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1.
Heliyon ; 10(10): e30871, 2024 May 30.
Article En | MEDLINE | ID: mdl-38784531

Dehiscence is a common complication of corneal transplant surgery involving separating the graft from the host eye. The present article aims to investigate fundamental insights into the mechanical and structural aspects of the graft-host junction (GHJ) of a graft that survived in a patient for 13 years after penetrating keratoplasty (PK). Additionally, it adopts the sutur retention strength (SRS) test procedure defined in ISO:7198-2016 and aims to provide a comprehensive test protocol to study the biomechanics of the GHJ in extracted PK buttons. A 9 mm corneal button with GHJ was extracted from a 46-year-old patient who underwent PK 13 years back. The strength of the GHJ was quantified using the SRS test. Corresponding control results were obtained from the SRS tests of a corneoscleral button with no history of any refractive procedure. Birefringence, histological, and scanning electron microscopy (SEM) imaging were used to visualize the microstructural details of the GHJ. The strength of the GHJ was observed to be ten times lower than the native cornea. Histopathological features, such as fragmented Bowman's layer, and fibrosis with a clear demarcation line between host and graft tissue, were observed at the GHJ, suggesting a weak bond across the GHJ. The low strength of the GHJ in PK indicates the high susceptibility of the GHJ towards wound dehiscence.

2.
BMJ Case Rep ; 17(5)2024 May 06.
Article En | MEDLINE | ID: mdl-38719245

We report a case of a woman in her 30s who underwent femtosecond LASIK (laser-assisted in situ keratomileusis) in both eyes to correct her simple myopic astigmatism. After the surgery, both eyes developed diffuse lamellar keratitis, and intensive topical steroids were initiated to control the same. Subsequently, central toxic keratopathy (CTK) developed bilaterally. Three weeks after the surgery, the right eye showed signs of progressive epithelial ingrowth involving the pupillary area. Surgical intervention in the form of flap relift followed by debridement of the epithelial cells and an alcohol interface wash were performed to treat the same. This is the first report of an epithelial ingrowth following CTK after femtosecond LASIK.


Epithelium, Corneal , Keratomileusis, Laser In Situ , Humans , Keratomileusis, Laser In Situ/adverse effects , Female , Adult , Epithelium, Corneal/pathology , Myopia/surgery , Postoperative Complications/etiology , Corneal Diseases/etiology , Debridement/methods , Astigmatism/etiology , Astigmatism/surgery , Surgical Flaps/adverse effects
3.
Int J Pharm ; 656: 124092, 2024 May 10.
Article En | MEDLINE | ID: mdl-38583820

Corneal collagen crosslinking (CXL) is an effective method to halt the disease progression of keratoconus, a progressive corneal dystrophy leading to cone shaped cornea. Despite the efficacy of standard protocol, the concerning step of this procedure is epithelial debridement performed to facilitate the entry of riboflavin drug. Riboflavin, a key molecule in CXL protocol, is a sparsely permeable hydrophilic drug in corneal tissues. The present study has employed cell penetrating peptide (CPP), Tat2, to enhance the penetration of riboflavin molecule, and thereby improve currently followed CXL protocol. This study demonstrates approximately two-fold enhanced uptake of CPP riboflavin conjugate, Tat2riboflavin-5'Phosphate (RiTe conjugate), both in vitro and in vivo. Two different CXL protocols (Epi ON and Epi OFF) have been introduced and implemented in rabbit corneas using RiTe conjugate in the present study. The standard and RiTe conjugate mediated CXL procedures exhibited an equivalent extent of crosslinking in both the methods. Reduced keratocyte loss and no endothelial damage in RiTe conjugate mediated CXL further ascertains the safety of the proposed CXL protocols. Therefore, RiTe conjugate mediated CXL protocols present as potential alternatives to the standard keratoconus treatment in providing equally effective, less invasive and patient compliant treatment modality.


Collagen , Cornea , Cross-Linking Reagents , Keratoconus , Riboflavin , Keratoconus/drug therapy , Keratoconus/metabolism , Animals , Rabbits , Collagen/metabolism , Riboflavin/pharmacology , Cross-Linking Reagents/chemistry , Cornea/metabolism , Cornea/drug effects , Cell-Penetrating Peptides , Photosensitizing Agents/pharmacology , Photosensitizing Agents/therapeutic use
4.
Eye (Lond) ; 2024 Jan 22.
Article En | MEDLINE | ID: mdl-38253864

OBJECTIVE: To evaluate the environmental and economic impact of teleophthalmological services provided by a primary (rural) and tertiary (urban) eyecare network in India. METHODS: This prospective study utilised a random sampling method, and administered an environmental and economic impact assessment questionnaire. The study included 324 (primary: 173; tertiary: 151) patients who received teleconsultations from July to September 2022. The primary network (rural) used a colour-coded triage system (Green: eye conditions managed by teleconsult alone; yellow: semi-urgent referral within 1 week to a month, red: urgent referral within a day to a week). The tertiary network (urban) included new and follow-up patients. The environmental impact was assessed by estimating the potential CO2 emissions saved by avoiding travel for various transport modes. Economic impact measured by the potential cost savings from direct (travel) and indirect (food and wages lost) expenses spent by yellow and red referrals (primary) and the first-visit expenses of follow-up (tertiary) patients. RESULTS: The primary rural network saved 2.89 kg CO2/person and 80 km/person. The tertiary urban network saved 176.6 kg CO2/person and 1666 km/person. The potential cost savings on travel expenses were INR 19,970 (USD 250) for the primary (average: INR 370 (USD 4.6) per patient) and INR 758,870 (USD 9486) for the tertiary network (average: INR 8339 (USD 104) per patient). Indirect cost savings (food and wages) were of INR 29,100 (USD 364) for the primary and INR 347,800 (USD 4347) for the tertiary network. CONCLUSION: Teleophthalmology offers substantial environmental and economic benefits in rural and urban eyecare systems.

5.
Cornea ; 43(4): 446-451, 2024 Apr 01.
Article En | MEDLINE | ID: mdl-38016022

PURPOSE: The aim of this study was to report a case series of central toxic keratopathy (CTK) after collagen cross-linking (CXL) in keratoconus. METHODS: This is a retrospective case series between January 2020 and September 2021. In this period, CXL was performed for progressive keratoconus in 964 eyes. CXL was performed using the epithelium-off accelerated protocol in all patients with a riboflavin soak time of 20 minutes and a UVA light exposure of 9 mW for 10 minutes using the Avedro KXL (Glaukos Inc, Aliso Viejo, CA) cross-linking system. RESULTS: Twelve of 964 eyes (1.2%) developed CTK within 1 week of CXL. All patients presented with well-circumscribed, central disciform haze that was broader in the anterior stroma and narrower in the posterior stroma. We noted initial flattening in keratometry up to 3 months post-CXL in these patients, which gradually steepened over 12 months, but did not reach preoperative levels. We also noted exuberant flattening in pachymetry in the first 3 months, which improved over 12 months. There was a statistically significant decrease in pachymetry in patients who developed CTK at 3 and 12 months postoperatively when compared to patients who underwent CXL but did not develop CTK. CONCLUSIONS: Several reports of CTK postrefractive surgery have been described previously. However, the association of CXL in the development of CTK has not been described previously. Here, we elucidated the clinical features of CTK after CXL and how it differs from corneal scarring or haze that occurs post-CXL.


Keratoconus , Photochemotherapy , Humans , Photosensitizing Agents/therapeutic use , Photochemotherapy/adverse effects , Photochemotherapy/methods , Keratoconus/drug therapy , Ultraviolet Rays , Retrospective Studies , Visual Acuity , Corneal Stroma , Follow-Up Studies , Corneal Topography , Riboflavin/therapeutic use , Collagen/therapeutic use , Cross-Linking Reagents/therapeutic use , Vision Disorders/drug therapy
6.
Indian J Ophthalmol ; 72(1): 105-110, 2024 Jan 01.
Article En | MEDLINE | ID: mdl-38131579

PURPOSE: This paper aims to describe the clinical presentation and demographic distribution of keratoconus (KCN) in India by analyzing the electronic medical records (EMR) of patients presenting at a multitier ophthalmology hospital network. METHODS: This cross-sectional hospital-based study included the data of 2,384,523 patients presenting between January 2012 and March 2020. Data were collected from an EMR system. Patients with a clinical diagnosis of KCN in at least one eye were included in this study. Univariate analysis was performed to identify the prevalence of KCN. A multiple logistic regression analysis was performed using R software (version 3.5.1), and the odds ratios are reported. RESULTS: Data were obtained for 14,749 (0.62%) patients with 27,703 eyes diagnosed with KCN and used for the analysis. The median age of the patients was 22 (inter-quartile range (IQR): 17-27). In total, 76.64% of adults (odds ratio = 8.77; P = <0.001) were affected the most. The majority of patients were male (61.25%), and bilateral (87.83%) affliction was the most common presentation. A significant proportion of the patients were students (63.98%). Most eyes had mild or no visual impairment (<20/70; 61.42%). Corneal signs included ectasia (41.35%), Fleischer ring (44.52%), prominent corneal nerves (45.75%), corneal scarring (13.60%), Vogts striae (18.97%), and hydrops (0.71%). Only 7.85% showed an association with allergic conjunctivitis. A contact lens clinic assessment was administered to 47.87% of patients. Overall, 10.23% of the eyes affected with KCN underwent a surgical procedure. the most common surgery was collagen cross-linking (8.05%), followed by deep anterior lamellar keratoplasty (1.13%) and penetrating keratoplasty (0.88%). CONCLUSION: KCN is usually bilateral and predominantly affects males. It commonly presents in the second and third decade of life, and only a tenth of the affected eyes require surgical treatment.


Keratoconus , Adult , Humans , Male , Female , Keratoconus/diagnosis , Keratoconus/epidemiology , Keratoconus/drug therapy , Cross-Sectional Studies , Data Science , Visual Acuity , India/epidemiology , Prevalence , Retrospective Studies
7.
Transl Vis Sci Technol ; 12(12): 21, 2023 12 01.
Article En | MEDLINE | ID: mdl-38149965

Purpose: The purpose of this study was to determine changes in spatial and depth vision with increasing severity of keratoconus and to model the structure-function relationship to identify distinct phases of loss in visual function with disease severity. Methods: Best-spectacle corrected, monocular high-contrast visual acuity, contrast sensitivity function (CSF) and stereoacuity of 155 cases (16-31 years) with mild to advanced bilateral keratoconus was determined using standard psychophysical tests. Disease severity was quantified using the multimetric D-index. The structure-function relationship was modeled using linear, positive exponential, negative exponential, and logistic nonlinear regression equations. Results: The logistic regression model explained the highest proportion of variance for spatial vision, without bias in the residual plots (R2 ≥ 66%, P < 0.001). Visual acuity showed a distinct ceiling phase and a steeper loss rate with increasing D-index (1.8 units/D-index) in this model. The area under the CSF lacked this ceiling phase and had a shallower loss rate (0.28 units/D-index). Stereoacuity loss with D-index was poorly explained by all models tested (P ≤ 0.2). Cases with lower and bilaterally symmetric D-index had better stereoacuity (181.6-376 arc seconds) than those with higher D-index (>400 arc second); both were significantly poorer than controls (approximately 30 arc second). Conclusions: Vision loss in keratoconus varies with the visual function parameter tested. Contrast sensitivity may be an earlier indicator of spatial vision loss than visual acuity. Depth perception is significantly deteriorated from very early stages of the disease. Translational Relevance: The study outcomes may be used to forecast longitudinal vision loss in keratoconus and to apply appropriate interventions for timely preservation/enhancement of vulnerable visual functions.


Keratoconus , Humans , Keratoconus/complications , Keratoconus/diagnosis , Visual Acuity , Structure-Activity Relationship
8.
Acta Biomater ; 171: 239-248, 2023 11.
Article En | MEDLINE | ID: mdl-37739249

The Descemet Membrane Endothelial Keratoplasty (DMEK) procedure for corneal transplantation is challenging due to the need to unscroll the donor graft within the recipient's eye. This process of unscrolling is complex, time-consuming, leads to a loss of endothelial cells and, most importantly, can negatively impact the graft's adhesion and integration with the host tissue after surgery. This problem is particularly evident when the graft is young. However, the physics behind this scrolling is not well understood, and therefore no sustainable solution is attained. Here, we propose that the concentration gradient of the medium used during transplant leads to a displacement gradient across the graft thickness, resulting in an out-of-plane folding or scrolling of the graft tissue. Using chitosan bilayer-based experimental models, it is experimentally demonstrated that this diffusion-coupled-deformation phenomenon can successfully explain why younger donor grafts tend to scroll tighter than older ones. Most importantly, we illustrate here through experiments that the medium can be engineered to reduce the scroll tightness and thus reduce the surgical inconveniences and improve post-transplant recovery. STATEMENT OF SIGNIFICANCE: This paper addresses a major issue that surgeons face while doing Descemet Membrane Endothelial Keratoplasty (DMEK) in unscrolling grafts during the graft insertion procedure. The currently used tapping method to unscroll the graft inside the patient's eye significantly reduces endothelial cell count, thus affecting its lifetime. Surprisingly, the physics behind graft scrolling is not well understood, so no sustainable solutions are proposed by the medical community. In this work, we present the underlying mechanism of DMEK graft scroll and illustrate experimentally the reason for scroll tightness through a chitosan bilayer based experiment model. Most importantly, we have successfully demonstrated that the preserving medium of the grafts can be engineered to reduce scroll tightness.


Chitosan , Descemet Stripping Endothelial Keratoplasty , Humans , Descemet Membrane/surgery , Endothelium, Corneal , Endothelial Cells , Tissue Donors , Descemet Stripping Endothelial Keratoplasty/methods , Cell Count
9.
Indian J Ophthalmol ; 71(9): 3229-3234, 2023 09.
Article En | MEDLINE | ID: mdl-37602613

Objective: The past few years have seen a rapid advancement in the management of keratoconus (KC). However, there is no prescribed standard of care for the management of KC. This study evaluated the prevailing practice patterns among Indian ophthalmologists in the diagnosis and treatment of KC via an online survey. Methods: This was a survey-based cross-sectional study in which a questionnaire (Supplement 1) was created. Questions pertaining to the practicing experience, setting of practice, and training background were asked in addition to the investigations done and decision making in KC management. Responses were collected via Survey Monkey (Survey Monkey, Palo Alto, California, USA) and statistical analysis performed using R software (4.1.3). Results: The survey was answered by 273 ophthalmologists. Pentacam was the most used topographer (195 users), followed by Orbscan (41 users), Sirius (34 users), and Galilei (3 users). The lowest limit of pachymetry for performing collagen crosslinking (CXL) was 400µ for most practitioners. More than half the respondents (50.55%) did not perform photorefractive keratectomy (PRK) or intracorneal ring segment (ICRS) implantation in a suitable patient. Accelerated 10-minute protocol (9 mW/cm2 for 10 minutes) was the most commonly (54.21%) used for CXL, followed by Dresden protocol (3 mW/cm2 for 30 minutes) (36.63%). When a patient was unsuitable for CXL, 55.31% surgeons advise contact lens (CL) trial, 35.16% surgeons advise keratoplasty, 26.74% surgeons perform stromal augmentation, and 7.69% surgeons advise spectacle correction. Corneal scar was the most common indication (49.45%) for performing keratoplasty. Conclusion: Topography remains the most used diagnostic modality for initial diagnosis. Optical coherence tomography and epithelial mapping are increasingly being used for early diagnosis of KC. Not all ophthalmologists were comfortable performing ICRS or PRK. When patients are unsuitable for CXL, CL trial remains the most frequently advised option followed by keratoplasty.


Keratoconus , Ophthalmologists , Humans , Asian People , Contact Lenses , Cross-Sectional Studies , Keratoconus/diagnosis , Keratoconus/epidemiology , Keratoconus/therapy , India , Practice Patterns, Physicians'
10.
Vision Res ; 212: 108310, 2023 Nov.
Article En | MEDLINE | ID: mdl-37582329

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.

11.
Surv Ophthalmol ; 68(6): 1129-1152, 2023.
Article En | MEDLINE | ID: mdl-37392969

Descemet membrane endothelial keratoplasty (DMEK) is a partial-thickness corneal transplantation procedure that involves selective transplantation of the Descemet membrane and endothelium. DMEK offers significant advantages over other keratoplasty techniques, such as faster visual rehabilitation, better final visual acuity due to minimal optical interface effects, lower risk of allograft rejection, and less long-term dependence on topical steroids. Despite all its advantages, DMEK has been found to be more challenging than other corneal transplantation techniques, and its steep learning curve appears to be an obstacle to its widespread use and adoption by corneal surgeons worldwide. DMEK surgical training laboratories (wet labs) provide a window of opportunity for surgeons to learn, prepare, manipulate, and deliver these grafts in a risk-free environment. Wet labs are a significant learning tool, especially for those institutions that have limited tissue availability in their local centers. We provide a step-by-step guide for preparing DMEK grafts using different techniques on human and nonhuman models with instructional videos. This article should eventually help the trainees and the educators understand the requirements for performing DMEK and conducting a DMEK wet lab and develop their skills and interests from a wide variety of available techniques.


Corneal Diseases , Descemet Stripping Endothelial Keratoplasty , Humans , Descemet Membrane/surgery , Laboratories , Descemet Stripping Endothelial Keratoplasty/methods , Cornea/surgery , Endothelium, Corneal/surgery , Corneal Diseases/surgery
12.
Indian J Ophthalmol ; 71(5): 2230-2233, 2023 05.
Article En | MEDLINE | ID: mdl-37202956

Here we describe a new, non-human, ex-vivo model (goat eye model) for training surgeons in DMEK surgeons. In a wet lab setting, goat eyes were used to obtain a pseudo-DMEK graft of 8 mm from the goat lens capsule that was injected into another goat eye with the same maneuvers described for human DMEK. The DMEK pseudo-graft can be easily prepared, stained, loaded, injected, and unfolded into the goat eye model reproducing the similar maneuvers used for DMEK in a human eye, except for the descemetorhexis, which cannot be performed. The pseudo-DMEK graft behaves similar to human DMEK graft and useful for surgeons to experience and understand steps of DMEK early in learning curve. The concept of a non-human ex-vivo eye model is simple and reproducible and obviates the need for human tissue and the issues of poor visibility in stored corneal tissue.


Descemet Stripping Endothelial Keratoplasty , Fuchs' Endothelial Dystrophy , Animals , Humans , Descemet Membrane/surgery , Goats , Cornea/surgery , Tissue Donors , Retrospective Studies , Endothelium, Corneal , Fuchs' Endothelial Dystrophy/surgery
14.
Optom Vis Sci ; 100(4): 239-247, 2023 04 01.
Article En | MEDLINE | ID: mdl-36856557

SIGNIFICANCE: Partial improvement in stereoacuity may be achieved by balancing the contrast input to the two eyes of patients with bilaterally asymmetric keratoconus. PURPOSE: Interocular differences in image quality, characterized by dissimilar contrast loss and phase shifts, are implicated in stereoacuity loss in keratoconus. This study determined whether contrast balancing improves stereoacuity in this disease condition and, if so, whether it is dependent on the baseline interocular contrast imbalance. METHODS: Interocular contrast imbalance and stereoacuity of 43 subjects (16 to 33 years) with bilaterally asymmetric keratoconus were tested with spectacle correction as baseline using a binocular rivalry paradigm and random-dot stereograms, respectively. Stereoacuity measurements were repeated in a subset of 33 subjects at their contrast balance point (i.e., contrast level in stronger eye allowing balanced rivalry with 100% contrast in weaker eye) and with contrast levels biased in favor of stronger or weaker eye, all conditions in randomized order. RESULTS: Contrast imbalance level was significantly correlated with the subject's stereoacuity at baseline ( r = -0.47, P = .002). The median (25th to 75th interquartile range) stereoacuity improved by 34.6% (19.0 to 65.1%) from baseline (748.8 arc sec [261.3 to 1257.3 arc sec]) to the contrast balanced condition (419.0 arc sec [86.6 to 868.9 arc sec]) ( P < .001), independent of their baseline stereoacuity or contrast imbalance levels ( r < 0.2, P > .26 for both). Contrast bias in favor of the weaker eye (881.3 arc sec [239.6 to 1707.6 arc sec]) worsened stereoacuity more than a bias toward the stronger eye (502.6 arc sec [181.9 to 1161.4 arc sec]), both relative to the contrast balanced condition ( P < .002). CONCLUSIONS: Interocular contrast balancing partially improves stereoacuity in bilaterally asymmetric keratoconus, independent of their baseline contrast imbalance level. Cyclopean viewing may be inherently biased toward the input from the stronger eye in keratoconus.


Depth Perception , Keratoconus , Humans , Keratoconus/diagnosis , Keratoconus/therapy , Vision, Binocular , Visual Acuity , Eye
15.
Semin Ophthalmol ; 38(3): 265-274, 2023 Apr.
Article En | MEDLINE | ID: mdl-36598277

PURPOSE: To enumerate the various diagnostic modalities used for keratoconus and their evolution over the past century. METHODS: A comprehensive literature search including articles on diagnosis on keratoconus were searched on PUBMED and summarized in this review. RESULTS: Initially diagnosed in later stages of the disease process through clinical signs and retinoscopy, the initial introduction of corneal topography devices like Placido disc, photokeratoscopy, keratometry and computer-assisted videokeratography helped in the earlier detection of keratoconus. The evolution of corneal tomography, initially with slit scanning devices and later with Scheimpflug imaging, has vastly improved the accuracy and detection of clinical and sub-clinical disease. Analyzing the alteration in corneal biomechanics further contributed to the earlier detection of keratoconus even before the tomographic changes became evident. Anterior segment optical coherence tomography has proven to be a helpful adjuvant in diagnosing keratoconus, especially with epithelial thickness mapping. Confocal microscopy has helped us understand the alterations at a cellular level in keratoconic corneas. CONCLUSION: Thus, the collective contribution of the various investigative modalities have greatly enhanced earlier and accurate detection of keratoconus, thus reducing the disease morbidity.


Keratoconus , Humans , Keratoconus/diagnosis , Biomechanical Phenomena , Reproducibility of Results , Cornea , Corneal Topography , Tomography, Optical Coherence/methods
17.
Indian J Ophthalmol ; 70(10): 3435-3439, 2022 10.
Article En | MEDLINE | ID: mdl-36190020
18.
Indian J Ophthalmol ; 70(10): 3508-3513, 2022 10.
Article En | MEDLINE | ID: mdl-36190036

Purpose: To study the demographics and clinical profile of keratoconus (KC) presenting in pre-teen children in India. Methods: This was a retrospective case series conducted as a single-institutional study at a tertiary eye center in India. A total of 586 eyes from 294 KC patients (aged 12 years or less) without any active comorbid conditions of the eye were included in the study. Slit-lamp biomicroscopy was used to document the clinical signs of KC. Information on age; gender; reason for consultation; family history; history of allergy, atopy, and eye rubbing; manifest refraction; uncorrected and best-corrected distance visual acuity (UCVA and BCVA, respectively); clinical presentation; and contact lens usage were also analyzed, along with data on types of medical and surgical treatments for KC and their outcomes. Results: The mean age of this pediatric KC patient cohort was 9.3 ± 1.8 years, and there was a male (70%) preponderance. Baseline mean UCVA, BCVA, steep keratometry, and flat keratometry were 0.86 ± 0.58 logMAR, 0.44 ± 0.38 logMAR, 54.82 ± 8.4 D, and 48.21 ± 9.5 D, respectively. Progression, necessitating collagen crosslinking (CXL), was noted in 12.7% eyes. Post-CXL, visual and topographic parameters remained stable without any complications till 6 months posttreatment. However, in eyes that did not undergo CXL, significant progression over time (P < 0.001) was observed. A keratoplasty was required in 2.3% eyes. Conclusion: KC was present at an advanced stage in 25% of the pre-teens in our series, and therefore, it is an important diagnostic entity when a refractive error is diagnosed, even in very young children.


Keratoconus , Adolescent , Child , Child, Preschool , Collagen/therapeutic use , Cornea , Corneal Topography , Cross-Linking Reagents/therapeutic use , Demography , Follow-Up Studies , Humans , Keratoconus/diagnosis , Keratoconus/epidemiology , Keratoconus/therapy , Male , Photosensitizing Agents/therapeutic use , Refraction, Ocular , Retrospective Studies , Riboflavin/therapeutic use , Ultraviolet Rays , Visual Acuity
19.
Optom Vis Sci ; 99(10): 763-773, 2022 10 01.
Article En | MEDLINE | ID: mdl-36067396

SIGNIFICANCE: Nonlinearity in the luminance profile of eccentric, infrared photorefraction may be used to differentiate corneal diseases such as keratoconus that distort the cornea, relative to regular refractive errors. PURPOSE: This study aimed to determine the profile of eccentric, infrared photorefraction in keratoconus as a prototypical disease model for distorted corneas and identify a parameter in this profile for differentiating such disease conditions from healthy controls. METHODS: Photorefraction reflex of 75 eyes with forme fruste to advanced keratoconic cases and that of 75 eyes of controls with regular refractive errors (spherical equivalent, +0.50 to -11.75 D; astigmatism, -0.50 to -4.50 D across 0 to 180° axes) were obtained over their natural pupils under unaided viewing using a custom-designed photorefractor placed at 1 m from the subject. The test was repeated in 10 controls with 4 and 6 D of trial-lens-induced myopia and myopic astigmatism at 0, 90, 45, and 135°. Linear regression was performed on the luminance profile across the pupil, and the departure of the data from linearity was estimated using the average residual error of the fit (Res avg ). RESULTS: Photorefraction profiles varied linearly across the pupil in controls, with slopes increasing with refractive error ( r = 0.87; P < .001) and Res avg remaining invariant of refractive error ( r = -0.29; P > .4). Corresponding profiles in keratoconus significantly departed from linearity, with Res avg progressively increasing with disease severity ( r = 0.66; P < .001). Res avg of 0.03 gray-scale units/pixel distinguished keratoconus from controls with sensitivity increasing from 66.7 to 100% for mild to advanced keratoconus and specificity remaining ≥97.1% across disease severity. Induced myopia and myopic astigmatism produced predictable changes in luminance profile slopes but with no change in Res avg values. CONCLUSIONS: Unlike regular myopia and astigmatism, the photorefraction reflex is significantly nonlinear in keratoconus because of the distorted cornea. Measures of nonlinearity in luminance profile may be incorporated in commercial photorefractors for differentiating such disease conditions from regular refractive errors.


Astigmatism , Keratoconus , Myopia , Refractive Errors , Astigmatism/diagnosis , Cornea , Corneal Topography , Humans , Keratoconus/diagnosis , Refraction, Ocular
20.
Indian J Ophthalmol ; 70(9): 3272-3277, 2022 09.
Article En | MEDLINE | ID: mdl-36018101

Purpose: To assess the role of remote teleconsultation (TC) follow-up care following a successful and uneventful laser vision correction. Methods: The study is a retrospective, comparative analysis of patients undergoing laser vision correction at tertiary care eye hospital in Southern India. The patients were divided into two groups. The first group included patients operated on before the coronavirus disease (COVID-19) pandemic and were followed up with physical consultations during their follow-up visit (Group 1). The second group comprised patients operated on during the pandemic and had at least one remote TC during their post-operative follow-up (Group 2). Results: A total of 1088 eyes of 564 patients and 717 eyes of 372 patients were included in Group 1 and 2, respectively. The mean number of visits for the patients from Group 2 during the COVID period (2.56 +/- 0.74 days) was significantly lesser (P < 0.0001) than that of Group 1 in the pre-COVID period (3.53 +/- 1.07 days). Close to 90% of the eyes achieved an uncorrected distance visual acuity (UDVA) of 20/20 in both groups (P = 0.925). 96.50% of the eyes in Group 1 and 98.18% of the eyes in Group 2 achieved UCVA 20/25 or better (P = 0.049). Eight eyes (0.73%) in Group 1 and one eye (0.14%) in Group 2 reported a loss of 2 or more lines. However, the results were not statistically significant (P = 0.156). None of the groups had any patients who had a sight-threatening complication. Conclusion: Remote TC following refractive surgery is safe and can be effectively integrated into routine refractive practice to reduce travel to the hospital for a physical consult.


COVID-19 , Keratomileusis, Laser In Situ , Myopia , Photorefractive Keratectomy , Refractive Surgical Procedures , Remote Consultation , Humans , Lasers, Excimer , Refraction, Ocular , Retrospective Studies , Treatment Outcome
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