The Retinal Nerve Fiber Layer Analysis in Eyes with Small Optic Disc

ABSTRACT

PURPOSE: Eyes with small optic disc may be infirm to glaucomatous damage but suitable and objective methods for monitoring glaucomatous optic nerve damage in small optic disc are limited. The purpose of this study was to evaluate the usefulness of the retinal nerve fiber layer (RNFL) analysis using scanning laser polarimetry in patients with small optic disc. METHODS: 63 patients with small optic disc were recruited in this study. Eyes with average disc diameter 1.617 mm or less which was 33 percentile by topographic scanning system in our normal population study were enrolled. There were 26 patients with normal tension glaucoma and 37 patients with normal visual fields. Each patient underwent RNFL analysis using GDx VCC. Measurements of axial length, intraocular pressure, refractive error, disc diameter and cup/disc ratio were fulfilled. Findings were compared with independent t-test between 2 groups. GDx VCC parameters were analyzed with multiple logistic regression analysis. RESULTS: No differences in age, axial length, intraocular pressure, refractive error and disc diameter were apparent between the two groups. However, significant differences were detected in GDx VCC parameters including TSNIT average, Superior average, TSNIT standard deviation, NFI, Superior ratio, Inferior ratio, Sup/nasal, Maximum modualation, Superior maximum and Normalized superior area (p<0.001). The RNFL damage of superior area was prominent. CONCLUSIONS: In the patients with small optic disc, it is hard to detect the pathologic glaucomatous change by their disc morphologies. Therefore, RNFL analysis could be useful for a glaucoma screening of the patients with small optic disc.