Evaluation of acquired color vision deficiency in patients with primary open angle glaucoma with Rabin Cone Contrast Test

Abstract

Purpose : Glaucoma is one of the main causes of blindness in the world, the loss of the photoreceptors function can serve as a screening to find color vision impairment, for this reason we performed a prospective, observational, descriptive to evaluate the relationship between the acquired color vision deficiency in patients with different stages of primary open angle glaucoma by using the Rabin cone contrast test (RCCT) [Innova Systems, Burr Ridge, IL] and a Humphrey Visual Field Analyzer.

Methods : Forty six eyes of (23 patients) with primary open angle glaucoma ( primary open angle glaucoma group) and thirty eyes of 15 normal subjects (control group) were included in this study. Long (L), medium (M), and short (S) CCT scores and Contrast Sensibility scores (L CCTs, M CCTs, S CCTs, and CS respectively) were measured using the RCCT in both groups. Visual field examinations were performed with a Humphrey visual field analyser, classifying each patient in a stage of glaucoma according to the new ICD-9 staging definitions (Mild/early-stage glaucoma, moderate-stage glaucoma and severe-stage glaucoma/advanced-stage glaucoma/end-stage glaucoma).

Results : The percentage of females in this study was 80.43% compared to 19.56% male subjects from whom we evaluated 46 eyes. The mean results for all groups (early, medium and advanced) were for L CCTs mean 71.09 (SD 14.79) with a range of 15-95, M CCTs mean 77.83 (SD 24.89) range 10-100, S CCTs mean 72.83 (SD 22.5) range de 10-100. Contrast Sensibility Test (CST) mean 1.46 SD 0.28 range .7- 1.8.
Using Pearson Chi-square we assessed the statistical significance of the relationship between CCTs and glaucoma stages. We found an inverse correlation between the increase of glaucoma stages and a decrease in the CCTs mainly in long waves (p=0.296, mean=74.64) and medium waves (p=0.253, mean=73.13).

Conclusions : According to our study, we found a tendency in the progression of the loss of photoreceptors as the stage of Glaucoma increased. An inverse relation was established between the three scores L CCTs, M CCTs and S CCTs and the stages of the disease, essentially for long and medium waves. A larger sample could confirm this tendency, even though our p showed no significance. This discloses new possibilities for the assessment of primary open angle glaucoma.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

 

Picture 1. Rabin Cone Contrast Test of a Patient with Primary Open Angle Glaucoma