Retinal Nerve Fiber Layer Thickness and Peripapillary Atrophy in Glaucoma with Small Discs

ABSTRACT

PURPOSE: To evaluate the usefulness of the retinal nerve fiber layer thickness and peripapillary atrophy in discrimination between normal and glaucoma patients with small optic discs which can be potentially misleading by cup-to-disc ratio. METHODS: Eyes with average disc diameter 1.617 mm or less which is 33 percentile by topographic scanning system (TopSST M, version 2.2, LDT, Inc., U.S.A) in our normal population study were enrolled. 82 eyes of 82normal subjects, 30 eyes of 30 patients with primary open-angle glaucoma (POAG), 16 eyes of 16 patientswith normal tension glaucoma (NTG) were studied. Program 30-2 of the Humphrey Field and scanning laser polarimetry (Nerve Fiber Analyzer II NFAII, version 2.1., LDT, Inc., U.S.A.) were performed and color optic disc photographs had been taken. The differences in NFA parameters and peripapillary atrophy (zone alpha and zone beta) between normal subjects and glaucoma patients were examined. RESULTS: Considering all the NFA parameters, superonasal ratio of POAG and NTG group was significantly lower than normal group (p=0.002, p=0.043, respectively) and inferonasal ratio of POAG group was significantly lower than normal group (p=0.020). Zone beta atrophy was detected more frequently in POAG and NTG group than normal group (p=0.015, 0.007, respectively). No significant correlation was found between superonasal, inferonsal ratio and visual field indices and the presence of zone beta was not associated with progression of visual field. CONCLUSIONS: In small optic discs which had been presented diagnostic difficulties with optic disc status, retinal nerve fiber layer thickness (superonasal or inferonasal ratio) and/or peripapillary atrophy (zone beta) analysis can be helpful in identifying glaucoma.