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Keratoconus (KCN) is an ectatic disorder with progressive corneal thinning and a clinical picture of corneal protrusion, progressive irregular astigmatism, corneal fibrosis and visual deterioration. Other ectatic corneal disorders include: post-LASIK ectasia (PLE) and pellucid marginal degeneration (PMD). Corneal crosslinking (CXL) is a procedure whereby riboflavin sensitization with ultraviolet A radiation induces stromal crosslinks. This alters corneal biomechanics, causing an increase in corneal stiffness. In recent years, CXL has been an established treatment for the arrest of KCN, PLE and PMD progression. CXL has also been shown to be effective in the treatment of corneal infections, chemical burns, bullous keratopathy and other forms of corneal edema. This is a current review of CXL - its biomechanical principles, the evolution of CXL protocols in the past, present and future, indications for treatment, treatment efficacy and safety.

PURPOSE: To compare the visual and refractive results obtained after photorefractive keratectomy (PRK) in patients who underwent one of three different epithelial removal techniques. METHODS: The authors reviewed the medical files of consecutive eyes with myopia and myopic astigmatism that were treated during a 10-year period by mechanical PRK, alcohol-assisted PRK, or transepithelial PRK (in the phototherapeutic keratectomy mode), and observed for more than 1 year. RESULTS: A total of 3,417 patients (3,417 eyes) were included in this study. At 3 and 6 months postoperatively, the outcome of alcohol-assisted PRK was superior both in efficacy (A total of 3,417 patients (3,417 eyes) were included in this study. At 3 and 6 months postoperatively, the outcome of alcohol-assisted PRK was superior both in efficacy ( P < .01) and safety ( P < .001) to those of both mechanical PRK and transepithelial PRK, which were similar. At more than 1 year postoperatively, the mean efficacy index was still high for alcohol-assisted PRK, but low for the transepithelial PRK, corresponding to a mean uncorrected visual acuity of more than one Snellen line lower than those of the other two techniques ( P < .0001). All three techniques showed a regression toward myopia more than 1 year postoperatively, with significant undercorrection obtained in eyes treated with transepithelial PRK ( P < .0001). CONCLUSIONS: Significant differences were detected in both the visual outcomes and the refractive results of the three epithelial removal techniques. The long-term outcomes were best for alcohol-assisted PRK. [[ J Refract Surg. 2015;31(11):760–766.]

Purpose: Post-Descemet stripping endothelial keratoplasty (DSEK) patients are prone for intraocular pressure (IOP) elevations and glaucoma. Corneal characteristics influence various IOP measuring devices in various ways. The aim of this study was to evaluate the agreement between four different IOP measuring devices: Goldmann applanation tonometer (GAT), I-care pro, Tonopen XL, and Schiotz tonometr in patients who underwent DSEK. Methods: This was a prospective comparative study using a convenience cohort of post-DSEK patients with compact grafts. Post-DSEK patients had IOP measured using GAT, I-care Pro, Tonopen XL, and Schiotz tonometer. Measurements were compared and agreement assessed. Wilcoxon signed-rank test was used for comparison of means as variables did not show a normal distribution. Bland-Altman plots were used for assessing agreement. Results: Thirty eyes of 24 patients were included in the study. Mean time from DSEK surgery was 25.31 ± 13.05 months. Mean IOP with GAT, I-care pro, Tonopen XL, and Schiotz tonometer was 13.99 ± 3.76, 13.92 ± 3.36, 13.31 ± 3.89, and 12.83 ± 4.07, respectively. GAT, I-care pro, and Tonopen XL had similar mean IOP measurements (P = 0.135 and P = 0.551, respectively), while Schiotz tonometry measurements were higher (P = 0.046). Bland-Altman plots show good agreement between GAT, Tonopen XL, and I-care pro. GAT and Schiotz tonometry show less agreement, with large variations in the differences of measured IOP. Conclusions: IOP measurements in post-DSEK patients showed good agreement between GAT and either Tonopen XL or I-care pro. Schiotz tonometer has large variations in this patient group. IOP measurements and IOP difference between devices were not dependent on central corneal thickness.

Purpose. To analyze the risk factors associated with a series of ectasia cases following photorefractive keratectomy (PRK) and all published cases. Methods. In a retrospective study on post-PRK ectasia patients, 9 eyes of 7 patients were included, in addition to 20 eyes of 13 patients from the literature. Risk of post-PRK ectasia was calculated using the ectasia risk score system (ERSS) for laser in situ keratomileusis (LASIK) patients. The percent tissue altered (PTA) was also evaluated. Results. ERSS scoring of zero for age, RSB, and spherical equivalent was found in 66%, 86%, and 86% of the eyes, respectively. Pachymetry risk score was 2 in 60% of the eyes and 3 or 4 in 16% of the eyes. Topography risk score was 3 in 41% of the eyes and 4 in 21% of the eyes. Cumulative ectasia risk score was ≥4 (high risk) in 77% of the eyes and ≥3 (medium and high risk) in 86% of the eyes. Average PTA was 23.2 ± 7.0%. All eyes but one had a PTA < 40%. Conclusions. Preoperative corneal topographic abnormalities and thin corneas may be significant risk factors for developing ectasia following PRK. Post-LASIK ectasia risk scoring also has relevance in the risk for developing post-PRK ectasia.

Objective. To analyze the safety and efficacy of high-myopic PRK as an alternative to LASIK surgery in patients with a high preoperative percentage tissue altered (PTA). Design. Retrospective interventional case series. Participants. Charts of 256 consecutive eyes that underwent PRK with application of mitomycin-C 0.02% for high myopia were retrospectively reviewed. Methods. Refractive (refraction and refractive accuracy) and visual outcomes (uncorrected and corrected visual acuities), as well as occurrence of haze in the eyes with preoperative PTA expected to be higher than 40% with a 110-micron flap if undergoing LASIK surgery, were analyzed. Results. Mean follow-up was 7.3 ± 4.8 months. A total of 187 of 256 eyes (73.0%) were included in the analysis because they were expected to have a PTA greater than 40%, should they have undergone LASIK surgery. The actual mean PTA of those eyes following PRK was 31.8 ± 2.2%, and none had a PTA ≥ 40%. UDVA of 20/16, 20/20, and 20/25 or better was achieved in 1.2% (2 eyes), 65.5% (112 eyes), and 85.4% (146 eyes), respectively. The percentage of eyes with postoperative SE within ±0.5 D and ±1.0 D of planned SE was 71% and 93%, respectively. None of the eyes lost 2 or more lines of CDVA. The rate of stromal haze, managed successfully with topical steroids only, was 4.8%. Conclusion. High-myopic PRK with application of mitomycin-C in the eyes at risk of developing ectasia because of high preoperative PTA was demonstrated to be a safe and effective alternative to the LASIK procedure.

PurposeTo construct an automatic machine-learning derived algorithm discriminating between normal corneas and suspect irregular or keratoconic corneas.MethodsA total of 8526 corneal tomography images of 4904 eyes obtained between November 2010 and July 2017 using a combined Scheimpflug/Placido tomographer were retrospectively evaluated. Each image was evaluated for acquisition quality and was labeled as normal, suspect irregular or keratoconic by a cornea specialist.Two algorithms were built. The first was based on 94 instrument-derived output parameters, and the second integrated keratoconus prediction indices of the device with the 94 instrument-derived output parameters. Both models were compared with the tomographer’s keratoconus detection algorithms. Out of the 8526 images evaluated, 7104 images of 3787 eyes had sufficient acquisition quality. Of those, 5904 examinations were randomly chosen for construction of the models using the random forest algorithm. The models were then validated using the remaining 1200 examinations.ResultsBoth RF algorithms had a larger AUC compared with any of the tomographer’s KC detection algorithms (p < 10–9). The first constructed model had 90.2% accuracy, sensitivity of 94.2%, and specificity of 89.6% (Youden 0.838). Calculated AUC was 0.964. The second model had 91.5% accuracy, sensitivity of 94.7%, and specificity of 89.8% (Youden 0.846). Calculated AUC was 0.969.ConclusionUsing the RF machine-learning algorithm, accuracy of discrimination between normal, suspect irregular and keratoconic corneas approximates that of an experienced corneal expert. Applying machine learning to corneal tomography can facilitate keratoconus screening in large populations as well as off-site screening of refractive surgery candidates.

Tube exposure is a serious complication of glaucoma drainage device implantation. We describe a novel surgical approach using a partial-thickness corneal patch graft with conjunctival autograft and fibrin glue in a setting of severe conjunctival deficiency. We describe a 72-year-old man with chronic angle-closure glaucoma who presented with tube exposure 1 year after Ahmed valve implantation. Risk factors included diabetes mellitus, a failed trabeculectomy, and prior vitrectomy. The conjunctiva surrounding the exposed tube was ischemic and immobile, and the original corneal patch graft had partially degraded. Revision surgery involved suturing a 4-mm partial-thickness corneal button over the exposed tube, anchored to the residual graft edge and sclera. Due to insufficient mobile conjunctiva, a 4 × 3 mm conjunctival autograft was harvested from the temporal bulbar conjunctiva and secured with fibrin glue at the border of the corneal button, partially covering it, to promote epithelialization. At 1-year follow-up, the tube remained fully covered with no recurrence. This unique surgical approach using a partial-thickness corneal button and conjunctival autograft offers a viable alternative in cases of tube exposure with severe conjunctival deficiency, where traditional techniques such as conjunctival advancement are not feasible.

ObjectiveTo report preliminary experience using the BeyeonicsOne (Beyeonics Vision, Haifa, Israel) digital visualization platform and the utilization of its three-dimensional (3D) head-mounted display (HMD) in cataract surgery.MethodsAn interventional case series including patients who underwent cataract surgery using the 3D HMD platform at the Tel Aviv Medical Center. The system uses the HMD unit to display high-resolution real-time 3D surgical field images. Collected data included patient demographics, ocular comorbidities, risk factors for complex cataract surgery, cataract grading, preoperative and postoperative best-corrected visual acuity (BCVA), and intra- and postoperative complications.ResultsIn total, 60 eyes of 60 subjects (mean age 73.1 ± 8.4 years) were included. Mean preoperative BCVA was 0.40 ± 0.30 logMAR (Snellen equivalent ~20/50) and improved to 0.10 ± 0.10 logMAR (Snellen equivalent ~20/25, p < 0.001). None of the patients suffered BCVA loss. All procedures and follow-ups were uneventful except for one case of a posterior capsular tear and one case of post-surgical cystoid macular edema.ConclusionThe visualization platform and its embedded 3D head-mounted display can be easily used in routine cataract surgery with the added benefits of improved ergonomics, high picture quality and enhanced image control.

PURPOSE: To identify the potential risk factors that increase the likelihood of requiring re-treatment following refractive surgery in patients with high astigmatism (3.00 diopters or greater). METHODS: This retrospective study included patients who underwent laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) between January 2005 and December 2019 at the Care-Vision Laser Centers, Tel-Aviv, Israel. Patients with high astigmatism (3.00 diopters or greater) were included and divided into two groups according to whether or not they underwent additional refractive surgery (re-treatment) during the study period. RESULTS: Overall, 2,024 eyes (2,024 patients) were included in the final analysis of this study. In total, 3.1% of the eyes (n = 63) underwent re-treatment. Throughout the study period, there was a significant reduction in the 2-year annual re-treatment rates, with a decline from 7.0% for primary surgeries performed in 2005 to 0.0% for primary surgeries performed in 2017 (r =−0.65, P = .015). The re-treatment group had significantly older preoperative age. They were also more likely to be male and have preoperative against-the-rule astigmatism and preoperative mixed astigmatism. Binary logistic regression analysis demonstrated that preoperative age, male gender, mixed astigmatism, and earlier year of surgery were all associated with higher re-treatment rates. CONCLUSIONS: The following factors are associated with higher rates of re-treatment in patients with high astigmatism: older preoperative age, male gender, and mixed astigmatism. These factors may be incorporated into nomograms to reduce future re-treatment rates in this population. [J Refract Surg. 2021;37(6):366–371.]

Abstract PurposeTo construct a new pediatric ocular trauma score for predicting visual outcome after open globe injuries (OGI) and to compare it to the ocular trauma score (OTS) and pediatric ocular trauma score (POTS).MethodsThis is a retrospective chart review study. For each case, the following data were collected: demographics, mechanism of the injury, initial ophthalmologic findings, presented and last follow-up visual acuity (VA), ocular treatments, and final ocular findings. We then analyzed the risk factors for the poor visual outcome (VA ≤ 20/200), and a modified pediatric ocular trauma score (MPOTS) was constructed accordingly and compared to the OTS and POTS for predicting poor outcome. Finally, a different cohort of pediatric OGIs was used for score validation.ResultsForty-five cases were included, significant predicting factors for poor visual outcome were initial VA ≤ 20/200, zone 2–3 locations of injury, presence of retinal detachment, vitreous hemorrhage, hyphema, and iris prolapse at initial presentation. The calculated Spearman correlation coefficients between each system score and poor visual outcome were OTS 0.56, POTS 0.57, and MPOTS 0.64 (P < 0.001 for all). A total of 71 new cases were used as validation cohort, and calculated Spearman correlation coefficients between each system score and poor visual outcome were: OTS 0.50, POTS 0.51, and MPOTS 0.53 (P < 0.001 for all).ConclusionsWe suggest a new scoring system for predicting poor final visual outcomes after OGI’s in children, which is simpler and more clinically suitable for this study population. It was found to be a better predictor of visual outcome in this scenario compared with existing scoring systems.