Treatment Of Keratoconus Research Articles

Success Rates and Prognostic Factors in the Management of Keratoconus: A 10-Year Retrospective Cohort Study at Siriraj Hospital

Objective: To evaluate the success rates of different treatment modalities, identify prognostic factors associated with treatment outcomes and factors influencing disease progression in keratoconus patients. Materials and Methods: A retrospective cohort study of keratoconus patients at Siriraj Hospital during January 2013 to December 2023 was done. Patient characteristics, symptoms and signs related to keratoconus, outcomes of corneal topography, treatment modalities, and best-corrected visual acuity (BCVA) before and after treatment were recorded. Treatment outcome was defined as a “success” when the BCVA post-treatment was equal to or better than 6/12. Progression of keratoconus was based on the Belin ABCD progression criteria. Results: Total 119 patients (231 eyes) were analyzed. The mean age at diagnosis was 28.0 ± 9.5 years. Two hundred and sixteen eyes (93.5%) were clinical keratoconus. The overall success rate of all treatment modalities was 87.4%. Contact lenses were the most frequent treatment modality (147 eyes, 72.4%) with the highest success rate (90.5%). A worse initial BCVA, high keratometric reading and thinner cornea were risk factors for treatment failure in this group. Of 133 eyes disease progression could be evaluated (median follow-up time; 33 months) and 58 eyes(43.6%) met criteria for disease progression (median survival time; 8.8 years). No significant factors were found to be associated with disease progression. Conclusion: Success rate in keratoconus treatment at Siriraj Hospital was 87.4%. Contact lenses were most frequently applied 72.4%. Factors associated with treatment failure were found in this group but for disease progressionremained unclear due to limitations of the study.

Advancing keratoconus treatment: the impact of bioengineered porcine constructs on corneal reshaping and visual acuity

Advancing keratoconus treatment: the impact of bioengineered porcine constructs on corneal reshaping and visual acuity

Socioeconomic and Demographic Disparities in Keratoconus Treatment

ObjectiveTo investigate healthcare disparities associated with keratoconus (KCN) patients receiving treatment (collagen cross-linking (CXL) and keratoplasty), as well as comorbidities associated with KCN. DesignRetrospective clinical cohort study. Subjects3224 patients from the UI-Health database from 2020 to 2024, including 1612 patients with an ICD-10 diagnosis of KCN and 1612 ophthalmology patients as a control group. MethodsMultivariable and univariable logistic regression were performed to evaluate association between sociodemographic traits and rates of CXL and keratoplasty. Sociodemographic traits included age, sex, race/ethnicity, insurance status, and neighborhood social vulnerability. Best corrected visual acuity (BCVA) and manifest cylinder were used as indicators of disease impact. Comorbid disease rates were compared to a 1:1 distance-matched control group. Main Outcome MeasuresOdds ratio of undergoing keratoplasty and CXL, and prevalence of comorbid conditions. ResultsFemales received less keratoplasty than males (OR=0.55, P<0.001). Black individuals received less CXL than White individuals (OR=0.68, P<0.05), as did those with Medicaid (OR=0.27, P<0.0001) or no insurance (OR=0.41, P<0.001) compared to those with commercial insurance. Socially vulnerable neighborhoods received less CXL (OR=0.56, P<0.01) and keratoplasty (OR=0.66, P<0.05). Black females were the most vulnerable, undergoing fewer procedures than White females (OR=0.58, P<0.01) and Black males (OR=0.65, P<0.05). Black and Hispanic/Latin-X individuals presented with more severe disease (P<0.01, P<0.0001). Down Syndrome was more common (P<0.01), and diabetes was less common (P<0.0001) in KCN patients. ConclusionsSignificant sociodemographic disparities exist in the treatment of KCN. While further research is necessary, addressing these disparities is crucial for ensuring equitable access to care.

Cost-Effectiveness of Corneal Collagen Crosslinking for Progressive Keratoconus: A Brazilian Unified Health System Perspective

Keratoconus is a burden to health systems and patients worldwide. Corneal collagen crosslinking (CXL) treatment has been shown abroad to be cost-effective for treating progressive keratoconus. However, no cost-effectiveness studies have been performed in Brazil. The aim of this study was to assess the cost-effectiveness of corneal collagen crosslinking (CXL) compared with the conventional treatment for progressive keratoconus from the Brazilian Unified Health System (SUS) payer’s perspective. A lifetime microsimulation model was utilized to compare the lifetime costs and quality-adjusted life years for patients undergoing corneal collagen CXL or conventional treatment. Two groups of 5000 18-year-old patients were simulated, with one group receiving corneal CXL at the outset and the control group remaining untreated. The TreeAge Pro Healthcare 2024 software was used for modeling and analysis. Corneal collagen CXL demonstrated superior cost-effectiveness compared to the conventional treatment, with an incremental cost-effectiveness ratio of 58.26 USD/quality-adjusted life years (QALY) gained (95% CI: 58.17–58.36) and a positive incremental net monetary benefit of USD 11,613.82 (95% CI: 11,605.66–11,621.99). CXL significantly reduced the number of required corneal transplants, with a mean of 968.8 (95% CI: 959–978.58) fewer transplants per 10,000 eyes treated. The variable with the most significant impact on the incremental net monetary benefit was the duration of the CXL effect. This study concluded that corneal CXL is a highly cost-effective intervention for progressive keratoconus within the Brazilian SUS. These findings advocate for broader accessibility to this vision-saving treatment within the SUS.

Epi-off riboflavin with vitamin E TPGS (Ribocross®) cross-linking: one-year outcome.

To assess the short and mid-term outcomes of epithelium-off (epi-off) corneal collagen cross-linking using Riboflavin with Vitamin E TPGS (Epi-off Ribocross® CXL) for progressive keratoconus (KC). Retrospective, single-center non-comparative interventional study. Patients with progressive keratoconus who underwent CXL using (Epi-off Ribocross® CXL) from May 2021 to May 2022 who completed at least 12months of follow-up in Humanitas Clinical and Research Center, Rozzano, Milan, Italy. Corrected distance visual acuity with spectable (CDVA), tomographic parameters (Belin ABCD) and topographic parameters were evaluated at baseline and at last follow up. Twenty eyes of twenty patients fulfilled inclusion criteria. CDVA remained stable at last follow up (0.88 ± 0.19 from 0.83 ± 0.21, p = 0.45) with a significant reduction in cylinder (1.97 ± 1.69 from 2.78 ± 2.19, p = 0.03). Kmax significantly improved from 53.18D ± 6.32 to 50.96 ± 5.3D (p = 0.005). At the last follow up, no case of progression was noted. Epi-off Ribocross® CXL proved to be a safe treatment for progressive KC, with a stabilization of all cases at the one year follow up. Further studies are needed to confirm long-term stability.

Customized Corneal Cross‐Linking with Microneedle‐Mediated Riboflavin Delivery for Keratoconus Treatment (Adv. Mater. 46/2024)

Customized Corneal Cross‐Linking with Microneedle‐Mediated Riboflavin Delivery for Keratoconus Treatment (Adv. Mater. 46/2024)

KeraRing Implantation with Femtosecond Laser in Keratoconus Treatment at Different Stages

Objective: To investigate the reliability and effectiveness of femtosecond laser-assisted KeraRing (Mediphacos, Belo Horizonte, Brazil) implantation in treating keratoconus. Methods: Intrastromal corneal ring segments (KeraRing, Mediphacos, Brazil) were implanted in 15 eyes of 14 patients unable to tolerate contact lenses. Femtosecond laser (Intralase, 60 Hz) was used for corneal tunnel creation. Based on the distribution of ectatic area on the cornea, dual segments were implanted in 9 eyes, while single segments were implanted in 6 eyes. Preoperative and postoperative uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), objective and subjective refraction, and topographic corneal curvature (K) values of the cases were compared using the Wilcoxon test. Results: The mean age of patients was 25±7.46 (range: 15-39) years, with a mean postoperative follow-up period of 10.8±7.37 (range: 1-24 months). BCVA improved in all eyes during the follow-up period, increasing from a mean of 0.12±0.1 to 0.38±0.24 (p

Evaluating the reliability of the responses of large language models to keratoconus-related questions

ABSTRACT Clinical relevance Artificial intelligence has undergone a rapid evolution and large language models (LLMs) have become promising tools for healthcare, with the ability of providing human-like responses to questions. The capabilities of these tools in addressing questions related to keratoconus (KCN) have not been previously explored. Background In this study, the responses were evaluated from three LLMs – ChatGPT-4, Copilot, and Gemini – to common patient questions regarding KCN. Methods Fifty real-life patient inquiries regarding general information, aetiology, symptoms and diagnosis, progression, and treatment of KCN were presented to the LLMs. Evaluations of the answers were conducted by three ophthalmologists with a 5-point Likert scale ranging from ‘strongly disagreed’ to ‘strongly agreed’. The reliability of the responses provided by LLMs was evaluated using the DISCERN and the Ensuring Quality Information for Patients (EQIP) scales. Readability metrics (Flesch Reading Ease Score, Flesch-Kincaid Grade Level, and Coleman-Liau Index) were calculated to evaluate the complexity of responses. Results ChatGPT-4 consistently scored 3 points or higher for all (100%) its responses, while Copilot had five (10%) and Gemini had two (4%) responses scoring 2 points or below. ChatGPT-4 achieved a ‘strongly agree’ rate of 74% across all questions, markedly superior to Copilot at 34% and Gemini at 42% (p < 0.001); and recorded the highest ‘strongly agree’ rates in general information and symptoms & diagnosis categories (90% for both). The median Likert scores differed among LLMs (p < 0.001), with ChatGPT-4 scoring highest and Copilot scoring lowest. Although ChatGPT-4 exhibited more reliability based on the DISCERN scale, it was characterised by lower readability and higher complexity. While all LLMs provided responses categorised as ‘extremely difficult to read’, the responses provided by Copilot showed higher readability. Conclusions Despite the responses provided by ChatGPT-4 exhibiting lower readability and greater complexity, it emerged as the most proficient in answering KCN-related questions.

Save sight keratoconus registry study: Transepithelial versus epithelium-off corneal crosslinking

PurposeCorneal collagen crosslinking (CXL) is the primary treatment for progressive keratoconus and can be performed with the epithelium on or off. Evidence is needed to guide clinicians and patients on whether they should have transepithelial or epithelium-off CXL. The aim of this study was to determine the safety and efficacy of transepithelial and epithelium-off CXL. DesignAn observational prospective study was conducted using real-world data from patients in the Save Sight Keratoconus Registry. MethodsPatients with no previous intervention before CXL were included. The primary outcomes were adverse events, change in Kmax, habitual visual acuity and minimum corneal thickness from baseline to 12 months follow up. Mixed effects regression models evaluated changes in outcomes adjusted for age, sex, eye laterality, practices, and baseline outcomes. ResultsThere were 46 eyes (37 patients) and 1203 eyes (976 patients) included treated with transepithelial and epithelium-off CXL, respectively. At 12 months follow up, the habitual visual acuity, pinhole visual acuity, Kmax, K2 and minimum corneal thickness were not significantly different between epithelium-off and transepithelial CXL. There were fewer adverse events recorded in transepithelial compared to epithelium-off CXL. ConclusionEpithelium-off and transepithelial CXL were similarly effective, measured by visual acuity and corneal curvature, to stabilise and prevent progression between baseline and 12 months follow-up in keratoconus. Transepithelial CXL had fewer adverse events compared to epithelium-off CXL.

Customized Corneal Cross-Linking with Microneedle-Mediated Riboflavin Delivery for Keratoconus Treatment.

In this study, a novel customized corneal cross-linking (CXL) treatment is explored that utilizes microneedles (MNs) for targeted riboflavin (RF) administration prior to the CXL procedure. Unlike the conventional "one-size-fits-all" approach, this protocol offers an option for more precise and efficacious treatment. To simulate a customized corneal crosslinking technique, four distinct microneedle (MN) molds designs, including circular, semi-circular, annular and butterfly shaped, are crafted for loading an optimized RF-hyaluronic acid solution and for the subsequent fabrication of MN arrays with varying morphologies. These MNs can gently puncture the corneal epithelium while preserving the integrity of the underlying stromal layer. Following the application of these microneedles, RF solution is replenished to enhance the RF content within the stroma through the punctures created by the MNs, resulting in exceptional customized corneal cross-linking effects that are comparable to the conventional epi-off CXL protocol. Additionally, it flattened the corneal curvature within the treated zone and facilitated rapid postoperative recovery of corneal tissue. These findings suggest that the integration of customized microneedle RF delivery with corneal crosslinking technology represents a potential novel treatment modality, holding promise for the tailored treatment of corneal pathologies, and offering a more precise and efficient alternative to traditional methods.

Pulsed corneal crosslinking in the treatment of Keratoconus: a systematic review and meta-analysis.

Corneal crosslinking (CXL) procedures are the treatment of choice in halting progressive corneal ectasia and preserving visual acuity due to keratoconus. Pulsed crosslinking (P-CXL) was developed using intermittent pulsing ultraviolet (UV) light to mitigate the depletion of oxygen levels that occurs with continuous UV exposure in standard crosslinking protocols (C-CXL). This study aimed to explore the use of P-CXL in the treatment of keratoconus and determine whether the availability of oxygen in P-CXL carries superior efficacy outcomes as an alternative to C-CXL modalities. This review was undertaken in accordance with PRISMA guidelines. A search of several databases conducted with two separate reviewers resulted in 29 papers meeting inclusion criteria for the review, 14 selected for meta-analysis. Primary outcomes assessed by the included papers included maximum keratometry (Kmax), corrected and uncorrected distance visual acuity (CDVA, UDVA), and secondary outcomes included central corneal thickness (CCT), endothelial cell count and demarcation line. Statistical analyses were carried out on Review Manager 5.4 and the meta-analysis employed a random-effects model, which estimated the weighted effect size of raw means using inverse variance weights. At 12 months P-CXL showed statistically significant reductions in Kmax (-0.75 D; p < 0.001) and improvement in CDVA (-0.10 logMAR; p < 0.001) compared to baseline. The meta-analysis of comparative studies determined that mean differences in Kmax, CDVA, UDVA, Kmean and CCT after 12 months were not statistically significant between pulsed and continuous crosslinking groups. Overall, P-CXL is effective in improving visual acuity and keratometry outcomes in keratoconus. The meta-analysis did not show a statistically significant difference in Kmax and CDVA between P-CXL and C-CXL, indicating a non-inferiority of P-CXL. However, findings of the meta-analysis are limited by the fact that different energy levels and exposure times were used for P-CXL in comparison to C-CXL in some studies, making it unsuitable to determine whether the efficacy of CXL is improved by the use of pulsed light. What is Known • Pulsed crosslinking (P-CXL) uses intermittent UV light to prevent oxygen depletion when using higher energy protocols, unlike continuous UV exposure in standard continuous crosslinking (C-CXL). • This should theoretically enhance the efficacy of the treatment by maintaining higher oxygen levels that are crucial to the cross-linking process. • There are no systematic reviews or meta-analyses directly comparing the efficacy or safety of P-CXL to C-CXL. What is New • Meta-analysis revealed differences in keratometry between P-CXL and C-CXL groups with equivalent fluence (7.2 J/cm2) at 12 months were not statistically significant (Kmax -0.04 dioptres; p = 0.84). • Meta-analysis revealed differences in visual acuity between P-CXL and C-CXL groups with equivalent fluence (7.2 J/cm2) at 12 months were not statistically significant (CDVA -0.01 logMAR letters; p = 0.57). • The use of intermittent pulsing in higher energy CXL protocols renders statistically similar outcomes as continuous light exposure at equivalent fluence (7.2 J/cm2).

A review of Bowman's layer structure, function, and transplantation.

Bowman's layer is an acellular corneal structure, which is considered to be a specially modified anterior stroma. It is presumed, that it forms as a result of ongoing epithelial-stromal interactions and no clear physiological purpose has been proven. Despite this fact, Bowman's layer has found its place in corneal transplantation. It has been performed for over adecade, mainly in treatment of advanced keratoconus with multiple modifications. Transplantation of Bowman's layer can be expected to become a widely used surgical procedure in the treatment of many corneal pathologies involving fragmentation and destruction of Bowman's layer. This article aims to summarize information available on its structure, possible function, and transplantation. A thorough literature search was performed in the PubMed database and Google Scholar using keywords: Bowman's layer, structure, function, preparation and corneal transplantation. All the relevant sources were used, which represent 77 peer-reviewed articles with information corcerning the topic of this article.

A bibliometric and citation network analysis of crosslinking.

Purpose: Research on crosslinking has focused mainly on trying to slow the progression of keratoconus. The objective of this bibliometric analysis is to determine the relationships between the different publications and authors. As well as to identify the different areas of research on crosslinking. Methods: Web of Science (WOS) was the database for the search of publications for the period 1972 to December 2023, using the terms: crosslinking, cross-linking, ocular, vision, visual, cornea, ectasia AND Keratoconus. The analysis of the publication was performed using the CitNetExplorer, VOSviewer and CiteSpace software. Results: 7161 publications and 59415 citation networks were found. The year with the most publications is 2021, a total of 571 (7.97%) publications and 135 citation networks. The most cited publication was "Riboflavin/ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus" published by Wollensak et al. in 2003, with a citation index of 1780. Using the Clustering function, five groups were found that cover the main research areas in this field: keratoconus, corneal transplantation, cataracts, corneal inflammation and axial growth. Conclusion: The treatment of keratoconus continues to be the topic of interest in this area of research. However, in recent years there has been an increase in research on how crosslinking helps to slow down axial growth.

Corneal Collagen Cross-linking for Keratoconus in Pediatric and Developmentally Delayed Patients.

Corneal cross-linking (CXL) is the standard of care in patients with keratoconus but presents unique challenges in children and developmentally delayed patients. We present our clinical decision-making algorithm, CXL surgical technique, and outcomes in these groups. A retrospective chart review was undertaken at a tertiary referral center of all patients who underwent CXL for keratoconus at University of Pittsburgh Medical Center (UPMC) Children's Hospital of Pittsburgh between October 1, 2017, and April 1, 2021. Demographic information along with preoperative, intraoperative, and postoperative ophthalmic examination findings were collected. The main outcome measures were indications of CXL, postoperative complications, and visual acuity (VA). Forty-eight eyes of 34 patients [21 patients (30 eyes) with developmental delay (DD) and 13 patients (18 eyes) with no DD (NDD)] underwent epithelium-off, standard CXL. General anesthesia was used for CXL in all patients except for 3 with NDD. A temporary central tarsorrhaphy was performed in all patients with DD and 7 patients with NDD. The remaining got a bandage contact lens. There were no immediate postoperative complications. A trend toward improvement in VA was noted postoperatively. The mean logMAR VA (with habitual correction) was 0.67 preoperatively and 0.57 postoperatively (P = 0.3) in DD and 0.52 and 0.36, respectively (P = 0.13), in NDD. This retrospective review presents a technique for assessment and treatment of keratoconus in children and those with DD. Our technique ensures timely diagnosis and provides a safe method for CXL in these groups. Temporary central tarsorrhaphy is a well-tolerated option to reduce postoperative pain.

Early findings in a randomised controlled trial on crosslinking protocols using isoosmolar and hypoosmolar riboflavin for the treatment of progressive keratoconus.

To present baseline characteristics and to present the perioperative corneal thickness during corneal crosslinking (CXL) treatment for progressive keratoconus and to describe how the addition of sterile water (SW) efficaciously can maintain the corneal thickness. The treatment efficacy will be evaluated when the 1-year follow-up is complete. A randomised clinical study using epithelium-off CXL with continuous UVA irradiation (9 mW/cm2) and two kinds of riboflavin solutions: (i) isoosmolar dextran-based riboflavin (n = 27) and (ii) hypoosmolar dextran-free riboflavin (n = 27). progressive keratoconus with an increase in maximum keratometry value (Kmax) of 1.0 dioptre (12 months) or 0.5 dioptres (6 months). Corneae thinner than 400 μm were also included. Perioperative corneal thickness and the effect of adding SW. Seventy-four per cent of the patients in the isoosmolar group and 15% in the hypoosmolar group required the addition of SW, which effectively maintained a corneal thickness of 400 μm in all cases during CXL. The addition of SW was primarily needed during the irradiation procedure and not the preoperative soaking period. Especially during the CXL irradiation phase, isoosmolar riboflavin causes a significant dehydrating effect leading to corneal thinning during CXL. The customised addition of SW is efficacious in maintaining the corneal thickness during CXL and could increase the safety of the procedure.

A sterile corneal perforation in a postpartum lactating mother after 10 years of CXL: A case report and review of literature

To report a case of corneal perforation following injury with a child’s finger in a postpartum lactating mother in a corneal collagen cross-linkage with 1% riboflavin (CXL)-treated eye. A 28-year-old-female presented to us with acute and severe ocular pain in the right eye to the emergency department. She gave history of CXL done 10 years back, and examination revealed central corneal perforation with a flat anterior chamber. We managed the case successfully with penetrating keratoplasty, followed by a glaucoma tube procedure for secondary glaucoma. CXL is the standard treatment for progressive keratoconus, and its long-term safety is well known. Corneal perforation as an adverse event following CXL has also been noted in a few case reports. This case emphasizes the need for close follow-up with serials documentation of corneal thickness and prompt intervention.

KeratoEL: Detection of keratoconus using corneal parameters with ensemble learning.

Keratoconus is a progressive eye condition in which the normally round cornea thins and bulges outwards into a cone shape. This irregular shape causes light to scatter in multiple directions as it enters the eye, leading to distorted vision, increased sensitivity to light and frequent changes in the prescription of glasses or contact lenses. Detecting keratoconus at an early stage is not only difficult but also challenging. The study has proposed an ensemble-based machine learning (ML) technique named KeratoEL to detect keratoconus at an early stage. The proposed KeratoEL model combines the basic machine learning algorithms, namely support vector machine (SVM), decision tree (DT), random forest (RF) and artificial neural network (ANN). Before employing the ML model for keratoconus detection, the data set is first preprocessed manually by eliminating some features that don't contribute any significant value to predict the exact class. Moreover, the output features are labelled into three different classes and Extra Trees Classifier is used to find out the important features. Then, the features are sorted in descending order and top 45, 30, and 15 features are taken as input datasets against the output. Finally, different machine learning models are tested using the input datasets and performance metrics are measured. The proposed model obtains 98.0%, 98.9% and 99.8% accuracy for top 45, 30, and 15 number of features respectively. Overall experimental results show that the proposed ensemble model outperforms the existing machine learning models. The proposed KeratoEL model effectively detects keratoconus at an early stage by combining SVM, DT, RF, and ANN algorithms, demonstrating superior performance over existing models. These results underscore the potential of the KeratoEL ensemble approach in enhancing early detection and treatment of keratoconus.

Clinical outcomes of femtosecond laser-assisted corneal allogenic intrastromal ring segment (CAIRS) in the treatment of keratoconus.

To evaluate the results of corneal allogenic intrastromal ring segment (CAIRS) implantation in keratoconus. The medical records of patients with keratoconus who underwent CAIRS implantation were reviewed. The CAIRS, prepared by trephination from the donor cornea, was implanted into a tunnel created using the femtosecond laser. The depth of the tunnel was 200 μ; the inner diameter of the tunnel was 4.5 mm; and the outer diameter was 7 mm. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), keratometry, minimum corneal thickness (CT), endothelial cell density (ECD), and high order aberration values were recorded preoperatively and at the 1st, 3rd, and 6th months postoperatively. A total of 23 eyes of 23 patients were included in the study. Preoperative UCVA (0.08 ± 0.01) and BCVA (0.25 ± 0. 11) values improved postoperatively and reached 0.40 ± 0.05 and 0.68 ± 0.09, respectively, at the end of the 6-month follow-up period (p1 < 0.001, p2 = 0.016; respectively). A statistically significant flattening of all keratometric values was observed in the postoperative period compared to preoperatively (p < 0.001 for all). There were no statistical differences between CT and ECC values at the preoperative and postoperative visits (p1 = 0.654, p2 = 0.769; respectively). In addition, coma aberration values were lower than the preoperative values at all postoperative visits (p < 0.05 for all). These results suggest that CAIRS implantation is a safe treatment option with good visual and keratometric outcomes for suitable patients with keratoconus.

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

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). 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). 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. 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.

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. 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. 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. 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.