Measurement of the retinal nerve fibre layer with scanning laser polarimetry in patients with previous demyelinating optic neuritis

Abstract

Objectives-Subjective visual deficits are common after demyelinating optic neuritis despite the frequent return of normal visual acuity. Visual and electrodiagnostic tests have demonstrated evidence of these persisting functional abnormalities, which are thought to be secondary to demyelination and variable axonal loss in the optic nerve. Scanning laser polarimetry (SLP) is a new image analysis technique which uses the polarising properties of the retinal nerve fibre layer (RNFL) to produce a quantitative measure of its thickness. This study was carried out to assess the prevalence, extent, and pattern of RNFL loss after demyelinating optic neuritis using SLP. Methods-Twenty four patients with a history of previous demyelinating optic neuritis were re-examined. Examination included measurement of logmar visual acuity, Pelli-Robson contrast sensitivity, and the presence of a relative aVerent pupil defect and optic atrophy. SLP was performed and a mean RNFL profile from a series of three images from each eye was constructed. This was compared with normative data from 20 age matched normal subjects. The lower 99.9% confidence limit of the normal data was calculated and used as the cut oV criterion for abnormality. Results-There were a total of 31 eyes with a history of demyelinating optic neuritis and SLP disclosed an abnormality in 29 (94%) of these. Twenty three eyes recovered an acuity of 0.0 or better, 21 of which had evidence of RNFL loss on polarimetry. Scanning laser polarimetry was the only abnormality found in nine of the 31 eyes (29%). The pattern and extent of RNFL loss was very variable and there was no significant diVerence in these indices between patients with multiple sclerosis compared with those with isolated demyelinating optic neuritis. Conclusion-Scanning laser polarimetry can provide a quantitative measure of RNFL loss after demyelinating optic neuritis, demonstrating its occurrence in a high percentage of patients recovering normal visual acuity. (J Neurol Neurosurg Psychiatry 1998;64:505-509)

Optical coherence tomography evaluation of retinal nerve fiber layer in longitudinally extensive transverse myelitis

“…This reduction is greater in NMO eyes than in MS eyes, thus suggesting that optic nerve damage is more severe in the former 17,27 . While axonal loss in eyes affected with ON is an expected finding, the subclinical axonal loss on OCT in eyes of patients with relapsing-remitting MS without a previous history of ON that has been observed in several studies 8,15,28,29 is somewhat more surprising. This is an important finding, because unaffected eyes of patients with relapsing-remitting MS may be evaluated very differently from the eyes of patients with LETM or NMO.…”

Inflammatory demyelination induces axonal injury and retinal ganglion cell apoptosis in experimental optic neuritis

“…retinal nerve fiber layer thinning, used as a surrogate marker for RGC axonal loss, correlates with vision loss after an episode of optic neuritis (Steel and Waldock, 1998;Parisi et al, 1999;Trip et al, 2005;Costello et al, 2006). Patients with multiple sclerosis also have retinal nerve fiber layer thinning correlating to decreased vision even without a documented episode of optic neuritis (Fisher et al, 2006), suggesting that RGC axonal loss mediates visual loss in this disease.…”

Avaliação da camada de fibras nervosas da retina nas afecções neuroftalmológicas da via óptica anterior

“…Sua capacidade de fornecer medidas quantitativas e reprodutíveis da camada da CFNR foi demonstrada em estudos experimentais e clínicos. (17,19,20) Embora a maioria dos estudos clínicos utilizando o GDx tenham sido realizados em pacientes com glaucoma, muitas outras neuropatias ópticas foram estudadas, incluindo neurite óptica desmielinizante, (21) trauma indireto do nervo óptico, (22) e neuropatia óptica isquêmica, (23) demonstrando que o GDx pode ser uma ferramenta útil na detecção da perda axonal em diversas afecções da via óptica anterior. Um dos problemas com esta tecnologia é que qualquer estrutura birrefringente por onde passe o feixe de laser altera o retardo do feixe.…”

“…(42) Embora a maior parte dos estudos tenha sido feita usando a TCO outros investigadores documentaram também a utilidade do polarímetro de varredura a laser na avaliação dos pacientes com esclerose múltipla. (21,43,44) A neurite óptica pode também fazer parte da neuromielite óptica (NMO) uma condição idiopática, desmielinizante e necrotizante do sistema nervoso central que acomete o nervo óptico e a medula espinhal. Estudos recentes indicam que se trata de uma doença distinta da EM, caracterizada pela presença de anticorpos antiaquaporina 4.…”