Rates of retinal nerve fiber layer loss in early-stage pseudoexfoliation and primary open-angle glaucoma patients using optical coherence tomography

Purpose To characterize glaucoma progression in early-stage patients with retinal nerve fiber layer (RNFL) using the change analysis software (CAS), which was utilized to track RNFL thinning. Methods We retrospectively analyzed 92 eyes of 92 patients with early-stage glaucoma. Patients were divided into two subgroups based on their diagnosis of pseudoexfoliation glaucoma (PEG) and primary open-angle glaucoma (POAG). A complete ophthalmologic examination was performed on all patients. Additionally, automated perimetry was conducted on each patient. Furthermore, Fourier-domain optical coherence tomography (OCT) was employed to measure RNFL and central corneal thickness. Using the OCT device's CAS, we computed the annual rate of total and glaucomatous RNFL thinning for each patient. Results A total of 44 PEG and 48 POAG patients were included in the study. The right eye measurements of these patients were analyzed and compared. The two groups were not significantly different in age, gender, and the number of visits per year (p > 0.05, for each). However, the difference between the mean RNFL thickness at baseline (91.39 +/- 10.71 and 96.9 +/- 8.6 mu m) and at the last visit (85.2 +/- 15.76 mu m and 91.56 +/- 9.58 mu m) was statistically significant between the two groups (p = 0.043, p = 0.039, respectively). Additionally, the difference in annual RNFL thinning rates (1.43 +/- 0.81 mu m and 1.07 +/- 0.32 mu m) between the two groups was statistically significant (p = 0.009). Conclusion The annual rate of glaucomatous RNFL loss in early-stage PEG patients (1.23 mu m) was higher than in POAG patients (0.87 mu m). However, despite these loss rates, scotoma was not detected in the visual field tests of these patients. Therefore, using CAS in the follow-up of early-stage glaucoma patients is a useful alternative for monitoring glaucomatous progression. Furthermore, this method can be utilized in future research for the diagnosis and follow-up of glaucoma in special populations (e.g., those with pathological myopia or high hyperopia) that are not included in normative databases.