Static magnetic field effects on the secondary structure and elasticity of collagen molecules; a possible biophysical approach to treat keratoconus.

Type I collagen is among the major extracellular proteins that play a significant role in the maintenance of the cornea's structural integrity and is essential in cell adhesion, differentiation, growth, and integrity. Here, we investigated the effect of 300 mT Static Magnetic Field (300 mT SMF) on the structure and molecular properties of acid-solubilized collagens (ASC) isolated from the rat tail tendon. The SMF effects at molecular and atomic levels were investigated by various biophysical approaches like Circular Dichroism Spectropolarimetery (CD), Fourier Transform Infrared Spectroscopy (FTIR), Zetasizer light Scattering, and Rheological assay. Exposure of isolated type I collagen to 300 mT SMF retained its triple helix. The elasticity of collagen molecules and the keratoconus (KCN) cornea treated with SMF decreased significantly after 5 min and slightly after 10, 15, and 20 min of treatments. The exposure to 300 mT SMF shifted the Amid I bond random coil to antiparallel wave number from 1647 to 1631 cm-1. The pH of the 300 mT SMF treated collagen solution increased by about 25 %. The treatment of the KCN corneas with 300 mT SMF decreased their elasticity significantly. The promising results of the effects of 300 mT SMF on the collagen molecules and KCN cornea propose a novel biophysical approach capable of manipulating the collagen's elasticity, surface charges, electrostatic interactions, cross binding, network formation and fine structure. Therefore, SMF treatment may be considered as a novel non-invasive, direct, non-chemical and fast therapeutic and manipulative means to treat KCN cornea where the deviated physico-chemical status of collagen molecules cause deformation.

Trends and Sociodemographic Patterns in Keratoconus Management 2015-2020: An American Academy of Ophthalmology IRIS® Registry Analysis.

PURPOSE: Investigate trends in keratoconus (KCN) treatment patterns and diagnosis age from 2015 to 2020 and evaluate sociodemographic associations with the treatment approach. DESIGN: Retrospective cohort study. PARTICIPANTS: Patients with a new KCN diagnosis from 2015 to 2020 were identified in the Academy IRIS® Registry (Intelligent Research in Sight). METHODS: Associations between sociodemographic factors and treatment were evaluated using multivariable logistic regression. MAIN OUTCOME MEASURES: Outcomes included percentages and rates of each treatment (collagen crosslinking [CXL], keratoplasty, or no procedure) from 2015 to 2020, age at diagnosis during this period, and sociodemographic factors associated with treatment type. RESULTS: A total of 66 199 patients with a new diagnosis of KCN were identified. The percentage of patients undergoing CXL increased from 0.05% in 2015 to 29.5% in 2020 (P = 0.008). The average age (standard deviation) of KCN patients decreased from 44.1 (±16.9) years in 2015 to 39.2 (±16.9) years in 2020 (P < 0.001). In multivariable analyses comparing CXL versus no procedure and keratoplasty versus no procedure, patients undergoing CXL tended to be younger with the odds of having CXL decreasing with increasing age, for example, comparing CXL and no procedure patients, using ages 0-20 years as reference, the odds ratio (OR) (95% confidence interval [CI]) decreased from 0.62 (0.57-0.67; P < 0.0001) for patients aged 21-40 years to 0.03 (0.02-0.04; P < 0.0001) for patients aged > 60 years. Men were more likely than women to have CXL (OR, 1.31; 95% CI, 1.23-1.40; P < 0.0001) and keratoplasty (OR, 1.30; 95% CI, 1.19-1.42; P < 0.0001). Black patients were less likely than White patients to have CXL (OR, 0.70; 95% CI, 0.63-0.77; P < 0.0001) and more likely to have keratoplasty (OR, 2.24; 95% CI, 2.01-2.50; P < 0.0001). Likewise, Hispanic patients had higher odds of CXL (OR, 1.12; 95% CI, 1.00-1.24; P < 0.05) and keratoplasty (OR, 1.29; 95% CI, 1.12-1.50; P < 0.001) compared with non-Hispanic patients. Collagen crosslinking and keratoplasty also varied by region and insurance status. CONCLUSIONS: A significant increase in use of CXL was noted from 2015 to 2020. Sociodemographic differences in treatment among KCN patients may reflect differences in access, use, or care patterns, and future studies should aim to identify strategies to improve access for all patients. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Impact of a 50bp insertion/deletion polymorphism of the superoxide dismutase-1 on oxidative stress status and risk of keratoconus.

Keratoconus (KC) is characterized by the predominant primary ectatic disease, affecting the cornea, necessitating corneal transplants in some cases. While some loci associated with KC risk have been identified, the understanding of the disease remains limited. Superoxide dismutase (SOD) enzymes play a crucial role in countering the reactive oxygen species and providing protection against oxidative stress (OS). Accordingly, the objective of this study was to investigate a potential association of a 50 nucleotide base pairs (bp) insertion/deletion (I/D) within the SOD1 promoter, and the located 1684 bp upstream of the SOD1 ATG, with KC in the Iranian population. Additionally, an assessment was conducted on SOD activity and the total antioxidant capacity (TAC), as determined by the ferric reducing-antioxidant power assay, along with malondialdehyde (MDA) levels. In this case-control study, genomic DNA was extracted from the blood cells of KC (n = 402) and healthy (n = 331) individuals. The genotype of this gene was determined using the PCR technique. Furthermore, the amount of SOD enzyme activity and the MDA and TAC levels were measured in the serum of the study groups. The (I/I) genotype was present in 84.23%, the (I/D) genotype in 15.06%, and the (D/D) genotype in 0.69% of both groups. A statistically significant relationship was seen between different genotypes and TAC, MDA, and SOD1 activity indices (P < 0.05). Individuals with the D/D genotype exhibited a decrease in total antioxidant capacity, an increase in the amount of MDA, and a decrease in SOD1 enzyme activity (P < 0.05). Moreover, the logistic regression analysis of KC development indicated that elevated levels of MDA increased the risk of KC incidence in the patient group compared to the healthy group, while a higher activity of SOD1 and greater values of TAC decreased the KC risk. The removal of the 50 bp fragment reduced SOD1 activity and elevated OS levels, thereby impacting the oxidant-antioxidant balance. This could potentially play a significant role in individuals afflicted by KC.

Assessment of large-diameter and small-diameter SoftK specialty contact lenses for early-stage keratoconus.

INTRODUCTION: Soft contact lenses may be a good alternative for early-stage keratoconus (KC) patients who do not tolerate rigid gas permeable (RGP) lenses due to ocular discomfort or complications. This prospective study compared outcomes obtained after 2 weeks of wearing two types of soft silicone hydrogel contact lenses for keratoconus that varied in their diameter and central thickness (cc). METHODS: Patients with Amsler-Krumeich grades I or II KC were fitted with small-diameter (14.2 or 14.8 mm) SoftK (SD-SoftK, cc = 0.48 mm) and large-diameter (17 mm) SoftK (LD-SoftK, cc = 0.60 mm) lenses, each worn for 2 weeks in a crossover design. Low (10%;10VA) and high (100%;100VA) contrast visual acuity, contrast sensitivity (CS, Pelli-Robson), higher order aberrations (HOAs, Visionix Vx130), the number of trial lens modifications during fitting and the subjectively preferred lens were compared using Friedman tests with post-hoc analysis. RESULTS: Forty eyes (N = 20, 10 males, mean age: 39.0 ± 9.9 years, range: 23-55 years) were examined. Their habitual median (interquartile1, interquartile3) 10VA (LogMAR), 100VA (LogMAR) and CS (LogCS) were 0.52 (0.30, 0.50), 0.14 (0.10, 0.15) and 1.35 (1.35, 1.50), respectively. For the SD-SoftK condition, the values were 0.23 (0.17, 0.30), 0.02 (0.00, 0.05) and 1.50 (1.50, 1.65), respectively. For the LD-SoftK condition, the respective values were 0.36 (0.27, 0.44), 0.09 (0.05, 0.13) and 1.50 (1.50, 1.60). SD-SoftK lenses significantly improved 10VA compared with habitual and LD-SoftK. SD-SoftK also significantly improved CS compared with habitual, but not LD-SoftK. LD-SoftK significantly improved spherical aberration compared with uncorrected (0.03 ± 0.10 µ vs. 0.07 ± 0.13 µ) but not SD-SoftK (0.04 ± 0.07 µ). Both lenses required a mean of 1.5 modifications prior to final lens fitting. Fewer adverse events were seen with SD-SoftK (N = 3) compared with LD-SoftK (N = 8), and 75% of participants preferred SD-SoftK lenses. CONCLUSION: SD-SoftK lenses were preferred by 75% of subjects, were associated with fewer adverse events and significantly improved 10VA compared with LD-SoftK lenses. SD-SoftK lenses also significantly improved CS compared with the habitual correction, but this did not differ significantly from the LD-SoftK lenses.

Keratoconus Management in the Community: A Survey of Optometrists.

OBJECTIVES: Defining the patterns of practice and referral criteria of optometrists within New Zealand to investigate the diagnosis and management of keratoconus. METHODS: Optometrists recruited through the New Zealand Association of Optometrists, Cornea and Contact Lens Society of New Zealand, and private practices were invited to complete an anonymous survey. RESULTS: Responses were received from 168 optometrists (representing 20.0% of the optometrist population). Half (48%) of optometrists had ≥15 years of experience, and 22% prescribed soft contact lenses daily, whereas only 6.4% prescribed rigid gas-permeable (RGP) lenses daily. The main barriers to prescribing RGPs were experience with fitting, low market demand, and patient discomfort. When referring to an ophthalmologist, 41% reported referring on progression of corneal parameters, 27% on initial diagnosis, 21% at no set time, and 10% with a reduction in visual acuity. Most optometrists (64%) would refer for possible surgery when visual acuity dropped between 6/9 and 6/12. Optometrists with greater experience were more likely to prescribe RGP lenses and co-manage patients with ophthalmologists. Ownership of a corneal imaging unit suggested an increased likelihood of prescribing RGP lenses but did not alter referral patterns. CONCLUSION: This survey provides an overview of current practice and highlights the importance of optometrists in the diagnosis and management of keratoconus. There was a significant discrepancy in keratoconus management, regarding optical correction modality and referral criteria for ophthalmology review. Further interdisciplinary work is required between optometry and ophthalmology to standardize referral guidelines and enhance visual outcomes.

Image- and Impression-Based Technology in Scleral Lens Fitting for Keratoconus: Availability and Utilization.

OBJECTIVE: Scleral lenses (SLs) can be customized using traditional diagnostic lens fitting or by using image- and/or impression-based technologies. This study describes the availability and usage of SL fitting technology in patients with keratoconus. METHODS: An online survey queried practitioners on the mode of practice, country of residence, and estimated number of SL fits completed for keratoconus. Practitioners were asked whether they had access to image- and/or impression-based technology and to estimate the percentage of fits completed using diagnostic fitting, image-based technology, and impression-based technology. Access and usage of technology was compared between academic and community practices, United States and non-United States, and high-volume (≥60 SLs) and low-volume fitters. RESULTS: 423 practitioners who fit SL for keratoconus participated. Image- and impression-based technologies were more frequently available in academic practices compared with community practices and high-volume compared with low-volume practitioners ( P <0.005). Practitioners with image-based technology used it for a median [interquartile range] 5 [25]% of SL fittings; those with impression-based technology used it for 8 [9]% of fittings, and those with both types of technology used image-based devices for 12 [23]% of fittings and impression-based for 5 [8]% of fittings. CONCLUSIONS: In this study, most participants report using diagnostic lenses to fit SLs for patients with keratoconus.

Mini-Scleral Lens: An Effective Mode of Visual Rehabilitation in Eyes With Resolved Hydrops.

OBJECTIVES: To evaluate the visual outcome of mini-scleral contact lenses (MSLs) in keratoconus following the resolution of acute hydrops. METHODS: This was a prospective observational case series of patients of healed hydrops in keratoconus fitted with an MSL (Keracare, Acculens, Lakewood, CO) who were managed for acute hydrops medically or surgically at least 3 months prior. Uncorrected visual acuity, best spectacles-corrected visual acuity, best lens-corrected visual acuity, topographic indices, keratometric indices, contact lens parameters, and ocular aberrometric changes were evaluated. All patients were followed up for at least 3 months. RESULTS: Eighteen eyes of 17 patients were included in the analysis. The mean post-hydrops topographic values of the eyes included flat keratometric value (K1) 64.93±10.88 (range 44.30-93.40) diopters (D), steep keratometric value (K2) 70.41±10.92 D (range 45.8-98.6 D), and Kmax of 79.53±17.73 D (range 50-130.2). The final mini-scleral lens's mean dioptric power was -8.56±3.96 D (range -18 to -4). Visual acuity significantly improved from post-hydrops resolution uncorrected visual acuity of 1.5±0.71 logMAR to 0.79±0.18 logMAR best spectacles-corrected visual acuity to 0.27±0.01 logMAR best lens-corrected visual acuity ( P -value <0.0001). Similarly, there was considerable improvement in corneal aberrometric values after wearing an MSL. At the 3-month follow-up, 15 patients (16 eyes) were compliant to contact lens use with a minimum of 6 to 8 hr daily while two patients (2 eyes) were poorly compliant. CONCLUSIONS: A MSL is a valuable option for visual rehabilitation in keratoconus following the resolution of acute hydrops.

Effect of Corneal and Lens Eccentricity Difference on Rigid Corneal Lens Treatment in Patients With Keratoconus.

OBJECTIVE: To evaluate the effects of rigid corneal lenses (RCL) in patients with keratoconus, based on eccentricity. METHODS: Eighty-four eyes from 84 patients were included in this retrospective comparative study. Based on the median value of eccentricity difference between the cornea and back surface of the RCL, the patients were divided into groups 1 (<0.08) and 2 (≥0.08). Visual acuity, refractive index, and corneal topography indices were compared before and three months after lens use. RESULTS: Visual acuity, astigmatism, refractive error, corneal curvature, and corneal thickness improved significantly in both groups. Apical power and anterior elevation improved significantly in group 1, with small differences in eccentricity, but not in group 2. Changes in apical power before and after lens use were significantly different between the two groups. CONCLUSION: The RCL was effective for the cornea of keratoconus, especially when the prescription was made with a small difference in eccentricity.

Higher order aberrations in keratoconus .

INTRODUCTION: Keratoconus is a progressive disorder of the cornea that causes thinning (Sedaghat et al. in Sci Rep 11(1):11971, 2021), ectasia, and irregular astigmatism, resulting in poor visual acuity that cannot be corrected with standard sphero-cylindrical spectacle lenses. One feature distinguishing keratoconic corneas is ocular aberrations, manifesting up to five or six times the amount of higher-order aberrations than a normal, healthy eye. These aberrations can cause visual disturbances even at the very early stages of the disease. METHODS: In the past, a diagnosis was derived from clinical symptoms, but technological advances have revealed multiple pre-clinical features, allowing for the differentiation between keratoconic and normal eyes at a much earlier stage. These include anterior and posterior corneal surface elevations, the corneal pachymetry profile, corneal epithelial patterns, wavefront aberration metrics, and corneal biomechanics (Sedaghat et al. in Sci Rep 11(1):11971, 2021).This review discusses the aberrations associated with keratoconus, how to measure them, and treatment methods to minimize their negative influence. CONCLUSIONS: Early diagnosis can lead to early treatment and may allow for arresting progression, thereby improving the long-term prognosis. With the acceleration of refractive surgery, it is important to identify patients with keratoconus, as they are usually contraindicated for refractive surgery.

[Comparative analysis of clinical and functional parameters in patients with stable stage II-III keratoconus after implantation of corneal segments and fitting of scleral rigid contact lenses]. / Sravnitel'nyi analiz kliniko-funktsional'nykh pokazatelei u patsientov so stabil'nym keratokonusom II­III stadii posle implantatsii rogovichnykh segmentov i podbora skleral'nykh zhestkikh kontaktnykh linz.

The modern treatment strategy for keratoconus (KC) involves sequential application of medical technologies aimed at stabilizing pathological changes in the cornea and restoring visual acuity. PURPOSE: This study compares the effect of implantation of intrastromal corneal ring segment (ICRS) and fitting of individual scleral rigid contact lenses (RCLs) on visual functions in patients with stage II-III KC after previously performed corneal collagen cross-linking. MATERIAL AND METHODS: The Helmholtz National Medical Research Center of Eye Diseases examined and treated 34 patients (69 eyes) aged 18 to 33 years with stage II-III KC. The study included patients who had previously undergone standard corneal collagen cross-linking. Depending on the type of optical correction, the patients were divided into two groups: patients in group 1 underwent ICRS implantation using a femtosecond laser; patients in group 2 were fitted with individual scleral RCLs. RESULTS: Improvement in clinical and functional parameters was observed in both groups. A higher clinical and functional result was achieved in group 2. CONCLUSION: For patients with stable stage II-III KC, it is advisable to recommend fitting of individual scleral RCLs for visual rehabilitation.

Diagnosis and management of keratoconus by eye care practitioners in Kenya.

BACKGROUND: To explore current eye care practice in keratoconus diagnosis and management in Kenya. METHODS: An online questionnaire was distributed to ophthalmic clinical officers (OCO) and optometrists. RESULTS: A total of 203 responses were received from 52 OCOs and 151 optometrists with a response rate of 24.4% and 53.5% respectively. The majority reported having access to retinoscopes (88.5%; p = 0.48) and slit lamps (76.7; p = 0.14). Few practitioners had access to a corneal topographer (13.5%; p = 0.08) and rigid contact lens (CL) fitting sets (OCOs 5.8%, optometrists 33.8%; p < 0.01). One-third did not feel that retinoscopy (38.7%; p = 0.21), slit lamp findings (30.3%; p = 0.10) and corneal topography (36.6%; p = 0.39) are important investigations in keratoconus diagnosis. Corneal topography was not recommended in two-thirds of patients (59.0%; p = 0.33) with vernal keratoconjunctivitis (VKC). The majority counselled against eye rubbing in mild (73.6%; p = 0.90) VKC, 52.9% in moderate (p = 0.40) and 43.6% in severe (p = 0.24) cases. The majority prescribed spectacles in mild (90.2%; p = 0.95), 29% (p = 0.97) in moderate and 1.9% (p = 0.05) in severe cases. When the binocular best corrected visual acuity (BCVA) with spectacles was ≤ 6/18, 76.9% of OCOs and 58.9% of optometrists referred for CLs (p = 0.02). When binocular BCVA with CLs dropped to ≤ 6/18, 83.7% (p = 0.18) referred to the ophthalmologist for surgical intervention. Few OCOs fitted rigid CLs (15.4% OCOs, 51.0% optometrists; p = 0.01), majority referred to optometrists (82.7% OCOs, 43.7% optometrists; p < 0.01). Progression was monitored in 70.1% (p = 0.11) of mild, 50.9% (p = 0.54) moderate and 25.3% (p = 0.31) advanced cases. Few OCOs (15.4%) performed corneal cross-linking (CXL). A few respondents (5.4%; p = 0.13) did not know when to refer keratoconus patients for CXL. Co-management with ophthalmologists was reported by 58.0% (p = 0.06) of respondents. CONCLUSION: The results of this study highlight the need to map services for keratoconus patients, review current curricula and continuous education priorities for mid-level ophthalmic workers, develop guidelines for the diagnosis and management of keratoconus and improve interdisciplinary collaboration.

Interocular Contrast Balancing Partially Improves Stereoacuity in Keratoconus.

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.

Case Report: Remote Scleral Lens Fitting for High Toric Scleras in a Keratoconus Patient.

SIGNIFICANCE: Technology plays a crucial role in customizing scleral lenses and improving lens alignment, especially in challenging scleral shapes. In addition, remote fitting technology allows optometrists to extend their expertise globally, empowering patients to access to customized lenses without travel expenses. PURPOSE: The objective of this study was to document the difficulties encountered in fitting a scleral lens in a patient with keratoconus and pronounced scleral toricity. In addition, the study aimed to present the successful remote fitting achieved by using advanced technology. CASE REPORT: An Irish male patient diagnosed with keratoconus exhibited high scleral toricity. Generally, keratoconus eyes often exhibit significant scleral asymmetry associated with cone decentration and disease severity. Improperly aligned scleral lenses can lead to regional changes in scleral shape, lens decentration, discomfort, and visual disturbances. Indeed, previous scleral lens fits were unsuccessful because of these issues. Corneoscleral profilometry was acquired in Ireland and then used in Italy to design customized lenses, which were then delivered to the patient's optometrist in Ireland. The first lenses designed and delivered demonstrated excellent overall performance without requiring adjustments. CONCLUSIONS: This report highlights the importance of corneoscleral profilometry to increase efficiency and reduce lens reorders and chair time, and the remote fitting in overcoming barriers to accessing specialized lens fitting.

Utilising a visual image quality metric to optimise spectacle prescriptions for eyes with keratoconus.

PURPOSE: To compare optical performance, visual performance, and patient-perceived quality of vision with: (1) spectacles determined using subjective refraction and (2) spectacles determined using an objective optimisation method based on wavefront aberration data for eyes with keratoconus. METHODS: Thirty-seven eyes (20 subjects) with keratoconus underwent both subjective refraction and uncorrected wavefront aberration measurement. Wavefront aberration data were used to objectively identify a sphero-cylindrical refraction that optimised the visual image quality metric visual Strehl ratio (VSX). The two refractions were assembled in trial frames and worn by the subject in a random order. High-contrast visual acuity (VA), letter contrast sensitivity (CS), and the patient's short-term subjective preference were recorded for each prescription. RESULTS: Median magnitude of the dioptric difference (a measure of similarity between the subjective and objective refractions) was 2.77 D (range = 0.21-20.44 D, first quartile = 1.02 D, third quartile = 4.36 D). Sixty-eight per cent of eyes had better VA with the objective refraction and 32% of eyes gained more than one line of VA. Monocularly, objective refraction was preferred 68% of the time when looking at a distant acuity chart and 76% of the time when viewing a real-world dynamic scene. CONCLUSIONS: Objective refraction based on visual image quality derived from wavefront aberration data can be valuable in the determination of monocular spectacle refractions for individuals with keratoconus.

Impact of Scleral Lens Front Surface Eccentricity on Visual Acuity, Contrast Sensitivity, and Higher-Order Aberrations in Eyes With Keratoconus.

PURPOSE: To investigate the effect of front surface eccentricity (FSE) of scleral lenses (SLs) on corrected distance visual acuity (CDVA), contrast sensitivity (CS), and higher-order aberrations (HOAs) in keratoconic eyes. METHODS: Fifteen keratoconic eyes fitted with BostonSight SCLERAL lenses of different eccentricity values (FSE0=0, FSE1=0.30, and FSE2=0.60). CDVA, CS, and HOAs were measured at baseline and after 30 min of SL wear. CDVA and CS were measured with the Early Treatment Diabetic Retinopathy Study and Pelli-Robson chart, respectively, and iTrace aberrometer was used to evaluate the HOAs. RESULTS: Baseline CDVA was 0.30±0.29, which significantly improved to 0.10±0.11, 0.05±0.06, and 0.05±0.08 logMAR with FSE0, FSE1, and FSE2, respectively ( P <0.05). The post hoc showed no significant difference between eccentricities. Baseline CS was 1.19±0.47, which improved to 1.54±0.12, 1.59±0.10, and 1.60±0.11 with FSE0, FSE1, and FSE2, respectively ( P <0.01), but post hoc showed no significant difference between eccentricities. A statistically significant reduction was found in HOAs when compared with baseline ( P <0.01). Comparison between eccentricities showed a significant difference only between FSE0 and FSE1 for RMS coma ( P =0.01) and RMS spherical aberrations ( P =0.004) where FSE1 showed better performance in reducing HOAs compared with FSE0. HO-RMS, RMS secondary astigmatism, and RMS trefoil showed no significant difference between eccentricities, but FSE1 and FSE2 performed superior to FSE0. CONCLUSION: BostonSight SCLERAL lenses with varying eccentricities corrected a significant amount of HOAs and improved CDVA and CS in keratoconus patients. Practitioners should be aware of this distinct feature of SLs and use it as needed to improve visual performance.

Baseline Characteristics of 1976 Patients With Ectatic Corneal Disorders at a Single Center From 2010 to 2021: A Cross-Sectional Study of the Homburg Keratoconus Center.

OBJECTIVES: The study objective was to analyze the baseline characteristics of keratoconus (KC) patients at the Homburg Keratoconus Center from 2010 to 2021. METHODS: This cross-sectional study included 3,674 eyes, with analysis of demographics, clinical findings, visual function, endothelial measurements, and topographic, tomographic, and corneal biomechanical data from the first visit. RESULTS: Mean patient age was 36.3±13.8 years. The mean uncorrected distance visual acuity in log of minimal angle of resolution was 0.60 (20/80, Snellen equivalent), and the corrected mean was 0.3 (20/40). Of 1976 patients, 48.9% reported eye rubbing. Mean values (ranges) were 49.4±6.3 (36.3-78.0) D for steep keratometry, 462.4±66.0 (48.0-659.0) µm for thinnest corneal thickness, 9.7±8.7 (-0.5 to 88.8) for Belin/Ambrósio enhanced ectasia total deviation, 0.8±0.4 (0.0-1.0) for the Corvis biomechanical index, 0.9±0.2 (0.0-1.0) for the tomographic biomechanical index, 0.1±0.5 (-0.9 to 2.0) for the KC match index, 8.3±1.8 (2.2-17.7) mm Hg for corneal hysteresis, 7.1±2.2 (0.0-17.0) mm Hg for corneal resistance factor, and 2,562.9±326.3 (1,011-3,937) cells/mm2 for endothelial cell density. The average ABCDE KC stage was A2B3C1D1E2. Distance-corrected visual acuity correlated strongly with topometric, tomographic, and biomechanical data ( P <0.001). CONCLUSIONS: This comprehensive description of baseline features of KC patients at a tertiary center provides a reference for further longitudinal and international multicentric studies.

Correlation of Manifest Refraction and Simulated Keratometry to Tomography Characteristics in Patients With Keratoconus.

OBJECTIVES: To report on baseline refractive and keratometric values and their correlation with tomographic characteristics of eyes with keratoconus (KC). METHODS: Retrospective chart review of patients treated in a single-center cornea and refractive surgery practice. Baseline topographic measurements were reviewed for 1,012 keratoconic eyes of 586 patients between 2008 and 2018. The manifest refraction, thinnest pachymetry (P thin ), corneal astigmatism (K astig ), and the maximum (K max ), steep (K steep ), flat (K flat ), and mean (K mean ) keratometry were analyzed. The location of K max (x, y) was used to determine central (<1 mm), paracentral (1-3 mm), pericentral (3-5 mm), or peripheral (>5 mm) cone locations. RESULTS: In the entire cohort, the mean manifest sphere was -2.2±4.4 diopters (D) and the cylinder was -3.2±2.3 D. In total, 48.6% of patients had against the rule (ATR) manifest astigmatism (M astig ). The average K astig was 3.8±2.7 D, and unlike the manifest axis, 50.2% of patients had with the rule (WTR) K astig . Patients with a K max less than 50 D had an M astig of -1.9±1.6 D, 45.9% of which was ATR M astig . With respect to baseline tomography measurements, K max , K steep , K flat , and K mean were 58.0±9.4, 50.6±6.5, 46.8±5.9, and 48.6±6.1 D, respectively. There was a weak correlation between K max and simulated keratometry (K steep , K flat , and K mean ) for patients with a K max less than 60 D. CONCLUSIONS: Simulated keratometry is poorly correlated with KC severity until the disease is more severe. M astig ≥2 D and ATR M astig were correlated with KC at all levels of severity. M astig ≥2 D and ATR M astig may serve as a simple, inexpensive, and widely available indicator for topographic analysis to identify possible KC and suggest further workup; however, further prospective studies are needed to confirm its utility.

Severe Complications after Corneal Collagen Cross-Linking (CXL).

PURPOSE: To present a case series of rare and severe complications after corneal collagen cross-linking (CXL) of keratoconus patients. METHODS: Single-center descriptive case series covering the period of 2012 to 2022 at the Department of Ophthalmology at the University Hospital, Zurich, Switzerland. RESULTS: We present four eyes of four patients that showed severe unusual complications within the first month after CXL. Three patients had been treated with the classical epithelium-off "Dresden" protocol. One patient had been treated with the accelerated epithelium-off protocol. One patient presented with extensive corneal edema due to rubbing the eye after treatment. Two patients showed a bacterial infectious keratitis: one due to Streptococcus pneumoniae and the other due to Staphylococcus hominis, Micrococcus luteus, and Streptococcus epidermidis. The latter of the two patients exhibited extensive infectious crystalline keratopathy. The fourth patient showed a severe ulcerative lesion where no infectious cause could be found. Therefore, an autoimmune keratolytic process had to be suspected. Apart from the corneal edema, which resolved ad integrum, the other complications resulted in permanent corneal scarring and thinning. One patient needed an emergency amniotic transplant. CONCLUSION: Severe complications after CXL remain rare. Most common causes are complications that are not directly associated with the treatment as such. Those indirect complications occur after the treatment during the healing course of the epithelium. Associations with bandage contact lenses, topical steroids, atopic disease, and inappropriate patient behavior are often suspected. Correctly performed corneal scrapings with repeated microbiological analysis and a detailed patient history are essential for establishing the correct diagnosis, especially in complicated cases that do not respond to a standard therapeutic regimen. This case series supports the efforts that are currently taken to improve the CXL technique in a way that postoperative complications are further reduced. A more efficient epithelium-on technique might be a step in that direction.

Choroidal thickness assessment in keratoconus patients treated with cross-linking compared to healthy population.

PURPOSE: To analyze the choroidal thickness between patients with keratoconus undergoing cross-linking treatment and a healthy population, as well as to determine the factors that influence choroidal thickness. METHODS: This was an observational, analytical, case-control study that was conducted from February 2021 to June 2021. Choroidal thickness was measured at different locations, including the subfoveal, nasal (1000 µm), temporal (1000 µm), superior (1000 µm) and inferior (1000 µm) locations using a Spectral-domain optical coherence tomography with enhanced depth imaging, which allowed us to obtain horizontal and vertical B-scans centered on the fovea. RESULTS: This study included 21 patients with keratoconus (mean age, 21.86 ± 5.28 years) and 28 healthy patients (mean age, 24.21 ± 4.71 years). Choroidal thickness was significantly greater in patients with keratoconus than in healthy patients in each of the following measured locations: subfoveal (P < 0.001); nasal (1000 µm) (P < 0.001), temporal (1000 µm) (P < 0.001), superior (1000 µm) (P < 0.001) and inferior (1000 µm) (P < 0.001) locations. Variables such as age (ρ = - 0.09; P = 0.50) and refraction (ρ = 0.14; P = 0.34) were not found to be associated with choroidal thickness. In a stepwise multiple linear regression, the group was the single variable correlated with choroidal thickness (ß = 0.88; P < 0.001). CONCLUSION: Choroidal thickness is thicker in keratoconus patients treated with cross-linking than in the healthy population. This finding could be associated with inflammatory choroidal mechanisms in keratoconus patients, but more studies are needed. Age and refractive error do not seem to influence choroidal thickness.

[Short term clinical observation of keratoconus treated with stromal lenticule addition keratoplasty combined with corneal collagen cross-linking].

Objective: To investigate the efficacy of Femtosecond laser-assisted stromal lenticule addition keratoplasty (SLAK) combined with corneal collagen cross-linking (CXL) in the treatment of middle and advanced Keratoconus. Methods: It was a retrospective case series study. Data of 23 cases (24 eyes) of keratoconus treated with femtosecond laser-assisted SLAK combined with CXL in Laser Vision Centre of Xi'an No.1 Hospital from September 2020 to June 2022 were collected, including 16 males and 7 females, aged (23.69±5.18) years. The thickness, diopter number and diameter of the donor corneal stromal lens were assessed. uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), and diopter were recorded before and 1, 3, and 6 months after surgery. Sirius 3D fault corneal topography instrument to measure flat simulated keratometry (Kf), steep simulated keratometry (Ks) and the difference between them (ΔK), as well as central corneal thickness (CCT) and corneal high-order aberration. Results: Six months after surgery, CCT (454.83±50.01) µm were significantly higher than before (384.92±35.45) µm (P<0.05). Six months after surgery, UCVA (1.41±0.32) was significantly lower than before (1.11±0.33)(P<0.05). Six months after surgery, spherical diopter [(-15.73±7.89) D], Kf [(56.82±4.76) D] and Ks [(61.00±4.70) D] were significantly higher than before [(-12.08±5.99) D, (53.55±4.95) D, (58.65±5.10) D] (P<0.05). There was no significant difference in BCVA, column mirror degree and higher order aberrations before and 6 months after surgery(P>0.05). No corneal stromal lens folds, melting and displacement were observed in all eyes during the follow-up period, and no corneal opacity or immune rejection was observed. Conclusions: femtosecond laser-assisted SLAK combined with CXL can significantly increase the corneal thickness of keratoconus and has good effectiveness. In addition, six months of postoperative follow-up of patients showed no significant changes in BCVA and high-order aberrations in the 6 mm central diameter of the cornea, and no postoperative adverse reaction were found in all eyes, indicating that the operation has certain safety.