Management of keratoconus: an updated review

Artificial intelligence applications in cataract and refractive surgeries

PURPOSE OF REVIEW

This review highlights the recent advancements in the applications of artificial intelligence within the field of cataract and refractive surgeries. Given the rapid evolution of artificial intelligence technologies, it is essential to provide an updated overview of the significant strides and emerging trends in this field.

RECENT FINDINGS

Key themes include artificial intelligence-assisted diagnostics and intraoperative support, image analysis for anterior segment surgeries, development of artificial intelligence-based diagnostic scores and calculators for early disease detection and treatment planning, and integration of generative artificial intelligence for patient education and postoperative monitoring.

SUMMARY

The impact of artificial intelligence on cataract and refractive surgeries is becoming increasingly evident through improved diagnostic accuracy, enhanced patient education, and streamlined clinical workflows. These advancements hold significant implications for clinical practice, promising more personalized patient care and facilitating early disease detection and intervention. Equally, the review also highlights the fact that only some of this work reaches the clinical stage, successful integration of which may benefit from our focus.

Effects and safety of combined corneal collagen crosslinking and intrastromal corneal ring segment treatment in patients with keratoconus: a retrospective study

PURPOSE

To evaluate the safety and efficacy of different time-point combinations of intrastromal corneal ring segment (ICRS) implantation using femtosecond technology) and corneal collagen crosslinking (CXL) for the treatment of moderate-to-severe keratoconus (KCC).

METHODS

This study included 69 eyes of 69 patients with keratoconus who underwent ICRS and CXL treatment at an Eye Hospital between March 2020 and March 2023. The patients were divided into two groups: Group 1 (n = 33 eyes of 33 patients), which received ICRS and CXL treatment in one session, and Group 2 (n = 36 eyes of 36 patients), which included treatment with ICRS for at least 6 months following CXL application. Preoperative and postoperative evaluations included visual acuity, autorefractometer refraction, corneal tomographic measurements using the Sirius (CSO) Scheimpflug camera and the TONOREF™ III device, and documentation of observed complications. Uncorrected visual acuity (UCVA) and best-corrected spectacle visual acuity (BCVA) were measured in each eye individually, and visual acuity was assessed using the logarithm of the minimum angle of resolution (logMAR).

RESULTS

In Group 1, mean UCVA improved from 0.81 ± 0.34 to 0.45 ± 0.25 (p < 0.01), and mean BCVA improved from 0.76 ± 0.35 to 0.38 ± 0.20 (p < 0.01). In Group 2, mean UCVA improved from 0.71 ± 0.32 to 0.43 ± 0.30 (p < 0.01), and mean BCVA improved from 0.65 ± 0.25 to 0.31 ± 0.23 (p < 0.01). Both groups showed significant reductions in manifest spherical and cylindrical refraction (p < 0.01). Group 1 exhibited greater reductions in maximum keratometry (Kmax), flat keratometry (K1), steep keratometry (K2) (p < 0.05), and astigmatic aberration compared with group 2 (p < 0.01). The use of simultaneous or separate CXL and ICRS does not significantly increase the incidence of complications.

CONCLUSIONS

Both combined and separate CXL and ICRS treatments resulted in significant improvement in UCVA and BCVA and reduced manifest refraction. Although improvements were observed in groups 1 and 2 in terms of K1, K2, and Kmax at 6 months, the improvements were more pronounced in Group 1. These results highlight the potential benefits of simultaneous ICRS + CXL treatment and underscore the importance of optimising the timing of CXL treatment to achieve the best visual outcomes.

Retinal neurovascular assessment and choroidal vascularity index in patients with keratoconus

This study aims to evaluate the macular and the optic nerve head thickness and vascular profiles in KC patients and compare them with two groups of healthy emmetrope and subjects with myopic-astigmatism. This cross-sectional study was conducted at Khatam-Al-Anbia Eye Hospital between 2022 and 2023. Subjects aged 18 to 40 were prone to be included in the study. The participants in this study were grouped into three categories: emmetrope (E), myopic-astigmatic (MA), and keratoconus (KC). All participants underwent a comprehensive ocular examination, as well as macular and optic nerve head (ONH) optical coherence tomography angiography (OCTA). In this study, 143 subjects, 50 cases in the KCN group, 46 cases in the E group, and 47 cases in the MA group, enrolled. There was no difference between the three groups regarding age (p = 0.123) and gender (p = 0.632). The superficial and deep capillary densities at the fovea, parafovea, and perifovea were significantly lower in KC patients than in the control groups (p < 0.01). The radial peripapillary capillary (RPC)- all vessels' density is significantly lower in the KC group (p < 0.001). Besides, the choroidal vascularity index (CVI) and choroidal luminal area (CLA) were considerably higher in KC patients (p < 0.001). The macular and ONH vascular profile in KC patients significantly differs from the vascular profile of healthy controls. Further scientific evidence regarding the systemic implications of keratoconus on the vascular system would be desirable to understand the connections between KC and vascular disease.

Pediatric keratoconus

Keratoconus is a common pediatric corneal disease, leading to vision impairment and amblyopia. Compared to its adult counterpart, pediatric keratoconus has an advanced presentation, rapid progression, higher incidence of complications such as corneal hydrops, and greater potential impact on the quality of life. It typically manifests during puberty and can evolve rapidly to more severe stages if left untreated. This rapid progression underscores the importance of early diagnosis through regular screening in pediatric populations and vigilant monitoring of pediatric keratoconus suspects. Concomitant ocular allergies, ocular anomalies, systemic diseases (e.g. syndromes), and poor compliance with contact lenses might impede prompt intervention and frequently postpone rehabilitation. Corneal collagen crosslinking is a crucial intervention in the management of pediatric keratoconus because it strengthens the corneal microstructure and halts the disease progression. When conservative measures fail, keratoplasty remains a viable option with generally favorable outcomes, though with unique challenges in post-operative care, including concerns related to sutures, long-term graft survival and need for repeated examinations under anesthesia. A multidisciplinary approach involving ophthalmologists, optometrists, pediatricians, and other healthcare professionals, focusing on early diagnosis and timely intervention, is essential for the comprehensive management of pediatric keratoconus and to mitigate its impact on children's lives.

Mendelian randomization reveals that abnormal lipid metabolism mediates the causal relationship between body mass index and keratoconus

Previous studies suggest that a high body mass index (BMI) may be a risk factor for keratoconus (KC), but the causal relationship remains unclear. This study used Mendelian randomization (MR) to investigate this connection and explore the mediating role of circulating serum metabolites and inflammatory factors in this association. Two-sample MR analysis was conducted to assess the relationship between BMI and KC. The study employed a two-step MR approach to evaluate the mediating roles of 91 inflammatory markers and 249 serum metabolites in the BMI-KC relationship. Inverse variance weighting (IVW) was the primary method, and multiple sensitivity analyses were performed to ensure robustness. IVW analysis revealed a positive causal relationship between BMI and KC (OR IVW = 1.811, 95% CI 1.005-3.262, P = 0.048). Although IL-12β and IL-4 were causally associated with KC, they did not mediate the BMI-KC relationship. Five serum metabolites were identified as potential mediators, with HDL cholesterol and triglyceride ratios showing significance. This study clarified the causal relationship between high BMI and KC, suggesting that high BMI may induce KC through lipid metabolism abnormalities. These findings underscore the importance of managing BMI for KC prevention.

Paradigm Shift in Eye Banking: From Tissue Retrieval to Cellular Harvesting and Bioengineering

ABSTRACT

An integrated cell, tissue, and eye bank is vital to meet the evolving needs of ocular transplant therapies. In addition to traditional corneal transplant tissues, it encompasses processing and delivery of transplant materials for newer treatments like cell-based therapies and gene-modified products, adhering to rigorous standards, optimizing tissue utilization with comprehensive services for surgeons.

Inflammatory and genomic interactions within keratoconus susceptible patients: a nationwide registered case-control study

PURPOSE

This study aimed to investigate the association between variants in the interleukin (IL)-1 gene cluster and susceptibility to keratoconus (KC) in an Iranian population.

METHODS

In the case group, there were 188 KC patients diagnosed by clinical findings and corneal tomography. The control group included all 205 healthy controls with no personal or family history of eye-related, metabolic, or immune system-related disease. Using the standard salting out extraction procedure, genomic DNA was isolated from peripheral blood leukocytes. The genotypes were determined by applying agarose gel electrophoresis for the IL-1RN 86 bp VNTR and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for rs16944 and rs1143634.

RESULTS

The results showed a significant association between the IL-1β rs1143634 (rs1143634 T allele, P = 0.008) and IL-1RN 86 bp VNTR polymorphisms (LL and LS genotype, P = 0.048 and 0.012 respectively) and susceptibility to KC in the Iranian population. The genotype distributions of rs1143634 (P = 0.004) and rs2234663 (P = 0.042) significantly differed between case and control groups, with certain genotypes demonstrating a protective effect against KC. Logistic regression analysis revealed a protective effect of the IL-1RN L allele [odds ratio (OR) = 0.367, 95% confidence interval (CI): 0.240-0.562; P = 0.000] and certain haplotypes (OR = 0.628, 95% CI: 0.447-0.884; P = 0.007) against KC. However, no significant association was found for the IL-1β rs16944 polymorphism.

CONCLUSION

This study provides evidence for an association between variants in the IL-1 gene cluster and susceptibility to KC in an Iranian population. Further research on larger and more diverse populations is warranted to validate these findings and explore the underlying mechanisms involved.

Risk Factors for Glaucoma and Ocular Hypertension and Post-Transplant Complications in Keratoconus: A Multivariable Analysis

Background: The purpose of this study was to investigate the risk factors for glaucoma in patients with keratoconus following keratoplasty and to identify potential factors that could affect post-transplant complications. Methods: A retrospective analysis was conducted on the medical records of 192 keratoconus patients who underwent keratoplasty. Data on treatment history, perioperative information, tissue bank data, postoperative regimens, complications, and infections were collected and analyzed. Statistical analysis was performed to identify risk factors associated with glaucoma and transplant complications. Results: There was a 41.6% incidence of glaucoma (high IOP) (p < 0.001), with the median time to glaucoma development being 314 ± 67 days post-transplant. A significant number of patients required surgical intervention, accounting for 48.05%. Our analysis revealed a 14% graft failure rate. On univariable Cox proportional hazard analysis, the following factors demonstrated statistically significant associations with the risk of glaucoma after transplantation: donor endothelial cell density, the use of a single continuous suture type, and the surgeon (performing the surgery). For many variables, the only factor that remained significant was the surgeon. Among the factors analyzed for risks of failure post-transplantation, significant associations were observed for the donor age, the time from harvest to transplant, and the surgeon. In the multivariable analysis, donor age emerged as a significant predictor of post-transplant complications. Conclusions: Risk factors such as donor endothelial cell density, suture type, surgeon, host and donor size, and host gender were found to increase the risk of developing glaucoma post-keratoplasty. Surgeon type was identified as a significant risk factor, while donor age was predictive of post-transplant complications.

Harnessing Corneal Stromal Regeneration for Vision Restoration: A Comprehensive Review of the Emerging Treatment Techniques for Keratoconus

Keratoconus is a progressive corneal disorder characterized by thinning and conical protrusion, leading to visual impairment that often necessitates advanced treatment strategies. Traditional management options, including corrective lenses, corneal cross-linking (CXL), and surgical interventions such as corneal transplants and intracorneal ring segments (ICRS), address symptoms but have limitations, especially in progressive or advanced cases. Recent advancements in corneal stromal regeneration offer promising alternatives for enhancing vision restoration and halting disease progression. This review explores emerging techniques focused on corneal stromal regeneration, emphasizing cell-based therapies, tissue engineering, and gene therapy. Cell-based approaches, including corneal stromal stem cells and adipose-derived stem cells, are promising to promote tissue repair and functional recovery. Tissue engineering techniques, such as developing synthetic and biological scaffolds and 3D bioprinting, are being investigated for their ability to create viable corneal grafts and implants. Additionally, gene therapy and molecular strategies, including gene editing technologies and the application of growth factors, are advancing the potential for targeted treatment and regenerative medicine. Despite these advancements, challenges remain, including technical limitations, safety concerns, and ethical considerations. This review aims to provide a comprehensive overview of these innovative approaches, highlighting their current status, clinical outcomes, and future directions in keratoconus management.

Mendelian randomization analysis does not reveal a causal influence between keratoconus and three major mental disorders

Background

Observational studies have suggested at a possible link between keratoconus (KC) and various mental disorders, but the exact direction of causation in these associations remains unclear. This study aims to investigate the potential causal link between KC and three prominent mental conditions: Anxiety, Depression, and Schizophrenia.

Methods

Using instrumental variables identified from Genome-wide association study (GWAS) data of European individuals, we conducted bidirectional two-sample Mendelian Randomization (MR) analyses to explore potential causal relationships between KC and the three major mental disorders. We primarily employed the Inverse-Variance Weighted (IVW) method to evaluate causality. In addition, we performed four supplementary MR methods (MR-Egger, Weighted Median, Simple Mode, and Weighted Mode). Furthermore, we conducted various sensitivity analyses to assess heterogeneity, horizontal pleiotropy, and result stability.

Results

Our findings did not reveal any concrete evidence of a causal link between KC and the three major mental disorders, namely anxiety, depression, and schizophrenia [anxiety: odds ratio (OR)=0.997, 95% confidence interval (CI)=0.988-1.008, p = 0.621; depression: OR=1.008, 95% CI=0.999-1.017, p = 0.084; schizophrenia: OR=1.002, 95% CI= 0.984-1.020, p = 0.840]. Similarly, the three major mental disorders were not caustically associated with KC [anxiety: OR=1.014, 95% CI=0.635-1.620, p = 0.953; depression: OR=1.109, 95% CI= 0.749-1.643, p = 0.604; schizophrenia: OR= 0.969, 95% CI= 0.884-1.062, p = 0.497]. The sensitivity analyses indicated that the results remained robust, with no signs of pleiotropy or heterogeneity.

Conclusions

Our study does not support a genetically determined significant causal connection between KC and the three major mental disorders. The increased occurrence of mental disorders observed in KC patients in observational reports likely arises from factors that can be modified. Further research is warranted to unveil the underlying mechanisms behind the associations observed in observational studies.

Topography-guided photorefractive keratectomy combined with accelerated corneal collagen cross-linking versus cross-linking alone for progressive keratoconus: a long-term prospective cohort study

Purpose

To comprehensively compare the long-term outcome of the combined topography guided photorefractive keratectomy (TG-PRK) with accelerated corneal cross-linking (ACXL) and ACXL alone in eyes with progressive keratoconus. The analysis focused on the changes in the detailed corneal aberrometric values.

Methods

This single-center, prospective cohort study included 28 patients (30 eyes) of the TG-PRK plus ACXL group and 14 patients (15 eyes) of the ACXL alone group. The mean duration of the follow-up was 44 ± 10.18 months (ranged from 31 to 65 months). The preoperative data and the postoperative measurement data at the last follow-up visit, including demographic data, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, corneal topography, pachymetry, aberrometry and densitometry were analyzed.

Results

The CDVA significantly improved in the TG-PRK plus ACXL group at the last follow-up visit (p = 0.006), while no significant improvement was found in the ACXL alone group (p = 0.432). The maximal keratometry of the anterior corneal surface (Kmax) of both groups significantly decreased at the last follow-up visit (p < 0.05). Compared with the ACXL alone group, the Kmax of the TG-PRK plus ACXL group showed a greater decline (p = 0.008). The total corneal aberrations, the corneal lower-order aberrations (LOAs), the corneal higher order aberrations (HOAs), the vertical coma and the spherical aberration (SA) at the 4.0 mm and 6.0 mm zone of the TG-PRK plus ACXL group significantly decreased at the last follow-up visit (all p < 0.05). The declines of the total corneal aberrations, the corneal LOAs, the corneal HOAs and the vertical coma at the 4.0 mm and 6.0 mm zone of the TG-PRK plus ACXL group were significantly higher than those in the ACXL alone group (p < 0.001).

Conclusion

Compared with ACXL alone, combined TG-PRK with ACXL procedure had a significantly higher reduction in the corneal HOAs and better CDVA, while providing a similar long-term stability and safety. For progressive keratoconus patients with adequate corneal thickness, the combined procedure might be a recommended treatment option.

Evolving Trends in the Diagnosis and Management of Keratoconus Over 3 Decades

PURPOSE

To report the trends in the clinical presentation, diagnosis, and management of keratoconus (KC) in patients presenting to a multitier hospital network over 33 years.

METHODS

This retrospective study included patients with KC presenting from 1987 to 2020. Patients with KC in at least 1 eye were included. The data of 20,576 patients included in this study were retrieved from the electronic medical record database. Data on patient demographics, ocular diagnosis, contact lens usage, and surgical history were collected and exported for analysis. Descriptive statistics and chi square test were used for statistical analysis.

RESULTS

A total of 20,576 KC cases were seen from 1987 to 2020. Mean age at diagnosis reduced from 29.3 years (1987-1991) to 22.2 years (2016-2020). Adults (76.64%) were commonly affected with a majority being male (61.25%). Use of contact lenses increased from 4.34% (2002-2006) to 11.23% (2016-2020). Of the total number of surgical interventions, collagen crosslinking (CXL) constituted more than 1/5th (22.28%) between 2007 and 2011, which increased to more than half between 2012 and 2016 (53.61%) and almost 3/4th (72.53%) between 2017 and 2020. Advances in lamellar surgery have led to more patients undergoing deep anterior lamellar keratoplasty (DALK) as compared with penetrating keratoplasty. In the last 8 years, 17.2% patients underwent surgery and the most common was CXL (14.77%) followed by DALK (1.72%) and penetrating keratoplasty (1.04%).

CONCLUSIONS

We report the trends in the clinical presentation and management of KC over 3 decades. In the last 33 years, advances in diagnostics have helped diagnose KC earlier. Contact lenses and advances in CXL have reduced the number of keratoplasties in KC, DALK being more common.

Exploring the causal relationship between body mass index and keratoconus: a Mendelian randomization study

Background

Despite reports suggesting a link between obesity and keratoconus, the causal relationship is not fully understood.

Methods

We used genome-wide association study (GWAS) data from public databases for a two-sample Mendelian randomization analysis to investigate the causal link between body mass index (BMI) and keratoconus. The primary method was inverse variance weighted (IVW), complemented by different analytical techniques and sensitivity analyses to ensure result robustness. A meta-analysis was also performed to bolster the findings' reliability.

Results

Our study identified a significant causal relationship between BMI and keratoconus. Out of 20 Mendelian randomization (MR) analyses conducted, 9 showed heterogeneity or pleiotropy. Among the 11 analyses that met all three MR assumptions, 4 demonstrated a significant causal difference between BMI and keratoconus, while the remaining 7 showed a positive trend but were not statistically significant. Meta-analysis confirmed a significant causal relationship between BMI and keratoconus.

Conclusion

There is a significant causal relationship between BMI and keratoconus, suggesting that obesity may be a risk factor for keratoconus.

Bowman Layer Transplantation With Stromal Inclusion Using Femtosecond Laser: 3-year Results

PURPOSE

The aim of this study was to evaluate the 3-year clinical results of Bowman layer with stromal inclusion (Bowman layer) transplantation using femtosecond laser for patients with advanced keratoconus.

METHODS

This single-center retrospective study included 7 eyes of 7 patients diagnosed with progressive keratoconus who underwent Bowman layer transplantation with stromal inclusion between 2018 and 2020. Follow-up was carried out from the date of surgery until 36 months later. Bowman layer grafts were positioned into a mid-stromal pocket performed by a femtosecond laser and patients were evaluated up to 3 years after surgery.

RESULTS

Corneal flattening of 5.49 D (P = 0.0020) in Kmax was observed, increased in corneal pachymetry, and an improvement best-corrected visual acuity measured in logarithm of minimum angle of resolution (LogMAR) from 0.89 to 0.60 and tolerance to contact lens from 42% of the patients to 100% of them. Stabilization of the cornea was achieved in 100% with no further progression of the keratoconus; all surgical procedures were uneventful, and no complications were observed during the 3 years of follow-up.

CONCLUSIONS

Bowman layer transplantation with stromal inclusion flattened the cornea improving best-corrected visual acuity and contact lens tolerance and stabilized keratoconus in 100% of the patients during 3 years of follow-up and may be a feasible option in patients with advanced and progressive KC to delay or avoid the need for PK or DALK.

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.

A Standardized Protocol of Simultaneous Transepithelial Phototherapeutic Keratectomy (PTK) Followed by Corneal Collagen Crosslinking for Keratoconus

PURPOSE

To report outcomes in patients with progressive keratoconus who underwent a standardized protocol of transepithelial phototherapeutic keratectomy (t-PTK) laser followed by accelerated corneal collagen crosslinking (CXL).

METHODS

All patients with progressive keratoconus undergoing our protocol at a London clinic between 2019 and 2023 were included. The protocol involved t-PTK at 58-μm central ablation depth at a 9-mm treatment zone on the Schwind Amaris 1050RS platform. Preoperative K readings of 43.0D (both K1 and K2) were inputted for all cases. Patients then underwent CXL with a pulsed-light accelerated protocol (30 mW/cm2 for 8 minutes of UVA exposure time with 1 second on/1 second off).

RESULTS

Seventy-nine eyes from 55 patients were included with an average follow-up of 12 months (range 6-24 months). Both mean uncorrected distance visual acuity (UDVA) and best spectacle-corrected visual acuity improved significantly from 0.42 preoperatively to 0.29 postoperatively (P < 0.01) and 0.11 to 0.06 postoperatively (P < 0.01), respectively. The refractive cylinder reduced significantly from -3.07D to -2.63D (P < 0.05). The mean Km improved from 46.15D to 45.44D (P < 0.01) and mean Kmax from 54.03D to 52.52D (P < 0.01). 77% of eyes (n = 61) exhibited Kmax improvement postoperatively, and 56% showed an improvement in UDVA (n = 44). 16% (n = 13) had worsening of vision, but of these, only 1 patient had visual loss of more than 2 lines. No eyes had corneal haze reported at the final follow-up, and none required additional treatment.

CONCLUSIONS

This standardized simultaneous t-PTK and CXL protocol is safe and effective for the treatment of progressive keratoconus, providing visual, refractive, and topographic improvements.

Long-Term Results of Sterile Corneal Allograft Ring Segments Implantation in Keratoconus Treatment

PURPOSE

To evaluate the efficacy and safety of sterile corneal allograft ring segments implantation for the treatment of keratoconus by analyzing long-term visual, refractive, and tomographic clinical outcomes.

METHODS

This prospective study included 62 eyes of 49 patients with keratoconus who underwent corneal allograft ring segments implantation at Istanbul Medipol University Faculty of Medicine between February 2020 and August 2022. Surgical outcomes using the Istanbul nomogram were evaluated in patients preoperatively and postoperatively at 1 month, 6 months, 1 year, and 3 years. Outcomes measured were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent (SE), spherical refraction (SR), cylindrical refraction (CR), topographic keratometric values, and corneal thickness at the thinnest point.

RESULTS

Preoperative mean UDVA and CDVA (LogMAR) were 0.96 ± 0.50 and 0.72 ± 0.47, respectively, and increased to 0.41 ± 0.34 and 0.22 ± 0.19 at the last visit (P < 0.001). There was a significant decrease in SE, SR, and keratometric values postoperatively (P < 0.001). There was no difference in CR and thinnest corneal thickness values (P = 0.333 and 0.154, respectively). The stromal and epithelial thicknesses measured by anterior segment optical coherence tomography were stabilized at 6 months and 1 year, respectively. No major complications or side effects were observed intraoperatively or postoperatively.

CONCLUSIONS

This study demonstrated that sterile corneal allograft ring segments implantation is a safe and feasible treatment for keratoconus, yielding notable long-term visual outcomes with minimal implant-related complications.

Cosmetic Contact Lenses in the United Kingdom: Assessment of Online Regulation and Quality of Consumer Health Information

OBJECTIVES

To determine the compliance of online vendors to the UK Opticians Act 1989 Section 27 requirements and safety regulations for cosmetic contact lens (CCL) sales and the quality of online CCL health information.

METHODS

The top 50 websites selling CCLs on each three search engines, namely Google, Yahoo, and Bing, were selected. Duplicates were removed, and the remaining websites were systematically analyzed in February 2023. UK legal authorization for CCL sales was assessed using the Opticians Act Section 27 and safety regulations determined by the presence of Conformité Européene (CE) marking. The quality and reliability of online information was graded using the DISCERN (16-80) and JAMA (0-4) scores by two independent reviewers.

RESULTS

Forty-seven eligible websites were analyzed. Only six (12.7%) met the UK legal authorization for CCL sales. Forty-nine different brands of CCLs were sold on these websites, of which 13 (26.5%) had no CE marking. The mean DISCERN and JAMA benchmark scores were 26 ± 12.2 and 1.3 ± 0.6, respectively (intraclass correlation scores: 0.99 for both).

CONCLUSIONS

A significant number of websites provide consumers with easy, unsafe, and unregulated access to CCLs. Most online stores do not meet the requirements set out in the Opticians Act for CCL sales in the United Kingdom. A significant number of CCLs lack CE marking, while the average quality of information on websites selling CCLs is poor. Together, these pose a risk to consumers purchasing CCLs from unregulated websites, and therefore, further stringent regulations on the online sales of these products are needed.

Advanced Surface Ablation in a Patient With Suspect Topography: A Case Report

The purpose of this clinical report is to describe a 10-year clinical outcome of advanced surface ablation with photorefractive keratectomy (PRK) in a patient who had been previously incorrectly diagnosed with keratoconus (KC). Corneal ectasia is a rare but extremely relevant complication of laser vision correction, and KC represents a major contraindication for these procedures. Nonetheless, some surface ablation procedures, such as PRK, might be a valid option for particular patients with atypical corneal topography or subclinical or mild forms of KC. Patient education and complete preoperative refractive multimodal imaging are essential for a more conscious therapeutic decision, minimizing iatrogenic ectasia, as well as decreasing the number of patients who are incorrectly denied refractive surgery, as was the patient presented in this study.

Reduced Retinal Blood Vessel Densities Measured by Optical Coherence Tomography Angiography in Keratoconus Patients Are Negatively Correlated with Keratoconus Severity

Keratoconus (KC) is the most common corneal ectasia. Optical coherence tomography angiography (OCT-A) is a relatively new non-invasive imaging technique that allows the visualization and quantification of retinal and choriocapillary blood vessels. The aim of this study is to assess retinal and choriocapillary vessel density (VD) differences between KC patients and healthy controls and to investigate correlations between VD and KC severity. Fifty-two eyes were included in this exploratory study: twenty-six eyes from 26 KC patients and twenty-six eyes from 26 age- and gender-matched healthy controls. All patients underwent Scheimpflug corneal topography with Pentacam, axis lengths measurement and optical coherence tomography angiography (OCT-A). The thinnest spot in corneal pachymetry, maximum K (Kmax) and KC severity indices from the Belin/Ambrósio enhanced ectasia display (BAD) were also assessed. There was a distinct reduction particularly in the retinal VD of the superficial capillary plexus (SCP). Correlation analyses showed strong and moderate negative correlations between the VD in the macular SCP and BAD KC scores and between the SCP VD and Kmax. There was no difference in retinal thickness between the KC and healthy controls. With this study, further evidence for altered VD measurements by OCT-A in KC patients is given. For the first time, we demonstrated negative correlations between BAD KC scores and retinal blood vessel alterations. A major limitation of the study is the relatively small sample size. Since an artefactual reduction of the quantitative OCT-A measurements due to irregular corneal topography in KC must be assumed, it remains to be investigated whether there are also actual changes in the retinal microcirculation in KC.

The candidate proteins associated with keratoconus: A meta-analysis and bioinformatic analysis

PURPOSE

Keratoconus (KC) is a multifactorial disorder. This study aimed to conduct a systematic meta-analysis to exclusively explore the candidate proteins associated with KC pathogenesis.

METHODS

Relevant literature published in the last ten years in Pubmed, Web of Science, Cochrane, and Embase databases were searched. Protein expression data were presented as the standard mean difference (SMD) and 95% confidence intervals (CI). The meta-analysis is registered on PROSPERO, registration number CRD42022332442 and was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement (PRISMA). GO and KEGG enrichment analysis were performed, as well as the miRNAs and chemicals targeting the candidate proteins were predicted. PPI was analyzed to screen the hub proteins, and their expression was verified by RT-qPCR.

RESULTS

A total of 21 studies were included in the meta-analysis, involving 346 normal eyes and 493 KC eyes. 18 deregulated proteins with significant SMD values were subjected to further analysis. In which, 7 proteins were up-regulated in KC compared with normal controls, including IL6 (SMD 1.54, 95%CI [0.85, 2.24]), IL1B (SMD 2.07, 95%CI [0.98, 3.16]), TNF (SMD 2.1, 95%CI [0.24, 3.96]), and MMP9 (SMD 1.96, 95%CI [0.68, 3.24]). While 11 proteins were down-regulated in KC including LOX (SMD 2.54, 95%CI [-4.51, -0.57]). GO and KEGG analysis showed that the deregulated proteins were involved in inflammation, extracellular matrix (ECM) remodeling, and apoptosis. MMP9, IL6, LOX, TNF, and IL1B were regarded as hub proteins according to the PPI analysis, and their transcription changes in stromal fibroblasts of KC were consistent with the results of the meta-analysis. Moreover, 10 miRNAs and two natural polyphenols interacting with hub proteins were identified.

CONCLUSION

This study obtained 18 candidate proteins and demonstrated altered cytokine profiles, ECM remodeling, and apoptosis in KC patients through meta-analysis and bioinformatic analysis. It will provide biomarkers for further understanding of KC pathogenesis, and potential therapeutic targets for the drug treatment of KC.

Prevalence of Keratoconus in the Young Eastern Population of Saudi Arabia

BACKGROUND

Keratoconus (KCN) is a progressive corneal ectasia that manifests at a young age and significantly impacts vision and quality of life. Early diagnosis allows for effective treatment with corneal collagen crosslinking, yet there is a lack of screening methods. This research aims to screen adolescents and young adults for this sight-threatening disease using quick corneal tomography mapping.

METHODS

This prospective cross-sectional study is being conducted at Johns Hopkins Aramco Healthcare in Saudi Arabia, focusing on subjects aged 13-23. We are presenting the data from our study as internal pilot study data. Bilateral corneal imaging with Pentacam HR (Oculus, Wetzlar, Germany), utilizing Scheimpflug corneal tomography, was performed. Historical data on allergies, eye rubbing, KCN, family history, previous eye surgery, and contact lens use were collected. The Belin Ambrosio Enhanced Ectasia Display total D value served as an objective criterion for suspect KCN (SKCN) diagnosis.

RESULTS

In this study with 110 participants, KCN was identified in 2.75% of participants and SKCN in 11.93%. Systemic allergies or eczema were reported by 2.80%, with no cases in the KCN or SKCN groups. Eye rubbing behavior was observed in 5.50%, with the highest prevalence (33.30%) in the KCN group. A family history of KCN was found in 21.10%, with SKCN having the highest prevalence (30.80%).

CONCLUSION

This restricted population study reveals a significant KCN rate of 2.75%. The condition, easily detected and treatable with corneal collagen crosslinking, highlights the need for larger population studies to determine the disease's true prevalence. Efficient screening programs tailored to regional data are essential for early detection and intervention.

Transepithelial Accelerated Crosslinking for Progressive Keratoconus: A Critical Analysis of Medium-Term Treatment Outcomes

Purpose

To report the 4-year outcomes of transepithelial accelerated corneal collagen crosslinking (TE-ACXL) in the treatment of eyes with progressive keratoconus (KC).

Methods

Eyes of patients who underwent TE-ACXL (6mW/cm2 for 15 minutes) for progressive KC and presented 48 months of follow-up were included. Corrected distance visual acuity (CDVA), keratometry measurements (Kmax, maximum keratometry, Kmean, mean keratometry and Astg, corneal astigmatism), thinnest corneal thickness (PachyMin), and topographic, and tomographic indices (specifically the posterior radius of curvature from the 3.0 mm centered on the thinnest point of the cornea (PRC), and the D-index) were analysed preoperatively and every 12 months after TE-ACXL, up to 48 months. Progression after TE-ACXL was considered when eyes presented ≥1 criteria: (1) increase of ≥1D in Kmax or increase of ≥0.75D in Kmean or increase of ≥1D in Astg; (2) reduction of ≥0.085 mm in PRC; (3) decrease ≥5% in PachyMin.

Results

41 eyes from 30 patients were included, with a mean age at crosslinking of 20.90±4.69 years. There was a significant increase in Kmean (+0.64±1.04 D, p<0.001; +0.98 ± 1.49 D, p<0.001; +1.27±2.01 D, p<0.001; +1.13±2.00 D, p=0.006) and a significant decrease in PRC throughout follow-up (-0.12±0.22, p=0.002; -0.15±0.24, p<0.001; -0.17±0.43, p=0.021; -0.16±0.43, p=0.027). PachyMin decreased significantly at 36 and 48 months (-8.50±15.93 μm, p=0.004; -7.82±18.37, p=0.033). According to our progression criteria, there was a major progression rate throughout follow-up (57.1%, 61.1%, 58.8%, and 67.9%, respectively). Surgery and follow-up were uneventful in all subjects. Eleven eyes (26.8%) required further procedures, ≥36 months after the initial TE-ACXL, due to persistent progressive disease.

Conclusion

TE-ACXL proved to be a safe therapeutic option for progressive KC. However, its efficacy is deemed unsatisfactory, as a notable proportion of affected eyes may continue to advance within a 4-year timeframe, necessitating additional procedures to halt the disease's course.

Headache Attributed to Refractive Error: Improvement after Topography-Guided Photorefractive Keratectomy with Corneal Cross-Linking in Patients with Keratoconus

PURPOSE

To investigate if topography-guided photorefractive keratectomy (TGPRK) alleviates headache, particularly headache attributed to refractive errors (HARE) in keratoconus.

METHODS

Patients diagnosed with keratoconus undergoing TGPRK for refractive correction were included. Best spectacle corrected visual acuity (BSCVA) using the logMAR scale and refractive error were measured. Patients answered a questionnaire exploring headaches, characteristics, treatment, and the Headache Impact Test (HIT-6) before and 6 months after the surgery.

RESULTS

40 patients were included. Preoperatively, 24 patients (60%) met criteria for headaches: five for migraine, 14 for HARE, and five for tension-type headache (TTH). Patients with headaches preoperatively were more likely to require bilateral TGPRK, and the mean sphere and cylindrical power were higher. Postoperatively, 15 out of the 24 patients of the headache group experienced complete resolution of headaches, and only nine patients met diagnostic criteria for headaches: two for migraine, six for HARE, and one for TTH. The number of headaches reduced from 4.4 ± 2.4 to 0.5 ± 0.7 days/week (p < 0.001). Headache duration decreased from 108.5 ± 100.7 min to 34.4 ± 63.5 min (p = 0.002). Postoperatively, the consumption of analgesia decreased. The HIT-6 revealed an improvement in the quality-of-life post-procedure (p < 0.001).

CONCLUSIONS

Surgical correction of irregular astigmatism in patients with keratoconus can alleviate or resolve headaches in a large proportion of patients, resulting in an improvement in their quality of life. Physicians should consider keratoconus in patients fitting criteria for HARE not alleviated by spectacle correction and suboptimal vision in glasses.

Clinical Applications of Anterior Segment Optical Coherence Tomography: An Updated Review

Since its introduction, optical coherence tomography (OCT) has revolutionized the field of ophthalmology and has now become an indispensable, noninvasive tool in daily practice. Most ophthalmologists are familiar with its use in the assessment and monitoring of retinal and optic nerve diseases. However, it also has important applications in the assessment of anterior segment structures, including the cornea, conjunctiva, sclera, anterior chamber, and iris, and has the potential to transform the clinical examination of these structures. In this review, we aim to provide a comprehensive overview of the potential clinical utility of anterior segment OCT (AS-OCT) for a wide range of anterior segment pathologies, such as conjunctival neoplasia, pterygium, scleritis, keratoconus, corneal dystrophies, and infectious/noninfectious keratitis. In addition, the clinical applications of AS-OCT (including epithelial mapping) in preoperative planning and postoperative monitoring for corneal and refractive surgeries are discussed.

Association between Polymorphism rs61876744 in PNPLA2 Gene and Keratoconus in a Saudi Cohort

The genetic etiology of Keratoconus (KC) in Middle Eastern Arabs of Saudi origin is still unclear. A recent genome-wide study identified two significant loci in the region of PNPLA2 (rs61876744) and CSNK1E (rs138380) for KC that may be associated with KC in the Saudi population. In addition, polymorphisms in the apolipoprotein E (APOE) gene, namely, rs429358 and rs7412, responsible for APOE allelic variants ε2, ε3, and ε4, may influence KC via oxidative stress mechanism(s). Thus, we investigated the possible association of polymorphisms rs61876744, rs138380, rs429358, rs7412, and APOE genotypes in KC patients of the Saudi population. This study included 98 KC cases and 167 controls. Polymorphisms rs6187644 and rs138380 were genotyped using TaqMan assays, and rs429358 and rs7412 were genotyped via Sanger sequencing. Although the allele frequency of rs61876744(T) in PNPLA2 was a protective effect against KC (odds ratio (OR) = 0.64, 95% confidence interval (CI) = 0.44-0.93), the p-value (p = 0.020) was not significant for multiple testing correction (p = 0.05/4 = 0.015). However, rs6187644 genotype showed a modestly significant protective effect in the dominant model (OR = 0.53, 95% CI = 0.32-0.88, p = 0.013). Polymorphisms rs138380, rs429358, and rs7412 showed no significant allelic or genotype association with KC. However, the ε2-carriers (ε2/ε2 and ε2/ε3 genotypes) exhibited a greater than 5-fold increased risk of KC, albeit non-significantly (p = 0.055). Regression analysis showed no significant effect of age, gender, and the four polymorphisms on KC. Our results suggest that polymorphism rs6187644 in PNPLA2 might be associated with KC in the Middle Eastern Arabs of Saudi origin but warrant a large-scale association analysis at this locus.

Prevalence and Associations of Keratoconus Among Children, Adults, and Elderly in the Population-Based Ural Eye Studies

PURPOSE

To estimate prevalence and associations of keratoconus in populations in Russia with an age from childhood to seniority.

METHODS

The study population consisted of the cohorts of 3 population-based studies performed in urban and rural areas within the same geographical region in Bashkortostan/Russia: the Ural Children Eye Study (UCES; age = 6-18 y; n = 4890), the Ural Eye and Medical Study (UEMS; age = >40 y; n = 5314), and the Ural Very Old Study (UVOS; age = >85 y; n = 651). Based on Scheimflug imaging, keratoconus was defined by a keratometric reading of ≥48 diopters (D) in any eye.

RESULTS

The mean maximal and minimal corneal refractive power increased from the UCES (43.58 ± 1.50 D and 42.70 ± 1.42 D, respectively) to the UEMS (44.26 ± 1.70 D and 43.61 ± 1.76 D, respectively) and to the UVOS (45.1 ± 1.72 D and 43.98 ± 1.68 D, respectively). Correspondingly, keratoconus prevalence increased from the UCES (42/4890; 0.086%; 95% CI = 0.060, 0.112) to the UEMS (112/5314; 2.11%; 95% CI = 1.72, 2.49) and to the UVOS (42/651; 6.45%; 95% CI = 4.56, 8.34). In the UCES, higher keratoconus prevalence was associated (multivariable analysis) with higher birth order [odds ratio (OR) = 2.34; 95% CI = 1.32, 4.15; P = 0.004], lower birth weight (OR = 0.99; 95% CI = 0.99, 0.99; P < 0.001), and shorter axial length (OR = 0.15; 95% CI = 0.08, 0.30; P < 0.001). In the UEMS, keratoconus prevalence correlated with shorter axial length (OR = 0.15; 95% CI = 0.10, 0.23; P < 0.001), larger corneal volume (OR = 1.17; 95% CI = 1.09, 1.25; P = 0.001), thicker lens (OR = 2.27; 95% CI = 1.06, 5.28; P = 0.04), cortical cataract degree (OR = 1.02; 95% CI = 1.01, 1.04; P = 0.01), and higher stage of age-related macular degeneration (OR = 1.65; 95% CI = 1.09, 2.51; P = 0.02). In the UVOS, keratoconus prevalence correlated with lower educational level (OR = 0.84; 95% CI = 0.71, 0.99; P = 0.04) and lower dynamometric handgrip force (OR = 0.92; 95% CI = 0.88, 0.97; P = 0.003).

CONCLUSIONS

In this study on multiethnic groups from Russia, keratoconus prevalence increased from the pediatric group (0.09%) to the adult group (2.11%) and seniority group (6.45%), correlated mostly with biometric ocular parameters and was in all age groups statistically independent of most systemic parameters.

Keratoconus Diagnosis: From Fundamentals to Artificial Intelligence: A Systematic Narrative Review

The remarkable recent advances in managing keratoconus, the most common corneal ectasia, encouraged researchers to conduct further studies on the disease. Despite the abundance of information about keratoconus, debates persist regarding the detection of mild cases. Early detection plays a crucial role in facilitating less invasive treatments. This review encompasses corneal data ranging from the basic sciences to the application of artificial intelligence in keratoconus patients. Diagnostic systems utilize automated decision trees, support vector machines, and various types of neural networks, incorporating input from various corneal imaging equipment. Although the integration of artificial intelligence techniques into corneal imaging devices may take time, their popularity in clinical practice is increasing. Most of the studies reviewed herein demonstrate a high discriminatory power between normal and keratoconus cases, with a relatively lower discriminatory power for subclinical keratoconus.