[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.

Evaluation of the results of contact lens assisted corneal cross-linking treatment in keratoconus patients with thin corneas.

PURPOSE: We aimed to compare the efficacy and safety of accelerated contact lens-assisted cross-linking (CA-CXL) with Lotrafilcon B and Comfilcon A lenses in keratoconus (KC) patients with thin corneas. STUDY DESIGN: Retrospective, single-center study. MATERIALS AND METHODS: We retrospectively included 51 eyes of 39 KC patients with corneal thickness <400µm after epithelial scraping (Epi-off), who underwent accelerated CA-CXL treatment with Lotrafilcon B (n=20) and Comfilcon A (n=31). Uncorrected and corrected distance visual acuity (UDVA and CDVA), manifest refraction values, corneal topographic data and endothelial cell density were recorded at preoperative and postoperative 1st, 3rd and 6th month controls. RESULTS: CDVA in the Comfilcon A group was higher than CDVA before surgery at 6 months postoperatively (p<0.001). When the two lenses were compared, CDVA was found to be significantly higher in the Lotrafilcon B group in the preoperative, postoperative 1st month and 3rd month values, but there was no significant difference between the postoperative 6th month values (p=0.028, p=0.018, p=0.044, p=0.181, respectively). The maximum keratometry (Kmax) value at the 6th month after surgery in the Comfilcon A group was significantly lower than in the Lotrafilcon B group (p=0,009). There was no significant difference between the endothelial cell density values between the groups (p=0.623, p=0.609, p=0.794, p=0.458, respectively). There was no significant difference between the progression, regression, and stability rates of the two groups (p=0.714). CONCLUSIONS: Accelerated CA-CXL with Lotrafilcon B and Comfilcon A silicone hydrogel lenses is a safe and effective method to stop progression in patients with thin corneas.

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.

Patterns in refractive error and treatment delay in keratoconus-An Australian study.

Keratoconus is the most common primary corneal ectasia and is associated with significant morbidity. In its early stages, keratoconus is often asymptomatic, making the identification of subclinical disease challenging. Refractive error is a parameter that is documented at most routine optometry visits, yet interestingly, changes in refraction of keratoconic patients over time have not yet been studied and compared with the general population. Early diagnosis of keratoconus facilitates timely referral for treatments such as corneal collagen cross-linking, which has been shown to slow disease progression. In this context, documenting delays between initial presentation to the optometrist and referral for collagen-cross-linking as well as comparing the trends in visual acuity and refractive error between keratoconic and non-keratoconic patients over time are particularly relevant.

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.

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.

Comparison of optical aberrations in keratoconus with scleral versus rigid gas permeable lenses.

PURPOSE: to assess optical aberrations under scleral (SL) versus rigid gas permeable (RGP) lenses in patients with keratoconus. METHODS: A prospective study including 25 eyes of 14 patients. The best-corrected visual acuity (BCVA) with corrective glasses, RGP and SL, stage of keratoconus (Amsler-Krumeich classification), minimum pachymetry, maximum keratometry, and corneal higher-order aberrations (i.e, total HOAs, coma, and trefoil) with RGP and with SL were collected. Aberrometry was performed using iTrace® aberrometer (Tracey Technologies, USA). RESULTS: 80% of the included keratoconus patients were stage 4, with a mean age of 34.3 years (±8.8). There were no significant differences in mean BCVA (logMAR) between SL and RGP. The mean BCVAs were significantly better both with SL (p < 0.0001) and RGP (p < 0.0001) compared with corrective glasses. Total HOAs (p = 0.01), coma (p = 0.003) and trefoil (p = 0.008) were significantly lower with SL compared with RGP. The BCVA decreased with the stage of keratoconus in SL (p = 0.01) and RGP (p = 0.02). The BCVA decreased with decreasing minimum pachymetry in SL (p = 0.02) and RGP (p = 0.002), and with increasing maximum keratometry in SL (p = 0.02) and RGP (p = 0.01). Significant correlations were found between BCVA, total HOAs (p = 0.008), and coma (p = 0.02) in SL. CONCLUSION: For the same keratoconus patients, total higher order, coma and trefoil optical aberrations were reduced with scleral lenses compared to rigid gas permeable lenses.

Preferred practice patterns for keratoconus: An e-survey among Indian cornea specialists.

PURPOSE: This study aimed to report practice patterns in the management of keratoconus in India. METHODS: An e-survey was conducted among members of the Cornea Society of India to assess preferred practice patterns for keratoconus. RESULTS: Of the 912 members, 234 (25.7%) completed the survey. About 88.4% worked in private eye care facilities and 76.1% in cities. Of all the respondents, 91.5% had access to a Scheimpflug-based device or an Orbscan II®; 71.4% of the respondents dispensed scleral contact lenses, and 66.7% dispensed Rose K contact lenses; 92.7% of the respondents performed corneal cross-linking (CXL); and 73.1% of the respondents performed deep anterior lamellar keratoplasty (DALK). A Scheimpflug device or Orbscan II®, Rose K or scleral contact lenses, and CXL were more readily available (P < 0.05) in private eye care facilities. The diagnostic criteria for keratoconus followed by the majority of the respondents (52.1%) were increase in corneal curvature, elevation, and thickness. An increase in keratometry values greater than 0.5 or 1.0D in a 6-month to 1-year period was considered the most favored criterion for keratoconus progression. Epithelium-off, 0.1% riboflavin solution in dextran, and accelerated protocol were the more commonly reported techniques in CXL. About 77.2% of the respondents routinely performed CXL in corneas <400 microns thick. Spectacles (91.0% of the respondents) and topography-guided photorefractive keratectomy (37.6% of the respondents) were, respectively, the preferred optical and surgical methods used to improve vision. CONCLUSION: While keratoconus management in India is comparable to other developed healthcare systems, the concentration of trained corneal surgeons in cities and private eyecare facilities may lead to less equitable distribution of treatment across the country.

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.

[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.

Novel deep learning approach to estimate rigid gas permeable contact lens base curve for keratoconus fitting.

INTRODUCTION: Rigid gas permeable contact lenses (RGP) are the most efficient means of providing optimal vision in keratoconus. RGP fitting can be challenging and time-consuming for ophthalmologists and patients. Deep learning predictive models could simplify this process. OBJECTIVE: To develop a deep learning model to predict the base curve (R0) of rigid gas permeable contact lenses for keratoconus patients. METHODS: We conducted a retrospective study at the Rothschild Foundation Hospital between June 2012 and April 2021. We included all keratoconus patients fitted with Menicon Rose K2® lenses. The data was divided into a training set to develop the model and a test set to evaluate the model's performance. We used a U-net architecture. The raw matrix of anterior axial curvature in millimeters was extracted from Scheimpflug examinations for each patient and used as input for the model. The mean absolute error (MAE) between the prediction and the prescribed R0 was calculated. Univariate and multivariate analyses were conducted to assess the model's errors. RESULTS: Three hundred fifty-eight eyes from 202 patients were included: 287 eyes were included in the training dataset, and 71 were included in the testing dataset. Our model's Pearson coefficient of determination (R2) was calculated at 0.83, compared to 0.75 for the manufacturer's recommendation (mean keratometry, Km). The mean square error of our model was calculated at 0.04, compared to 0.11 for Km. The predicted R0 MAE (0.16 ± 0.13) was statistically significantly different from the Km MAE (0.23 ± 0.23) (p = 0.02). In multivariate analysis, an apex center outside the central 5 mm region was the only factor significantly increasing the prediction absolute error. CONCLUSION: Our deep learning approach demonstrated superior precision in predicting rigid gas permeable contact lens base curves for keratoconus patients compared to the manufacturer's recommendation. This approach has the potential to be particularly beneficial in complex fitting cases and can help reduce the time spent by ophthalmologists and patients during the process.

Clinical Performance and Patient Satisfaction of Hybrid Contact Lenses in Patients with Keratoconus.

Objectives: The aim of the study was to evaluate the fitting process, clinical performance, and patient satisfaction of hybrid contact lenses (HCL) in patients with keratoconus (KC). Materials and Methods: Sixty-eight KC patients (35 female, 33 male) who were prescribed HCL were included in the study. Corneal topographic parameters, best corrected visual acuity (BCVA) with eyeglasses, the number of HCL trials, prescribed HCL base curve (BC), and visual acuity with HCL were recorded from hospital records. A contact lens satisfaction survey was sent to the patients via email or WhatsApp and the data was statistically analyzed using IBM SPSS Statistics version 22.0. Results: The study included 110 eyes of 68 patients with a mean age of 27.34±8 years (range: 12-48 years). According to the Amsler-Krumeich classification, 35.5% of the eyes were stage 1, 50.9% were stage 2, and 13.5% were stage 3 or 4. Mean K1, K2, and Kmean values were 7.14±0.50 mm (range 5.72-8.30 mm), 6.63±0.49 mm (range 5.07-7.84 mm), and 6.89±0.48 mm (range 5.39-8.06 mm), respectively. The average number of lens trials was 1.59±0.82 (range 1-4). The mean BC of the prescribed HCL was 6.84±0.50 mm (range 5.60-8.00 mm). BCVA with glasses was 0.36±0.2 (range 0.05-0.8), and 0.80±0.14 (range 0.3-1.0) with HCL (p<0.0001). The overall survey score was 3.54 out of 5, the overall satisfaction score was 3.27, the average vision satisfaction score was 3.62, the average satisfaction score for lens insertion and removal was 3.01, and the average satisfaction score for lens comfort was 2.97. Conclusion: Prescribed HCL BC is usually close to the topographic Kmean value and in most of the patients, fitting was successful with the first or second CL trial. The overall satisfaction score was moderate to good and the disadvantages were low comfort compared to soft CL, difficulty with insertion and removal, short lens life, and high cost.

Prevailing practice patterns in keratoconus among Indian ophthalmologists.

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.

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.

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.

Diagnosis and management of keratoconus in the paediatric age group: a review of current evidence.

The diagnosis and management of keratoconus in the paediatric age group presents additional challenges to those encountered in adults. The most significant of these, encountered in some young patients, are delayed presentation of unilateral disease, more advanced disease at diagnosis, difficulty in obtaining reliable corneal imaging, faster rates of disease progression and challenges in contact lens management. The stabilisation effect of corneal cross-linking (CXL), more extensively studied in adults with randomised trials and long-term follow-up, has been much less rigorously examined in children and adolescents. The high heterogeneity of published studies in younger patients, particularly in the choice of tomography parameters designated as primary outcome measures and the definitions of progression, indicates that improved standardisation for future studies on CXL will be necessary. There is no evidence that corneal transplant outcomes in young patients are poorer than those in adults. This review provides a current perspective on the optimal diagnosis and treatment of keratoconus in children and adolescents.

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.

Comparison of Hybrid Contact Lenses and Rigid Gas-Permeable Contact Lenses in Moderate and Advanced Keratoconus.

Objectives: We aimed to compare the clinical results and topographic data of the new generation hybrid contact lens (HCL) and rigid gas-permeable contact lens (RGPCL) in patients with moderate and advanced keratoconus. Materials and Methods: In this prospective study, HCL users comprised group 1 and RGPCL users comprised group 2. Snellen uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), and lens-corrected visual acuity (LCVA); manifest spherical-cylindrical values; corneal topography measurements (flat keratometry [K1], vertical keratometry [K2], mean K, maximum K [Kmax], central corneal thickness [CCT], and thinnest corneal thickness [TCT]); and cone location were recorded. Results: The study included 83 eyes of 51 patients in group 1 and 61 eyes of 40 patients in group 2. The groups were similar in age and gender (p>0.05). Mean LCVA (logMAR) was significantly lower than BCVA in both groups (p<0.001). The mean visual gain with contact lenses (Snellen chart) was 3.4±1.8 lines in group 1 and 4.0±2.1 lines in group 2. There was no significant difference between the two groups in BCVA, LCVA, or lines gained (p>0.05). There was also no significant difference between the two groups in terms of keratoconus stages, mean Kmax, CCT, TCT, or cone location (p>0.05), while mean UCVA (logMAR) and mean K were higher in group 2 (p<0.05). In both groups, the visual gain with lenses was higher in eyes with central cones, and there was significantly greater visual increase in group 2 (p=0.039). Conclusion: In moderate and advanced keratoconus, HCLs improved vision as much as RGPCLs and both lenses were more effective for central cones. Nevertheless, longer term of follow-up and larger numbers of patients are needed for long term follow-up results of HCL.