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Schachar RA, Schachar IH, Kumar S, Feldman EI, Pierscionek BK, Cosman PC. Model of zonular forces on the lens capsule during accommodation. Sci Rep 2024; 14:5896. [PMID: 38467700 PMCID: PMC10928188 DOI: 10.1038/s41598-024-56563-8] [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] [Received: 10/04/2023] [Accepted: 03/08/2024] [Indexed: 03/13/2024] Open
Abstract
How the human eye focuses for near; i.e. accommodates, is still being evaluated after more than 165 years. The mechanism of accommodation is essential for understanding the etiology and potential treatments for myopia, glaucoma and presbyopia. Presbyopia affects 100% of the population in the fifth decade of life. The lens is encased in a semi-elastic capsule with attached ligaments called zonules that mediate ciliary muscle forces to alter lens shape. The zonules are attached at the lens capsule equator. The fundamental issue is whether during accommodation all the zonules relax causing the central and peripheral lens surfaces to steepen, or the equatorial zonules are under increased tension while the anterior and posterior zonules relax causing the lens surface to peripherally flatten and centrally steepen while maintaining lens stability. Here we show with a balloon capsule zonular force model that increased equatorial zonular tension with relaxation of the anterior and posterior zonules replicates the topographical changes observed during in vivo rhesus and human accommodation of the lens capsule without lens stroma. The zonular forces required to simulate lens capsule configuration during in vivo accommodation are inconsistent with the general belief that all the zonules relax during accommodation.
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Affiliation(s)
- Ronald A Schachar
- Department of Physics, University of Texas at Arlington, Arlington, TX, USA.
| | - Ira H Schachar
- North Bay Vitreoretinal Consultants, Santa Rosa, CA, USA
| | - Shubham Kumar
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA, USA
| | | | - Barbara K Pierscionek
- Faculty of Health, Medicine and Social Care, Medical Technology Research Centre, Anglia Ruskin University, Chelmsford, UK
| | - Pamela C Cosman
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA, USA
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2
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Lee DC, Lee SY, Jun JH. Alterations of lower- and higher-order aberrations after unilateral horizontal rectus muscle surgery in children with intermittent exotropia: A retrospective cross-sectional study. PLoS One 2022; 17:e0264037. [PMID: 35176076 PMCID: PMC8853472 DOI: 10.1371/journal.pone.0264037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 02/01/2022] [Indexed: 12/04/2022] Open
Abstract
Background This retrospective, cross-sectional study investigated changes in corneal lower- and higher-order aberrations that cause visual disturbance after lateral rectus recession and medial rectus resection in children. Methods Eighty-five eyes of 85 patients (44 boys; 8.64±2.88 years) who underwent lateral rectus recession and medial rectus resection to correct intermittent exotropia were assessed. The Galilei G4 Dual Scheimpflug Analyzer was used for wavefront analysis. Risk factors (age, sex, amount of surgery, preoperative axial length, preoperative intraocular pressure) were determined. Outcome measures included simulated and ray-tracing mode keratometry with secondary defocus, oblique, and vertical astigmatism (for lower-order aberrations) and the root mean square, 3rd-order vertical and horizontal coma, oblique and horizontal trefoil, 4th-order spherical aberration, oblique and vertical secondary astigmatism, and oblique and vertical quadrafoil (2nd‒8th sums) (for higher-order aberrations). Results Myopic with-the-rule changes in low-order aberrations and increases in simulated and ray-tracing mode keratometry during the 3 months following lateral rectus recession and medial rectus resection were attributed to muscle healing and stability changes. High-order aberrations altered in the week following surgery almost returned to normal within 3 months. Axial length, the amount of surgery, age, and sex affected astigmatism due to differences in patients’ scleral states. Conclusions Clinicians should consider changes in high-order aberrations of young individuals who underwent lateral rectus recession and medial rectus resection and may not be able to verbalize changes in vision.
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Affiliation(s)
- Dong Cheol Lee
- Department of Ophthalmology, School of Medicine, Keimyung University, Daegu, Korea
| | - Se Youp Lee
- Department of Ophthalmology, School of Medicine, Keimyung University, Daegu, Korea
| | - Jong Hwa Jun
- Department of Ophthalmology, School of Medicine, Keimyung University, Daegu, Korea
- * E-mail:
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3
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Cho HK, Choae W. Long-Term Outcome of Corneal and Anterior Chamber Angle Parameters after Combined Laser Iridotomy and Iridoplasty Using Dual Scheimpflug Analyzer: 1 Year Results. J Clin Med 2022; 11:jcm11030813. [PMID: 35160264 PMCID: PMC8836430 DOI: 10.3390/jcm11030813] [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: 12/24/2021] [Revised: 01/21/2022] [Accepted: 02/02/2022] [Indexed: 02/04/2023] Open
Abstract
Background: To investigate the outcomes of corneal and anterior chamber angle (ACA) parameters after laser iridotomy (LI) combined with peripheral iridoplasty (PI) using dual Scheimpflug analyzer in the long term. Methods: Fifty-eight eyes (58 subjects) with shallow AC were included in this prospective cohort study. Images of the Dual Scheimpflug analyzer were obtained before, 1 week, and 1 year after LI and PI. Pachymetry from three zones (central, middle, and peripheral), corneal aberration, and spherical equivalent (SE) were acquired. AC depth (ACD), AC volume (ACV), ACA from four quadrants, and intraocular pressure (IOP) were also obtained. For comparison of the results, the linear mixed-effects model was employed. Results: ACD significantly increased from 2.09 ± 0.25 mm to 2.10 ± 0.23 mm at 1 year after laser (all p < 0.05). ACV and ACA increased significantly after laser at 1 year (all p < 0.05). IOP significantly decreased from 15.97 ± 4.20 mmHg to 13.73 ± 2.63 mmHg at 1 year (all p < 0.0001). No significant changes were found in the coma, trefoil, total corneal aberration, pachymetry from three zones, corneal volume, central corneal thickness, and SE after LI and PI until 1 year (all p > 0.05). Conclusions: LI plus PI ameliorated parameters of ACA efficiently and significantly reduced IOP in eyes with shallow AC until 1 year of long-term follow-up. However, parameters of the cornea and SE were not influenced by LI with PI until after 1 year.
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Affiliation(s)
- Hyun-kyung Cho
- Department of Ophthalmology, School of Medicine, Gyeongsang National University Changwon Hospital, Gyeongsang National University, Changwon 51472, Korea
- lnstitute of Health Sciences, School of Medicine, Gyeongsang National University, Jinju 52727, Korea
- Correspondence: or ; Tel.: +82-55-214-2410; Fax: +82-55-214-3257
| | - Wooseok Choae
- Department of Ophthalmology, Barunsungmo Eye Clinic, Busan 49247, Korea;
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Sánchez-González JM, Flikier D, Nebro-Cobos S, Zamorano-Martín F, Rachwani-Anil R, García-Lorente M, Borroni D, Peraza-Nieves J, Rocha-de-Lossada C. The Combined Effect of Tropicamide and Phenylephrine on Corneal Astigmatism Axis. Curr Eye Res 2021; 47:179-186. [PMID: 34437825 DOI: 10.1080/02713683.2021.1971720] [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: 10/20/2022]
Abstract
PURPOSE To analyze astigmatism axis changes after tropicamide and phenylephrine combined instillation. METHOD One hundred and thirty-one eyes from 66 patients enrolled this cross-sectional study. An extensive ocular examination was carried out prior to tropicamide and phenylephrine instillation. Power and axis value from flat, steep, and mean keratometry were calculated using an Auto Kerato-Refractometer (AKR). Later, topography and tomography maps were evaluated with Pentacam HR® (Oculus, Wetzlar, Germany). Subsequently, a single drop of tropicamide 1% and phenylephrine hydrochloride 10% were instilled twice, with a five-minute gap between each instillation. After 30 minutes, the AKR and Pentacam HR® tests were repeated. RESULTS Incyclotorsion was found in 59 eyes (45.1%) and mean absolute incyclotorsion change was 3.91 ± 3.62 degrees (0.10 to 14.20). Excyclotorsion was found in 72 eyes (54.9%) and mean excyclotorsion change was 4.99 ± 5.94 degrees (0.20 to 36.20). We observed that 74.6% and 68.1% of eyes experienced incyclotorsion and excyclotorsion within 0 to 5 degrees, respectively. Fewer patients experienced incyclotorsion and excyclotorsion changes within 5 to 10 degrees, precisely 11.8% and 19.4%, respectively. Eyes that experienced over 10 degrees of incyclotorsion and excyclotorsion were 13.6% and 12.5%, respectively. CONCLUSION Astigmatism axis could change after combined tropicamide and phenylephrine instillation. Reference axis marking in astigmatism correction surgery should be performed under the same circumstances as the astigmatism axis has been measured.
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Affiliation(s)
| | - David Flikier
- Department of Ophthalmology, Ocular Surgery Institute, San José, Costa Rica
| | | | | | - Rahul Rachwani-Anil
- Department of Ophthalmology, Regional University Hospital of Málaga, Málaga, Spain
| | - María García-Lorente
- Department of Ophthalmology, Regional University Hospital of Málaga, Málaga, Spain
| | - Davide Borroni
- Department of Doctoral Studies, Riga Stradins University, Riga, Latvia.,Ophthalmology, Fondazione Banca Degli Occhi del Veneto Onlus, Venezia, Italy
| | | | - Carlos Rocha-de-Lossada
- Department of Ophthalmology, Clinic Barcelona Hospital, Barcelona, Spain.,Department of Ophthalmology (Qvision), Vithas Virgen del Mar Hospital, Almería, Spain.,Department of Ophthalmology, Hospital Virgen de Las Nieves, Granada, Spain
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Suryakumar R, Maxwell A. Biometric assessment of pseudophakic subjects during objective accommodative stimulation: a prospective observational study. Clin Exp Optom 2021; 105:398-403. [PMID: 34228948 DOI: 10.1080/08164622.2021.1924624] [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: 10/20/2022] Open
Abstract
Clinical relevance: Ultrasound biomicroscopy is an objective method for assessing changes in anterior segment biometry. There is a paucity of data on the reliability of this method. A reliable method for assessing anterior segment changes during physiologically driven accommodation can be a useful tool for clinicians, researchers, and industry.Background: To assess the test-retest reliability of ultrasound biomicroscopy for measurements of change in anterior chamber depth during a distance to near fixation task in pseudophakic subjects.Methods: Subjects were adults with monofocal intraocular lenses implanted in both eyes who completed a 6-month post-operative period and had monocular uncorrected distance visual acuity of 6/15 (0.4 logMAR) or better. The change in anterior chamber depth during a distance to near fixation task was measured with a 35-MHz VuMAX HD ultrasound biomicroscopy device (Sonomed Escalon, New Hyde Park, NY) during two separate visits. An asymmetrical vergence paradigm allowed evaluation of anterior segment biometry at 22-µm axial resolution in one eye, while the fellow eye fixated on the target. To assess the test-retest reliability, 2-sided 95% CI from a paired t test was calculated for the difference in anterior chamber depth change from distance to near between visits.Results: The mean (standard deviation) near-focused anterior chamber depth measured by ultrasound biomicroscopy was 4.331 (0.237) and 4.333 (0.241) mm at visits 1 and 2, respectively. In response to a change in fixation from distance (4 m) to near (40 cm), the mean anterior chamber depth change was -0.012 (0.038) and 0.003 (0.039) mm at visits 1 and 2, respectively. Analysis of the difference in the change in anterior chamber depth between visits was -0.015 mm (95% CI, -0.035 to 0.003).Conclusion: Ultrasound biomicroscopy is a repeatable, objective method for assessing change in anterior segment biometry during physiological changes in fixation from distance to near.
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Lee DC, Lee SY. Analysis of astigmatism outcomes after horizontal rectus muscle surgery in patients with intermittent exotropia. PLoS One 2020; 15:e0240026. [PMID: 33031390 PMCID: PMC7544045 DOI: 10.1371/journal.pone.0240026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 09/18/2020] [Indexed: 11/19/2022] Open
Abstract
This study examined the factors affecting corneal curvature change after lateral rectus recession and medial rectus resection surgery in patients with intermittent exotropia. This was a retrospective cross-sectional study in intermittent exotropia patients who underwent rectus resection surgery. The study involved 41 male and 42 female patients (mean age: 9.55 ± 5.03 years, range: 3-28 years). Corneal astigmatism analysis was performed using the Galilei G4 Dual Scheimpflug Analyzer. The values of simulated and ray tracing corneal keratometry (K) of astigmatism, including axis changes, were determined preoperatively and at 1 week and 3 months postoperatively. The factors found to affect corneal curvature change were sex, extent of surgery, and axial length. Simulated and ray tracing changes were significant preoperatively and at 1 week and 3 months after rectus resection surgery (p < 0.05); however, there were no differences in astigmatism (D) at any time. The spherical equivalent had a myopic change after rectus resection surgery with cycloplegic refraction, and in ray tracing mode, flat K was decreased at 1 week from baseline and increased 3 months later. Steep, mean K, and axis increased continuously from baseline to 1 week and 3 months. Astigmatism, in contrast, was increased at 1 week, but decreased at 3 months, with no return to baseline. Univariable linear regression analyses showed that the extent of surgery had an effect on flat K change and that sex had an effect on steep K and axis. Additionally, axial length affected steep K and astigmatism, while age had no effect on any variable. Ray tracing values were significantly different from simulated values. In ray tracing mode, rectus resection surgery may result in astigmatism shifted toward with-the-rule, and myopic changes may be caused by differences in thickness and flexibility of the sclera. Notably, age did not affect any variable.
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Affiliation(s)
- Dong Cheol Lee
- Department of Ophthalmology, School of Medicine, and Institute for Medical Science, Keimyung University, Daegu, Korea
| | - Se Youp Lee
- Department of Ophthalmology, School of Medicine, Keimyung University, Daegu, Korea
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Niyazmand H, Read SA, Atchison DA, Collins MJ. Effects of accommodation and simulated convergence on anterior scleral shape. Ophthalmic Physiol Opt 2020; 40:482-490. [DOI: 10.1111/opo.12697] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 05/07/2020] [Indexed: 12/15/2022]
Affiliation(s)
- Hamed Niyazmand
- Contact Lens and Visual Optics Laboratory Institute of Health & Biomedical Innovation School of Optometry and Vision Science Queensland University of Technology Brisbane Australia
| | - Scott A Read
- Contact Lens and Visual Optics Laboratory Institute of Health & Biomedical Innovation School of Optometry and Vision Science Queensland University of Technology Brisbane Australia
| | - David A Atchison
- Visual and Ophthalmic Optics Laboratory Institute of Health & Biomedical Innovation School of Optometry and Vision Science Queensland University of Technology Brisbane Australia
| | - Michael J Collins
- Contact Lens and Visual Optics Laboratory Institute of Health & Biomedical Innovation School of Optometry and Vision Science Queensland University of Technology Brisbane Australia
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8
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Analysis of corneal real astigmatism and high order aberration changes that cause visual disturbances after lower eyelid epiblepharon repair surgery. Sci Rep 2020; 10:7498. [PMID: 32366891 PMCID: PMC7198593 DOI: 10.1038/s41598-020-64386-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 04/15/2020] [Indexed: 12/19/2022] Open
Abstract
This retrospective, cross-sectional study investigated changes in corneal low and high order aberrations (LOAs and HOAs) after lower eyelid epiblepharon repair surgery. In total, 108 eyes from 54 patients were evaluated. Wavefront analyses for calibrated LOAs and HOAs were performed using a Galilei G4 Dual Scheimpflug Analyzer before surgery and during the first and second follow-ups (f/u), adjusting for several risk factors. Flat keratometry (K) and axis values decreased significantly from baseline at the first f/u. At the second f/u, mean K and axis values decreased. Coma and trefoil increased from baseline at the first f/u and normalized by the second f/u. Spherical aberrations (SA) only decreased at the second f/u. After correction for risk factors, cylinder, coma, trefoil, and SA significantly increased at the first f/u; axis and flat K values decreased. At the second f/u, cylinder increased while axis and mean K values significantly decreased. Epiblepharon repair surgery may result in a shift from 'with-the-rule' to 'against-the-rule' axis change. Flat K, coma, and trefoil may be affected by mechanical force changes immediately post-surgery, while mean K values and SA may also change with corneal state changes including corneal erosion healing after the second f/u during the postoperative period.
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9
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Kim SJ, Cho HK, Park YM, Han YS, Park JM. Corneal topography and angle parameters after laser iridotomy combined with iridoplasty assessed by dual Scheimpflug analyzer. Int Ophthalmol 2019; 40:447-457. [PMID: 31720953 DOI: 10.1007/s10792-019-01205-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 10/22/2019] [Indexed: 12/19/2022]
Abstract
PURPOSE To investigate the changes in corneal topography including parameters such as corneal curvature and corneal aberrations, along with anterior chamber angle (ACA) after laser iridotomy (LI) combined with peripheral iridoplasty (PI) using dual Scheimpflug analyzer. METHODS In this prospective observational study, dual Scheimpflug analyzer images were acquired before and 1 week after LI plus PI. Corneal curvature of both axial and instantaneous maps from anterior and posterior surface, respectively, and total corneal power (TCP) were acquired. These corneal parameters from three zones (central, middle, and peripheral) and total corneal wavefront aberration, trefoil, and coma were obtained. The ACA from four quadrants, anterior chamber depth (ACD), anterior chamber volume (ACV), and intraocular pressure (IOP) were also inspected. RESULTS ACD increased significantly from 2.15 ± 0.25 to 2.18 ± 0.24 mm (P = 0.002). ACV and ACA from all four quadrants increased significantly after the laser treatment (all P < 0.05). IOP decreased significantly from 16.9 ± 3.1 to 14.7 ± 2.9 mmHg following LI plus PI (P = 0.000). No significant changes were detected in corneal axial and instantaneous curvature from three zones on the anterior and posterior corneal surface after LI plus PI (all P > 0.05). The TCP, total corneal wavefront aberration, trefoil, and coma also revealed no significant changes after the laser procedure (all P > 0.05). CONCLUSIONS Treatment with LI combined with PI did not affect the corneal topographic parameters from both anterior and posterior surfaces. However, LI plus PI improved ACA parameters significantly and effectively.
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Affiliation(s)
- Su Jin Kim
- Department of Ophthalmology, Pusan National University Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Republic of Korea
| | - Hyun-Kyung Cho
- Department of Ophthalmology, Gyeongsang National University Changwon Hospital, Gyeongsang National University, School of Medicine, 11 Samjeongja-ro, Seongsan-gu, Changwon, Gyeongsangnam-do, 51472, Republic of Korea. .,Institute of Health Sciences, School of Medicine, Gyeongsang National University, Jinju, Republic of Korea.
| | - Young Min Park
- Department of Ophthalmology, Gyeongsang National University Changwon Hospital, Gyeongsang National University, School of Medicine, 11 Samjeongja-ro, Seongsan-gu, Changwon, Gyeongsangnam-do, 51472, Republic of Korea
| | - Yong Seop Han
- Department of Ophthalmology, Gyeongsang National University Changwon Hospital, Gyeongsang National University, School of Medicine, 11 Samjeongja-ro, Seongsan-gu, Changwon, Gyeongsangnam-do, 51472, Republic of Korea
| | - Jong Moon Park
- Department of Ophthalmology, Gyeongsang National University Hospital, Gyeongsang National University, School of Medicine, Jinju, Republic of Korea.,Institute of Health Sciences, School of Medicine, Gyeongsang National University, Jinju, Republic of Korea
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10
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Del Águila-Carrasco AJ, Kruger PB, Lara F, López-Gil N. Aberrations and accommodation. Clin Exp Optom 2019; 103:95-103. [PMID: 31284325 DOI: 10.1111/cxo.12938] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 05/22/2019] [Accepted: 05/23/2019] [Indexed: 12/26/2022] Open
Abstract
Modern methods of measuring the refractive state of the eye include wavefront sensors which make it possible to monitor both static and dynamic changes of the ocular wavefront while the eye observes a target positioned at different distances away from the eye. In addition to monitoring the ocular aberrations, wavefront refraction methods allow measurement of the accommodative response while viewing with the eye's habitual chromatic and monochromatic aberrations present, with these aberrations removed, and with specific aberrations added or removed. A large number of experiments describing the effects of accommodation on aberrations and vice versa are reviewed, pointing out the implications for fundamental questions related to the mechanism of accommodation.
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Affiliation(s)
| | - Philip B Kruger
- College of Optometry, The State University of New York, New York, NY, USA
| | - Francisco Lara
- Vision Science Research Group (CiViUM), Instituto Universitario de Investigación en Envejecimiento (IUIE), University of Murcia, Murcia, Spain
| | - Norberto López-Gil
- Vision Science Research Group (CiViUM), Instituto Universitario de Investigación en Envejecimiento (IUIE), University of Murcia, Murcia, Spain
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Wallace HB, McKelvie J, Green CR, Misra SL. Corneal Curvature: the Influence of Corneal Accommodation and Biomechanics on Corneal Shape. Transl Vis Sci Technol 2019; 8:5. [PMID: 31316864 PMCID: PMC6615368 DOI: 10.1167/tvst.8.4.5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 05/11/2019] [Indexed: 12/22/2022] Open
Abstract
Purpose Variation in the presence and magnitude of corneal conformational changes during accommodation may predict postoperative ectasia following refractive surgery and assist in the early diagnosis of corneal ectatic disorders. The current study aimed to establish a baseline for corneal refractive changes during ocular accommodation and to clarify the role of biomechanical factors in predicting these changes in a population without corneal pathology. Methods GALILEI G2 corneal tomography was assessed in 63 participants in both the accommodated and unaccommodated states. Four diopters (D) of physiological accommodation were induced using near-acuity calibrated words viewed through an externally mounted beam splitter mounted on a three-dimensional-printed frame. Corneal biomechanical characteristics were assessed with the CorVis-ST instrument, and statistical analysis was completed in R software. Results Anterior chamber depth was reduced by 0.10 ± 0.07 mm with accommodation (P < 0.01). Areas of statistically significant change in corneal curvatures were seen in all participants with accommodation. Mean anterior instantaneous corneal power increased in the superior-nasal periphery (0.1 D, 95% confidence interval [CI] = 0.05–0.2 D) and decreased in the inferior-temporal periphery (0.1 D, 95% CI = −0.05 to −0.15 D). Corneal stiffness and the corneal deformation amplitude ratio predicted peripheral corneal curvature changes with accommodation (P < 0.05). Conclusion Corneal conformational changes occur during accommodation in normal subjects. Further studies are required to assess the magnitude of corneal changes during accommodation in patients with corneal ectasia. Translational Relevance An externally mounted beam splitter can be used to modify the visual target presented by clinical ocular imaging instruments. Corneal conformational changes during accommodation may be useful in the diagnosis of corneal ectasia.
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Affiliation(s)
- Henry B Wallace
- Department of Ophthalmology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - James McKelvie
- Department of Ophthalmology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Stuti L Misra
- Department of Ophthalmology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
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Domínguez-Vicent A, Brautaset R. Agreement and Repeatability of Two Biometers to Measure Anterior Segment Components: Refractive Error Effect. Med Sci Monit 2018; 24:8056-8063. [PMID: 30414377 PMCID: PMC6240168 DOI: 10.12659/msm.907683] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND To assess the repeatability and agreement between a new high-resolution optical coherence tomographer (OCT) and a Scheimpflug topographer. MATERIAL AND METHODS Sixty phakic and healthy participants were measured in this study, and one eye per participant was analyzed. Depending on their refractive error, each participant was allocated into a myopic, hyperopic, or emmetropic group. The Cirrus HD-OCT 5000 (Carl Zeiss Meditec, Jena, Germany), and the Sirius Scheimpflug topographer (Costruzione Strumenti Oftalmici, Florence, Italy) were used to take all measurements. RESULTS The repeatability of these instruments to measure the anterior chamber depth, angle-to-angle, thinnest pachymetry, and both nasal and temporal angles was smaller than 0.15 mm, 0.40 mm, 10 µm, and 10 degrees, respectively. However, the repeatability of the Scheimpflug instrument to measure the apex pachymetry was about 15 µm, and for the OCT, it was about 4 µm for all groups. On average, the Sirius Scheimpflug instrument measured shallower anterior chamber depth (about 0.10 mm), shorter angle-to-angle (about 0.5 mm), thinner corneas (approximately 10 µm), and narrower angles (around 5 degrees) for all refractive groups. CONCLUSIONS The repeatability of the Cirrus OCT and Sirius Scheimpflug instrument was good and independent of the refractive error. Nevertheless, to judge whether these instruments could be used interchangeable, clinical criteria are needed.
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Affiliation(s)
- Alberto Domínguez-Vicent
- Unit of Optometry, Department of Clinical Neuroscience, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Rune Brautaset
- Unit of Optometry, Department of Clinical Neuroscience, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
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13
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Grzybowski A, Schachar RA, Gaca-Wysocka M, Schachar IH, Pierscionek BK. Maximum human objectively measured pharmacologically stimulated accommodative amplitude. Clin Ophthalmol 2018; 12:201-205. [PMID: 29403261 PMCID: PMC5784748 DOI: 10.2147/opth.s154432] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Purpose To measure the maximum, objectively measured, accommodative amplitude, produced by pharmacologic stimulation. Methods Thirty-seven healthy subjects were enrolled, with a mean age of 20.2±1.1 years, corrected visual acuity of 20/20, and mean spherical equivalent refraction (SER) =-0.83±1.60 diopters. For each subject, the right pupil was dilated with phenylephrine 10%. After 30 minutes, the pupil was measured, the left eye was patched, and the right eye was autorefracted. Pilocarpine 4% was then instilled in the right eye, followed by phenylephrine. At 45 minutes after the pilocarpine, autorefraction and pupil size were again measured. Results Mean pupil size pre- and postpilocarpine was 8.0±0.8 mm and 4.4±1.9 mm, respectively. Pre- and postpilocarpine, the mean SER was -0.83±1.60 and -10.55±4.26 diopters, respectively. The mean pilocarpine-induced accommodative amplitude was 9.73±3.64 diopters. Five subjects had accommodative amplitudes ≥14.00 diopters. Accommodative amplitude was not significantly related to baseline SER (p-value =0.24), pre- or postpilocarpine pupil size (p-values =0.13 and 0.74), or change in pupil size (p-value =0.37). Iris color did not statistically significantly affect accommodative amplitude (p-value =0.83). Conclusion Following topically applied pilocarpine, the induced objectively measured accommodation in the young eye is greater than or equal to the reported subjectively measured voluntary maximum accommodative amplitude.
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Affiliation(s)
- Andrzej Grzybowski
- Institute for Research in Ophthalmology, Foundation for Ophthalmology Development, Poznan.,Department of Ophthalmology, University of Warmia and Mazury, Olsztyn, Poland
| | | | | | - Ira H Schachar
- Byers Eye Institute of Stanford University, Palo Alto, CA, USA
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Bagheri A, Feizi M, Shafii A, Faramarzi A, Tavakoli M, Yazdani S. Effect of Cycloplegia on Corneal Biometrics and Refractive State. J Ophthalmic Vis Res 2018; 13:101-109. [PMID: 29719636 PMCID: PMC5905301 DOI: 10.4103/jovr.jovr_196_17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Purpose To determine changes in refractive state and corneal parameters after cycloplegia with cyclopentolate hydrochloride 1% using a dual Scheimpflug imaging system. Methods In this prospective cross-sectional study patients aged 10 to 40 years who were referred for optometric evaluation enrolled and underwent autorefraction and corneal imaging with the Galilei dual Scheimpflug system before and 30 minutes after twice instillation of medication. Changes in refraction and astigmatism were investigated. Corneal biometrics including anterior and posterior corneal curvatures, total corneal power and corneal pachymetry were compared before and after cycloplegia. Results Two hundred and twelve eyes of 106 subjects with mean age of 28 ± 5 years including 201 myopic and 11 hyperopic eyes were evaluated. Mean spherical equivalent refractive error before cycloplegia was -3.4 ± 2.6 D. A mean hyperopic shift of 0.4 ± 0.5 D occurred after cycloplegia (P < 0.001). The astigmatism power did not significantly change (P = 0.8), however, 26.8% of eyes with significant astigmatism experienced a change of more than 5 degrees in the axis of astigmatism. Changes in posterior corneal curvature were scant but statistically significant (P = 0.001). Moreover, corneal thickness was slightly increased in the central and paracentral regions (P < 0.001 and P < 0.001, respectively). Conclusion Cycloplegia causes a hyperopic shift and astigmatism axis changes, along with an increase in central and paracentral corneal thickness and change in posterior corneal curvature. The effects of cycloplegia on refraction and corneal biometrics should be considered before cataract and refractive surgeries.
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Affiliation(s)
- Abbas Bagheri
- Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohadeseh Feizi
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Aliakbar Shafii
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Amir Faramarzi
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mehdi Tavakoli
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Shahin Yazdani
- Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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15
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Ferrer-Blasco T, Esteve-Taboada JJ, Monsálvez-Romín D, Aloy MA, Adsuara JE, Cerdá-Durán P, Montés-Micó R. Ocular biometric changes with different accommodative stimuli using swept-source optical coherence tomography. Int Ophthalmol 2017; 39:303-310. [PMID: 29260498 DOI: 10.1007/s10792-017-0813-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 12/11/2017] [Indexed: 05/09/2023]
Abstract
PURPOSE To evaluate ocular biometric changes with different accommodative stimuli using a new swept-source optical biometer. METHODS Only the right eye was analyzed. Each subject was measured six times with the IOLMaster 700 swept-source optical biometer (Carl Zeiss Meditec, Jena, Germany) with the subject looking at the stimulus shown by the instrument and with the subject looking at a target placed outside the instrument at 0D of vergence. Axial length (AL), anterior chamber depth (ACD), central corneal thickness (CCT), lens thickness (LT), white-to-white (WTW), and keratometry readings (K1 and K2) were evaluated in both cases. To assess if the changes found may affect the intraocular (IOL) power calculation for surgical applications, we have applied some formulae, using the software provided by the optical biometer manufacturer, to the ocular parameters found in both situations for three different types of IOLs. RESULTS No statistically significant differences were found for AL, CCT, WTW, K1 and K2 between the subject looking at the stimulus of the biometer and looking at the outside target at 0D of vergence (p > 0.05). However, the measurement of ACD revealed a statistically significant reduction of 20 microns (p = 0.03) and, on the contrary, LT increased significantly 30 microns (p = 0.02). ACD and LT changes were highly correlated (R2 = 0.91). As for the IOL power calculation, in all cases, the mean change was lower than 0.25 D both for IOL power selection and residual refraction. CONCLUSIONS Although ACD and LT change significantly with different accommodative stimuli measured by swept-source optical biometry, these changes are not clinically relevant.
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Affiliation(s)
- Teresa Ferrer-Blasco
- Department of Optics and Optometry and Vision Sciences, University of Valencia, C/Dr. Moliner, 50, 46100, Burjassot, Spain
| | - José J Esteve-Taboada
- Department of Optics and Optometry and Vision Sciences, University of Valencia, C/Dr. Moliner, 50, 46100, Burjassot, Spain.
| | - Daniel Monsálvez-Romín
- Department of Optics and Optometry and Vision Sciences, University of Valencia, C/Dr. Moliner, 50, 46100, Burjassot, Spain
| | - Miguel A Aloy
- Department of Astronomy and Astrophysics, University of Valencia, C/Dr. Moliner, 50, 46100, Burjassot, Spain
| | - José E Adsuara
- Department of Astronomy and Astrophysics, University of Valencia, C/Dr. Moliner, 50, 46100, Burjassot, Spain
| | - Pablo Cerdá-Durán
- Department of Astronomy and Astrophysics, University of Valencia, C/Dr. Moliner, 50, 46100, Burjassot, Spain
| | - Robert Montés-Micó
- Department of Optics and Optometry and Vision Sciences, University of Valencia, C/Dr. Moliner, 50, 46100, Burjassot, Spain
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16
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Mechanism of accommodation assessed by change in precisely registered ocular images associated with concurrent change in auto-refraction. Graefes Arch Clin Exp Ophthalmol 2017; 256:395-402. [PMID: 29147767 DOI: 10.1007/s00417-017-3843-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 09/27/2017] [Accepted: 11/04/2017] [Indexed: 10/18/2022] Open
Abstract
PURPOSE Our purpose was to determine the changes in anterior chamber depth (ACD) and central lens thickness (CLT) during pharmacologically induced accommodation. METHODS Following pupillary dilation with phenylephrine 10%, baseline auto-refractions and swept-source optical coherence tomographic biometric images (Zeiss IOLMaster 700) were obtained from the right eyes of 25 subjects aged 19 to 24 years. Pilocarpine 4% and phenylephrine 10% were then instilled into these right eyes. One hour later, auto-refractions and biometric imaging were repeated. Only data from eight of 25 subjects met the following stringent criteria to be included in the study analysis: pre and post-pilocarpine biometric foveal images were registerable, the images of the corneal centers were shifted by ≤100 μm, pupils >5 mm and the pharmacologically induced refractive change was ≥ -7 diopters. RESULTS The mean auto-refractive accommodative change for the eight included subjects was -12.45 diopters (± 3.45 diopters). The mean change in CLT was 81 μm (± 54 μm) and the mean change in ACD was -145 μm (± 86 μm). Superimposition of the registered pre and post-pilocarpine biometric images of the sagittal sections of the whole eye from each subject demonstrated that the position of the whole lens did not shift either anteriorly, posteriorly or vertically during pharmacologically induced accommodation. CONCLUSIONS A small increase in lens thickness was associated with a large change in accommodative amplitude and no significant change in lens position as predicted by the Schachar theory.
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17
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Ocular anatomic changes for different accommodative demands using swept-source optical coherence tomography: a pilot study. Graefes Arch Clin Exp Ophthalmol 2017; 255:2399-2406. [DOI: 10.1007/s00417-017-3801-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Revised: 09/02/2017] [Accepted: 09/08/2017] [Indexed: 01/07/2023] Open
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Schachar RA, Mani M, Schachar IH. Image registration reveals central lens thickness minimally increases during accommodation. Clin Ophthalmol 2017; 11:1625-1636. [PMID: 28979092 PMCID: PMC5602687 DOI: 10.2147/opth.s144238] [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] [Indexed: 11/23/2022] Open
Abstract
Purpose To evaluate anterior chamber depth, central crystalline lens thickness and lens curvature during accommodation. Setting California Retina Associates, El Centro, CA, USA. Design Healthy volunteer, prospective, clinical research swept-source optical coherence biometric image registration study of accommodation. Methods Ten subjects (4 females and 6 males) with an average age of 22.5 years (range: 20–26 years) participated in the study. A 45° beam splitter attached to a Zeiss IOLMaster 700 (Carl Zeiss Meditec Inc., Jena, Germany) biometer enabled simultaneous imaging of the cornea, anterior chamber, entire central crystalline lens and fovea in the dilated right eyes of subjects before, and during focus on a target 11 cm from the cornea. Images with superimposable foveal images, obtained before and during accommodation, that met all of the predetermined alignment criteria were selected for comparison. This registration requirement assured that changes in anterior chamber depth and central lens thickness could be accurately and reliably measured. The lens radii of curvatures were measured with a pixel stick circle. Results Images from only 3 of 10 subjects met the predetermined criteria for registration. Mean anterior chamber depth decreased, −67 μm (range: −0.40 to −110 μm), and mean central lens thickness increased, 117 μm (range: 100–130 μm). The lens surfaces steepened, anterior greater than posterior, while the lens, itself, did not move or shift its position as appeared from the lack of movement of the lens nucleus, during 7.8 diopters of accommodation, (range: 6.6–9.7 diopters). Conclusion Image registration, with stable invariant references for image correspondence, reveals that during accommodation a large increase in lens surface curvatures is associated with only a small increase in central lens thickness and no change in lens position.
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Affiliation(s)
- Ronald A Schachar
- Department of Physics, University of Texas at Arlington, Arlington, TX
| | | | - Ira H Schachar
- Byers Eye Institute of Stanford University, Palo Alto, CA, USA
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Scheimpflug image-based changes in anterior segment parameters during accommodation induced by short-term reading. Eur J Ophthalmol 2017; 27:301-307. [PMID: 27646325 DOI: 10.5301/ejo.5000853] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2016] [Indexed: 12/25/2022]
Abstract
PURPOSE To analyze the effect of the accommodation on the anterior segment data (corneal and anterior chamber parameters) induced by short-time reading in a healthy, nonpresbyopic adult patient group. METHODS Images of both eyes of nonpresbyopic volunteers were captured with a Scheimpflug device (Pentacam HR) in a nonaccommodative state. Fifteen minutes of reading followed and through fixation of the built-in target of Pentacam HR further accommodation was achieved and new images were captured by the device. Anterior segment parameters were observed and the differences were analyzed. RESULTS Fifty-two healthy eyes of 26 subjects (range 20.04-28.58 years) were analyzed. No significant differences were observed in the keratometric values before and after the accommodative task (p = 0.35). A statistically significant difference was measured in the 5.0-mm-diameter and the 7.0-mm-diameter corneal volume (p = 0.01 and p = 0.03) between accommodation states. Corneal aberrometric data did not change significantly during short-term accommodation. Significant differences were observed between nonaccommodative and accommodative states of the eyes for all measured anterior chamber parameters. CONCLUSIONS Among the parameters of the cornea, only corneal volume changed during the short-term accommodation process, showing some fine changes with accommodation of the cornea in young, emmetropic patients. The position of the pupil and the anterior chamber parameters were observed to change with accommodation as captured by a Scheimpflug device.
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Scleral changes with accommodation. Ophthalmic Physiol Opt 2017; 37:263-274. [DOI: 10.1111/opo.12377] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 02/21/2017] [Indexed: 11/26/2022]
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Esteve-Taboada JJ, Domínguez-Vicent A, Monsálvez-Romín D, Del Águila-Carrasco AJ, Montés-Micó R. Non-invasive measurements of the dynamic changes in the ciliary muscle, crystalline lens morphology, and anterior chamber during accommodation with a high-resolution OCT. Graefes Arch Clin Exp Ophthalmol 2017; 255:1385-1394. [DOI: 10.1007/s00417-017-3663-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 03/22/2017] [Accepted: 03/27/2017] [Indexed: 01/28/2023] Open
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22
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Domínguez-Vicent A, Trussardi C, Wogatai U, Montés-Micó R, Brautaset R. Precision of High-Resolution OCT for Anterior Chamber Measurement: Agreement With Scheimpflug Imaging. J Refract Surg 2016; 32:766-772. [DOI: 10.3928/1081597x-20160721-03] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 06/23/2016] [Indexed: 11/20/2022]
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Niyaz L, Can E, Seymen Z, Eraydin B. Comparison of Anterior Segment Parameters Obtained by Dual-Scheimpflug Analyzer Before and After Cycloplegia in Children. J Pediatr Ophthalmol Strabismus 2016; 53:234-7. [PMID: 27182749 DOI: 10.3928/01913913-20160427-02] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 03/08/2016] [Indexed: 11/20/2022]
Abstract
PURPOSE To assess the changes of anterior segment parameters with cycloplegia. METHODS A cross-sectional study of healthy pediatric patients was performed. Anterior segment parameters were obtained by the Galilei Dual-Scheimpflug analyzer (Ziemer Group, Port, Switzerland) before and 40 minutes after the instillation of cyclopentolate. The effect of gender was evaluated. RESULTS There were 43 boys and 50 girls with a mean age of 7.76 ± 2.7 years. There was a significant increase in anterior chamber depth, anterior chamber volume, and pupil diameter after the cycloplegia (P < .05). The anterior chamber angle increased after cycloplegia in the nasal, temporal, and inferior quadrants (P < .05), but not in the superior quadrant (P > .05). The mean values of anterior segment parameters were similar in both genders. CONCLUSIONS The values of anterior chamber depth, anterior chamber volume, anterior chamber angle, and pupil diameter measured with the Galilei Dual-Scheimpflug analyzer increased significantly after cycloplegia. Gender did not have an effect on anterior segment parameters. [J Pediatr Ophthalmol Strabismus. 2016;53(4):234-237.].
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