Abstract
PURPOSE: The purpose of the study is to evaluate the percentage differences in ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (pRNFL) parameters in fellow eyes of the same patient with varying severities of glaucomatous damage. As only the eyes of the same patient with different severities of glaucoma were included in the present study, it could be inferred that the difference in parameters represents the loss leading to the next stage of glaucoma. METHODS: This was a cross-sectional study of 136 adult primary glaucoma eyes of 68 patients. They were divided as follows: Group 1 - normal visual field in one eye and superior nasal step, (mild), in the other, Group 2 - superior nasal step in one eye and superior arcuate scotoma, (moderate) in the other, and Group 3 - superior arcuate scotoma in one eye and biarcuate scotoma, (severe) in the other. GCC and pRNFL measurements on spectral domain optical coherence tomography (SD-OCT) were statistically assessed as applicable. RESULTS: The percentage difference in GCC parameters in fellow eyes from normal field to mild, mild to moderate, and moderate to severe glaucoma in average GCC was 10.04 ± 6.33%, (P = 0.0001), 15.77 ± 9.62%, (P = 0.0001), and 9.06 ± 6.41%, (P = 0.021); in inferior GCC, it was 13.25 ± 8.7%, (P = 0.0002), 18.94 ± 12,61%, (P = 0.0001), and 9.02 ± 6.92%, (P = 0.658), and in superior GCC, it was 7.42 ± 5.79%, (P = 0.002) 15.31 ± 11.07%, (P = 0.004), and 11.23 ± 9.82%,(P = 0.003), respectively. The percentage difference in average pRNFL of fellow eyes from normal field to mild, mild to moderate, and moderate to severe glaucoma in was 16.9 ± 9.85%, (P = 0.001), 18.23 ± 10.47%, (P < 0.0001), and 9.0 ± 7.35%, (P = 0.0004); in inferior pRNFL, it was 18.76 ± 12.38%, (P = 0.001), 19.6 ± 10.3%, (P < 0.0001), and 8.41 ± 7.3%, (P = 0.019), and in superior pRNFL, it was 15.3 ± 9.8%, (P = 0.015), 18.24 ± 13.56%, (P = 0.0003), and 11.46 ± 9.74%, (P = 0.001), respectively. A total of 136 eyes were regrouped by glaucoma severity, and in mild, moderate, and severe glaucoma subgroups. The percentage difference in average GCC was 11.01 ± 9.07%, 17.53 ± 11.29%, and 18.48 ± 11.69%. CONCLUSION: A percentage difference of GCC and pRNFL values could be used for both diagnosis and progression of glaucoma.