A Novel Approach for Anterior Chamber Angle Analysis – Anterior Chamber Angle Detection With Edge Measurement and Identification Algorithm (ACADEMIA)

Abstract

 

Purpose:

 

To describe a novel approach for measurements of anterior chamber angle dimensions and configurations.

 

Methods:

 

Ultrasound biomicroscopy images were analyzed pixel by pixel and the edge points corresponding to the corneal endothelium / trabecular meshwork and the anterior iris surface outlining the anterior chamber angle were detected and fitted with straight lines based on mathematical equations with the least–absolute distances optimization technique (Figure 1). The dimensions and the profile of anterior chamber angles were analyzed. Correlation between the derived angle parameters and the established standards – angle opening distance (AOD 500) and the trabecular–iris angle (TIA) were examined in 30 randomly selected images.

 

Results:

 

Three basic types of angle configuration were identified based on the derived angle profiles: (1) constant (2) increasing and (3) decreasing, which are corresponding to flat, bowed forward and bowed backward iris contours respectively. The angle measurements demonstrated high correlation with AOD 500 and TIA. The strongest association was found between the averaged angle derived from the angle profile and the AOD 500 (r = 0.91).

 

Conclusions:

 

The proposed algorithm was found to have high correlation with AOD/TIA with the added advantages of being fully automated, reproducible, and able to capture the characteristic angle configurations.  

 

Keywords: anterior chamber • anatomy • anterior segment