Abstract
Purpose :
Old branch retinal vein occlusion (BRVO) and primary open-angle glaucoma (POAG) present a diagnostic challenge due to their similar clinical features, including thinning of the inner retina on Optical Coherence Tomography (OCT) and hemifield defects. Given the impact of POAG on the ganglion cell complex (GCC), we hypothesized that unlike BRVO, which thins both GCC and IPL, POAG would show disproportionately greater thinning in the GCC, and tested if the GCC/IPL ratio could differentiate between these two conditions.
Methods :
We conducted a retrospective case series of macular OCT images (Spectralis [Heidelberg Engineering, Germany]) from patients diagnosed with old BRVO or POAG. Inclusion criteria were 1) BRVO diagnosis at least 6 months, without macular edema at the time of imaging, and 2) POAG with an arcuate or altitudinal hemifield defect on Humphrey Visual Field (Carl Zeiss Meditec, Inc., Dublin, CA) (Mean Deviation worse than -12dB). Exclusion criteria were the presence of poor-quality OCT scans, corneal, retinal, or neuroophthalmology conditions. Using the Heidelberg automated segmentation analysis of the macula cube (20° PMB grid), we generated GCC and IPL thickness maps in a 6x10 grid centered on the fovea. At each location, the GCC/IPL ratio was calculated by dividing the GCC by the corresponding IPL thickness. The final GCC/IPL ratio in the affected hemisphere was the average of these ratios. The Wilcoxon rank-sum test was used to compare the GCC/IPL ratios. (MedCalc Statistical Software, Ostend, Belgium).
Results :
Final analysis included 33 eyes of 33 patients (mean age of 63±13 years; 63% female; 45% African American, 27% Hispanic, 7% White and 17% as others). The GCC/IPL ratio was statistically significant lower in the POAG group (n=20), compared to that of BRVO (n=13) group (p < 0.01). The median GCC/IPL ratio was 1.17 (95% CI [1.12,1.18]) and 0.92 (95% CI [0.85,0.96]) in the BRVO and POAG groups, respectively. By adopting the GCC/IPL ratio less than 1 as a diagnostic marker for POAG, the area under the curve (AUC) was 0.90, with a sensitivity of 95.0% and specificity of 84.6%.
Conclusions :
Our findings, characterized by high AUC, sensitivity and specificity, suggest that the GCC/IPL ratio is a promising marker for distinguishing between old BRVO and advanced POAG. Future studies are needed to validate and refine the clinical utility of the GCC/IPL ratio.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.