Detection and Quantification of Retinal Nerve Fiber Layer Thickness in Optic Disc Edema Using Stratus OCT

Abstract

Quantification of the peripapillary retinal nerve fiber layer (RNFL) thickness can provide clinicians with objective information about the optic nerve in different pathologic conditions. Several imaging techniques can be used to obtain such a measurement; most recently, optical coherence tomography (OCT) has demonstrated several merits. This technology has been used extensively to quantify RNFL thickness in atrophic diseases such as glaucoma, Leber hereditary optic neuropathy, traumatic optic neuropathy, and band atrophy.^1-4 In all of these pathologic conditions, OCT has demonstrated an ability to clearly identify reductions in RNFL thickness; however, few studies^5,6 have used OCT to investigate optic neuropathies in which RNFL thickening occurs due to optic disc edema. Such RNFL thickening has not been fully evaluated or thoroughly defined using other instruments, such as scanning laser polarimetry (SLP) or confocal scanning laser ophthalmoscopy. Results of the only 2 studies^7,8 performed using SLP suggest that this technology may, indeed, be unable to detect increases in RNFL thickness during the acute phase of optic neuritis or anterior ischemic optic neuropathy (AION). Conversely, confocal scanning laser ophthalmoscopy has been shown to accurately detect optic nerve changes in papilledema, but investigations using this instrument have focused more on optic disc volume than on RNFL thickness.^9-11