Retinal vessel diameter in bilateral glaucoma suspects: comparison between the eye converted to glaucoma and the contralateral non-converted eye

Purpose: To investigate retinal vessel diameter in patients classified as bilateral glaucoma suspects who showed unilateral glaucomatous conversion. Methods: This retrospective study included 21 patients who had initially been diagnosed as bilateral glaucoma suspects but showed unilateral glaucomatous conversion during a follow-up period of more than 2 years. Conversion to glaucoma was determined either by documentation of a new retinal nerve fiber layer defect on red-free photography or a reproducible glaucomatous visual field defect. The central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) were measured from fundus photographs taken at baseline and at the point of glaucoma conversion. Results: The mean CRAE of the converted eyes was significantly lower than that of the non-converted eyes at baseline (164.9 ± 13.2 μm vs 175.2 ± 15.6 μm; p = 0.001), but no significant difference was observed in the mean CRVE (p = 0.108). The mean CRAE of the converted eyes was also lower than in the non-converted eyes at the point of glaucoma conversion (158.6 ± 13.5 μm vs 168.0 ± 17.2 μm; p = 0.011). Conclusion: In bilateral glaucoma suspects, there was a significant inter-eye difference in CRAE at baseline between eyes that converted to glaucoma and those that did not. These findings suggest that measurement of retinal arteriolar diameter may help clinicians when evaluating the risk of conversion in glaucoma suspects.