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Antonov AA, Volzhanin AV, Klinicheva EA, Karpilova MA. [Influence of corneal curvature and peripheral thickness on tonometry readings]. Vestn Oftalmol 2024; 140:43-50. [PMID: 38739130 DOI: 10.17116/oftalma202414002243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
PURPOSE This study investigates the influence of peripheral corneal thickness (PCT) and its curvature on tonometry readings. MATERIAL AND METHODS The study included 49 patients (49 eyes) who were indicated for glaucoma surgery. Using bidirectional applanation tonometry, the following parameters were obtained: IOPcc, IOPg - intraocular pressure (IOP) corrected for corneal compensation, taken as the most reliable indicator; IOP converted to Goldmann measurement, taken as the result of applanation tonometry, ΔIOP (IOPcc-IOPg), CH and CRF (corneal hysteresis and corneal resistance factor). During corneal topography, the corneal thickness was studied in the center, PCT at 1.5; 2, 3, 4 and 5 mm from the center in four meridians, as well as ΔPCT (PCT 3 mm - PCT 1.5 mm), the curvature of the anterior and posterior surfaces of the cornea and the depth of the anterior chamber. Aberrometry was used to obtain refractometry data and the curvature of the anterior surface of the cornea. The influence of the studied parameters on ΔIOP was evaluated. RESULTS ΔIOP correlated with CRF (r= -0.652), CH (r= -0.873), central corneal thickness (r= -0.293), PCT at all distances except 5 mm (r= -0.297; -0.287; -0.302; -0.303), with the strong and weak meridians of the anterior surface of the cornea (r=0.328; r=0.315), with the strong and weak meridians of the posterior surface, as well as the average curvature of the posterior surface (r=0.307; r=0.332; r=0.328). After step-by-step selection of the above parameters for creating a linear regression model for ΔIOP calculation, CH, CRF and PCT1.5mm remained in the model. The model describes ΔIOP with high accuracy (R2=0.974). CONCLUSION Biomechanical parameters of the cornea are the leading factor of applanation tonometry error. Individual linear dimensions of the cornea (thickness, curvature) have a lesser effect.
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Affiliation(s)
- A A Antonov
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
| | - A V Volzhanin
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
| | - E A Klinicheva
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
| | - M A Karpilova
- Krasnov Research Institute of Eye Diseases, Moscow, Russia
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Chen H, Wang Z, Li K, Wang Y, Li X, Du L, Lin M, Savini G, Wang Q, Yu A, Chen S. Agreement Between Predicted and Actual Measured Ablation Depth After FS-LASIK Using Different Rotating Scheimpflug Cameras and OCT. Front Med (Lausanne) 2022; 9:907334. [PMID: 35665335 PMCID: PMC9160334 DOI: 10.3389/fmed.2022.907334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 04/26/2022] [Indexed: 11/13/2022] Open
Abstract
PurposeTo compare the predicted ablation depth (AD) with the postoperatively measured corneal ablation depth (postop-AD) at central, paracentral, and midperipheral locations using two rotating Scheimpflug analyzers and a Fourier-domain optical coherence tomographer in eyes that underwent femtosecond laser-assisted LASIK (FS-LASIK).MethodsThe values of corneal thickness were measured preoperatively and postoperatively at one and three months. The difference between preoperative and postoperative was defined as postop-AD. Measurements were performed at the corneal vertex and mid-peripheral area. The mid-peripheral corneal thickness was measured at the superior, inferior, nasal, and temporal locations at a distance of 1.0 or 2.5 mm from the corneal vertex. The predicted AD was calculated by ORK-CAM software (Schwind eye tech-solutions GmbH, Kleinostheim, Germany), and the difference between the predicted AD and postop-AD was defined as Δ-AD. Paired t-test analysis was employed to evaluate the differences, agreement was assessed by the Bland-Altman method.ResultsForty-two eyes of 42 patients were investigated. At one month, the predicted AD in the central and paracentral areas was underestimated by the Pentacam HR (Oculus, Wetzlar, Germany), Sirius (Costruzione Strumenti Oftalmici, Florence, Italy) and RTVue OCT (Optovue Inc., Freemont, CA, United States), whereas Δ-AD was negative as established by all devices and predominantly statistically significant. The Δ-AD values approximated zero at three months. The mean difference of Δ-AD at three months at the corneal vertex was 0.67 ± 9.39 mm, −7.92 ± 9.05 mm and −1.36 ± 8.31 mm, respectively. The mid-peripheral measurements had positive values at one month and even more highly positive at three months (with statistically significant differences in most of the cases). The agreement between the predicted and postop-AD was moderate with all devices, but slightly better with RTVue.ConclusionThe predicted AD seems to be underestimated in the central and paracentral corneal area and overestimated in the mid-periphery.Translational RelevanceThe study could help to partly explain and prevent the refractive errors after FS-LASIK.
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Affiliation(s)
- Hao Chen
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Ziqian Wang
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Kunke Li
- Shenzhen Eye Hospital, Shenzhen Key Ophthalmic Laboratory, Jinan University, Shenzhen, China
| | - Yiran Wang
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Xin Li
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Lan Du
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Meimin Lin
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | | | - Qinmei Wang
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
- *Correspondence: Qinmei Wang,
| | - Ayong Yu
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
- Ayong Yu,
| | - Sisi Chen
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
- Sisi Chen,
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Alhussain SHA, Mallen EAH, Strang NC, Jonuscheit S. The role of peripheral ocular length and peripheral corneal radius of curvature in determining refractive error. JOURNAL OF OPTOMETRY 2022; 15:129-137. [PMID: 33879375 PMCID: PMC9068529 DOI: 10.1016/j.optom.2021.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 01/28/2021] [Accepted: 02/10/2021] [Indexed: 05/06/2023]
Abstract
PURPOSE The purpose of this study was to extend the knowledge of peripheral biometric component and its relationship to refractive status in healthy individuals by determining the correlation between peripheral ocular length to peripheral corneal radius ratio and the refractive error. METHODS This prospective study was conducted on thirty-three healthy adult participants. Refractive error was assessed objectively and subjectively and recorded as the mean spherical equivalent. Central and peripheral ocular lengths at 30° were assessed using partial coherence interferometry under dilation with 1% tropicamide. Central and peripheral corneal radius of curvature was assessed using Scheimpflug topography. Peripheral ocular lengths at 30° were paired with peripheral corneal curvatures at the incident points of the IOLMaster beam (3.8mm away from corneal apex) superiorly, inferiorly, temporally and nasally to calculate the peripheral ocular length-peripheral corneal radius ratio. Descriptive statistics were used to describe the distribution and spread of the data. Pearson's correlation analysis was used to present the association between biometric and refractive variables. RESULTS Refractive error was negatively correlated with the axial length-central corneal radius ratio (r=-0.91; p<0.001) and with 30° peripheral ocular length-peripheral corneal radius ratio in all four meridians (r≤-0.76; p<0.001). The strength of the correlation was considerably lower when only axial length or peripheral ocular lengths were used. CONCLUSION Using the ratios of peripheral ocular length-peripheral corneal radius to predict refractive error is more effective than using peripheral corneal radius or peripheral ocular length alone.
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Affiliation(s)
- Saleh H A Alhussain
- Department of Vision Sciences, School of Health & Life Sciences, Glasgow Caledonian University, Glasgow, United Kingdom.
| | - Edward A H Mallen
- School of Optometry &Vision Science, University of Bradford, Bradford, United Kingdom
| | - Niall C Strang
- Department of Vision Sciences, School of Health & Life Sciences, Glasgow Caledonian University, Glasgow, United Kingdom
| | - Sven Jonuscheit
- Department of Vision Sciences, School of Health & Life Sciences, Glasgow Caledonian University, Glasgow, United Kingdom
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Kinoshita S, Sugita S, Yoshida A. Corneal thickness in the case of familial lecithin-cholesterol acyltransferase deficiency. Am J Ophthalmol Case Rep 2021; 24:101211. [PMID: 34604605 PMCID: PMC8473656 DOI: 10.1016/j.ajoc.2021.101211] [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: 08/03/2020] [Revised: 05/14/2021] [Accepted: 09/20/2021] [Indexed: 11/26/2022] Open
Abstract
Purpose We report our findings of a patient with a definitive diagnosis of familial lecithin-cholesterol acyltransferase deficiency (FLD), whose corneal thickness was measured using swept-source optical coherence tomography (OCT) and who underwent an ophthalmologic therapeutic intervention. Observations The patient was a 78-year-old Japanese man diagnosed with FLD at the age of 52 years. This was his first ever visit to an ophthalmology clinic. Slit lamp microscopy revealed bilateral diffuse corneal opacities and cataracts, angioid streaks of the retina, and macular atrophy in the fundus. The central corneal thickness, measured with swept-source OCT, was within the normal range in both eyes. Deep lamellar keratoplasty, phacoemulsification, and intraocular lens insertion were performed simultaneously for the left eye. The right eye was treated only using deep lamellar keratoplasty. Conclusions and importance As seen in patients with fish-eye disease, the central corneal thickness in this patient with FLD was within the normal range. Since FLD is a rare disease, it is essential to collect and examine further data on corneal thickness.
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Affiliation(s)
- Shinsuke Kinoshita
- MIE Eye Clinic Yokkaichi, 4F Yokkaichi Suwamachi Building, 4-5 Suwamachi, Yokkaichi, Mie, Japan.,National Health Insurance Sakashita Hospital, 722-1, Sakashita, Nakatsugawa, Gifu, Japan
| | - Seiichiro Sugita
- Sugita Eye Hospital, 5-1-30, Sakae, Nagoya Naka-ku, Aichi, Japan
| | - Akihiro Yoshida
- National Health Insurance Sakashita Hospital, 722-1, Sakashita, Nakatsugawa, Gifu, Japan
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Phu J, Tong J, Kalloniatis M. Intra-session repeatability of anterior chamber depth across the chamber width using Pentacam Scheimpflug imaging in healthy subjects. Ophthalmic Physiol Opt 2021; 41:1273-1284. [PMID: 34490921 DOI: 10.1111/opo.12880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 07/25/2021] [Accepted: 07/26/2021] [Indexed: 11/26/2022]
Abstract
PURPOSE Despite the importance of anterior chamber depth (ACD) measurements in disease and ageing, the repeatability and their threshold for change is not known. Our purpose was to determine the intra-session repeatability of Pentacam Scheimpflug photography for measuring the ACD across the chamber width in healthy subjects and thus inform expected limits of normality. METHODS Pentacam Scheimpflug photography was used to obtain ACD measurements at 57 points across the central 8mm of the chamber width from one randomly selected eye of 130 healthy (normal vision and no ocular diseases, except age-normal cataracts) subjects (median age 58.0 years, interquartile range 46.3-63.0 years; 48 males, 82 females). Intra-session ACD measurements were compared. Univariate and multivariate linear regression was performed to identify categorical and continuous variables demonstrating a significant relationship with ACD and its repeatability. RESULTS Bland-Altman analyses showed no directional or depth-dependent bias in the difference between the first and second tests (mean bias -0.003 mm, 95% limits of agreement -0.115 to +0.109 mm). Multivariate analysis found gender to be a significant factor (p < 0.0001), but not age (p = 0.69) nor ethnicity (p = 0.65), although the model fit was poor (R2 = 0.004). There were no regional differences in repeatability measures found in males, but six locations in the superior aspect in females were found to be significantly different in their repeatability characteristics. Tolerance limits used to calculate the number of step sizes between <20 and >60-year-old age groups found 8.1-11.5 steps for females, and 7.5-9.2 steps for males. CONCLUSIONS Scheimpflug imaging using the Pentacam has excellent intra-session repeatability. Only gender appeared to affect repeatability characteristics, manifesting with a greater number of meaningful steps of change between two extremes of age range in females compared to males, which provides guidance for identifying clinically significant and measurable change between tests.
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Affiliation(s)
- Jack Phu
- Centre for Eye Health, University of New South Wales, Kensington, New South Wales, Australia.,School of Optometry and Vision Science, University of New South Wales, Kensington, New South Wales, Australia
| | - Janelle Tong
- Centre for Eye Health, University of New South Wales, Kensington, New South Wales, Australia.,School of Optometry and Vision Science, University of New South Wales, Kensington, New South Wales, Australia
| | - Michael Kalloniatis
- Centre for Eye Health, University of New South Wales, Kensington, New South Wales, Australia.,School of Optometry and Vision Science, University of New South Wales, Kensington, New South Wales, Australia
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Yu AY, Ye J, Savini G, Wang Y, Zhang T, Chen M, Wang Q, Huang J. Reliability and agreement of the central and mid-peripheral corneal thickness measured by a new Scheimpflug based imaging. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1136. [PMID: 34430577 PMCID: PMC8350684 DOI: 10.21037/atm-20-7895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 04/24/2021] [Indexed: 11/06/2022]
Abstract
Background To assess the intra-observer repeatability and inter-observer reproducibility of central corneal thickness (CCT) and mid-peripheral corneal thickness (MPCT) measurements using a new Scheimpflug imaging instrument (Scansys) and compare the agreement with the rotating Scheimpflug corneal tomographer (Pentacam HR). Methods The same well-trained operator performed the measuring using the two devices, after which Scansys measurements were repeated by another operator. Both instruments required three consecutive measurements per subject. Corneal thickness measurements were obtained by each instrument, including CCT, thinnest corneal thickness (TCT), pupil corneal thickness (PCT), and MPCT. Test-retest repeatability (TRT), within-subject coefficient of variation (CoV), and intra-class correlation coefficient (ICC) were used to evaluate repeatability and reproducibility. A paired t-test was used to compare the differences between Scansys and Pentacam, and the agreement was compared with Bland-Altman plots. Results This study enrolled 112 healthy subjects. The CoV were <0.91% and 0.55% for repeatability and reproducibility, respectively. The ICC was close to 1 in all measurements. For intra-observer repeatability in the CT2mm region, TRT was <10.30 µm. Moreover, TRT was <15.26 µm within the CT5mm region. The paired t-test showed significant differences in all corneal thickness measurements (P<0.001). The central region and CT2mm agreement were high, but the largest range of 95% limits of agreement (LoA) appeared in the CTnasal-5mm. Conclusions The new Scheimpflug imaging instrument showed excellent intra-observer repeatability and inter-observer reproducibility for corneal thickness measurements. The agreement analysis suggested that Scansys and Pentacam could be interchangeably used between the central region and CT2mm, except CT5mm.
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Affiliation(s)
- A-Yong Yu
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.,State Key Laboratory of Optometry, Ophthalmology and Vision Science, Wenzhou, China
| | - Junming Ye
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | | | - Yiran Wang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Tianjiao Zhang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Min Chen
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Qinmei Wang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.,State Key Laboratory of Optometry, Ophthalmology and Vision Science, Wenzhou, China
| | - Jinhai Huang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.,State Key Laboratory of Optometry, Ophthalmology and Vision Science, Wenzhou, China
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Pérez-Corral J, Cardona G, Piñero DP, Aradilla Y, García M. Should Overnight Orthokeratology Patients Wear Their Lenses During Their Afternoon Nap? Eye Contact Lens 2021; 47:91-97. [PMID: 32701767 DOI: 10.1097/icl.0000000000000732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2020] [Indexed: 11/25/2022]
Abstract
PURPOSE The purpose of this study was to evaluate changes in visual acuity, corneal curvature, elevation, pachymetry, and objective quality of vision of experienced orthokeratology patients using their contact lenses during a simulated 30-min afternoon nap. METHOD Twelve patients aged 30.8±8.3 years were recruited for the study, with a history of overnight orthokeratology of 27.4±23.0 months. Patients were instructed to close their eyes for 30 min while wearing their contact lenses or without lenses. Anterior corneal curvature, elevation, and corneal pachymetry were assessed with the Pentacam Scheimpflug System at 17 predefined corneal locations, and the HD Analyzer (Terrassa, Spain) was used to measure objective quality of vision. Measurements were conducted before eye closure (baseline), immediately after eye opening/lens removal (M1), and 30 min later (M2). RESULTS No statistically significant differences were found in anterior corneal curvature and elevation between baseline values and M1 or M2, with and without contact lenses. Corneal swelling at M1 was greater without contact lenses (change in central corneal thickness of 2.3%±3.1%, P=0.001) than with contact lenses (1.7%±1.3%, P<0.001). Recovery at M2 was slower when lenses were worn. A statistically significant improvement in objective quality of vision and visual acuity was found only when patients napped with their lenses. CONCLUSIONS Even if no significant changes were found in corneal curvature and elevation, patients of overnight orthokeratology may benefit from using their contact lenses during their afternoon nap in terms of objective quality of vision and visual acuity.
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Affiliation(s)
- Joan Pérez-Corral
- Department of Optics and Optometry (J.P.-C., G.C.), Universitat Politècnica de Catalunya, School of Optics and Optometry, Terrassa, Spain; Department of Optics, Pharmacology, and Anatomy (D.P.P.), University of Alicante, Alicante, Spain; and Department of Contact Lenses (Y.A., M.G.), Institut Català de Retina, Barcelona, Spain
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Hu L, Hu Z, Savini G, Yu J, Zhou H, Chen S, Ning R, Jin Y, Huang J. Repeatability and agreement of corneal thickness measurements by three methods of pachymetry in small incision lenticule extraction eyes. Expert Rev Med Devices 2020; 17:1323-1332. [PMID: 33135507 DOI: 10.1080/17434440.2020.1845139] [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: 10/23/2022]
Abstract
Background: The accurate evaluation of corneal thickness (CT) post small incision lenticule extraction (SMILE) is clinically relevant to reduce the risk of complications. We aimed to analyze repeatability and agreement of central corneal thickness (CCT), thinnest corneal thickness (TCT), and mid-peripheral corneal thickness (MPCT) measurements using Scheimpflug imaging, anterior segment swept-source optical coherence tomography (AS-SS-OCT, CASIA 1000, Tomey), and ultrasound pachymetry (USP, SP-3000, Tomey) in eyes with previous SMILE. Methods: Ninety-one eyes of 91 patients were included. Within-subject standard deviation (Sw), test-retest repeatability (TRT), intraclass correlation coefficient (ICC), and coefficient of variation (CoV) were used to evaluate repeatability. Agreement was assessed by repeat-measurement analysis of variance and Bland-Altman analysis. Results: The above three instruments revealed that Sw was <5.91 µm, CoV was <1.08%, TRT was <16.38 µm, and ICC was >0.94. The 95% limits of agreement were relatively narrow and Bland-Altman plots were more concentrated at the CCT, at the TCT, and at the CT2mm. However, it was shown to be wide at the CT5mm. Conclusions: The three devices provide good repeatability of CT measurements in patients who undergone SMILE. Agreement between measurements at the CCT, TCT, and CT2mm were high, but measurement agreements among CT5mm revealed poor agreement.
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Affiliation(s)
- Liang Hu
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University , Wenzhou, Zhejiang, China.,Key Laboratory of Vision Science, Ministry of Health P.R. China , Wenzhou, Zhejiang, China
| | - Zhongli Hu
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | | | - Jinjin Yu
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Haitao Zhou
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Sisi Chen
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University , Wenzhou, Zhejiang, China.,Key Laboratory of Vision Science, Ministry of Health P.R. China , Wenzhou, Zhejiang, China
| | - Rui Ning
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Yili Jin
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University , Wenzhou, Zhejiang, China
| | - Jinhai Huang
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University , Wenzhou, Zhejiang, China.,Key Laboratory of Vision Science, Ministry of Health P.R. China , Wenzhou, Zhejiang, China
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Alvarez ER, Montesinos GM, Torres Piedra DM, Palacios NT, Téllez OF. Corneal Indices Determined with Pentacam in Possible Candidates for Corneal Refractive Surgery. Open Ophthalmol J 2020. [DOI: 10.2174/1874364102014010039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Objective:
To describe the level of correlation of clinical refractive variables with corneal indices in Pentacam Scheimpflug tomography, demonstrate the usefulness of the study of corneal indices in the diagnosis of keratoconus (KC), and identify the corneal indexes with the greatest influence on the diagnosis of KC.
Methods:
A descriptive, retrospective, and cross-sectional study was conducted in 69 patients (138 eyes) with refractive disorders, possible candidates for corneal refractive surgery, at the Exilaser Ophthalmological Center, Cuenca, Ecuador, from March to August 2019. Corneal indices were studied using Pentacam. Statistical correlation methods, Levene’s test, Fisher’s exact test, Cramérs’ V coefficient, and multiple correspondence analyses were used.
Results:
The variables refractive cylinder and central keratometry had a direct correlation with the corneal indices (p<0.001). An inverse correlation was obtained between central pachymetry and corneal indices (p<0.001). A high level of dependence on central KC index (CKI) (Cramér V = 0.785) and KC index (KI) (Cramér V = 0.775) was obtained with the diagnosis of KC.
Conclusion:
Pentacam is a valuable tool in the analysis of corneal indices for the diagnosis of KC, given its high level of correlation with clinical refractive variables. The selection of candidates for refractive surgery, even when there is no diagnosis of KC, is strengthened with the analysis of the corneal indices. The indices with the most intense level of dependence with the diagnosis of KC are, in order, the following indices: CKI, KI, vertical asymmetry, minimum radius, and variation of the surface.
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Corneal Stromal Transplantation With Human-derived Acellular Dermal Matrix for Pellucid Marginal Corneal Degeneration: A Nonrandomized Clinical Trial. Transplantation 2019; 103:e172-e179. [DOI: 10.1097/tp.0000000000002681] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Comparing Change in Anterior Curvature After Corneal Cross-linking Using Scanning-slit and Scheimpflug Technology. Am J Ophthalmol 2018; 191:129-134. [PMID: 29729256 DOI: 10.1016/j.ajo.2018.04.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Revised: 04/19/2018] [Accepted: 04/20/2018] [Indexed: 10/17/2022]
Abstract
PURPOSE To evaluate the correlation between anterior axial curvature difference maps following corneal cross-linking (CXL) for progressive keratoconus obtained from Scheimpflug-based tomography and Placido-based topography. DESIGN Between-devices reliability analysis of randomized clinical trial data. METHODS Corneal imaging was collected at a single-center institution preoperatively and at 3, 6, and 12 months postoperatively using Scheimpflug-based tomography (Pentacam; Oculus Inc, Lynnwood, Washington, USA) and scanning-slit, Placido-based topography (Orbscan II; Bausch & Lomb, Rochester, New York, USA) in patients with progressive keratoconus receiving standard protocol CXL (3 mW/cm2 for 30 minutes). Regularization index (RI), absolute maximum keratometry (K Max), and change in K Max (ΔK Max) were compared between the 2 devices at each time point. RESULTS Fifty-one eyes from 36 patients were evaluated at all time points. Values were significantly different at all time points (56.01 ± 5.3 diopters [D] Scheimpflug vs 55.04 ± 5.1 D scanning-slit preoperatively [P = .003]; 54.58 ± 5.3 D Scheimpflug vs 53.12 ± 4.9 D scanning-slit at 12 months [P < .0001]) but strongly correlated between devices (r = 0.90-0.93) at all time points. The devices were not significantly different at any time point for either ΔK Max or RI but were poorly correlated at all time points (r = 0.41-0.53 for ΔK Max, r = 0.29-0.48 for RI). At 12 months, 95% limits of agreement were 7.51 D for absolute K Max, 8.61 D for ΔK Max, and 19.86 D for RI. CONCLUSIONS Measurements using Scheimpflug and scanning-slit Placido-based technology are correlated but not interchangeable. Both devices appear reasonable for separately monitoring the cornea's response to CXL; however, caution should be used when comparing results obtained with one measuring technology to the other.
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Doğan AŞ, Gürdal C, Köylü MT. Does Dry Eye Affect Repeatability of Corneal Topography Measurements? Turk J Ophthalmol 2018; 48:57-60. [PMID: 29755816 PMCID: PMC5938476 DOI: 10.4274/tjo.10179] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 10/16/2017] [Indexed: 02/01/2023] Open
Abstract
Objectives: The purpose of this study was to assess the repeatability of corneal topography measurements in dry eye patients and healthy controls. Materials and Methods: Participants underwent consecutive corneal topography measurements (Sirius; Costruzione Strumenti Oftalmici, Florence, Italy). Two images with acquisition quality higher than 90% were accepted. The following parameters were evaluated: minimum and central corneal thickness, aqueous depth, apex curvature, anterior chamber volume, horizontal anterior chamber diameter, iridocorneal angle, cornea volume, and average simulated keratometry. Repeatability was assessed by calculating intra-class correlation coefficient. Results: Thirty-three patients with dry eye syndrome and 40 healthy controls were enrolled to the study. The groups were similar in terms of age (39 [18-65] vs. 30.5 [18-65] years, p=0.198) and gender (M/F: 4/29 vs. 8/32, p=0.366). Intra-class correlation coefficients among all topography parameters within both groups showed excellent repeatability (>0.90). Conclusion: The anterior segment measurements provided by the Sirius corneal topography system were highly repeatable for dry eye patients and are sufficiently reliable for clinical practice and research.
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Affiliation(s)
- Aysun Şanal Doğan
- University of Health Sciences, Dışkapı Yıldırım Beyazıt Training and Research Hospital, Ophthalmology Clinic, Ankara, Turkey
| | - Canan Gürdal
- University of Health Sciences, Dışkapı Yıldırım Beyazıt Training and Research Hospital, Ophthalmology Clinic, Ankara, Turkey
| | - Mehmet Talay Köylü
- University of Health Sciences, Dışkapı Yıldırım Beyazıt Training and Research Hospital, Ophthalmology Clinic, Ankara, Turkey
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Saenz-Frances F, Sanz-Pozo C, Borrego-Sanz L, Jañez L, Morales-Fernandez L, Martinez-de-la-Casa JM, Garcia-Sanchez J, Garcia-Feijoo J, Santos-Bueso E. Dependence of dynamic contour and Goldmann applanation tonometries on peripheral corneal thickness. Int J Ophthalmol 2017; 10:1521-1527. [PMID: 29062770 DOI: 10.18240/ijo.2017.10.07] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 08/11/2016] [Indexed: 11/23/2022] Open
Abstract
AIM To determine the effects of peripheral corneal thickness (PCT) on dynamic contour tonometry(DCT) and Goldmann applanation tonometry (GAT). METHODS A cross-sectional study. We created a software which calculates the corneal contour (CC) as a function of the radius from the corneal apex to each pixel of the contour. The software generates a central circumference with a radius of 1 mm and the remainder of the cornea is segmented in 5 rings concentric with corneal apex being its diameter not constant around the corneal circumference as a consequence of the irregular CC but keeping constant the diameter of each ring in each direction of the contour. PCT was determined as the mean thickness of the most eccentric ring. Locally weighted scatterplot smoothing (LOWESS) regression was used to determine the pattern of the relationship between PCT and both DCT and GAT respectively. Thereafter, two multivariable linear regression models were constructed. In each of them, the dependant variable was intraocular pressure (IOP) as determined using GAT and DCT respectively. In both of the models the predictive variable was PCT though LOWESS regression pattern was used to model the relationship between the dependant variables and the predictor one. Age and sex were also introduced control variables along with their first-degree interactions with PCT. Main outcome measures include amount of IOP variation explained through regression models (R2) and regression coefficients (B). RESULTS Subjects included 109 eyes of 109 healthy individuals. LOWESS regression suggested that a 2nd-degree polynomial would be suitable to model the relationship between both DCT and GAT with PCT. Hence PCT was introduced in both models as a linear and quadratic term. Neither age nor sex nor interactions were statistically significant in both models. For GAT model, R2 was 17.14% (F=9.02; P=0.0002), PCT linear term B was -1.163 (95% CI: -1.163, -0.617). PCT quadratic term B was 0.00081 (95% CI: 0.00043, 0.00118). For DCT model R2 was 14.28% (F=9.29; P=0.0002), PCT linear term B was -0.712 (95% CI: -1.052, -0.372), PCT quadratic term was B=0.0005 (95% CI: 0.0003, 0.0007). CONCLUSION DCT and GAT measurements are conditioned by PCT though this effect, rather than linear, follows a 2nd-degree polynomial pattern.
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Affiliation(s)
- Federico Saenz-Frances
- Ophthalmology Department, Clinico Universitario San Carlos Hospital, Complutense University, Madrid 28040, Spain
| | - Claudia Sanz-Pozo
- Ophthalmology Department, Clinico Universitario San Carlos Hospital, Complutense University, Madrid 28040, Spain
| | - Lara Borrego-Sanz
- Ophthalmology Department, Clinico Universitario San Carlos Hospital, Complutense University, Madrid 28040, Spain
| | - Luis Jañez
- Institute of Knowledge Technology, Complutense University, Madrid 28003, Spain
| | - Laura Morales-Fernandez
- Ophthalmology Department, Clinico Universitario San Carlos Hospital, Complutense University, Madrid 28040, Spain
| | | | - Julian Garcia-Sanchez
- Ophthalmology Department, Clinico Universitario San Carlos Hospital, Complutense University, Madrid 28040, Spain
| | - Julian Garcia-Feijoo
- Ophthalmology Department, Clinico Universitario San Carlos Hospital, Complutense University, Madrid 28040, Spain
| | - Enrique Santos-Bueso
- Ophthalmology Department, Clinico Universitario San Carlos Hospital, Complutense University, Madrid 28040, Spain
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Chetty E. Precision of anterior and posterior corneal curvature measurements taken with the Oculus Pentacam. AFRICAN VISION AND EYE HEALTH 2016. [DOI: 10.4102/aveh.v75i1.329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
In the era of rapid advances in technology, new ophthalmic instruments are constantly influencing health sciences and necessitating investigations of the accuracy and precision of the new technology. The Oculus Pentacam (70700) has been available for some time now and numerous studies have investigated the precision of some of the parameters that the Pentacam is capable of measuring. Unfortunately some of these studies fall short in confusing the meaning of accuracy and precision and in not being able to analyse the data correctly or completely. The aim of this study was to investigate the precision of the anterior and posterior corneal curvature measurements taken with the Oculus Pentacam (70700) holistically with sound multivariate statistical methods. Twenty successive Pentacam measurements were taken over three different measuring sessions on one subject. Keratometric data for both the anterior and posterior corneal surfaces were analysed using multivariate statistics to determine the precision of the Oculus Pentacam. This instrument was found to have good precision both clinically and statistically for anterior corneal measurements but only good clinical precision for the posterior corneal surface. Key words: Oculus Pentacam; keratometric variation; corneal curvature; multivariate statistics
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