Optic disc and peripapillary morphology in unilateral nonarteritic anterior ischemic optic neuropathy and age- and refraction-matched normals.Ophthalmology. 2008 Sep; 115(9):1585-90.O
To compare optic disc morphologic features and peripapillary retinal nerve fiber layer (RNFL) thickness between the unaffected eyes of patients with unilateral nonarteritic anterior ischemic optic neuropathy (NAION) and their affected eyes and the eyes of age- and refraction-matched normal control subjects.
Cross-sectional comparative study.
Thirty-one patients with unilateral NAION and 62 age- and refraction-matched normal control subjects.
Optic disc morphologic features and peripapillary RNFL thickness were evaluated in both eyes of patients with unilateral NAION and in one randomly chosen eye of the normal control subjects.
MAIN OUTCOME MEASURES
Optic disc and cup parameters were measured using the Heidelberg Retina Tomograph II (Heidelberg Engineering GmbH, Dossenheim, Germany), and RNFL thickness was measured by scanning laser polarimetry with variable corneal compensation (GDx VCC; Carl Zeiss Meditec, Dublin, CA).
There was no significant difference in the disc area between the NAION affected eyes and the unaffected fellow eyes. The cup area, cup-to-disc area ratio, cup volume, and cup shape measure were greater, whereas the peripapillary RNFL thickness was smaller in the former than the latter (P = 0.001 to approximately 0.043). When the unaffected eyes of patients with NAION and the age- and refraction-matched normal control eyes were compared, the disc area, cup area, cup-to-disc area ratio, cup volume, mean cup depth, and cup shape measure were smaller in the former (P = 0.0006 to approximately 0.03); there was no significant difference in the RNFL thickness between the two (P>0.06).
A comparison of the eyes with NAION and the fellow eyes indicated that the cup was slightly larger in the former than in the latter, suggesting the acquired enlargement of the cupping after NAION develops. A comparison of the unaffected fellow eyes in patients with NAION and the age- and refraction-matched normal control eyes suggested that a smaller disc area and smaller cupping were predisposing risk factors for the development of NAION.