Correlation Between Heidelberg Retina Tomograph (HRT) Glaucoma Probability Score (GPS) and Standard Automated Perimetry (SAP) Global Indices in the Diagnostic Innovations in Glaucoma Study (DIGS)

Abstract

Purpose: : To determine the relationship between the newly developed HRT Glaucoma Probability Score (GPS) that is independent of the operator defined contour line and global visual field sensitivity measured using standard automated perimetry (SAP).

Methods: : Three hundred forty eyes of 340 participants enrolled in the UCSD Diagnostic Innovations in Glaucoma Study (DIGS) with HRT imaging and SAP–SITA (Swedish Interactive Testing Algorithm) testing within a period of 6 months were studied. DIGS participants were included regardless of their diagnosis (i.e., healthy, glaucoma suspect, glaucoma). The associations between HRT GPS and SAP MD and PSD were assessed using linear regression. Also assessed were the associations between MD and PSD and rim area (a previously available HRT II parameter dependent on the operator drawn contour line) and 5 new contour line–independent parameters that contribute to the calculation of the GPS (horizontal retinal nerve fiber layer curvature, vertical retinal nerve fiber layer curvature, cup depth, rim steepness, and cup size).

Results: : Significant associations were observed between the GPS and visual sensitivity (R²= 0.12 for MD, R² = 0.14 for PSD) and between rim area and visual sensitivity (R² = 0.09 for MD, R² = 0.10 for PSD) (all associations p < 0.0001). Of the 5 parameters that contribute to GPS calculation, only horizontal retinal nerve fiber layer curvature was significantly associated with MD and PSD (R² = 0.11 and 0.12, respectively, both p = 0.0001) after correction for multiple comparisons.

Conclusions: : Similar to rim area, the newly developed GPS is significantly associated with visual function, although not strongly. These results demonstrate that HRT parameters that are independent of contour line placement have a similar strength of association with visual sensitivity as do HRT parameters that depend on contour line placement by an expert observer.

Keywords: imaging/image analysis: clinical • visual fields