Changes in retinal nerve fiber layer and optic disc algorithms by optical coherence tomography in glaucomatous Arab subjects

Ferial M Zeried, Uchechukwu L Osuagwu

Department of Optometry and Vision Sciences College of Applied Medical Sciences, King Saud University, Riyadh, Kingdom of Saudi Arabia

Purpose: To assess the difference in retinal nerve fiber layer (RNFL) and optic disc algorithms between glaucomatous and normal Arab subjects using optical coherence tomography (OCT).
Methods: RNFL thickness and optic disc parameters were obtained in 65 patients aged 50.1 ± 7.7 years. Percentage differences in all parameters were calculated and analyzed between groups.
Results: The mean RNFL thickness around the disc and at all quadrants was significantly thinner in glaucomatous eyes than in normal eyes (P < 0.01). The greatest decrease in RNFL thickness was observed at the inferior (39.5%) and superior (39.3%) quadrants and at 1 o’clock (43%) and 5 o’clock (40%) hour sectors. Significant differences were observed between glaucomatous and control eyes in all disc parameters (P < 0.005) assessed. The disc area, cup area, mean cup/disc ratio, and vertical and horizontal cup/disc ratios were significantly larger (P < 0.01), whereas the vertical integrated rim area, horizontal integrated rim width, and rim area were significantly smaller (P < 0.001) in glaucomatous eyes than in normal eyes.
Conclusion: Stratus OCT is still a valuable tool in the diagnosis of early glaucoma changes and, as such, its use should be encouraged in glaucoma clinics in Saudi Arabia. The best OCT parameters for detecting early glaucoma change were RNFL thickness in the inferior, superior, and 1 o’clock hour sector; the cup area; and the vertical integrated rim area of the optic disc.

Keywords: glaucoma, Stratus optical coherence tomography, optic disc, retinal nerve fiber layer (RNFL), age, Saudi Arabia