5.2 Exploring The Evolution Of Structural and Functional Changes After Optic Neuritis

Saturday, June 1, 2013: 11:25 AM
Fiona Costello, MD, FRCPC , University of Calgary, Calgary, AB, Canada
Jodie M Burton, MD, MSc, FRCPC , Clinical Neurosciences, University of Calgary, Calgary, AB, Canada
Jessie Trufyn, BSc , University of Calgary, Calgary, AB, Canada
William Hodge, MD, FRCP , Ophthalmology, University of Western Ontario, London, ON, Canada
Irene Pan, Msc , Ophthalmology, University of Western Ontario, London, ON, Canada

Background: Spectral-Domain OCT (SD-OCT) detects axonal loss [retinal nerve fiber layer (RNFL) thinning] and neuronal degeneration [macular volume (MV) loss] in ON and multiple sclerosis (MS) patients. SD-OCT has been proposed as an outcome measure in the ON model of central nervous system (CNS) inflammation.

Objectives: To determine the temporal evolution of function and structural changes in retinal architecture after optic neuritis (ON).

Methods: In this prospective cohort study, 50 patients with acute ON underwent serial vision, SD-OCT, and neurological testing  within 30 days  of symptom onset (baseline), 3-months, 6-months, and 12-months.   Descriptive statistics were calculated for patient demo-graphics.  For analysis of correlated data, random effects mixed model (mixed effect, maximum likelihood regression) was fitted to account for random effects of patient and follow-up time when determining the relationship between RNFL and visual recovery over time. To test potential predictors of change in RNFL thickness, multiple linear regression model was used.

Results: The mean age of patients was 35.5 years (43 females).  Mean RNFL thickness in ON eyes decreased from baseline [102.8 µm] to 3-months [85.3µm] (p < 0.05); from 3-months to 6-months [77.7µm] (p < 0.05); and from 6-months to 12-months [72.1µm] (P < 0.05).    Acutely, higher RNFL values corresponded to more severe vision loss, whereas during recovery, higher RNFL measures were associated with better visual function.  Male patients on average lost 35µm of RNFL thickness more than female patients (p=0.05). Older patients developed less RNFL loss:  at 6-months, an older ON patient manifested 18um (p=0.015) less RNFL thinning than a patient 10 years younger. 

Conclusions: SD-OCT captures RNFL and macular volume changes after acute ON.  The impact of gender, age, disease duration and other factors needs to be considered in future MS trials using OCT as an outcome measure.