Optical coherence tomography angiography (OCT-A) is an ophthalmic imaging technique which has recently been introduced to clinical use. OCT-A provides visualization of the retinal vascularization in three dimensions, without injection of contrast agents. OCT-A could thus replace the current standard of opthalmic imaging, which is 2D only and requires contrast agents. However, quantitative studies remain to be carried out to assess the full potential of OCT-A. In this context, the present work proposes a methodology to perform OCT-A in a more reproducible and precise way. We introduce a procedure to automatically extract the area of interest in avascular regions, which we demonstrate on various avascular areas with a focus on the optic nerve extracted in 2-dimensional images for a selected depth. We then study the repeatability of OCT-A with our segmentation technique when implemented on various clinical devices. For illustration, we apply this segmentation to healthy control group and to patients presenting different stages of glaucoma, a disease of clinical interest. The variability observed between these two cohorts compares favorably to the variability due to instrumental limitations or the segmentation algorithm. Our results thus constitute a significant step toward a more quantitative use of OCT-A in a clinical context.
Purpose: To compare the impact of total corneal astigmatism (TCA) estimated with the Abulafia-Koch formula (TCA ABU ) versus measured by Total Keratometry (TK), swept-source optical coherence tomography (OCT) coupled with telecentric keratometry (TCA TK ) on the refractive outcomes after cataract surgery with toric intraocular lens (IOL) implantation. Methods: Two hundred one eyes of 146 patients who underwent cataract surgery with toric IOL implantation (XY1AT; HOYA Corporation) were included in this single-center, retrospective study. For each eye, TCA ABU (estimated from the anterior keratometry values measured with the IOLMaster 700 [Carl Zeiss Meditec AG]) and TCA TK (measured using TK IOLMaster 700) were entered into the HOYA Toric Calculator. Patients were operated on based on TCA ABU . For each eye, centroid and mean absolute error in predicted residual astigmatism (EPA) were calculated according to TCA used (TCA ABU or TCA TK ). The cylinder power and the axis of the posterior chamber IOL were compared. Results: The mean uncorrected distance visual acuity was 0.07 ± 0.12 logMAR, the mean spherical equivalent was 0.11 ± 0.40 D, and mean residual astigmatism was 0.35 ± 0.36 D. Mean centroid EPA was 0.28 D at 132° with TCA ABU and 0.35 D at 148° with TCA TK ( P (x) < .001; P (y) < .01). Mean absolute EPA was 0.46 ± 0.32 D with TCA ABU and 0.50 ± 0.37 D with TCA TK ( P < .01). In the with-the-rule astigmatism subgroup, a deviation from the target of less than 0.50 D was achieved in 68% of eyes with TCA ABU versus 50% of eyes with TCA TK . The proposed posterior chamber IOL was different depending on the calculation methods used in 86% of cases. Conclusions: Both calculation methods showed excellent results. However, the predictability error was significantly reduced when TCA ABU was used compared to TCA TK measured with the IOLMaster 700 in the whole cohort. Finally, TCA was overestimated by TK in the with-the-rule astigmatism subgroup. [ J Refract Surg. 2023;39(3):171–179.]
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.