Abstract
Purpose::
A case-control study comparing rate of change of the retinal nerve fiber layer (RNFL) thickness in unaffected eyes of patients following unilateral demyelinating optic neuritis associated with clinically diagnosed Multiple Sclerosis (CDMS).
Methods::
At least 2 fast RNFL thickness optical coherence tomography (OCT) scans were performed on fellow eyes in 20 patients at various stages of optic neuritis using the Zeiss Stratus OCT III imaging device. The patients were divided into two groups: CDMS patients (n=10) and Non-CDMS control patients (n=10). The rate of attrition of the RNFLs in each group was determined by calculating the average thickness derived from serial OCTs performed on each of the 20 fellow eyes, then graphically representing these data over time (in weeks) from onset of optic neuritis. A best-fit line was used to determine the slope of individual sets of data points in each group. The slopes of both groups were then used to determine x-intercepts as an endpoint to total loss of RNFL.
Results::
The CDMS group demonstrated an average RNFL thickness of 95.3 microns (SD, +/-8.8) while the Non-CDMS group demonstrated an average of 92.9 microns (SD, +/-16.4). The average interval from onset of optic neuritis to OCT in the CDMS group was 213 weeks (range, 1-913; SD, +/-336) and in the Non-CDMS group 135 weeks (range, 1-452; SD, +/-171). The best-fit line representing the rate of change in RNFL thickness of the CDMS group showed a negative slope of 0.0014 (SE, +/-9.2 microns), whereas the Non-CDMS group showed a positive slope of 0.0007 (SE, +/-17.1 microns) at half the grade and in the opposite direction of the CDMS group slope. The x-intercept of the CMDS group was 68,289 weeks but the x-intercept of the Non-CDMS group was a negative integer (-132,624 weeks). The respective regression lines establish a theoretical timeline to monitor the demyelinating optic neuritis process as as it relates to diagnosis of Multiple Sclerosis.
Conclusions::
In our cohort of 20 patients with unilateral demyelinating optic neuritis, the fellow eye in CDMS patients demonstrates a greater trend toward attrition of the RNFL when compared to the fellow eye in Non-CDMS patients. Implementation of a higher resolution OCT device may provide greater characterization of the RNFL to help discern gliosis from healthy axons.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • autoimmune disease • neuro-ophthalmology: optic nerve