Enhancing Glaucoma Detection in African Ancestry Patients: A Comparative Analysis of Color Codes from the Cirrus HD-OCT Normative Database.

Abstract

Purpose : Structural differences in the retinal nerve fiber layer (RNFL) of African ancestry individuals are inadequately represented in the Cirrus HD-OCT normative database, potentially leading to either over or underdiagnosis of glaucoma in this ancestry group. This study compared the characterization of color codes between the Cirrus Normative Database and values from African ancestry patients to determine whether an ancestry-adjusted interpretation of the normative database more accurately reflects glaucomatous changes determined by visual field perimetry.

Methods : We examined the color codes from a sample of 256 eyes from subjects recruited into the Primary Open-Angle African American Glaucoma Genetics (POAAGG) study. Mild POAG cases were identified using the Glaucoma Staging System 2. Using age-stratified cutoff values of RNFL thickness we previously derived from the POAAGG control cohort without POAG (PMID: 34033949), we reclassified Cirrus HD-OCT color codes, adjusting for RNFL thickness in the African ancestry population. Reclassified color codes specific to the African ancestry group were compared with the original Cirrus HD-OCT normative database codes to evaluate their agreement in identifying mild POAG cases using weighted kappa and Bowker's Symmetry Test.

Results : In analyses of average RNFL, the race-based database reported fewer abnormal yellow and red color codes (16.4% and 6.3%) than the Cirrus normative database (18.0% and 9.4%, P <0.001). Comparisons between databases for each quadrant are shown in Table 1.

In analyses of each quadrant, the temporal quadrant had a lower proportion of yellow and red color codes (7.0% and 0.0%) in the race-based database versus Cirrus (13.0% and 6.1%, P <0.001) for patients with stage 0 (normal visual field tests). Database comparisons by stage are shown in Table 2.

Conclusions : Findings highlight a discrepancy in the color probability code classification of mild POAG cases between the existing Cirrus HD-OCT normative database and our ancestry-adjusted database. This suggests that an ancestry-conscious normative database may prevent overdiagnosis of POAG. Similar comparisons for patients with moderate to severe VF defects are necessary to validate the clinical utility of an ancestry-based normative database.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Table 1: Reclassified Color by Quadrant (N=256 eyes)

 

Table 2: Reclassified color by Stage and Quadrant