COMMENTARY

NAION and the Optic Disc

Rod Foroozan, MD

Disclosures

October 02, 2008

Introduction

Nonarteritic anterior ischemic optic neuropathy (NAION) is the most common acute optic neuropathy occurring in patients older than the age of 50 years. Optic disc edema is accompanied by variable loss of visual acuity, field, and color vision. The premorbid configuration of the optic disc has been noted to be an important risk for the development of NAION, with most patients having a small optic disc and cup.[1] After the disc edema resolves, optic disc pallor ensues with little cupping of the optic disc. The authors of this cross-sectional comparative study reviewed the findings of 31 patients with unilateral NAION and 62 age- and refraction-matched normal control subjects to compare optic disc morphologic features and peripapillary retinal nerve fiber layer (RNFL) thickness between affected and unaffected eyes.

Optic Disc and Peripapillary Morphology in Unilateral Nonarteritic Anterior Ischemic Optic Neuropathy and Age- and Refraction-Matched Normals

Saito H, Tomidokoro A, Tomita G, Araie M, Wakakura M
Ophthalmology. 2008;115:1585-1590

Summary

Optic disc morphology was determined using multiple imaging modalities, including scanning laser polarimetry (SLP) and retinal tomography (RT). There was no statistically significant difference in the disc area between eyes affected by NAION and those that were not affected. The cup area, cup-to-disc ratio, cup volume, and cup shape were greater, and the RNFL thickness less in eyes with NAION compared with those that were not affected. There was no difference in RNFL thickness in unaffected eyes of patients with unilateral NAION, compared with age- and refraction-matched controls; however, the cup-to-disc ratio, disc area, and disc volume were smaller in eyes with NAION.

Comment

Although NAION remains the most common acute optic neuropathy in patients older than the age of 50 years, the pathogenesis remains unclear. One of the most important risk factors is the morphology of the optic disc. Although prior studies have considered the importance of this optic disc morphology, a study of the premorbid condition of the optic disc in NAION is difficult. In lieu of this approach, the authors compared age- and refraction-matched controls and compared the optic disc morphology of the fellow, unaffected eye. In normal subjects there is good correlation of the morphology of the optic disc between the 2 eyes.[2]

The small amount of optic disc cupping that occurred in eyes with NAION is in agreement with a prior study.[3] The current study is also the first to show a thinner RNFL thickness of eyes with NAION when compared with the fellow, unaffected eyes. Unfortunately, these findings do not shed any additional insight into the cause of NAION.

Abstract

Comments

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