Refractive error and axial length in nonarteritic anterior ischemic optic neuropathy

The aim of this study was to evaluate the ocular axial length and refractive error as risk factors for development of nonarteritic anterior ischemic optic neuropathy (NAION).This prospective study included 78 patients with NAION and 80 normal volunteers. Axial length and refractive error of NAION eyes were compared with the normal fellow eyes and control eyes.The 2 groups were frequency matched by sex and age. The mean refractive error (in spherical equivalent) was -0.07 +/- 1.60 diopters (D) in NAION eyes, 0.00 +/- 1.6 D in normal fellow eyes (P = 0.7), and -0.04 +/- 1.1 D in control eyes (P = 0.9). No significant difference was found between axial length measurements of NAION eyes (22.86 +/- 0.82 mm) and fellow eyes (22.80 +/- 0.88 mm; P = 0.8) and control eyes (23.1 +/- 0.78 mm; P = 0.1). Most of the NAION eyes (50%) were emmetropic (between +0.5 and -0.5 D).Axial length and refractive error may not be risk factors in NAION.