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Kumar P, Vaddavalli PK, Campbell P, Hull CC, Bharadwaj SR. Suprathreshold contrast perception of resolvable high spatial frequencies remain intact in keratoconus. Vision Res 2023; 212:108310. [PMID: 37582329 DOI: 10.1016/j.visres.2023.108310] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 07/29/2023] [Accepted: 07/29/2023] [Indexed: 08/17/2023]
Abstract
Contrast detection thresholds are elevated with optical quality loss in keratoconus. This study hypothesized that suprathreshold contrast perception is also impaired in keratoconus, with the impairment being predictable from the pattern of loss in threshold-level performance. Contrast detection thresholds were determined across a range of spatial frequencies in 12 cases with mild to severe keratoconus and 12 age-similar controls. These values were used to predict the contrast needed to achieve perceptual matches between reference and test spatial frequency pairs (peak of CSF Vs. 0.3x, 0.5x, 2x or 3x spatial frequency from the peak) for stimuli at 10% and 50% suprathreshold contrast. Contrast thresholds predicted a 1.5 to 6.7-fold increase in the test pattern's contrast to obtain a perceptual match with the reference pattern in keratoconus, relative to controls. Contrary to predictions, the empirical data of contrast matches between test and reference patterns were similar for higher than peak spatial frequencies at both contrast levels. However, as predicted, test patterns required higher contrast than the reference pattern for a perceptual match for lower than peak spatial frequencies. These results were similar to controls and invariant of disease severity, interocular asymmetry and short-term changes in optical quality. Unlike thresholds, suprathreshold contrast perception of resolvable high spatial frequencies appears immune to optical quality losses in keratoconus. These results are discussed in the context of the prevailing models of contrast constancy in healthy humans. Breakdown of contrast constancy at lower than peak spatial frequencies may reflect the properties of the testing paradigm employed here.
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Affiliation(s)
- Preetam Kumar
- Department of Optometry and Visual Science, School of Health and Psychological Sciences, City, University of London, Northampton Square, London EC1V 0HB, United Kingdom; Brien Holden Institute of Optometry and Vision Sciences, L V Prasad Eye Institute, Road no. 2, Banjara Hills, Hyderabad 500034, Telangana, India; Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, L V Prasad Eye Institute, Road no. 2, Banjara Hills, Hyderabad 500034, Telangana, India
| | - Pravin Krishna Vaddavalli
- The Cornea Institute, L V Prasad Eye Institute, Road no. 2, Banjara Hills, Hyderabad 500034, Telangana, India
| | - Peter Campbell
- Department of Optometry and Visual Science, School of Health and Psychological Sciences, City, University of London, Northampton Square, London EC1V 0HB, United Kingdom
| | - Christopher C Hull
- Department of Optometry and Visual Science, School of Health and Psychological Sciences, City, University of London, Northampton Square, London EC1V 0HB, United Kingdom
| | - Shrikant R Bharadwaj
- Brien Holden Institute of Optometry and Vision Sciences, L V Prasad Eye Institute, Road no. 2, Banjara Hills, Hyderabad 500034, Telangana, India; Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, L V Prasad Eye Institute, Road no. 2, Banjara Hills, Hyderabad 500034, Telangana, India.
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Wang Y, Guo Y, Wei S, Wu T, Yuan Y, Zhang Y, Li X, Chen Y. Dynamic Visual Acuity After Small Incision Lenticule Extraction for Myopia Patients. Percept Mot Skills 2023; 130:403-418. [PMID: 36226374 DOI: 10.1177/00315125221133434] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the present study we compared dynamic visual acuity (DVA) of 84 eyes (for 42 adults with myopia; M age = 28.4, SD = 6.6 years; males = 38.1%, females = 61.9%) at 40 and 80 degree per second (dps) before surgery with eyeglass corrections and after a surgical procedure - a small incision lenticule extraction (SMILE). Participants underwent binocular SMILE surgery with plano refraction targets. Their eyeglass-corrected binocular DVA at 40 and 80 dps was evaluated preoperatively, and their uncorrected binocular DVA was assessed post-operatively at 1 week, 1 month and 3 months. The mean logMAR (logarithm of the minimum angle of resolution) uncorrected and corrected distance visual acuities (UDVA and CDVA) were -0.09 and -0.11 respectively, 3 months postoperatively. The mean preoperative eyeglass-corrected DVAs at 40 and 80 dps were 0.141 and 0.184, respectively, and significant improvements were observed for 40 dps and 80 dps DVAs 3 months postoperatively. Pearson's correlations were statistically significant between the postoperative DVAs at 3 months and for both the preoperative DVA and postoperative UDVA at both 40 dps and 80 dps. The change in the DVAs at 3 months were significantly associated with the preoperative DVAs at 40 dps and 80 dps. In conclusion, myopic patients' DVAs significantly improved following SMILE in comparison to corrected preoperative visual acuity when wearing eyeglasses. The post-SMILE DVA was associated with both the preoperative DVA and the postoperative UDVA.
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Affiliation(s)
- Yuexin Wang
- Department of Ophthalmology, 66482Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Beijing, China
| | - Yining Guo
- Department of Ophthalmology, 66482Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Beijing, China
| | - Shanshan Wei
- Department of Ophthalmology, 66482Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Beijing, China
| | - Tingyi Wu
- Department of Ophthalmology, 66482Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Beijing, China
| | - Yifei Yuan
- Department of Ophthalmology, 66482Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Beijing, China
| | - Yu Zhang
- Department of Ophthalmology, 66482Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Beijing, China
| | - Xuemin Li
- Department of Ophthalmology, 66482Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Beijing, China
| | - Yueguo Chen
- Department of Ophthalmology, 66482Peking University Third Hospital, Beijing, China.,Beijing Key Laboratory of Restoration of Damaged Ocular Nerve, Beijing, China
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Ding X, Tan J, Meng J, Shao Y, Shen M, Dai C. Time-Serial Evaluation of the Development and Treatment of Myopia in Mice Eyes Using OCT and ZEMAX. Diagnostics (Basel) 2023; 13:diagnostics13030379. [PMID: 36766483 PMCID: PMC9914737 DOI: 10.3390/diagnostics13030379] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 01/17/2023] [Indexed: 01/20/2023] Open
Abstract
Myopia is a significant cause of visual impairment which may lead to many complications. However, the understanding of the mechanisms of myopia is still limited. In this paper, in order to investigate the development and the treatment of myopia, we analyzed the biological structure parameters of mice eyes, obtained from optical coherence tomography (OCT), and the optical performance of mice eyes calculated using ZEMAX software (ZEMAX Development Corporation, Kirkland, WA, USA) in which the optical model was built on the segment-by-segment optically corrected OCT 3D-images. Time-serial evaluation of three groups of mice eyes (form-deprivation myopia mice eyes, normal mice eyes, and atropine-treated myopia mice eyes) was performed. In addition to the biological structure parameters, imaging performance with the development of root-mean-square wavefront aberration at six filed angles was compared and analyzed. Results show that the biological structure parameters of the eye are closely related to the development of myopia. The peripheral defocus of the retina has a significant impact on inducing myopia, which verifies the new theory of myopia development. The delaying effect of atropine solution on myopia development is shown to verify the therapeutic effect of the medicine. This study provides technical support for the investigation of the myopia mechanism.
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Affiliation(s)
- Xueqing Ding
- College of Science, Shanghai Institute of Technology, Shanghai 201418, China
| | - Jinzhen Tan
- College of Computer Science, Qufu Normal University, Qufu 276825, China
| | - Jing Meng
- College of Computer Science, Qufu Normal University, Qufu 276825, China
| | - Yilei Shao
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou 325035, China
| | - Meixiao Shen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou 325035, China
- Correspondence: (M.S.); (C.D.); Tel.: +86-21-13564027065 (C.D.)
| | - Cuixia Dai
- College of Science, Shanghai Institute of Technology, Shanghai 201418, China
- Correspondence: (M.S.); (C.D.); Tel.: +86-21-13564027065 (C.D.)
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González-Cruces T, Villarrubia A, Sánchez Ventosa Á, Palacín Miranda E, Castillo Eslava R, Gomera Martinez A, García Párrizas JA, Torres Huelva P, Sánchez-González JM, Cano-Ortiz A. Comparison Between the Wavefront-Optimized and Custom-Q Aspheric Ablation Profiles in Myopic Eyes With Two Different Q-targets: A Contralateral Eye Study. J Refract Surg 2022; 38:698-707. [DOI: 10.3928/1081597x-20221005-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Long Y, Li X, Zhou T, Ye B, Guo D, Shen Y. Short-term Evaluation of Visual Quality, Amplitude of Accommodation, and Stereoacuity Between Patients With Moderate-to-High Myopia Who Underwent ICLV4c Implantation and SMILE. J Refract Surg 2022; 38:632-640. [DOI: 10.3928/1081597x-20220919-02] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Devi P, Kumar P, Marella BL, Bharadwaj SR. Impact of Degraded Optics on Monocular and Binocular Vision: Lessons from Recent Advances in Highly-Aberrated Eyes. Semin Ophthalmol 2022; 37:869-886. [PMID: 35786147 DOI: 10.1080/08820538.2022.2094711] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
PURPOSE Optical imperfections of the eye, characterized by higher-order wavefront aberrations, are exaggerated in corneal disease (e.g., keratoconus) and iatrogeny (e.g., keratorefractive surgery for myopia correction, keratoplasty for optical clarity restoration). This article reviews the recent advances on this topic for a comprehensive understanding of how optical degradations in disease models impact retinal image quality and monocular and binocular visual performance. METHODS Published literature over the last decade on retinal image quality and/or monocular and binocular visual functions with corneal irregularity was reviewed based on their relevance to the current topic, study population and strength of study design. The literature was summarized into four themes: 1) wavefront errors and retinal image quality of highly aberrated eyes, 2) monocular and binocular vision loss consequent to degraded optics and visual strategies to optimize performance, 3) impact of optical correction modalities on visual performance and 4) implications for clinical management of patients. RESULTS Across the 46 articles reviewed, the results clearly indicated that an increase in higher-order aberrations across these conditions had a significant negative impact on the patient's retinal image quality, and monocular and binocular visual functions. Interocular differences in retinal image quality deteriorated visual performance more than an overall worsening of image quality bilaterally. Minimizing optical degradation using rigid contact lenses and adaptive optics technology significantly improves retinal image quality and monocular and binocular vision, but performance remains sub-optimal relative to age-similar healthy controls. CONCLUSION Corneal disease and iatrogeny are useful models to understand the impact of optical degradation on retinal image quality and visual performance. Clinical management will greatly benefit from equalizing retinal image quality of both eyes of these patients. Future studies that deepen our understanding of the structure-function relation in these conditions are desirable for advancing vision science in this area and for developing novel clinical management strategies.
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Affiliation(s)
- Preetirupa Devi
- Brien Holden Institute of Optometry and Vision Sciences, L V Prasad Eye Institute, Hyderabad, India.,Prof Brien Holden Eye Research Centre, L V Prasad Eye Institute, Hyderabad, India.,School of Health Sciences, Division of Optometry and Visual Sciences, City, University of London, London, UK
| | - Preetam Kumar
- Brien Holden Institute of Optometry and Vision Sciences, L V Prasad Eye Institute, Hyderabad, India.,Prof Brien Holden Eye Research Centre, L V Prasad Eye Institute, Hyderabad, India.,School of Health Sciences, Division of Optometry and Visual Sciences, City, University of London, London, UK
| | - Bhagya Lakshmi Marella
- Brien Holden Institute of Optometry and Vision Sciences, L V Prasad Eye Institute, Hyderabad, India.,Prof Brien Holden Eye Research Centre, L V Prasad Eye Institute, Hyderabad, India.,School of Health Sciences, Division of Optometry and Visual Sciences, City, University of London, London, UK
| | - Shrikant R Bharadwaj
- Brien Holden Institute of Optometry and Vision Sciences, L V Prasad Eye Institute, Hyderabad, India.,Prof Brien Holden Eye Research Centre, L V Prasad Eye Institute, Hyderabad, India
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Sarkar S, Devi P, Vaddavalli PK, Reddy JC, Bharadwaj SR. Differences in Image Quality after Three Laser Keratorefractive Procedures for Myopia. Optom Vis Sci 2022; 99:137-149. [PMID: 34974458 DOI: 10.1097/opx.0000000000001850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
SIGNIFICANCE Psychophysical estimates of spatial and depth vision have been shown to be better after bilateral ReLEx small-incision lenticule extraction (SMILE) refractive surgery for myopia, relative to photorefractive keratectomy (PRK) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK). The present study provides the optical basis for these findings using computational image quality analysis. PURPOSE This study aimed to compare longitudinal changes in higher-order wavefront aberrations and image quality before and after bilateral PRK, FS-LASIK, and SMILE refractive procedures for correcting myopia. METHODS Wavefront aberrations and image quality of both the eyes of 106 subjects (n = 40 for FS-LASIK and SMILE and n = 26 for PRK) were determined pre-operatively and at 1-week, 1-month, 3-month, and 6-month post-operative intervals using computational through-focus analysis for a 6-mm pupil diameter. Image quality was quantified in terms of its peak value and its interocular difference, residual defocus that was needed to achieve peak image quality (best focus), and the depth of focus. RESULTS The increase in root mean squared deviations of higher-order aberrations post-operatively was lesser after SMILE (1-month visit median [25th to 75th interquartile range], 0.34 μm (0.28 to 0.39 μm]) than after PRK (0.80 μm [0.74 to 0.87 μm]) and FS-LASIK (0.74 μm [0.59 to 0.83 μm]; P ≤ .001), all relative to pre-operative values (0.20 μm [0.15 to 0.30 μm]). The peak image quality dropped and its interocular difference increased, best focus shifted myopically by 0.5 to 0.75 D, and depth of focus widened significantly after PRK and FS-LASIK surgeries, all relative to pre-operative values (P < .001). All these changes were negligible but statistically significant in a minority of instances after SMILE surgery (P ≥ .01). CONCLUSIONS Although all three refractive surgeries correct myopia, the image quality and its similarity between eyes are better and closer to pre-operative values after SMILE, compared with FS-LASIK and PRK. These results can be explained from the underlying increase in higher-order wavefront aberrations experienced by the eye post-operatively.
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Affiliation(s)
| | | | | | - Jagadesh C Reddy
- The Cornea Institute, L V Prasad Eye Institute, Hyderabad, Telangana, India
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Peyman A, Pourazizi M, Akhlaghi M, Feizi A, Rahimi A, Soltani E. Stereopsis after corneal refractive surgeries: a systematic review and meta-analysis. Int Ophthalmol 2022; 42:2273-2288. [PMID: 35041131 DOI: 10.1007/s10792-021-02201-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 12/21/2021] [Indexed: 11/25/2022]
Abstract
PURPOSE To systematically review the published manuscripts on stereopsis after corneal refractive surgery. METHODS The Web of Science, PubMed, Scopus, ProQuest, Clinical Key, Embase, and Cochrane Library were searched for relevant articles published until August 2020. The fixed- or random-effects models were used to estimate the Weighted mean difference (WMD) or Relative risk (RR) and 95% Confidence interval (CI) for postoperative stereopsis changes and incidence when applicable. Meta-regression was conducted for adjusting the effects of potential confounders. RESULTS Seven studies (1266 eyes) in adults and ten studies in pediatrics (259 eyes) were included. In adults, stereopsis improved significantly compared to the preoperative state (WMD = - 27.4, 95% CI = - 40.0, - 14.7; I2 = 97.8%; P < 0.001). In pediatrics, proportion of patients with stereoacuity postoperatively was 2.18 times compared to preoperative evaluation. (RR = 2.18, 95% CI = 1.2, 3.9; I2 = 68.6%, P < 0.001). CONCLUSIONS Stereopsis improves after corneal refractive surgery in adults and pediatrics.
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Affiliation(s)
- Alireza Peyman
- Isfahan Eye Research Center, Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mohsen Pourazizi
- Isfahan Eye Research Center, Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mohamadreza Akhlaghi
- Isfahan Eye Research Center, Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Awat Feizi
- Biostatistics and Epidemiology Department, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Alireza Rahimi
- Health Information Research Center, Medical Informatics Department, Faculty of Medical Management and Information Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Elham Soltani
- Isfahan Eye Research Center, Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran.
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Impact on binocular visual function of small-incision lenticule extraction for high myopia. J Cataract Refract Surg 2021; 47:430-438. [PMID: 33181628 DOI: 10.1097/j.jcrs.0000000000000480] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 09/28/2020] [Indexed: 11/26/2022]
Abstract
PURPOSE To assess whether small-incision lenticule extraction (SMILE) for high myopia reduces the binocular visual function assessed by stereoacuity, binocular visual acuity, binocular contrast sensitivity, and binocular summation. SETTING University hospital. DESIGN Prospective case series. METHODS Patients with a myopic spherical equivalent of at least 6.00 diopters (D) scheduled for SMILE aimed at emmetropia were included. Psychophysical testing was performed with correction preoperatively but no correction postoperatively. Stereoacuity was assessed with the Randot Circles test and the near Frisby test, visual acuity (monocular and binocular) was assessed with high-contrast Early Treatment Diabetic Retinopathy Study charts, and contrast sensitivity (monocular and binocular) was assessed with the Pelli-Robson chart and the Freiburg Acuity and Contrast Test. Binocular summation was calculated by comparing the binocular score against the best monocular score. RESULTS A total of 138 eyes of 69 patients were included. The mean spherical equivalent changed from -7.46 D ± 1.06 (SD) to -0.23 D ± 0.40 postoperatively. Stereoacuity did not change significantly postoperatively; median change (interquartile range) was -0.32 (-6.21 to 1.55) seconds of arc with the Frisby test and 0.00 (-7.5 to 5.0) seconds of arc with the Randot test (P ≥ .06). Binocular postoperative uncorrected distance visual acuity was not different from the preoperative corrected distance visual acuity (P = .40). Contrast sensitivity declined slightly monocularly with both tests of contrast sensitivity but was unaltered binocularly (P ≥ .08). Binocular summation for visual acuity and contrast sensitivity was unaltered following surgery (P ≥ .09). CONCLUSIONS SMILE for high myopia did not reduce the binocular function assessed by stereoacuity, binocular visual acuity, binocular contrast sensitivity, and binocular summation.
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Detection of Static and Dynamic Stereopsis after Femtosecond Laser Small Incision Lenticule Extraction for High Myopia. J Ophthalmol 2021; 2021:6667263. [PMID: 34221494 PMCID: PMC8213482 DOI: 10.1155/2021/6667263] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 06/03/2021] [Indexed: 11/30/2022] Open
Abstract
Purpose The purpose of this study is to test binocular visual function after femtosecond laser small incision lenticule extraction (SMILE) for high myopia. The traditional Titmus stereotest and dynamic stereotest based on the visual perception biological model were used for comparative analysis. Methods A total of 43 patients were enrolled in this prospective study. At Week 1, Month 1, and Month 3 after surgery, the Titmus stereotest and dynamic stereotest generated by MATLAB were conducted. Dynamic stereopsis consists of randomly flickering Gabor spots and is divided into two models of high energy and low energy according to flicker frequency. Results The preoperative manifest refraction spherical equivalent was −7.21 ± 0.70 D. The preoperative anisometropia was 0.52 ± 0.54D. The quartiles of static stereoacuity in preoperation and 3 follow-ups were as follows: 50.00 (25.00, 100.00) in preoperation, 63.00 (40.00, 63.00) at Week 1, 40.00 (32.00, 63.00) at Month 1, and 40.00 (25.00, 50.00) at Month 3. Static stereopsis improved at Month 1 and Month 3 compared with preoperation and Week 1 (P < 0.05). There were statistically significant differences in high energy dynamic stereopsis at Week 1 and Month 1 compared to preoperation (P < 0.05). In addition, significant differences in low energy dynamic stereopsis were detected between Month 1 and preoperation and also at Month 3 compared to Month 1 (P < 0.05). Conclusion Most high myopia patients have a dynamic stereopsis deficiency before refractive correction. SMILE surgery can improve both static and dynamic stereopsis early in the postoperation period. However, in the long term, there is no significant difference or even a decrease in dynamic stereopsis.
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Marella BL, Conway ML, Suttle C, Bharadwaj SR. Contrast Rivalry Paradigm Reveals Suppression of Monocular Input in Keratoconus. Invest Ophthalmol Vis Sci 2021; 62:15. [PMID: 33570601 PMCID: PMC7884294 DOI: 10.1167/iovs.62.2.12] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Keratoconus results in image quality loss in one or both eyes due to increased corneal distortion. This study quantified the depth of monocular suppression in keratoconus due to this image quality loss using a binocular contrast rivalry paradigm. Methods Contrast rivalry was induced in 50 keratoconic cases (11–31 years) and 12 age-matched controls by dichoptically viewing orthogonal Gabor patches of 5 cycles per degree (cpd) and 1.5 cpd spatial frequency for 120 seconds with their best-corrected spectacles and rigid gas permeable (RGP) contact lenses. The dwell time on each eye's percept was determined at baseline (100% contrast bilaterally) and at varying contrast levels (80–2.5%) in the stronger eye of keratoconus or dominant eye of controls. The contrast reduction needed in the stronger eye to balance dwell times on both eyes was considered a measure of suppression depth. Results At baseline with 5 cpd stimuli and spectacle correction, the rivalry switches were less frequent and biased toward the stronger eye of cases, all relative to controls (P < 0.001). The contrast balance point of cases (20.51% [10.7–61%]) was lower than the controls (99.80% [98.6–100%]; P < 0.001) and strongly associated with the overall and interocular difference in disease severity (r = 0.83, P < 0.001). The suppression depth reduced for 1.5 cpd (70.8% [21.7–94%]), relative to 5 cpd stimulus (P < 0.001) and with contact lenses (80.1% [49.5–91.7%]), relative to spectacles (P < 0.001). Conclusions The eye with lesser disease severity dominates binocular viewing in keratoconus. The suppression depth of the poorer eye depends on the extent of bilateral disease severity, optical correction modality, and the target spatial frequency.
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Affiliation(s)
- Bhagya Lakshmi Marella
- Brien Holden Institute of Optometry and Vision Sciences, L V Prasad Eye Institute, Banjara Hills, Hyderabad, Telangana, India.,Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, L V Prasad Eye Institute, Banjara Hills, Hyderabad, Telangana, India.,School of Health Sciences, Division of Optometry and Visual Sciences, City, University of London, Northampton Square, London, United Kingdom
| | - Miriam L Conway
- School of Health Sciences, Division of Optometry and Visual Sciences, City, University of London, Northampton Square, London, United Kingdom
| | - Catherine Suttle
- School of Health Sciences, Division of Optometry and Visual Sciences, City, University of London, Northampton Square, London, United Kingdom
| | - Shrikant R Bharadwaj
- Brien Holden Institute of Optometry and Vision Sciences, L V Prasad Eye Institute, Banjara Hills, Hyderabad, Telangana, India.,Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, L V Prasad Eye Institute, Banjara Hills, Hyderabad, Telangana, India
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12
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Zhang J, He F, Liu Y, Fan X. Implantable collamer lens with a central hole for residual refractive error correction after corneal refractive surgery. Exp Ther Med 2020; 20:160. [PMID: 33093898 PMCID: PMC7571336 DOI: 10.3892/etm.2020.9289] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 09/11/2020] [Indexed: 11/06/2022] Open
Abstract
The present study aimed to assess the visual and refractive outcomes of an implantable collamer lens with a central hole (ICL V4c) for residual refractive error correction after corneal refractive surgery in individuals with myopia. A total of 16 eyes of eight consecutive patients with myopia undergoing ICL V4c implantation after corneal refractive surgery were investigated. The uncorrected visual acuity (VA) and best-corrected VA were examined prior to surgery and at 1, 3 and 6 months after surgery. The post-operative values of the modulation transfer function (MTF) cutoff frequency, Strehl ratio (SR), objective scattering index (OSI) and Optical Quality Analysis System (OQAS) values (OVs) were quantitatively assessed using an OQAS. At 6 months after surgery, the mean uncorrected LogMAR VA was 0.06±0.10 and the values had improved in 100% of the eyes. The mean MTF cutoff frequency, SR, OSI, OV 100%, OV 20% and OV 9%, were 31.294±4.321 cycles/degree, 0.187±0.039, 1.399±0.274, 1.066±0.261, 0.748±0.287 and 0.509±0.229, respectively. In conclusion, ICL V4c implantation for the correction of residual refractive error after corneal refractive surgery appeared feasible and safe and also had an excellent optical performance. However, long-term changes in visual quality require further investigation.
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Affiliation(s)
- Jing Zhang
- Department of Ophthalmology, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, P.R. China
| | - Fanglin He
- Department of Ophthalmology, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, P.R. China
| | - Yan Liu
- Department of Ophthalmology, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, P.R. China
| | - Xianqun Fan
- Department of Ophthalmology, Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, P.R. China
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