Abstract
Purpose :
RNFL and GCL/inner plexiform layer (GCL+IPL) thickness, as measured by optical coherence tomography (OCT), are reduced in MS and correlate with visual acuity (VA). Myopia, as measured by spherical equivalent (SE) or axial length, is associated with peripapillary RNFL and macular thinning. We conducted a secondary analysis using a case-control study to examine the contribution of myopia to RNFL/GCL+IPL thinning in MS.
Methods :
Study participants with MS (n=447, mean age 46.3±10.4, 72.7% female) and disease-free controls (n=230, mean age 34.4±10.6, 69.1% female) with SEs of 0.5 to -16.0 diopters (D) underwent spectral-domain OCT and VA testing. Exclusion criteria included recent history (≤ 3 mos.) of optic neuritis (ON) or, for controls, eye disease other than refractive error or BCVA<20/20. Thickness of the peripapillary RNFL and GCL+IPL, average macular thickness and volume, high-contrast VA, low-contrast letter acuity at 2.5% and 1.25% contrast, and 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) scores were obtained. The relation of SE to retinal thickness and VA were examined with generalized estimating equation models, accounting for age and within-patient, inter-eye correlations.
Results :
Within the control cohort, more myopic SEs were a significant predictor of thinning of the RNFL (P<0.001) and GCL+IPL (P=0.005), average macular thickness (P=0.011), macular volume (P=0.012), monocular high-contrast VA (P<0.001) and 2.5% low-contrast acuity (P=0.04). Binocular VA, 2.5% and 1.25% low-contrast acuity (P<0.001), and NEI-VFQ-25 scores (P=0.005) were worse among controls with more myopic SEs. In the MS cohort, SE was also a significant predictor of lower RNFL thickness (P<0.001), though each negative D corresponded to a smaller thickness reduction than observed in controls. This relation was significant among MS eyes with and without ON (P=0.001-0.008).
Conclusions :
Higher degrees of myopia contribute significantly to RNFL thinning among both MS patients and controls. The relation between SE and RNFL thickness was stronger among controls, reflecting the known role that MS has in RNFL and GCL+IPL thinning. The potential influence of myopia is noteworthy when interpreting OCT data in MS patients. Furthermore, even among controls without MS history, higher degrees of myopia predict worse visual function and quality of life.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.