Author Block: Jérémy Claes, Emmanuelle Chalifoux, David Simonyan, Andréane Lavallée

Author Disclosure Block: J. Claes: None. E. Chalifoux: None. D. Simonyan: None. A. Lavallée: None.

Abstract Body:

Purpose: To evaluate the correlation between average ganglion cell layer (GCL) thickness at the time of diagnosis of optic neuritis and the resulting visual function at 6 months. Study Design: This study is prospective, longitudinal and descriptive. 

Methods: 25 patients with first episode of optic neuritis confirmed by a neuro-ophthalmologist were included. All patients had no risk factors for other optic neuropathy or macular pathology. Macular Ganglion Cell Analysis determined by Cirrus HD Optical Coherence Tomography was performed at diagnosis and repeated at 6 months with best corrected visual acuity (BCVA), HRR color vision test (HRR) and Humphrey 30-2 fast perimetry (VF). The study methods have been reviewed by a local ethic in research committee and respect the declaration of Helsinki. 

Results: Demographic data were similar to those found in the literature. 84% of patients were women with a mean age of 35 years old. 60% of optic neuritis were associated with multiple sclerosis and 28% of patients received high-dose systemic steroids. Average GCL thickness dropped from 79.8 microns (75.9; 83.8) at baseline to 68.0 microns (62.7; 73.3) at 6 months. Statistically significant correlations were measured between average GCL thickness at baseline and BCVA (Spearman Correlation Estimate=-0.48, p<0.05) and HRR (Spearman Correlation Estimate=0.37, p<0.15) at 6 months. Correlation with VF mean deviation was not statistically significant (Spearman Correlation Estimate=0.27, p=0.22) at 6 months. Statistically significant correlations were found between average GCL thickness at 6 months and BCVA (Spearman Correlation Estimate=-0.60, p=0.001), HRR (Spearman Correlation Estimate=0.69, p<0.0001) and VF mean deviation (Spearman Correlation Estimate=0.30, p<0.15) at 6 months. Accessorily, 42.9% of patients with a confirmed multiple sclerosis diagnosis showed an abnormal baseline GCL thickness (≤75 microns) compared to 22.2% of other patients (p=0.55). Also, treated patients' average GCL thickness at 6 months (78.6 microns (67.9; 89.2)) was statistically different compared to untreated patients (65.5 microns (59.7; 71.3)) (p<0.05). Conclusions: Baseline measurement of average GCL thickness does not represent the progressive atrophic structural damage induced by optic neuritis, nor the residual visual function at 6 months. Therefore, visual function cannot be predicted by Ganglion Cell Analysis.