Artificial Neural Network for Automated Keratoconus Detection Using a Combined Placido Disc and Anterior Segment Optical Coherence Tomography Topographer.

Purpose: To assess the efficacy of an automated program for keratoconus and keratoconus suspect detection based on corneal measurements provided by a combined Placido disc and anterior segment optical coherence tomography (OCT) topographer. Methods: In a multicentric cross-sectional study, an artificial neural network (ANN) was created using 6677 eyes from an equal number of patients (classified as 2663 normal eyes, 1616 keratoconus eyes, 210 keratoconus suspect eyes, 1519 myopic postoperative eyes, and 669 abnormal eyes). Each group was randomly divided into a training set (70% of the dataset) and a validation set (the remaining 30%). A multilayer perceptron network with a backpropagation learning algorithm was developed for the study. Indexes used to train the ANN were based on curvature and elevation of both the anterior and posterior corneal surfaces and the new corneal OCT indexes-based on corneal, stromal, and epithelial thicknesses. Results: For keratoconus detection, our ANN showed an accuracy of 98.6%, precision of 96%, recall of 97.9%, and F1-score of 96.9%. For keratoconus suspect detection, our ANN showed an accuracy of 98.5%, precision of 83.6%, recall of 69.7%, and F1-score of 76%. Conclusions: Compared to previous literature, the addition of new OCT-based epithelial and stromal thickness indexes improves ANN detection capacity of keratoconus suspect eyes. For already stablished keratoconus our ANN detection capacity is excellent, but equivalent to previous evidence without incorporating such new OCT-based indexes. Translational Relevance: OCT-based epithelial and stromal thickness indexes improve ANN detection capacity of keratoconus on its early stages.

Comparison of a new implantable collamer lens formula to standards formulas using spectral domain optical coherence tomography.

PURPOSE: To use spectral-domain optical coherence tomography (SD-OCT) data to develop a new implantable collamer lens (ICL) sizing formula and compare vault outcomes with the Online Calculation and Ordering System™ (OCOS) and the NK2 formula. METHODS: Consecutive eyes (n = 237) were evaluated that had undergone ICL/toric ICL implantation. Actual ICL vaults were measured, and a what-if analysis was performed to predict vault values with the NK2 formula using SD-OCT data. To develop a new formula (EPB), multiple regression analysis was performed with different parameters than the NK2 formula. Predicted vaults with NK2 and EPB formulas were compared to the actual vaults. RESULTS: Parameters that were correlated with optimal ICL size were white-to-white, anterior chamber width, lens rise and desired refractive correction. The mean postoperative vault was 489 ± 258 µm. At last visit, 94.5% of eyes were within the manufacturer's acceptable vault range. Predicted vaults in the acceptable range were 74 and 87% with the NK2 and EPB formulas, respectively. Six percent had a predicted vault less than 100 µm with the EPB formula compared to 1% for actual outcomes. The NK2 formula resulted in a shift toward higher predicted vaults while the EPB formula was similar to the actual postoperative vaults but with slightly more cases with extremely low and high vaults. CONCLUSION: SD-OCT data with OCOS result in good postoperative vaults. Further refinement is required to the NK2 for use with SD-OCT data. Although the EPB formula provides acceptable predicted vaults, further refinement with a larger sample size is needed.

Transepithelial corneal crosslinking with oxygen enhancement and pulsed light for progressive ectasia: one-year results.

PURPOSE: To evaluate the efficacy and safety of transepithelial accelerated crosslinking (TE-ACXL) using pulsed light and supplemental oxygen. METHODS: Thirty eyes of 30 consecutive patients with progressive keratoconus or post-LASIK ectasia were enrolled in a prospective non-comparative study conducted at the Magrabi Eye Center (Jeddah, Saudi Arabia). All eyes underwent TE-ACXL with supplemental oxygen. Primary outcome measures were the mean change in corrected distance visual acuity (CDVA) (logMAR) and maximum keratometry (max K) from preoperatively to 12 months postoperatively. Secondary outcome measures included change in manifest refractive spherical equivalent (MRSE), refractive cylinder, keratometry, symmetry index (SI), center-surrounding index (CSI) and ectasia index (EI) of the anterior and posterior corneal surfaces, corneal and epithelial thickness at corneal vertex and thinnest location, corneal densitometry, corneal high order aberrations (HOA) and endothelial cell density (ECD). RESULTS: Mean age was 29.6 ± 8.2 years. At 1 year, the follow up rate was 93.3%. CDVA improved statistically significantly at 12 months (p = 0.027). Measures of corneal keratometry or pachymetry did not change significantly (p < 0.05). Postoperatively, a demarcation line was documented in 78.6% eyes at 1 month, and in 12 (42.9%) eyes at 12 months. The mean depth of the demarcation line was 341.9 ± 49.4 µm. Corneal densitometry increased significantly at 1- and 3-months (p < 0.05) and returned to normal levels at 6- and 12-months postoperatively. CONCLUSION: TE-ACXL with oxygen supplement is effective at halting the progression of corneal ectasia for at least 1 year and can be a refractive neutral procedure.

Clinical Outcomes After Phacoemulsification With Implantation of Trifocal and Toric Trifocal Intraocular Lenses.

PURPOSE: To evaluate the visual and refractive outcomes, visual quality, patient satisfaction, and spectacle independence after phacoemulsification with bilateral implantation of a diffractive trifocal intraocular lens (IOL). METHODS: The study sample comprised 36 consecutive patients (72 eyes). Twenty-three (64%) patients underwent refractive lens exchange and 13 (36%) underwent cataract surgery. Exclusion criteria included previous ocular surgery, corneal higher order aberrations of greater than 0.4 µm, angle kappa of greater than 0.6 mm, and corneal astigmatism of greater than 5.00 diopters (D). All eyes were targeted for emmetropia. A toric IOL was used in 35 (48.6%%) eyes with corneal astigmatism of greater than 1.00 D. Uncorrected distance visual acuity (UDVA) and distance-corrected visual acuity were measured at 4 m and 80 and 40 cm. Patients underwent routine ophthalmic examination for 6 months postoperatively. Patient satisfaction was assessed with a subjective questionnaire at 6 months postoperatively. A P value of less than .05 was statistically significant. RESULTS: At 6 months postoperatively, the mean manifest refractive spherical equivalent was -0.01 ± 0.51 D. Binocular UDVA at 4 m and 80 and 40 cm was -0.02 ± 0.10, -0.07 ± 0.11, and 0.08 ± 0.10 logMAR, respectively. Binocular defocus curves presented two peaks of -0.07 and -0.02 logMAR for 0.00 and -2.00 D defocus, respectively. The Objective Scatter Index score decreased significantly in the cataract group and increased significantly in the refractive lens exchange group (P < .05, both cases). All patients were satisfied or very satisfied with the postoperative outcome. CONCLUSIONS: Bilateral implantation of a diffractive trifocal IOL resulted in good visual performance at all distances with high patient satisfaction and spectacle independence at 6 months postoperatively. [J Refract Surg. 2021;37(6):372-379.].

Long-Term Effect of Anterior Chamber Depth on Endothelial Cell Density in Patients With Iris-Fixated Phakic Intraocular Lenses.

PURPOSE: To evaluate the long-term endothelial cell density (ECD) change and its correlation with preoperative anterior chamber depth (ACD) and aqueous depth (AQD) in patients with iris-fixated phakic intraocular lenses (pIOLs). METHODS: A total of 90 eyes from 57 patients who underwent pIOL implantation were retrospectively enrolled. Correlation between ACD and endothelial cell loss (ECL) was investigated. Optimal cut-off values for ACD and AQD were assessed. RESULTS: The average follow-up period was 11.8 ± 2.0 years (range: 9.1 to 17.3 years). Compared to the baseline data, the mean ECD change was -894 ± 732 cells/mm2 (range: -2,281 to 389 cells/mm2). The mean ECD change from baseline was -53.5% ± 19.1% (range: -75.1% to -5.2%) in eyes with preoperative ACD of 3.20 mm or greater -26.0% ± 26.6% (range: -74.1% to 0.9%) in eyes with ACD of 3.21 to 3.49 mm, and -5.2 ± 8.7% (range: -21.3% to 16.8%) in eyes with ACD of 3.50 mm or greater (P < .001). No eyes with ACD of 3.50 mm or greater had significant endothelial cell loss (SECL), whereas 84% of the eyes with ACD of 3.20 mm or less experienced SECL (P < .001). There was a significant negative correlation between ECL and ACD (r = -0.70, P < .001) and AQD (r = -0.65, P < .001). Receiver operating characteristic curve analysis revealed that ACD of 3.35 mm provides 84% sensitivity and 88% specificity and AQD of 2.75 mm provides 88% sensitivity and 81% specificity for preventing SECL. CONCLUSIONS: Smaller ACD and AQD are significantly correlated with more ECL. Minimum ACD of 3.35 mm or AQD of 2.75 mm are recommended for better long-term endothelial safety. [J Refract Surg. 2019;35(8):493-500.].