of lens dislocation were also investigated. RESULTS Lower applanation 1 velocity (A1V) (0.13 ± 0.004 vs. 0.15 ± 0.003, P = 0.016), shorter applanation 2 time (A2T)(22.64 ± 0.11 vs. 22.94 ± 0.11, P = 0.013), longer peak distance (PD) (5.03 ± 0.07 vs. 4.81 ± 0.05, P = 0.008), longer radius (R) of highest concavity (7.44 ± 0.16 vs. 6.93 ± 0.14, P = 0.012), greater Ambrosio relational thickness horizontal (ARTh) (603 ± 20 vs. 498 ± 12, P < 0.001), and integrated radius (IR) (8.32 ± 0.25 vs. 8.95 ± 0.21, P = 0.033) were detected among Marfan eyes compared with controls (all P < 0.05). Marfan individuals with more severe lens dislocation tended to have increased stiffness parameter as longer A1T, slower A1V, shorter A2T, slower application 2 velocity (A2V), smaller PD and smaller Distance Amplitude (DA) (P < 0.05). CONCLUSION Marfan patients were detected to have increased corneal stiffness compared with normal subjects. Corneal biomechanical parameters were significantly associated with the severity of lens dislocation in Marfan patients.
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Affiliation(s)
- Guangming Jin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Minjie Zou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Longhui Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Zhenzhen Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Charlotte Young
- Albany Medical College, 49 New Scotland Ave, Albany, NY, USA
| | - Haotian Qi
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Danying Zheng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China.
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Dawson S, Mohite A. Use of Ocular Response Analyzer Output Data in the Management of Low Intraocular Pressure after Glaucoma Filtration Surgery. J Curr Glaucoma Pract 2023; 17:104-105. [PMID: 37485464 PMCID: PMC10357027 DOI: 10.5005/jp-journals-10078-1402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 01/27/2023] [Indexed: 07/25/2023] Open
Abstract
Aim To highlight potential benefits of using Reichert's ocular response analyzer (ORA) for intraocular pressure (IOP) measurement following glaucoma filtering surgery (GFS), especially in cases of low IOP. Background Goldmann applanation tonometry (GAT) is widely regarded as the gold standard of IOP measurement in clinical practice. The ORA also calculates corneal biomechanics, which is used in the calculation of the cornea-compensated IOP (IOPcc).1 This useful, previously unknown information can be used to guide management in challenging clinical cases. Case description A 78-year-old lady underwent right trabeculectomy with mitomycin C. During the first 9 months postoperatively, IOP's when measured with GAT, were found to be low (ranging between 2 mm Hg and 5 mm Hg). The patient displayed no clinical features of hypotony and visual acuity remained stable throughout. IOP was also measured with Reichert's ORA, which gives readings for corneal hysteresis (CH), corneal resistance factor and corneal corrected IOP. IOPcc measurements obtained with ORA were consistently higher, ranging from 6.7 mm Hg to 9.3 mm Hg and were more in keeping with the clinical features of the case. Conclusion This case highlights the possibility that GAT can underestimate the true IOP in eyes with low IOP following GFS, as it does not account for corneal biomechanical properties. Clinical significance Ocular response analyzer (ORA)-measured IOPcc may be a useful adjunct in reassuring surgeons to manage postoperative numerical hypotony conservatively in the absence of any clinical signs of hypotony. How to cite this article Dawson S, Mohite A. Use of Ocular Response Analyzer Output Data in the Management of Low Intraocular Pressure after Glaucoma Filtration Surgery. J Curr Glaucoma Pract 2023;17(2):104-105.
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Affiliation(s)
- Sarah Dawson
- Department of Ophthalmology, The Royal Wolverhampton NHS Trust (RWT), Wolverhampton, West Midlands, England
| | - Abhijit Mohite
- Department of Ophthalmology, The Royal Wolverhampton NHS Trust (RWT), Wolverhampton, West Midlands, England
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Li F, Wang K, Liu Z. In Vivo Biomechanical Measurements of the Cornea. BIOENGINEERING (BASEL, SWITZERLAND) 2023; 10:bioengineering10010120. [PMID: 36671692 PMCID: PMC9854753 DOI: 10.3390/bioengineering10010120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 01/11/2023] [Accepted: 01/13/2023] [Indexed: 01/18/2023]
Abstract
In early corneal examinations, the relationships between the morphological and biomechanical features of the cornea were unclear. Although consistent links have been demonstrated between the two in certain cases, these are not valid in many diseased states. An accurate assessment of the corneal biomechanical properties is essential for understanding the condition of the cornea. Studies on corneal biomechanics in vivo suggest that clinical problems such as refractive surgery and ectatic corneal disease are closely related to changes in biomechanical parameters. Current techniques are available to assess the mechanical characteristics of the cornea in vivo. Accordingly, various attempts have been expended to obtain the relevant mechanical parameters from different perspectives, using the air-puff method, ultrasound, optical techniques, and finite element analyses. However, a measurement technique that can comprehensively reflect the full mechanical characteristics of the cornea (gold standard) has not yet been developed. We review herein the in vivo measurement techniques used to assess corneal biomechanics, and discuss their advantages and limitations to provide a comprehensive introduction to the current state of technical development to support more accurate clinical decisions.
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Affiliation(s)
- Fanshu Li
- Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Health Science Center, Peking University, Beijing 100191, China
| | - Kehao Wang
- Beijing Advanced Innovation Center for Biomedical Engineering, School of Engineering Medicine, Beihang University, Beijing 100191, China
| | - Ziyuan Liu
- Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Health Science Center, Peking University, Beijing 100191, China
- Correspondence:
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Shokrollahzadeh F, Hashemi H, Yekta A, Ostadimoghaddam H, Khabazkhoob M. Corneal Biomechanical Parameters after 60-Year-Old. J Curr Ophthalmol 2022; 34:284-289. [PMID: 36644461 PMCID: PMC9832466 DOI: 10.4103/joco.joco_201_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 01/08/2022] [Accepted: 01/12/2022] [Indexed: 12/09/2022] Open
Abstract
Purpose To determine the distribution of corneal biomechanical parameters in an elderly population. Methods This cross-sectional study was conducted in subjects above 60 years living in Tehran. The participants were selected using multi-stage cluster sampling. Corneal biomechanical parameters were measured in a randomly selected subsample of this population using the Reichert Ocular Response Analyzer (Reichert Ophthalmic Instruments, Inc., Buffalo, NY, USA). Results Of 470 subjects, the data of 420 participants aged over 60 years were analyzed (mean age: 69.3 ± 6.5 years and range: 61-88 years), 363 (86.4%) of whom were male. The mean and standard deviation of corneal hysteresis (CH) and corneal resistance factor (CRF) were 8.37 ± 1.55 mmHg (95% confidence interval [CI]: 8.02-8.72) and 9.06 ± 1.70 mmHg (95% CI: 8.69-9.44), respectively. The mean CH was 8.27 ± 1.54 mmHg in men and 9.25 ± 1.28 mmHg in women, and the mean CRF was 9.00 ± 1.71 mmHg in men and 9.63 ± 1.37 mmHg in women. According to the results of multiple linear logistic regression analysis, CH had a significant association with younger age (β = -0.05, P = 0.032), female sex (β = 1.83, P < 0.001), reduced maximum keratometry (β = -0.22, P = 0.06), and increased anterior chamber volume (β = 0.01, P = 0.007). CRF had a significant correlation with a younger age (β = -0.06, P = 0.02), female sex (β = 1.01, P = 0.05), central corneal thickness (β = 0.02, P < 0.001), and reduced maximum keratometry (β = -0.39, P = 0.010). Conclusion The mean CH and CRF values were low in this sample of the Iranian population aged over 60 years indicating the weaker elasticity of the corneal connective tissue.
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Affiliation(s)
- Fereshteh Shokrollahzadeh
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Hassan Hashemi
- Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran
| | - Abbasali Yekta
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran,Address for correspondence: Abbasali Yekta, Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran. E-mail:
| | - Hadi Ostadimoghaddam
- Refractive Errors Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mehdi Khabazkhoob
- Department of Basic Sciences, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Diurnal Variation of Corneal Hysteresis in Patients With Untreated Primary Open Angle Glaucoma and Normal Individuals. J Glaucoma 2022; 31:891-897. [PMID: 35980846 DOI: 10.1097/ijg.0000000000002112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 07/19/2022] [Indexed: 02/04/2023]
Abstract
PRCIS Corneal hysteresis in both patients with untreated open angle glaucoma and normal individuals demonstrated significant diurnal variation independent of confounding factors and was higher in the nighttime than in the daytime. PURPOSE To investigate diurnal variations in corneal hysteresis (CH) in patients with untreated primary open angle glaucoma (POAG) and normal individuals by using an ocular response analyzer. MATERIALS AND METHODS This prospective study included 72 eyes of 53 patients with untreated POAG and 53 eyes of 47 normal individuals. Intraocular pressure (IOP) and CH were measured using Goldmann applanation tonometry (GAT) and ocular response analyzer, respectively, every 3 hours from 9:00 to 24:00. Mixed-effects models were used to determine factors associated with CH values and CH amplitude (maximum values minus minimum values) and to examine the diurnal variations in GAT IOP and CH in each group. Significant differences between time points were defined as significant variations. RESULTS The diurnal average GAT IOP and CH in patients with POAG were significantly higher and lower than those in normal individuals ( P =0.001, 0.002). In the multivariate analysis, the larger central corneal thickness was associated with larger CH values in POAG and normal eyes (both P <0.001). A larger amplitude of GAT IOP was significantly associated with a larger CH amplitude in POAG and normal eyes ( P =0.010, 0.013). CH, in both groups, showed similar significant diurnal variation and was higher in the nighttime than in the daytime, even after adjusting for confounding factors, while IOP showed an antiphase pattern. CONCLUSION CH in both untreated POAG patients and normal participants demonstrated similar diurnal variations, that is, higher at night, independent of confounding factors. These findings suggest that viscoelastic properties of the cornea may fluctuate diurnally independent of IOP.
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Díaz-Barreda MD, Sánchez-Marín I, Boned-Murillo A, Pérez-Navarro I, Martínez J, Pardina-Claver E, Pérez D, Ascaso FJ, Ibáñez J. Modification of Corneal Biomechanics and Intraocular Pressure Following Non-Penetrating Deep Sclerectomy. J Clin Med 2022; 11:jcm11051216. [PMID: 35268307 PMCID: PMC8911357 DOI: 10.3390/jcm11051216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/16/2022] [Accepted: 02/21/2022] [Indexed: 12/18/2022] Open
Abstract
Changes in the cornea can influence outcomes in patients with primary open-angle glaucoma (POAG). We aimed to evaluate the relevance of changes in corneal biomechanics and intraocular pressure (IOP) in patients undergoing non-penetrating deep sclerectomy (NPDS) with the Esnoper V2000 implant® (AJL Ophthalmic S.A., Gasteiz, Spain). We included 42 eyes of 42 patients with POAG scheduled for NPDS with the Esnoper V2000 implant. Biomechanical properties were measured by Ocular Response Analyzer® G3 (ORA; Reichert Inc., Depew, NY, USA). Corneal hysteresis (CH), corneal resistance factor (CRF), corneal compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg) were measured the day before surgery and on day 1, 7, and 30 and 2 and 3 months after surgery. CH initially increased, fell below the presurgical value at 30 days after the surgery, and increased again at 2 and 3 months. CRF, IOPcc, and IOPg decreased on the first day after surgery, then followed a trend of increasing but stayed below pre-surgery levels. All values reached statistical significance. While observed changes in corneal biomechanics after NPDS and Esnoper V2000 implant were significant, more studies are needed if we are to understand their influence on corneal biomechanics and their clinical relevance in POAG.
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Affiliation(s)
- María Dolores Díaz-Barreda
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
- Department of Surgery, School of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
- Correspondence: (M.D.D.-B.); (F.J.A.); Tel.: +34-629-863-827 (M.D.D.-B.); +34-686-574-389 (F.J.A.)
| | - Ignacio Sánchez-Marín
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
| | - Ana Boned-Murillo
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
- Department of Surgery, School of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
| | - Itziar Pérez-Navarro
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
| | - Juana Martínez
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
| | - Elena Pardina-Claver
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
| | - Diana Pérez
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
- Department of Surgery, School of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
| | - Francisco Javier Ascaso
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
- Department of Surgery, School of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
- Correspondence: (M.D.D.-B.); (F.J.A.); Tel.: +34-629-863-827 (M.D.D.-B.); +34-686-574-389 (F.J.A.)
| | - Juan Ibáñez
- Department of Ophthalmology, Hospital Clínico Universitario Lozano Blesa, 50009 Zaragoza, Spain; (I.S.-M.); (A.B.-M.); (I.P.-N.); (J.M.); (E.P.-C.); (D.P.); (J.I.)
- Department of Surgery, School of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
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Rojananuangnit K. Corneal Hysteresis in Thais and Variation of Corneal Hysteresis in Glaucoma. CLINICAL OPTOMETRY 2021; 13:287-299. [PMID: 34629920 PMCID: PMC8493478 DOI: 10.2147/opto.s324187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
PURPOSE To collect the normal value data of corneal hysteresis in Thais and study the variation of corneal hysteresis in glaucomatous eyes. METHODS Retrospective cross-sectional study of corneal hysteresis (CH) in healthy non-glaucomatous and glaucomatous eyes. Demographic data, type and staging of glaucoma, Goldmann applanation tonometry (GAT) and ocular response analyzer parameters; CH, corneal-compensated intraocular pressure (IOPcc) and Goldmann-correlated intraocular pressure (IOPg) were collected. RESULTS Data from one eye of 465 normal participants were included for the normal value data of CH. Mean CH, IOPcc and IOPg were 10.18 ± 1.48, 15.01 ± 3.04 and 14.16 ± 3.06 mmHg, respectively. Average age was 57.21 ± 14.4 years. CH at the fifth percentile was 8.0 mmHg. Women had significantly higher CH than men (10.29 ± 1.46 vs 9.90 ± 1.49 mmHg, p=0.009). Moderate negative correlation was found between age and CH, r = -0.338, p<0.001. There were 695 glaucomatous eyes from 429 patients including primary-open angle glaucoma (POAG), primary close-angle glaucoma (PACG), normal tension glaucoma (NTG) and ocular hypertension (OHT). CH in each glaucoma type and severity stage (early, moderate and severe) were as follows: POAG: 8.74 ± 1.52 mmHg (9.22 ± 1.47, 8.74 ± 1.23 and 7.92 ± 1.40 mmHg, p<0.001), PACG: 9.09 ± 1.72 mmHg (9.85 ± 1.45, 9.04 ± 1.68 and 8.45 ± 1.74 mmHg, p= 0.004), NTG: 9.55 ± 1.67 mmHg (9.47 ± 1.38, 9.75 ± 2.42 and 9.77 ± 1.34 mmHg, p 0.525) and OHT: 10.10 ± 1.40 mmHg. CONCLUSION Compared with normal value data of corneal hysteresis, CH in glaucomatous eyes was lower. The more advanced glaucoma stage was associated with lower CH. Arising from normal value data, a low percentile of CH could be applied as the deviation value from normal and this dynamic property of CH could represent a glaucoma predictor in an effort to improve glaucoma care.
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Affiliation(s)
- Kulawan Rojananuangnit
- Glaucoma Unit, Ophthalmology Department, Mettapracharak (Wat Rai Khing) Hospital, Nakhon Pathom, Thailand
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Razeghinejad MR, Farsiani AR, Salout R, Owji N, Masoumpour M, Kharmandar A, Zamani M. Corneal biomechanical properties in hyperthyroidism and thyroid eye disease. Saudi J Ophthalmol 2021; 34:251-255. [PMID: 34527867 PMCID: PMC8409357 DOI: 10.4103/1319-4534.322605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 04/21/2020] [Accepted: 07/06/2020] [Indexed: 11/17/2022] Open
Abstract
PURPOSE: The purpose of this study is to compare the corneal biomechanical properties of hyperthyroids without ophthalmopathy (HWO), thyroid eye disease (TED), and euthyroid participants. METHODS: In this prospective comparative study, one eye per patient included in the analysis and according to exclusion criteria, 38 eyes of 40 HWO patients, 31 eyes of 40 TED patients, and 150 eyes of 160 age- and sex-matched euthyroid participants were enrolled. All participants were evaluated by an endocrinologist and oculoplastic surgeon for evaluation of thyroid function and orbitopathy, respectively. Measurements of corneal biomechanical properties were performed using ocular response analyzer and Corvis ST tonometers. RESULTS: In the HWO group, applanation-1 length (A1 L), applanation-2 velocity (A2V) (P < 0.001), and corneal resistant factor (P = 0.043) were higher than the control group and corneal hysteresis (CH) was lower (P = 0.018). In the TED group, A1 L, A2V (P < 0.001), and highest concavity radius (HCR) (P = 0.027) were higher than the control group, and the CH (P = 0.007) and highest concavity deformation amplitude (HCDA) (P = 0.001) were lower. Furthermore, the level HCDA in the TED group was lower than HWO group (P = 0.011). The level of upper scleral show and palpebral fissure had a negative correlation with CH and HCDA. The amount of exophthalmos level had a positive correlation with HCR. CONCLUSION: Corneal biomechanical properties in the HWO and TED groups were different from the normal euthyroid individuals and may be taken into account in managing situation like glaucoma and refractive surgeries.
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Affiliation(s)
- M Reza Razeghinejad
- Poostchi Ophthalmology Research Center, Department of Ophthalmology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.,Glaucoma Research Center, Wills Eye Hospital, Philadelphia, PA, USA
| | - Amir R Farsiani
- Poostchi Ophthalmology Research Center, Department of Ophthalmology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.,Department of Ophthalmology, School of Medicine, Zanjan University of Medical sciences, Zanjan, Iran
| | - Ramin Salout
- Poostchi Ophthalmology Research Center, Department of Ophthalmology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.,Salouti Eye Research Center, Salouti Eye Clinic, Shiraz, Iran
| | - Naser Owji
- Poostchi Ophthalmology Research Center, Department of Ophthalmology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Masoumeh Masoumpour
- Poostchi Ophthalmology Research Center, Department of Ophthalmology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Alireza Kharmandar
- Endocrine and Metabolism Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Zamani
- Salouti Eye Research Center, Salouti Eye Clinic, Shiraz, Iran
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Lopes BT, Bao F, Wang J, Liu X, Wang L, Abass A, Eliasy A, Elsheikh A. Review of in-vivo characterisation of corneal biomechanics. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2021. [DOI: 10.1016/j.medntd.2021.100073] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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Wilson A, Marshall J. A review of corneal biomechanics: Mechanisms for measurement and the implications for refractive surgery. Indian J Ophthalmol 2021; 68:2679-2690. [PMID: 33229643 PMCID: PMC7856929 DOI: 10.4103/ijo.ijo_2146_20] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Detailed clinical assessment of corneal biomechanics has the potential to revolutionize the ophthalmic industry through enabling quicker and more proficient diagnosis of corneal disease, safer and more effective surgical treatments, and the provision of customized and optimized care. Despite these wide-ranging benefits, and an outstanding clinical need, the provision of technology capable of the assessment of corneal biomechanics in the clinic is still in its infancy. While laboratory-based technologies have progressed significantly over the past decade, there remain significant gaps in our knowledge regarding corneal biomechanics and how they relate to shape and function, and how they change in disease and after surgical intervention. Here, we discuss the importance, relevance, and challenges associated with the assessment of corneal biomechanics and review the techniques currently available and underdevelopment in both the laboratory and the clinic.
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Affiliation(s)
- Abby Wilson
- Wolfson School of Mechanical, Manufacturing and Electrical Engineering, Loughborough University, Loughborough, UK
| | - John Marshall
- Wolfson School of Mechanical, Manufacturing and Electrical Engineering, Loughborough University, Loughborough, UK
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Radhakrishnan H, Miranda MA, O'donnell C. Corneal biomechanical properties and their correlates with refractive error. Clin Exp Optom 2021; 95:12-8. [DOI: 10.1111/j.1444-0938.2011.00696.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Hema Radhakrishnan
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom, E‐mail:
| | - Marco A Miranda
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom, E‐mail:
| | - Clare O'donnell
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom, E‐mail:
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Palamar M, Dag MY, Yagci A. The effects of Valsalva manoeuvre on Ocular Response Analyzer measurements. Clin Exp Optom 2021; 98:447-50. [DOI: 10.1111/cxo.12303] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 11/28/2014] [Accepted: 02/03/2015] [Indexed: 12/01/2022] Open
Affiliation(s)
- Melis Palamar
- Department of Ophthalmology, Ege University Faculty of Medicine, Izmir, Turkey,
| | - Medine Yilmaz Dag
- Department of Ophthalmology, Ege University Faculty of Medicine, Izmir, Turkey,
| | - Ayse Yagci
- Department of Ophthalmology, Ege University Faculty of Medicine, Izmir, Turkey,
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Wong Y, Lam AK. Influence of corneal astigmatism, corneal curvature and meridional differences on corneal hysteresis and corneal resistance factor. Clin Exp Optom 2021; 94:418-24. [DOI: 10.1111/j.1444-0938.2011.00591.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Yin‐zhi Wong
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong SAR, China. E‐mail:
| | - Andrew Kc Lam
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong SAR, China. E‐mail:
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14
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Zhang H, Eliasy A, Lopes B, Abass A, Vinciguerra R, Vinciguerra P, Ambrósio R, Roberts CJ, Elsheikh A. Stress-Strain Index Map: A New Way to Represent Corneal Material Stiffness. Front Bioeng Biotechnol 2021; 9:640434. [PMID: 33777912 PMCID: PMC7991572 DOI: 10.3389/fbioe.2021.640434] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 02/11/2021] [Indexed: 11/23/2022] Open
Abstract
Purpose To introduce a new method to map the mechanical stiffness of healthy and keratoconic corneas. Methods Numerical modeling based on the finite element method was used to carry out inverse analysis of simulated healthy and keratoconic corneas to determine the regional variation of mechanical stiffness across the corneal surface based on established trends in collagen fibril distribution. The Stress–Strain Index (SSI), developed and validated in an earlier study and presented as a parameter that can estimate the overall stress–strain behavior of corneal tissue, was adopted in this research as a measure of corneal stiffness. The regional variation of SSI across the corneal surface was estimated using inverse analysis while referring to the common features of collagen fibrils’ distribution obtained from earlier x-ray scattering studies. Additionally, for keratoconic corneas, a method relating keratoconic cone features and cornea’s refractive power to the reduction in collagen fibril density inside the cone was implemented in the development of SSI maps. In addition to the simulated cases, the study also included two keratoconus cases, for which SSI maps were developed. Results SSI values varied slightly across corneal surface in the simulated healthy eyes. In contrast, both simulated and clinical keratoconic corneas demonstrated substantial reductions in SSI values inside the cone. These SSI reductions depended on the extent of the disease and increased with more considerable simulated losses in fibril density in the cone area. SSI values and their regional variation showed little change with changes in IOP, corneal thickness, and curvature. Conclusion SSI maps provide an estimation of the regional variation of biomechanical stiffness across the corneal surface. The maps could be particularly useful in keratoconic corneas, demonstrating the dependence of corneal biomechanical behavior on the tissue’s microstructure and offering a tool to fundamentally understand the mechanics of keratoconus progression in individual patients.
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Affiliation(s)
- Haixia Zhang
- School of Engineering, University of Liverpool, Liverpool, United Kingdom.,School of Biomedical Engineering, Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, China
| | - Ashkan Eliasy
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Bernardo Lopes
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Ahmed Abass
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, Liverpool, United Kingdom.,Department of Production Engineering and Mechanical Design, Faculty of Engineering, Port Said University, Port Fouad, Egypt
| | - Riccardo Vinciguerra
- Department of Ophthalmology, Humanitas San Pio X Hospital, Milan, Italy.,The School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Paolo Vinciguerra
- Humanitas Clinical and Research Center, IRCCS, Rozzano, Italy.,Department of Biomedical Sciences, Humanitas University, Milan, Italy
| | - Renato Ambrósio
- Department of Ophthalmology, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.,Department of Ophthalmology, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | - Cynthia J Roberts
- Department of Ophthalmology and Visual Sciences and Biomedical Engineering, The Ohio State University, Columbus, OH, United States
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, United Kingdom.,Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China.,NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust, UCL Institute of Ophthalmology, London, United Kingdom
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15
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Colakoglu A, Colakoglu IE, Cosar CB. Correlation between corneal thickness, keratometry, age, and differential pressure difference in healthy eyes. Sci Rep 2021; 11:4133. [PMID: 33603061 PMCID: PMC7893151 DOI: 10.1038/s41598-021-83683-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 02/03/2021] [Indexed: 01/31/2023] Open
Abstract
To determine the use of differential pressure difference (DPD), in air-puff differential tonometry, as a potential biomechanical measure of the cornea and elucidate its relationship with the intraocular pressure (IOP), central corneal thickness, corneal curvature, and age. This study comprised 396 eyes from 198 patients and was conducted at Acibadem University, School of Medicine, Department of Ophthalmology, Istanbul, Turkey. The central corneal curvature and refraction of the eyes were measured using an Auto Kerato-Refractometer (KR-1; Topcon Corporation, Tokyo, Japan). IOP and central corneal thickness were measured using a tono-pachymeter (CT-1P; Topcon Corporation, Tokyo, Japan), wherein two separate readings of IOP were obtained using two different modes: 1-30 and 1-60. The difference between these two readings was recorded as the DPD. The factors affecting the DPD were determined by stepwise multiple linear regression analysis. DPD varied over a dynamic range of - 3.0 to + 5.0 mmHg and was weakly correlated with the central corneal thickness (r = 0.115, p < 0.05). DPD showed no significant correlation with IOP 1-30 (p > 0.05). A weak but statistically significant (p < 0.05) positive correlation of DPD was observed with age (r = 0.123), Kavg (r = 0.102), and the CCT (r = 0.115). There was a significant correlation between DPD and Kavg, CCT, and age. There was no significant correlation between DPD and IOP 1-30. Age-related changes in the corneal ultrastructure may be a plausible explanation for the weak positive association between age and DPD. The proposed method may prove a valid non-invasive tool for the evaluation of corneal biomechanics and introduce DPD in the decision-making of routine clinical practice.
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Affiliation(s)
- Ahmet Colakoglu
- Department of Ophthalmology, Acibadem University School of Medicine, Icerenkoy, 34752, Istanbul, Turkey.
| | | | - Cemile Banu Cosar
- Department of Ophthalmology, Acibadem University School of Medicine, Icerenkoy, 34752, Istanbul, Turkey
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16
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Changes in Corneal Biomechanics and Glaucomatous Visual Field Loss. J Glaucoma 2021; 30:e246-e251. [PMID: 33596020 DOI: 10.1097/ijg.0000000000001819] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 01/25/2021] [Indexed: 11/25/2022]
Abstract
PRECIS A lower baseline corneal hysteresis and a decrease in corneal resistance factor (CRF) over time are associated with higher risk of visual field progression in glaucomatous and glaucoma suspect eyes. PURPOSE The aim was to investigate the longitudinal change in CRF and cornea hysteresis (CH) as risk factors for visual field progression. MATERIALS AND METHODS In this prospective observational cohort study, 72 eyes of 48 glaucoma or glaucoma suspect patients were followed for an average of 4.5 years. Baseline and follow-up CH and CRF measurements were performed with the Ocular Response Analyzer (Reichert Ophthalmic Instruments Inc., Depew, N.Y.). Evaluation of rates of visual field change during follow-up was performed using visual field mean deviation. Univariable and multivariable linear mixed models assessed the relationship of visual field progression with baseline CRF and CH as well as with changes in CRF and CH. RESULTS The mean baseline CH was 9.0 (95% confidence interval: 8.6-9.4) mm Hg and the mean baseline CRF was 9.3 (95% confidence interval: 8.8-9.9) mm Hg. There was no statistically significant difference in average CH and CRF measurements over time. In multivariable modeling adjusting for age, race, and mean intraocular pressure during follow-up, each 1 mm Hg lower in baseline CH and 1 mm Hg decrease in CRF over time were associated with a 0.12 (P=0.042) and 0.14 dB/year (P=0.007) faster rate of visual field mean deviation loss, respectively. Similar findings were found in glaucoma eyes but not found in glaucoma suspect eyes. CONCLUSION Visual field progression was associated with a lower baseline CH and a decrease in CRF over time. Assessment of corneal resistance and elasticity at baseline and during follow-up examinations should be considered to identify those eyes at highest risk of visual field progression.
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17
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Alahmadawy Y, Nossair A, Kassem M, Eltanamly R. Corneal hysteresis, central corneal thickness, and intraocular pressure in rheumatoid arthritis, and their relation to disease activity. Middle East Afr J Ophthalmol 2021; 28:174-179. [PMID: 35125800 PMCID: PMC8763098 DOI: 10.4103/meajo.meajo_434_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/30/2021] [Indexed: 11/25/2022] Open
Abstract
PURPOSE: To evaluate biomechanical properties, corneal thickness, and intraocular pressure (IOP) in patients with rheumatoid arthritis (RA) and correlate them with rheumatoid activity. PATIENTS AND METHODS: Forty RA eyes were enrolled in a cross-sectional study. Clinical Disease Activity Index (CDAI) was used to assess the rheumatoid activity by a rheumatologist. Corneal hysteresis (CH), corneal resistance factor (CRF), and IOP corneal compensated, IOP Goldmann corrected were assessed using ocular response analyzer (ORA), Corneal thickness was measured using optical coherence tomography, and IOP using Goldman applanation tonometer (IOP GAT). RESULTS: There was a positive correlation between CH and CRF (P < 0.001 and r = 0.818) and (P < 0.001 and r = 0.714) in the active and inactive groups respectively, also between CRF and central corneal thickness (CCT) (P value 0.05 and r = 0.0435) in Inactive Group only. No correlation was found between CDAI score and ORA parameters. There was a negative correlation between CDAI and CCT in Active Group only (P < 0.001 and r = −0.823). CONCLUSION: Corneal biomechanical properties could be affected in rheumatoid patients in both active and remission phases, which may indicate that any corneal changes may be irreversible. These changes are of important significance regarding IOP measurement in rheumatoid patients. CCT may be a new parameter in the follow up of disease activity.
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Feizi S, Karjou Z, Abbasi H, Javadi MA, Azari AA. Characterization of In Vivo Biomechanical Properties in Macular Corneal Dystrophy. Am J Ophthalmol 2020; 215:8-13. [PMID: 32205123 DOI: 10.1016/j.ajo.2020.03.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 02/29/2020] [Accepted: 03/05/2020] [Indexed: 12/24/2022]
Abstract
PURPOSE To measure and compare corneal biomechanics in patients with macular corneal dystrophy (MCD), versus those who underwent penetrating keratoplasty (PK) for MCD, versus normal subjects. DESIGN Cross-sectional study. METHODS This study enrolled 24 eyes with MCD, 25 eyes that underwent PK in patients with preoperative diagnosis of MCD, and 28 normal eyes. The ocular response analyzer was used to measure corneal biomechanical properties, including corneal resistance factor (CRF) and corneal hysteresis (CH). Intraocular pressure (IOP) was measured using a Goldmann applanation tonometer, and central corneal thickness (CCT) was measured using an ultrasonic pachymeter. The CCT, CRF, CH, and IOP were compared among the study group. RESULTS CCT was significantly lower in the MCD group (423 ± 47 mμ) than in the PK group (541 ± 31 mμ; P < .001) and the controls (540 ± 26 mμ; P < .001). Meanwhile, CCT was comparable between the PK and control groups (P = .98). CRF did not differ between the MCD (8.34 ± 2.12 mm Hg) and the PK (8.66 ± 1.66 mm Hg) groups (P = .89); however, both of these groups had lower CRF values than the control (9.76 ± 1.83 mm Hg, P = .02) group. No significant differences were observed among the 3 groups in CH (P = .13). IOP values did not differ between the MCD (11.25 ± 1.69 mm Hg) and PK (12.0 ± 2.67 mm Hg) groups (P = .95); however, the IOP values for both of these groups differed significantly from those of the controls (13.46 ± 2.17 mm Hg; P = .006). CONCLUSIONS CRF was significantly reduced in MCD and did not return to normal values even after PK. The reduced corneal rigidity could result in underestimating IOP in patients with MCD and in those undergoing PK for this stromal dystrophy.
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Affiliation(s)
- Sepehr Feizi
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Zahra Karjou
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hamed Abbasi
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Ali Javadi
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Amir A Azari
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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19
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Pandey N, Kaur Chhabra A. Evaluation of corneal biomechanical properties on ocular response analyzer and their correlation with the clinical profile of the patients with thyroid-associated ophthalmopathy. Orbit 2020; 40:193-198. [PMID: 32515628 DOI: 10.1080/01676830.2020.1772316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Purpose: The study evaluates the corneal biomechanical properties on Ocular Response Analyzer (ORA) and aims to establish their correlation with the clinical profile of patients with TAO.Methods: A tertiary care centre-based cross-sectional observational study was conducted. Eighty patients with stage I and II TAO (EUGOGO classification), categorized as group A, were age and sex matched with 85 controls constituting group B. The disease activity was assessed using clinical activity score (CAS). The thyroid hormonal profile of within one-week duration was recorded for each patient of group A. Mean IOP-GAT (IOP using Goldmann applanation tonometer), IOPg (Goldmann-correlated IOP value), IOPcc (cornea-compensated IOP value), CRF (corneal resistance factor), and mean corneal hysteresis (CH) of group A and B were compared. The variation of CH with disease severity, activity, and thyroid status in group A was evaluated.Results: Mean GAT, IOPg, and IOPcc of group A were significantly higher than that of group B (p < .001). Mean CH of group A i.e the visco-elastic dampening ability of cornea was significantly lower than that of group B (p < .001). In group A, mean CH of patients with stage 1 disease severity and CAS<3 was significantly higher than that of patients with stage 2 severity and CAS≥3 (p < .001). CH of hyperthyroid patients was significantly lower than CH of hypothyroid patients (p < .01).Conclusion: TAO affects the biomechanical properties of the globe as reflected by the corneal biomechanics on ORA. The disease severity, activity, and hyperthyroid status are negatively correlated with the CH.
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Affiliation(s)
- Nitika Pandey
- Department of Ophthalmology, King George's Medical University, Lucknow, India
| | - Apjit Kaur Chhabra
- Department of Ophthalmology, King George's Medical University, Lucknow, India
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20
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Can ME, Kızıltoprak H, Buluş AD, Özkoyuncu D, Koç M, Özdemir Yıldız Z. Corneal Biomechanical Properties in Childhood Obesity. J Pediatr Ophthalmol Strabismus 2020; 57:103-107. [PMID: 32203594 DOI: 10.3928/01913913-20200131-02] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 12/30/2019] [Indexed: 11/20/2022]
Abstract
PURPOSE To investigate corneal biomechanical properties in patients with childhood obesity. METHODS The study included 47 patients with childhood obesity (study group) and 39 healthy patients (control group). Corneal hysteresis, corneal resistance factor, corneal compensated intraocular pressure (IOPcc), and Goldmann-correlated IOP (IOPg) were measured with the Ocular Response Analyzer (Reichert, Ophthalmic Instruments, Buffalo, NY) in each eye. Central corneal thickness (CCT), anterior chamber angle (ACA), anterior chamber volume (ACV), and anterior chamber depth (ACD) measurements were obtained by the Pentacam rotating Scheimpflug camera (Oculus Optikgeräte GmBh, Wetzlar, Germany). RESULTS The mean corneal hysteresis was 10.56 ± 1.52 mm Hg in the study group and 11.16 ± 1.92 mm Hg in the control group (P = .022). The mean IOP was 14.9 ± 2.0 mm Hg in the study group and 14.1 ± 1.3 mm Hg in the control group (P = .003). Corneal hysteresis showed a significant, positive correlation with corneal resistance factor (P < .001, r = 0.851), IOPg (P = .044, r = 0.213), CCT (P < .001, r = 0.477), and IOP (P = .005, r = 0.295). Corneal hysteresis showed a significant, negative correlation with IOPcc (P = .001, r = -0.355), ACA (P = .005, r = -0.294), ACV (P = .019, r = -0.246), and ACD (P = .046, r = -0.211). CONCLUSIONS Patients with childhood obesity have lower corneal hysteresis and higher IOPcc measurements when compared with healthy patients. Corneal tissue changes may occur in early life in childhood obesity, which could lead to ocular disease in the future. [J Pediatr Ophthalmol Strabismus. 2020;57(2):103-107.].
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21
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Maczynska E, Rzeszewska-Zamiara J, Jimenez Villar A, Wojtkowski M, Kaluzny BJ, Grulkowski I. Air-Puff-Induced Dynamics of Ocular Components Measured with Optical Biometry. Invest Ophthalmol Vis Sci 2019; 60:1979-1986. [PMID: 31050724 DOI: 10.1167/iovs.19-26681] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To analyze the dynamics of all optical components of the eye and the behavior of the eyeball under air-puff conditions in vivo. To determine the impact of the intraocular pressure (IOP) on the air-puff-induced deformation of the eye. Methods Twenty eyes of 20 healthy subjects were included in this study. The dynamics of the ocular components, such as the cornea, the crystalline lens, and the retina, was measured by a prototype swept source optical coherence tomography biometer integrated with the air-puff system. The system allows to acquire a series of axial scans at the same location as a function of time with no transverse scanning. Several parameters were extracted from optical coherence tomography data. The IOP was measured using a Goldmann applanation tonometry. The measurements of the eyes were performed before and 2 hours after administration of IOP-reducing drops, namely, 0.2 % brimonidine tartrate. Results There is a statistically significant correlation of corneal thickness, vitreous depth, and eye length with IOP. The deformation amplitudes of the cornea and the crystalline lens are inversely proportional to the IOP, but statistical significance is achieved only for the cornea. The crystalline lens is displaced without compression, and the return has the form of wobbling. The reduction of IOP level induces corresponding changes in the extracted parameters. Conclusions Optical biometry combined with air puff provides comprehensive information on the in vivo behavior of all ocular components, including the crystalline lens. Measurement of the axial length dynamics of during deformation enables correcting the deformation for eye retraction.
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Affiliation(s)
- Ewa Maczynska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun, Poland
| | - Jagoda Rzeszewska-Zamiara
- Division of Ophthalmology and Optometry, Department of Ophthalmology, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Alfonso Jimenez Villar
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun, Poland
| | - Maciej Wojtkowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun, Poland.,Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Bartlomiej J Kaluzny
- Division of Ophthalmology and Optometry, Department of Ophthalmology, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Ireneusz Grulkowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun, Poland
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22
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Mayali H, Altinisik M, Sencan S, Pirildar T, Kurt E. A multimodal ophthalmic analysis in patients with systemic sclerosis using ocular response analyzer, corneal topography and specular microscopy. Int Ophthalmol 2019; 40:287-296. [PMID: 31564047 DOI: 10.1007/s10792-019-01173-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Accepted: 09/19/2019] [Indexed: 11/30/2022]
Abstract
PURPOSE To conduct a multimodal ophthalmic evaluation of systemic sclerosis (SSc) in patients using ocular response analyzer (ORA), Pentacam, and specular microscopy (SM). METHODS Thirty-one SSc patients and a group of age- and sex-matched controls were enrolled in this cross-sectional study. Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc), and Goldmann-correlated IOP (IOPg) were measured with ORA. Anterior chamber depth (ACD), central corneal thickness (CCT), and corneal volume (CV) measurements were obtained using Pentacam. Corneal endothelial cell density (ECD) and CCT were evaluated by SM. RESULTS SSc patients had significantly lower CH, ACD, and ECD values compared to the control group (p = 0.018; < 0.001; < 0.001, respectively). There was no significant difference regarding CRF, IOP, CV, or CCT measurements acquired by Pentacam and SM. Regarding CCT, SM and Pentacam showed relatively better agreement in SSc patients. CONCLUSIONS Multimodal imaging can provide more comprehensive and useful information regarding the ocular involvement of systemic diseases. The multimodal evaluation in our study demonstrated that the pathologic effects of SSc may manifest as reductions in ACD, corneal elasticity, and ECD before there are any detectable changes in corneal thickness or IOP.
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Affiliation(s)
- Huseyin Mayali
- Ophthalmology Department, Medical School, Manisa Celal Bayar University, Manisa, Turkey
| | - Muhammed Altinisik
- Ophthalmology Department, Medical School, Manisa Celal Bayar University, Manisa, Turkey.
| | - Secil Sencan
- Ophthalmology Department, Tinaztepe Hospital, Izmir, Turkey
| | - Timur Pirildar
- Ophthalmology Department, Medical School, Manisa Celal Bayar University, Manisa, Turkey
| | - Emin Kurt
- Ophthalmology Department, Medical School, Manisa Celal Bayar University, Manisa, Turkey
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Susanna BN, Ogata NG, Jammal AA, Susanna CN, Berchuck SI, Medeiros FA. Corneal Biomechanics and Visual Field Progression in Eyes with Seemingly Well-Controlled Intraocular Pressure. Ophthalmology 2019; 126:1640-1646. [PMID: 31519385 DOI: 10.1016/j.ophtha.2019.07.023] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 07/23/2019] [Accepted: 07/24/2019] [Indexed: 11/18/2022] Open
Abstract
PURPOSE To investigate the incidence and risk factors for glaucomatous visual field progression in eyes with well-controlled intraocular pressure (IOP). DESIGN Prospective cohort. PARTICIPANTS A total of 460 eyes of 334 patients with glaucoma under treatment. METHODS Study subjects had a mean follow-up of 4.3±0.8 years. Patients were classified as well controlled if all IOP measurements were less than 18 mmHg. Rates of visual field progression were calculated using ordinary least-squares linear regression of standard automated perimetry (SAP) mean deviation (MD) values over time. Progression was defined as a significantly negative MD slope (alpha = 0.05). MAIN OUTCOME MEASURES Rates of SAP MD change; mean and peak IOP, and IOP fluctuation; and corneal biomechanics: corneal hysteresis (CH), central corneal thickness (CCT), and corneal index. RESULTS Of the 179 eyes with well-controlled IOP, 42 (23.5%) demonstrated visual field progression. There was no significant difference between progressing and stable patients in baseline MD (-6.4±7.1 decibels [dB] vs. -6.0±6.2 dB; P = 0.346), mean IOP (11.7±2.0 mmHg vs. 12.1±2.3 mmHg; P = 0.405), IOP fluctuation (1.6±0.6 mmHg vs. 1.6±0.5 mmHg; P = 0.402), or peak IOP (14.3±1.9 mmHg vs. 14.6±2.1 mmHg; P = 0.926). Progressing eyes had significantly lower CH (8.6±1.3 mmHg vs. 9.4±1.6 mmHg; P = 0.014) and thinner CCT (515.1±33.1 μm vs. 531.1±42.4 μm; P = 0.018, respectively) compared with stable eyes. In the multivariate analysis, a 1 standard deviation lower corneal index, a summation of normalized versions of CH and CCT, resulted in a 68% higher risk of progression (odds ratio, 1.68; 95% confidence interval, 1.08-2.62; P = 0.021). CONCLUSIONS Approximately one-quarter of eyes with well-controlled IOP may show visual field progression over time. Thin cornea and low CH are main risk factors.
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Affiliation(s)
- Bianca N Susanna
- Duke Eye Center and Department of Ophthalmology, Duke University, Durham, North Carolina; ABC Foundation School of Medicine, Santo André, Brazil; Hamilton Glaucoma Center, University of California, San Diego, La Jolla, California
| | - Nara G Ogata
- Duke Eye Center and Department of Ophthalmology, Duke University, Durham, North Carolina
| | - Alessandro A Jammal
- Duke Eye Center and Department of Ophthalmology, Duke University, Durham, North Carolina
| | - Carolina N Susanna
- Duke Eye Center and Department of Ophthalmology, Duke University, Durham, North Carolina; ABC Foundation School of Medicine, Santo André, Brazil; Hamilton Glaucoma Center, University of California, San Diego, La Jolla, California
| | - Samuel I Berchuck
- Duke Eye Center and Department of Ophthalmology, Duke University, Durham, North Carolina; Department of Statistical Science and Forge, Duke University, Durham, North Carolina
| | - Felipe A Medeiros
- Duke Eye Center and Department of Ophthalmology, Duke University, Durham, North Carolina.
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24
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Zhang B, Shweikh Y, Khawaja AP, Gallacher J, Bauermeister S, Foster PJ. Associations with Corneal Hysteresis in a Population Cohort: Results from 96 010 UK Biobank Participants. Ophthalmology 2019; 126:1500-1510. [PMID: 31471087 DOI: 10.1016/j.ophtha.2019.06.029] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 06/07/2019] [Accepted: 06/28/2019] [Indexed: 11/16/2022] Open
Abstract
PURPOSE To describe the distribution of corneal hysteresis (CH) in a large cohort and explore its associated factors and possible clinical applications. DESIGN Cross-sectional study within the UK Biobank, a large cohort study in the United Kingdom. PARTICIPANTS We analyzed CH data from 93 345 eligible participants in the UK Biobank cohort, aged 40 to 69 years. METHODS All analyses were performed using left eye data. Linear regression models were used to evaluate associations between CH and demographic, lifestyle, ocular, and systemic variables. Piecewise logistic regression models were used to explore the relationship between self-reported glaucoma and CH. MAIN OUTCOME MEASURES Corneal hysteresis (mmHg). RESULTS The mean CH was 10.6 mmHg (10.4 mmHg in male and 10.8 mmHg in female participants). After adjusting for covariables, CH was significantly negatively associated with male sex, age, black ethnicity, self-reported glaucoma, diastolic blood pressure, and height. Corneal hysteresis was significantly positively associated with smoking, hyperopia, diabetes, systemic lupus erythematosus (SLE), greater deprivation (Townsend index), and Goldmann-correlated intraocular pressure (IOPg). Self-reported glaucoma and CH were significantly associated when CH was less than 10.1 mmHg (odds ratio, 0.86; 95% confidence interval, 0.79-0.94 per mmHg CH increase) after adjusting for covariables. When CH exceeded 10.1 mmHg, there was no significant association between CH and self-reported glaucoma. CONCLUSIONS In our analyses, CH was significantly associated with factors including age, sex, and ethnicity, which should be taken into account when interpreting CH values. In our cohort, lower CH was significantly associated with a higher prevalence of self-reported glaucoma when CH was less than 10.1 mmHg. Corneal hysteresis may serve as a biomarker aiding glaucoma case detection.
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Affiliation(s)
- Bing Zhang
- Department of Psychiatry, University of Oxford, Oxford, United Kingdom
| | - Yusrah Shweikh
- National Institute for Health Research Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom; UCL Institute of Ophthalmology, London, United Kingdom
| | - Anthony P Khawaja
- National Institute for Health Research Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom; UCL Institute of Ophthalmology, London, United Kingdom
| | - John Gallacher
- Department of Psychiatry, University of Oxford, Oxford, United Kingdom
| | | | - Paul J Foster
- National Institute for Health Research Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom; UCL Institute of Ophthalmology, London, United Kingdom.
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Jiménez-villar A, Mączyńska E, Cichański A, Wojtkowski M, Kałużny BJ, Grulkowski I. High-speed OCT-based ocular biometer combined with an air-puff system for determination of induced retraction-free eye dynamics. BIOMEDICAL OPTICS EXPRESS 2019; 10:3663-3680. [PMID: 31467798 PMCID: PMC6706022 DOI: 10.1364/boe.10.003663] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 06/16/2019] [Accepted: 06/16/2019] [Indexed: 05/20/2023]
Abstract
We demonstrate a swept source OCT-based ocular biometer integrated with an air-puff stimulus to study the reaction of the eye to mechanical stimulation in vivo. The system enables simultaneous measurement of the stimulus strength and high-speed imaging of the eye dynamics along the visual axis. We characterize the stimulus and perform optimization of the data acquisition for a proper interpretation of the results. Access to the dynamics of axial eye length allows for a determination of the eye retraction, which is used to correct the air-puff induced displacement of ocular structures. We define the parameters to quantify the reaction of the eye to the air puff and determine their reproducibility in a group of healthy subjects. We observe the corneal deformation process and axial wobbling of the crystalline lens. OCT biometer combined with the air puff is the first instrument with the potential to provide comprehensive information on the biomechanics of ocular components.
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Affiliation(s)
- Alfonso Jiménez-villar
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, ul. Grudziądzka 5, 87-100 Toruń, Poland
| | - Ewa Mączyńska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, ul. Grudziądzka 5, 87-100 Toruń, Poland
| | - Artur Cichański
- Institute of Mechanics and Machine Design, Faculty of Mechanical Engineering, UTP University of Science and Technology, Al. Prof. S. Kaliskiego 7, 85-796 Bydgoszcz, Poland
| | - Maciej Wojtkowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, ul. Grudziądzka 5, 87-100 Toruń, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Bartłomiej J. Kałużny
- Division of Ophthalmology and Optometry, Department of Ophthalmology, Collegium Medicum, Nicolaus Copernicus University, ul. Ujejskiego 75, 85-168 Bydgoszcz, Poland
| | - Ireneusz Grulkowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, ul. Grudziądzka 5, 87-100 Toruń, Poland
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Ivarsdottir EV, Benonisdottir S, Thorleifsson G, Sulem P, Oddsson A, Styrkarsdottir U, Kristmundsdottir S, Arnadottir GA, Thorgeirsson G, Jonsdottir I, Zoega GM, Thorsteinsdottir U, Gudbjartsson DF, Jonasson F, Holm H, Stefansson K. Sequence variation at ANAPC1 accounts for 24% of the variability in corneal endothelial cell density. Nat Commun 2019; 10:1284. [PMID: 30894546 PMCID: PMC6427039 DOI: 10.1038/s41467-019-09304-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 02/28/2019] [Indexed: 12/20/2022] Open
Abstract
The corneal endothelium is vital for transparency and proper hydration of the cornea. Here, we conduct a genome-wide association study of corneal endothelial cell density (cells/mm2), coefficient of cell size variation (CV), percentage of hexagonal cells (HEX) and central corneal thickness (CCT) in 6,125 Icelanders and find associations at 10 loci, including 7 novel. We assess the effects of these variants on various ocular biomechanics such as corneal hysteresis (CH), as well as eye diseases such as glaucoma and corneal dystrophies. Most notably, an intergenic variant close to ANAPC1 (rs78658973[A], frequency = 28.3%) strongly associates with decreased cell density and accounts for 24% of the population variance in cell density (β = -0.77 SD, P = 1.8 × 10-314) and associates with increased CH (β = 0.19 SD, P = 2.6 × 10-19) without affecting risk of corneal diseases and glaucoma. Our findings indicate that despite correlations between cell density and eye diseases, low cell density does not increase the risk of disease.
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Affiliation(s)
- Erna V Ivarsdottir
- deCODE genetics/Amgen, Reykjavik, Iceland
- School of Engineering and Natural Sciences, University of Iceland, Reykjavik, Iceland
| | | | | | | | | | | | | | | | - Gudmundur Thorgeirsson
- deCODE genetics/Amgen, Reykjavik, Iceland
- Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland
- Division of Cardiology, Department of Internal Medicine, Landspitali, The National University Hospital of Iceland, Reykjavik, Iceland
| | - Ingileif Jonsdottir
- deCODE genetics/Amgen, Reykjavik, Iceland
- Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland
- Department of Immunology, Landspitali, The National University Hospital of Iceland, Reykjavik, Iceland
| | - Gunnar M Zoega
- Department of Ophthalmology, Landspitali, The National University Hospital of Iceland, Reykjavik, Iceland
| | - Unnur Thorsteinsdottir
- deCODE genetics/Amgen, Reykjavik, Iceland
- Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland
| | - Daniel F Gudbjartsson
- deCODE genetics/Amgen, Reykjavik, Iceland
- School of Engineering and Natural Sciences, University of Iceland, Reykjavik, Iceland
| | - Fridbert Jonasson
- Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland
- Department of Ophthalmology, Landspitali, The National University Hospital of Iceland, Reykjavik, Iceland
| | - Hilma Holm
- deCODE genetics/Amgen, Reykjavik, Iceland.
| | - Kari Stefansson
- deCODE genetics/Amgen, Reykjavik, Iceland.
- Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland.
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Changes in Corneal Wound Healing and Graft Biomechanics After Primary Penetrating Keratoplasty Versus Repeat Penetrating Keratoplasty. Cornea 2019; 38:1006-1010. [DOI: 10.1097/ico.0000000000001928] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Wan K, Cheung SW, Wolffsohn JS, Orr JB, Cho P. Role of corneal biomechanical properties in predicting of speed of myopic progression in children wearing orthokeratology lenses or single-vision spectacles. BMJ Open Ophthalmol 2018; 3:e000204. [PMID: 30687783 PMCID: PMC6326267 DOI: 10.1136/bmjophth-2018-000204] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Objective To determine the characteristics of children who were likely to progress rapidly and gain the greatest benefit from orthokeratology (ortho-k) treatment. Methods and analysis The files of 113 children who participated in two myopia control studies and wore either ortho-k lenses (n=62) or single-vision spectacles (SVS) (n=51) were reviewed. Baseline cycloplegic subjective refraction, central corneal thickness, axial length, keratometry, intraocular pressure, corneal biomechanical properties and 24-month axial length data were retrieved and analysed. Results Multivariate analysis showed that there was significant negative correlation between axial elongation and baseline age and corneal hysteresis (p<0.05) in the SVS group. In the ortho-k group, only baseline age was significantly and negatively associated with axial elongation (p<0.01). Conclusion Corneal biomechanical properties and baseline age can predict the rate of axial elongation in myopic children. It may be beneficial for younger myopic children with low corneal hysteresis to commence ortho-k treatment as early as possible.
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Affiliation(s)
- Kin Wan
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
| | - Sin Wan Cheung
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
| | - James S Wolffsohn
- School of Life and Health Sciences, Aston University, Birmingham, UK
| | - Janis B Orr
- School of Life and Health Sciences, Aston University, Birmingham, UK
| | - Pauline Cho
- School of Optometry, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
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Bueno-Gimeno I, Martínez-Albert N, Gené-Sampedro A, España-Gregori E. Anterior Segment Biometry and Their Correlation with Corneal Biomechanics in Caucasian Children. Curr Eye Res 2018; 44:118-124. [PMID: 30346843 DOI: 10.1080/02713683.2018.1539181] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
PURPOSE To assess the relationship between the corneal biomechanical parameters and the anterior segment parameters in Caucasian children. METHODS This study included 293 eyes from 293 healthy children aged between 6 and 17 years. Corneal hysteresis (CH) and corneal resistance factor (CRF) were evaluated with the Ocular Response Analyzer, axial length (AL) with IOLMaster and the anterior segment with Pentacam. Anterior segment parameters obtained were the following: central corneal thickness (CCT), corneal volume (CV), anterior chamber depth (ACD), anterior chamber volume (ACV) and mean anterior and posterior keratometry. Two multiple linear regression models were constructed to assess the association between CH and CRF with anterior segment parameters. A value of p < 0.05 was taken as the criterion for statistical significance in all analyses. RESULTS The mean CH and CRF were 12.12 ± 1.71 and 12.30 ± 1.89 mmHg, respectively. Multiple linear regression revealed that CH and CRF were associated negatively with AL in both models, and positively with CCT and CV in the first and second model, respectively. Meanwhile ACD, ACV or mean keratometry did not correlated with CH and CRF. Moreover, when CCT was in the model, it explained more variability for both CH (22.1%) and CRF (30.9%) than when CV was included (16.2% for CH and 16.5% for CRF). CONCLUSIONS CH and CRF were correlated positively with CCT and CV, and negatively with AL in healthy Caucasian children. Moreover, corneal parameters were the most contributory variables to CH and CRF changes.
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Affiliation(s)
| | - Noelia Martínez-Albert
- a Department of Optics and Optometry and Vision Sciences , University of Valencia , Spain
| | - Andrés Gené-Sampedro
- a Department of Optics and Optometry and Vision Sciences , University of Valencia , Spain
| | - Enrique España-Gregori
- b Department of Surgery , University of Valencia , Spain.,c University Hospital La Fe , Spain
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Küçümen RB, Şahan B, Yıldırım CA, Çiftçi F. Evaluation of Corneal Biomechanical Changes After Collagen Crosslinking in Patients with Progressive Keratoconus by Ocular Response Analyzer. Turk J Ophthalmol 2018; 48:160-165. [PMID: 30202610 PMCID: PMC6126096 DOI: 10.4274/tjo.56750] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 10/31/2016] [Indexed: 12/01/2022] Open
Abstract
Objectives: To evaluate corneal biomechanics before and after collagen crosslinking (CXL) in patients with progressive keratoconus. Materials and Methods: In this prospective study, CXL was performed under topical anesthesia after removal of the epithelium (epi-off technique) by applying ultraviolet A (UVA) light at a wavelength of 365 nm and power of 3 mW/cm2 or 5.4 joule/cm2. Isoosmolar 0.1% riboflavin solution was administered before and during UVA irradiation. In addition to ophthalmologic examination, ocular response analyzer measurements were performed pre- and postoperatively. Corneal hysteresis (CH), corneal resistance factor (CRF), corneal compensated intraocular pressure (IOPcc), Goldmann-correlated intraocular pressure (IOPg), and central corneal thickness (CCT) were recorded. Results: The study included 35 eyes of 30 patients with progressive keratoconus. The mean age was 28.2±6.5 years and postoperative follow-up time was 20.2±14.7 months (range: 6-74 months). The mean CH was 8.60±1.23 mmHg preoperatively, 8.96±2.05 mmHg in the early postoperative period (1-6 months), (p=0.28) and 8.96±1.28 mmHg in the late postoperative period (10-29 months) (p=0.48). Mean CRF was 7.13±1.50 mmHg preoperatively, 8.48±2.16 mmHg in the early postoperative period (p=0.009), and 7.71±1.29 mmHg in the late postoperative period (p=0.40). Mean IOPcc was 12.78±2.34 mmHg preoperatively, 15.38±4.21 mmHg in the early postoperative period (p=0.12) and 13.68±3.61 mmHg in the late postoperative period (p=0.48). Mean IOPg was 9.56±2.73 mmHg preoperatively, 13.01±4.45 mmHg in the early postoperative period (p=0.046), and 10.86±3.47 mmHg in the late postoperative period (p=0.44). Mean CCT was 484.43±41.26 µm preoperatively, 474.16±64.74 µm in the early postoperative period (p=0.70), and 470.38±33.64 µm in late postoperative period (p=0.71). Conclusion: CXL is a treatment modality believed to affect corneal biomechanics in keratoconus, but the results of larger patient series with longer follow-up periods may enable a better evaluation.
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Affiliation(s)
- Raciha Beril Küçümen
- Yeditepe University Faculty of Medicine, Department of Ophthalmology, İstanbul, Turkey
| | - Berna Şahan
- Yeditepe University Faculty of Medicine, Department of Ophthalmology, İstanbul, Turkey
| | - Canan Aslı Yıldırım
- Dokuz Eylül University Faculty of Medicine, Department of Ophthalmology, İzmir, Turkey
| | - Ferda Çiftçi
- Yeditepe University Faculty of Medicine, Department of Ophthalmology, İstanbul, Turkey
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Gobeka H, Barut Selver Ö, Palamar Onay M, Eğrilmez S, Yağcı A. Corneal Biomechanical Properties of Keratoconic Eyes Following Penetrating Keratoplasty. Turk J Ophthalmol 2018; 48:171-177. [PMID: 30202612 PMCID: PMC6126104 DOI: 10.4274/tjo.79664] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 01/03/2018] [Indexed: 12/01/2022] Open
Abstract
Objectives To investigate the corneal biomechanical properties of keratoconic eyes following penetrating keratoplasty (PKP). Materials and Methods Thirty-five patients (70 eyes) were enrolled to this prospective study. Operated and contralateral keratoconic eyes were defined as Group 1 and 2, respectively. All patients underwent ophthalmological examination and measurements of corneal biomechanical properties by Ocular Response Analyzer (ORA), intraocular pressure (IOP) by Goldmann applanation tonometry, and central corneal thickness (CCT) by Pentacam. Shapiro-Wilk W test was performed to test normality of the data. The statistical significance was evaluated with the paired t-test and Wilcoxon signed ranks test. Pearson correlation and Spearman rho tests were used for correlation analysis. Results The average age and male/female ratio were 31.34±11.65 (15-60) years and 21/14, respectively. The mean values of the data obtained from Group 1 and 2 respectively were: corneal hysteresis (CH): 9.35±1.66, 8.18±1.84 mmHg (p=0.013), corneal resistance factor (CRF): 9.48±1.96, 7.14±2.05 mmHg (p<0.001), IOPcc: 16.90±4.32, 14.26±3.69 mmHg (p=0.004), IOPg: 15.45±4.61, 10.91±3.97 mmHg (p<0.001), IOPapl: 14.26±3.11, 13.09±2.54 mmHg (p=0.046), and central corneal thickness (CCT): 545.64±60.82, 442.60±68.14 μM (p<0.001). The positive correlation between CH and CRF was moderate (r=0.444) in Group 1 and strong (r=0.770) in Group 2. There was a moderate negative correlation between CH and IOPcc in both groups (r=-0.426, r=-0.423), but CH was not correlated with IOPg or IOPapl in either group. There were weak to strong positive correlations between CRF and all IOP values in both groups. There was no correlation between CRF and CCT in Group 1 (r=0.075) and a very weak correlation in Group 2 (r=0.237). Only IOPcc and IOPg were strongly correlated in both groups. Conclusion Better understanding of corneal biomechanical properties is essential for elucidating the pathophysiology and diagnosis of several corneal pathologies such as keratoconus. The biomechanical properties of keratoconic eyes seem to be closer to normal values after PKP.
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Affiliation(s)
- Hamidu Gobeka
- Ege University Faculty of Medicine, Department of Ophthalmology, İzmir, Turkey
| | - Özlem Barut Selver
- Ege University Faculty of Medicine, Department of Ophthalmology, İzmir, Turkey
| | - Melis Palamar Onay
- Ege University Faculty of Medicine, Department of Ophthalmology, İzmir, Turkey
| | - Sait Eğrilmez
- Ege University Faculty of Medicine, Department of Ophthalmology, İzmir, Turkey
| | - Ayşe Yağcı
- Ege University Faculty of Medicine, Department of Ophthalmology, İzmir, Turkey
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Damgaard IB, Reffat M, Hjortdal J. Review of Corneal Biomechanical Properties Following LASIK and SMILE for Myopia and Myopic Astigmatism. Open Ophthalmol J 2018; 12:164-174. [PMID: 30123381 PMCID: PMC6062908 DOI: 10.2174/1874364101812010164] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/08/2018] [Accepted: 01/20/2018] [Indexed: 11/22/2022] Open
Abstract
Worldwide, femtosecond Laser Assisted In-situ Keratomileusis (LASIK) is a well known and commonly used refractive technique, although Small Incision Lenticule Extraction (SMILE) has become increasingly popular since it was introduced in 2011. In LASIK, a corneal flap is cut with a microkeratome or femtosecond laser, followed by thinning of the stromal bed with excimer laser ablation. In SMILE, a minor intrastromal lenticule is cut with a femtosecond laser and subsequently removed through a small incision, leaving the anterior and strongest part of the cornea almost intact. Both LASIK and SMILE require cutting of corneal lamellae that may reduce the biomechanical stability of the cornea, with the potential risk of corneal iatrogenic ectasia as a severe complication. However, SMILE preserves the anterior corneal integrity and may, in theory, better preserve the corneal biomechanical strength than LASIK after surgery. A review aimed to examine the current literature that describes and compares the corneal biomechanical properties after Laser Assisted In-situ Keratomileusis (LASIK) and Small Incision Lenticule Extraction (SMILE). A comprehensive search was performed in Pubmed.gov using the following search queries: Corneal biomechanical properties, corneal biomechanics, ocular response analyser, ocular response analyzer, ORA, ex vivo, in vitro, Corvis, Corvis ST, LASIK, and SMILE.
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Affiliation(s)
- Iben Bach Damgaard
- Department of Ophthalmology, Aarhus University Hospital, Aarhus, Denmark
| | | | - Jesper Hjortdal
- Department of Ophthalmology, Aarhus University Hospital, Aarhus, Denmark
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Palamar M, Onay H, Atik T, Güven Yilmaz S, Özkınay F. Akondroplazi olgularında ön segment ve kornea biyomekaniği. EGE TIP DERGISI 2018. [DOI: 10.19161/etd.414705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Corneal Biomechanical Properties in Children with Diabetes Mellitus. Eur J Ophthalmol 2018; 23:27 - 32. [DOI: 10.5301/ejo.5000196] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/26/2012] [Indexed: 11/20/2022]
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Biomechanical Properties of Axially Myopic Cornea. Eur J Ophthalmol 2018; 22 Suppl 7:S24-8. [DOI: 10.5301/ejo.5000010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2011] [Indexed: 11/20/2022]
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Corneal Biomechanical Properties and Central Corneal Thickness in Pediatric Noninfectious Uveitis: A Controlled Study. Eye Contact Lens 2017; 44 Suppl 2:S60-S64. [PMID: 29283900 DOI: 10.1097/icl.0000000000000465] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To compare the corneal biomechanics, intraocular pressure (IOP), and central corneal thickness (CCT) of 37 patients with pediatric noninfectious uveitis with 36 healthy children. METHODS Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated and corneal-compensated IOP (IOPg and IOPcc, respectively), and CCT were measured. RESULTS The mean CRF was significantly lower in the pediatric uveitic eyes than controls (9.7±1.9 vs. 10.8±1.5 mm Hg, P=0.009), whereas there was no significant difference for mean CH, IOPg, IOPcc, and CCT between the two groups (10.1±1.9 vs. 10.8±1.7, 12.9±3.3 vs. 13.9±3.1, 13.8±2.8 vs. 13.6±3.2 mm Hg, and 550.7±49.5 vs. 555.1±33.5 μm, respectively, all P>0.05). The CCT values correlated with CH and CRF, with a Pearson correlation of 0.511 and 0.670 (P=0.013 and P<0.001, respectively), whereas disease duration did not correlate with any corneal biomechanics or CCT in pediatric uveitic eyes (all P>0.05). CONCLUSIONS Pediatric noninfectious uveitic eyes have lower CRF than controls but the CH, IOPg, IOPcc, and CCT values are similar.
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Kim HJ, Seo YH, Kim BH. New intraocular pressure measurement method using reflected pneumatic pressure from cornea deformed by air puff of ring-type nozzle. PLoS One 2017; 12:e0186738. [PMID: 29216189 PMCID: PMC5720722 DOI: 10.1371/journal.pone.0186738] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 10/08/2017] [Indexed: 11/18/2022] Open
Abstract
In this study, a non-contact type intraocular pressure (IOP) measuring system using reflected pneumatic pressure is proposed to overcome the disadvantages of existing measurement systems. A ring-type nozzle, a key component in the proposed system, is designed via computational fluid analysis. It predicts the reflected pneumatic pressure based on the nozzle exit angle and inner and outer diameters of the nozzle, which are 30°, 7 mm, and 9 mm, respectively. Performance evaluation is conducted using artificial eyes fabricated using polydimethylsiloxane with the specifications of human eyes. The IOP of the fabricated artificial eyes is adjusted to 10, 30, and 50 mm Hg, and the reflected pneumatic pressure is measured as a function of the distance between the ring-type nozzle and artificial eye. The measured reflected pneumatic pressure is high when the measurement distance is short and eye pressure is low. The cornea of an artificial eye is significantly deformed at a low IOP, and the applied pneumatic pressure is more concentrated in front of the ring-type nozzle because of the deformed cornea. Thus, the reflected pneumatic pressure at a low IOP has more inflows into the pressure sensor inserted inside the nozzle. The sensitivity of the output based on the IOP at measurement distances between 3-5 mm is -0.0027, -0.0022, -0.0018, -0.0015, and -0.0012. Sensitivity decreases as the measurement distance increases. In addition, the reflected pneumatic pressure owing to the misalignment at the measurement distances of 3-5 mm is not affected within a range of 0.5 mm. Therefore, the measurement range is acceptable up to a 1 mm diameter from the center of an artificial eye. However, the accuracy gradually decreases as the reflected pneumatic pressure from a misalignment of 1 mm or more decreases by 26% or more.
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Affiliation(s)
- Hyung Jin Kim
- Department of Mechanical and Mechatronics Engineering, Kangwon National University, Chuncheon, Republic of Korea
| | - Yeong Ho Seo
- Department of Mechanical and Mechatronics Engineering, Kangwon National University, Chuncheon, Republic of Korea
| | - Byeong Hee Kim
- Department of Mechanical and Mechatronics Engineering, Kangwon National University, Chuncheon, Republic of Korea
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Goussous IA, El-Agha MS, Awadein A, Hosny MH, Ghaith AA, Khattab AL. The effect of flap thickness on corneal biomechanics after myopic laser in situ keratomileusis using the M-2 microkeratome. Clin Ophthalmol 2017; 11:2065-2071. [PMID: 29200820 PMCID: PMC5701557 DOI: 10.2147/opth.s148216] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Purpose The purpose of this study was to determine the effect of flap thickness on corneal biomechanics after myopic laser in situ keratomileusis (LASIK). Methods This is a prospective controlled non-randomized, institutional study. Patients underwent either epi-LASIK with mitomycin (advanced surface ablation [ASA]), thin-flap LASIK (90 µm head), or thick-flap LASIK (130 µm head). In ASA, the Moria Epi-K hydroseparator was used. LASIK flaps were created using the Moria M-2 mechanical microkeratome. The corneal hysteresis (CH) and corneal resistance factor (CRF) were measured preoperatively and 3 months after surgery, using the Ocular Response Analyzer®. Results Ten patients (19 eyes) underwent ASA, 11 patients (16 eyes) underwent thin-flap LASIK, and 11 patients (16 eyes) underwent thick-flap LASIK. The mean preoperative CH was 10.47±0.88, 10.52±1.4, and 11.28±1.4 mmHg (p=0.043), respectively, decreasing after surgery by 1.75±1.02, 1.66±1.00, and 2.62±1.03 mmHg (p=0.017). The mean reduction of CH per micron of central corneal ablation was 0.031, 0.023, and 0.049 mmHg/µm (p=0.005). Mean preoperative CRF was 10.11±1.28, 10.34±1.87, and 10.62±1.76 mmHg (p=0.66), decreasing after surgery by 2.33±1.35, 2.77±1.03, and 2.92±1.10 mmHg (p=0.308). The mean reduction of CRF per micron of central corneal ablation was 0.039, 0.040, and 0.051 mmHg/µm (p=0.112). Conclusion Thick-flap LASIK caused a greater reduction of CH and CRF than thin-flap LASIK and ASA, although this was statistically significant only for CH. ASA and thin-flap LASIK were found to be biomechanically similar.
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Affiliation(s)
- Iyad A Goussous
- Department of Ophthalmology, Faculty of Medicine, Cairo University, Cairo
| | | | - Ahmed Awadein
- Department of Ophthalmology, Faculty of Medicine, Cairo University, Cairo
| | - Mohamed H Hosny
- Department of Ophthalmology, Faculty of Medicine, Cairo University, Cairo
| | - Alaa A Ghaith
- Faculty of Medicine, Alexandria University, Alexandria, Egypt
| | - Ahmed L Khattab
- Faculty of Medicine, Alexandria University, Alexandria, Egypt
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Estimation of the Corneal Young's Modulus In Vivo Based on a Fluid-Filled Spherical-Shell Model with Scheimpflug Imaging. J Ophthalmol 2017; 2017:5410143. [PMID: 29250440 PMCID: PMC5698833 DOI: 10.1155/2017/5410143] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 07/19/2017] [Accepted: 08/01/2017] [Indexed: 11/23/2022] Open
Abstract
Current intraocular pressure (IOP) measurement using air puff could be erroneous without applying proper corrections. Although noncontact tonometry is not considered to be accurate, it is still popularly used by eye clinics. It is thus necessary to extract the correct information from their results. This study proposes a practical approach to correctly measure IOP in vivo. By embedding a new model-based correction to the Corvis® ST, we can extract the corneal Young's modulus from the patient data. This Young's modulus can be used to correct the IOP readings. The tests were applied to 536 right eyes of 536 healthy subjects (228 male and 308 female) between March of 2012 and April of 2016. The tests were applied to patients at the Department of Ophthalmology, National Taiwan University Hospital and the Hung-Chuo Eye Clinics. The statistical analysis showed that the value for the Young's modulus was independent of all the other parameters collected from the Corvis ST, including the corneal thickness and the intraocular pressure. Therefore, it is important to independently measure the Young's modulus instead of depending on the correlation with the other parameters. This study adds the methodology of measuring corneal stiffness in vivo for ophthalmologists' reference in diagnosis.
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Celebi ARC, Kilavuzoglu AE, Altiparmak UE, Cosar Yurteri CB. Age-related change in corneal biomechanical parameters in a healthy Caucasian population. Ophthalmic Epidemiol 2017; 25:55-62. [PMID: 28891725 DOI: 10.1080/09286586.2017.1351997] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE To determine the effect of aging on corneal biomechanical parameters measured via ocular response analyzer in a homogenous healthy Caucasian population. METHODS A total of 2039 Caucasian adults were consecutively recruited and divided into seven groups according to decades of age. The difference in mean corneal hysteresis (CH), mean corneal resistance factor (CRF), mean Goldmann-correlated intraocular pressure (IOPg), and mean corneal-compensated IOP (IOPcc) between decades of age were investigated. The strength of the correlations between corneal biomechanical parameters, and between each biomechanical parameter and age were evaluated. The effect of age on each corneal biomechanical parameter was analyzed. RESULTS Mean age of the participants (1173 female and 866 male) was 43.30 ± 14.64 years. Mean CH, CRF, IOPcc, and IOPg were 11.49 ± 1.89 mmHg, 11.40 ± 2.30 mmHg, 15.01 ± 3.11 mmHg, and 15.72 ± 3.80 mmHg, respectively. There were significant differences in mean CH, CRF, IOPcc, and IOPg between groups (p < 0.001 for all parameters). There was a significant negative correlation between age and CH (r = -0.067 and p = 0.003), and a significant negative correlation between age and CRF (r = -0.053 and p = 0.017). There was a significant positive correlation between age and IOPg (r = 0.25 and p < 0.001), and between age and IOPcc (r = 0.20 and p < 0.001). Linear regression analysis showed that for every 1-year increase CH decreased 0.011 mmHg, CRF decreased 0.004 mmHg, IOPcc increased 0.053 mmHg, and IOPg increased 0.047 mmHg. CONCLUSIONS Aging can cause significant changes in corneal biomechanical parameters. Corneal biomechanical parameters were correlated with each other, and each was correlated with aging.
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Affiliation(s)
- Ali Riza Cenk Celebi
- a Acibadem University School of Medicine , Department of Ophthalmology , Istanbul , Turkey
| | - Ayse Ebru Kilavuzoglu
- a Acibadem University School of Medicine , Department of Ophthalmology , Istanbul , Turkey
| | - Ugur Emrah Altiparmak
- a Acibadem University School of Medicine , Department of Ophthalmology , Istanbul , Turkey
| | - C Banu Cosar Yurteri
- a Acibadem University School of Medicine , Department of Ophthalmology , Istanbul , Turkey
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Wu N, Christenbury JG, Dishler JG, Bozkurt TK, Duel D, Zhang L, Hamilton DR. A Technique to Reduce Incidence of Opaque Bubble Layer Formation During LASIK Flap Creation Using the VisuMax Femtosecond Laser. J Refract Surg 2017; 33:584-590. [DOI: 10.3928/1081597x-20170621-06] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 06/07/2017] [Indexed: 11/20/2022]
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Can Corneal Biomechanical Properties Give Clues About Elasticity of Optic Nerve Scleral Component in Nonarteritic Anterior Ischemic Optic Neuropathy? J Neuroophthalmol 2017; 36:285-9. [PMID: 27389626 DOI: 10.1097/wno.0000000000000406] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To investigate corneal biomechanical properties among individuals with unilateral nonarteritic anterior ischemic optic neuropathy (NAION) compared to healthy gender- and age-matched subjects. METHODS The study subjects were separated into 2 groups: 66 eyes of 33 patients with unilateral NAION (study group) and 33 eyes of 33 healthy individuals (control group). Reichert ocular response analyzer (Reichert Ophthalmic Instruments) was used to assess corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc), and Goldmann-correlated intraocular pressure values. Also, central corneal thickness was measured using Scheimpflug camera combined with a Placido disc corneal topographer (Sirius; Costruzioni Strumenti Oftalmici). RESULTS Mean CH and median CRF values were significantly lower in the affected eyes (8.8 ± 1.8 mm Hg, 9.4 mm Hg, respectively) and contralateral unaffected eyes (9.1 ± 1.6 mm Hg, 9.8 mm Hg, respectively) of NAION patients than those in the control group (9.9 ± 1.3 mm Hg, 10.4 mm Hg, respectively; all P < 0.017). Mean IOPcc was significantly higher in the affected eyes of NAION patients (19.2 ± 3.5 mm Hg) than in the eyes of control group (17.1 ± 3.6 mm Hg; P = 0.002). CONCLUSIONS CH and CRF are significantly reduced in patients with NAION, possibly indirectly reflecting structural weakness in the lamina cribrosa.
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Age-Related Variations of Rabbit Corneal Geometrical and Clinical Biomechanical Parameters. BIOMED RESEARCH INTERNATIONAL 2017; 2017:3684971. [PMID: 29104870 PMCID: PMC5574220 DOI: 10.1155/2017/3684971] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 05/23/2017] [Accepted: 06/27/2017] [Indexed: 11/30/2022]
Abstract
Purpose To study the variations in corneal clinical biomechanical parameters (CCBP) and corneal geometrical parameters of rabbit in relation to age. Methods Rabbits aged 3, 7, 12, 18, and 24 months were enrolled. Each eye of the rabbits was tested with Ocular Response Analyzer (ORA), Optical Coherence Tomography (OCT), and Pachymeter to obtain the intraocular pressure (IOP): Goldmann-correlated IOP (IOPg) and Corneal Compensated Intraocular Pressure (IOPcc); CCBP: Corneal Hysteresis (CH) and Corneal Resistance Factor (CRF); corneal geometric parameters: corneal curvature radius (CCR) and central corneal thickness (CCT). Results The IOP of the rabbits changes slightly from 3 to 7 months of age, while it significantly decreases from 7 to 18 months of age and increases from 18 to 24 months of age; CH and CRF decrease with the increase of age; CCT increases from 7 to 18 months and decreases from 3 to 7 months of age and from 18 to 24 months of age; CCR presents an upward trend from 3 to 18 months and a significant decrease between 18 and 24 months of age. Conclusion CH and CRF are negatively correlated with age. CCT and CCR are positively correlated with age.
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Alterations in biomechanical properties of the cornea among patients with polycystic kidney disease. Int Ophthalmol 2017; 38:1559-1564. [PMID: 28664236 DOI: 10.1007/s10792-017-0619-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 06/20/2017] [Indexed: 12/17/2022]
Abstract
PURPOSE The aim of this study was to evaluate the corneal biomechanical features in polycystic kidney disease (PKD) patients and compare them with the healthy individuals. METHODS Totally 81 patients with a mean age of 48.46 ± 14.51 years and 60 control cases with a mean age of 44.68 ± 12.69 years were included in the study. All of the subjects underwent a complete ophthalmological examination, including visual acuity testing, biomicroscopic anterior and posterior segment examinations. Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated intraocular pressure (IOPcc) were evaluated with the ocular response analyzer, and the central corneal thickness was evaluated with Sirius® corneal topography. RESULTS PKD patients had significantly increased CH values, without any alterations in IOP or CCT values, compared with the control cases (p:0.001). Among PKD patients, 23 were having liver cysts accompanying renal cysts. There was not any statistically significant difference between PKD patients with or without liver cysts regarding biomechanical properties of the cornea. However, both patient groups had statistically significantly increased CH values compared with the control cases. CONCLUSION Patients with PKD present with higher CH values than age-matched controls. Larger studies are warranted to elucidate the alterations in corneal biomechanical properties and their clinical relevance in PKD patients.
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He M, Ding H, He H, Zhang C, Liu L, Zhong X. Corneal biomechanical properties in healthy children measured by corneal visualization scheimpflug technology. BMC Ophthalmol 2017; 17:70. [PMID: 28514942 PMCID: PMC5436434 DOI: 10.1186/s12886-017-0463-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 05/08/2017] [Indexed: 11/30/2022] Open
Abstract
Background The aim of this study was to evaluate corneal biomechanical properties in a population of healthy children in China using corneal visualization Scheimpflug technology (CST). Methods All children underwent complete bi-ocular examinations. CST provided intraocular pressure (IOP) and corneal biomechanical parameters, including time, velocity, length and deformation amplitude at first applanation (A1T, A1V, A1L, A1DA), at second applanation (A2T, A2V, A2L, A2DA), highest concavity time (HCT), maximum deformation amplitude (MDA), peak distance (PD), and radius of curvature (RoC). Pearson correlation analysis was used to assess the impacts of demographic factors, central corneal thickness (CCT), spherical equivalent (SE), and IOP on corneal biomechanics. Results One hundred eight subjects (32 girls and 76 boys) with the mean age of 10.80 ± 4.13 years (range 4 to18 years) were included in the final analyses. The right and left eyes were highly symmetrical in SE (p = 0.082), IOP (p = 0.235), or CCT (p = 0.210). Mean A1T of the right eyes was 7.424 ± 0.340 ms; the left eyes 7.451 ± 0.365 ms. MDA was 0.993 ± 0.102 mm in the right eyes and 0.982 ± 0.100 mm in the left eyes. Mean HCT of the right eyes was 16.675 ± 0.502 ms; the left eyes 16.735 ± 0.555 ms. All CST parameters of both eye were remarkably symmetrical with the exception of A2L (p = 0.006), A1DA (p = 0.025). The majority of CST parameters of both eyes were significantly correlated with CCT and IOP (p < 0.05). However, age, SE, and sex exert little influence on the CST measurements. Conclusions This study found interocular symmetry in corneal biomechanics in healthy children eyes. Several CST biomechanical parameters in children are modified by CCT and IOP.
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Affiliation(s)
- Miao He
- Zhongshan Ophthalmic Center and State Key Laboratory of Ophthalmology, Sun Yat-sen University, 54S Xianlie Road, 510060, Guangzhou, China
| | - Hui Ding
- Hainan Eye Hospital, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, China
| | - Hong He
- Hainan Eye Hospital, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, China
| | - Chi Zhang
- Zhongshan Ophthalmic Center and State Key Laboratory of Ophthalmology, Sun Yat-sen University, 54S Xianlie Road, 510060, Guangzhou, China
| | - Liangping Liu
- Zhongshan Ophthalmic Center and State Key Laboratory of Ophthalmology, Sun Yat-sen University, 54S Xianlie Road, 510060, Guangzhou, China
| | - Xingwu Zhong
- Zhongshan Ophthalmic Center and State Key Laboratory of Ophthalmology, Sun Yat-sen University, 54S Xianlie Road, 510060, Guangzhou, China. .,Hainan Eye Hospital, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, China.
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Comparison of Corneal Biomechanical Properties between Indian and Chinese Adults. Ophthalmology 2017; 124:1271-1279. [PMID: 28461014 DOI: 10.1016/j.ophtha.2017.03.055] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 03/29/2017] [Accepted: 03/29/2017] [Indexed: 01/31/2023] Open
Abstract
PURPOSE To investigate the difference in corneal hysteresis (CH) and corneal resistance factor (CRF) between Indian and Chinese populations. DESIGN Population-based cross-sectional study. PARTICIPANTS Three hundred eighty-two Singaporean Indian persons and 764 Singaporean Chinese 50 years of age or older were included from the Singapore Indian Eye Study and Singapore Chinese Eye Study, respectively. METHODS Participants underwent standardized systemic and ocular examinations and interviewer-administered questionnaires for risk factor assessment. The CH and CRF were measured with the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, NY). Information on genetic ancestry was derived using principal component analysis. Linear regression models were used to investigate the association of CH and CRF with potential risk factors. MAIN OUTCOME MEASURES Corneal hysteresis and CRF. RESULTS After excluding participants with a history of intraocular surgery, a diagnosis of glaucoma suspect or glaucoma, refractive surgery, or presence of corneal abnormalities, CH and CRF readings were available for 382 Indian persons. For each Indian participant, 2 Chinese participants were selected and matched for age and gender (n = 764). There were no differences in the clinical measurements of CH (10.6±1.6 mmHg; P = 0.670) or CRF (10.3±1.7 mmHg; P = 0.103) between the ethnic groups. However, after adjusting for covariates, Indian persons had, on average, 0.18-mmHg higher CH levels than in Chinese (95% confidence interval [CI], 0.02-0.38; P = 0.031). Consistently, CH level was correlated significantly with genetic ancestry in the Southeast Asian population. Corneal resistance factor level was not associated independently with self-reported ethnicity (95% CI, -0.10 to 0.29; P = 0.335). CONCLUSIONS Chinese have lower CH than Indian persons, and this disparity may reflect biomechanical differences of the cornea.
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Murphy ML, Pokrovskaya O, Galligan M, O'Brien C. Corneal hysteresis in patients with glaucoma-like optic discs, ocular hypertension and glaucoma. BMC Ophthalmol 2017; 17:1. [PMID: 28068950 PMCID: PMC5223406 DOI: 10.1186/s12886-016-0396-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 12/16/2016] [Indexed: 12/14/2022] Open
Abstract
Background To compare corneal hysteresis (CH) measurements between patients with glaucoma, ocular hypertension (OHT) and glaucoma-like optic discs (GLD)- defined as a cup to disc ratio greater than or equal to 0.6 with normal intraocular pressure (IOP) and visual fields. The secondary aim was to investigate whether corneal resistance factor (CRF) and central corneal thickness (CCT) differ between patient groups. Methods In this cross sectional study a total of 123 patients (one eye each) were recruited from a glaucoma outpatient department to undergo ocular response analyser (ORA) testing and ultrasound pachymetry as well as clinical examination. A One-way Analysis of Covariance (ANCOVA) was conducted to evaluate the mean difference in CH between the three diagnostic groups (glaucoma, OHT and GLD) correcting for potential confounding factors, IOP and age. Analysis was repeated for CRF and CCT. Results There was a significant difference in mean CH across the three diagnosis groups; F(2, 115) = 96.95; p < 0.001. Mean CH significantly higher for GLD compared to glaucoma (mean difference 1.83, p < 0.001), and significantly higher for OHT compared to glaucoma (mean difference 2.35, p < 0.001). Mean CH was slightly lower in patients with GLD than those with OHT but this difference was not statistically significant. A similar pattern was seen when the analysis was repeated for CRF and CCT. Conclusions Higher CH in GLD and OHT compared to glaucoma suggests increased viscoelasticity of ocular tissues may have a protective role against glaucoma.
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Affiliation(s)
- Melissa L Murphy
- School of Medicine and Medical Sciences, Mater Misericordiae University Hospital, Eccles Street Dublin 7, Dublin, Ireland.
| | - Olya Pokrovskaya
- School of Medicine and Medical Sciences, Mater Misericordiae University Hospital, Eccles Street Dublin 7, Dublin, Ireland
| | - Marie Galligan
- School of Medicine and Medical Sciences, Mater Misericordiae University Hospital, Eccles Street Dublin 7, Dublin, Ireland
| | - Colm O'Brien
- School of Medicine and Medical Sciences, Mater Misericordiae University Hospital, Eccles Street Dublin 7, Dublin, Ireland
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Normative values and contralateral comparison of anterior chamber parameters measured by Pentacam and its correlation with corneal biomechanical factors. Saudi J Ophthalmol 2016; 31:7-10. [PMID: 28337056 PMCID: PMC5352957 DOI: 10.1016/j.sjopt.2016.11.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 11/14/2016] [Accepted: 11/22/2016] [Indexed: 11/21/2022] Open
Abstract
PURPOSE To evaluate the normative values of anterior chamber parameters measured by Pentacam and corneal hysteresis (CH) and corneal resistance factor (CRF) measured by Ocular Response Analyzer (ORA) and their relationship. METHODS In an observational cross-sectional study, patients aged 18-35 years were included. Exclusion criteria were history of any intraocular or corneal disease, anomaly or surgery; hyperopic spherical refraction more than +3, and myopic spherical refraction less than -5.00 diopters (D) or cylindrical refraction more than 2.00 D. ORA was used to measure CH and CRF. Corneal volume (CV), anterior and posterior Q value (QA and QP), anterior and posterior elevation (AE and PE), central corneal thickness (CCT), corneal thinnest thickness (CTT), anterior chamber depth (ACD), anterior chamber volume (ACV) and anterior chamber angle (ACA) were measured with Pentacam. RESULTS This study evaluated 506 eyes of 253 cases (182 females) with a mean age of 28.43 ± 6.36 years. The average CH and CRF were 10.07 ± 1.61 and 10.33 ± 1.68 mmHg. CH and CRF were not correlated with PQ, AQ, AE and PE. CH and CRF were significantly correlated with CCT (r = 0.499, p < 0.0001 and r = 0.591, p < 0.0001 respectively), CTT (r = 0.469, p < 0.0001 and r = 0.593, p < 0.0001 respectively) and CV (r = 0.443, p < 0.0001 and r = 0.526, p < 0.0001 respectively). CONCLUSION A significant positive correlation was found between CH and CRF, and CCT, CTT and CV. This study also provided data about wide range normative values of corneal parameters.
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The Effect of Dehydration and Fasting on Corneal Biomechanical Properties and Intraocular Pressure. Eye Contact Lens 2016; 42:392-394. [DOI: 10.1097/icl.0000000000000220] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Biomechanical evaluation of cornea in patients with ankylosing spondylitis. Int Ophthalmol 2016; 37:1017-1024. [DOI: 10.1007/s10792-016-0368-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 09/30/2016] [Indexed: 10/20/2022]
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