Automated Analysis of the Foveal Avascular Zone in Optical Coherence Tomography Angiography Before and After Phacoemulsification.

Objective

This study aimed to compare two methods for measuring the foveal avascular zone (FAZ) before and after phacoemulsification: a script-based semiautomated algorithm and a machine learning (ML)-based semiautomated algorithm.

Methods

Optical coherence tomography angiography (OCTA) images were obtained with a Spectralis OCTA system (Heidelberg Engineering, Germany) preoperatively and in three postoperative visits. The FAZ was measured using both methods.

Results

The study analyzed 708 OCTA scans from 59 eyes. Correlation analyses showed strong agreement between the semiautomated script-based and ML-based methods in the three plexuses, with Pearson correlation coefficients of r = 0.836 (95% CI: 0.74-0.89), r = 0.646 (95% CI: 0.45-0.78), and r = 0.861 (95% CI: 0.78-0.92), respectively (p < 0.0001 for all). In longitudinal analysis, the FAZ in the SVP decreased significantly after phacoemulsification at 1 and 2 months postoperatively with both the script-based method (p = 0.017 and p = 0.039) and the ML-based method (p < 0.0001 and p = 0.004).

Conclusions

Our findings suggest that the ML-based approach is a reliable method for measuring the FAZ on OCTA, comparable to the semiautomated script-based algorithm, and may serve as a practical alternative. Moreover, a significant reduction in FAZ within the SVP was observed two months after phacoemulsification.