Distance-Thresholded Intercapillary Area Analysis Versus Vessel-Based Approaches to Quantify Retinal Ischemia in OCTA

Area of Science:

• Ophthalmology
• Medical Imaging
• Retinal Disease Research

Background:

• Optical coherence tomography angiography (OCTA) is crucial for visualizing retinal vasculature.
• Quantifying retinal ischemia using OCTA requires robust and standardized analytical methods.
• Existing vessel-based approaches may not fully capture the extent of ischemic changes.

Purpose of the Study:

• To develop and compare analytical methods for quantifying retinal ischemia using OCTA.
• To evaluate vessel-based approaches against intercapillary area (ICA) analysis.
• To determine the most effective method for distinguishing healthy from ischemic retinal tissue.

Main Methods:

• Retrospective analysis of en face OCTA images from healthy eyes and eyes with various ischemic retinal diseases.
• Comparison of vessel-based metrics (mean gray scale, perfusion density, vessel density) with ICA analysis.
• ICA analysis involved measuring distances from intercapillary pixels to surrounding vessels using a vector method and varying distance thresholds.

Main Results:

• All analytical approaches demonstrated significant differences between healthy and ischemic retinas (P < 0.001).
• Receiver operating characteristic (ROC) curve analysis showed superior discrimination between healthy and ischemic retinas with ICA analysis, particularly using a locally set threshold for the shortest distance.
• ICA analysis proved more effective than vessel-based methods in quantifying retinal ischemia.

Conclusions:

• Intercapillary area (ICA) analysis is a superior method for quantifying retinal ischemia compared to vessel-based approaches in OCTA.
• Defining local or global distance thresholds in ICA analysis enhances its effectiveness.
• Standardized, device-independent OCTA analysis methods, like ICA analysis, are essential for clinical and scientific implementation.