Macular Retinal and Nerve Fiber Layer Thickness in Early Glaucoma: Clinical Correlations

Purpose: Previous studies have evaluated macular retinal thickness (RT) and nerve fiber layer thickness (RNFLT) changes in early glaucoma using elaborate optical coherence tomography (OCT) scanning protocols. Materials and Methods: This study examines RT and RNFLT using standard scanning protocols in early glaucoma. In this prospective, nonrandomized case series, 95 eyes of 95 patients were evaluated, including 29 nonglaucomatous subjects (control group), 34 glaucoma suspects, and 32 early manifest glaucoma patients. RT and RNFLT were measured using scanning fast macular thickness map and Fast RNFLT (3.4) protocols on a 1.70 mm radius around the macular center (respectively) in all four quadrants. The fast RNFLT (3.4) protocol was transposed on the macula from the peri-papillary area. Data were statistically analyzed for differences between groups, and for correlations between parameters. P < 0.5 was statistically significant. Results: Both early manifest glaucoma patients and glaucoma suspects had significantly lower RT than controls in all quadrants. RNFLT differences in all quadrants were not statistically significant (P > 0.05). RT was significantly inversely correlated with axial length in early manifest glaucoma patients and glaucoma suspects but not in controls. Conclusions: The finding that RT was significantly lower in early manifest glaucoma patients and glaucoma suspects indicates that the transposition of the OCT fast RNFL thickness (3.4) protocol from the peri-papillary area to the peri-macular area can be used for early glaucoma diagnosis. Intraretinal changes in early glaucoma, likely precede nerve fiber changes.