Retinal layer thickness independently predicts disability accumulation in newly diagnosed relapsing MS (RMS), creating an added value to established markers. This is especially true for macular ganglion cell-inner plexiform layer (GCIPL), more than for peripapillary retinal nerve fiber layer (pRNFL), according to findings presented at EAN 2023.
“pRNFL and GCIPL have not been studied as predictors of disability accumulation in newly diagnosed RMS and within the framework of known baseline demographic, clinical, and radiological risk factors,” said Gabriel Bsteh, MD, PhD.
The study included patients from whom a spectral- domain optical coherence tomography (OCT) scan was obtained within 90 days after RMS diagnosis. Follow-up was at least 12 months. The primary endpoint was time to disability accumulation, defined as a confirmed Expanded Disability Status Scale (EDSS) score of 3.0 or greater.
The study included 231 patients (mean age, 30.3; 74% women). Mean time to MS diagnosis was 45 days. The mean number of T2-lesions on baseline MRI was 11 (range, 0-45). Baseline mean pRNFL and GCIPL thickness were 91.9 μm and 80.2 μm, respectively.
Median follow-up was 61 months. An EDSS score of 3 or greater was reached by 28 patients (12.1%) after a median of 49 months. An EDSS score of 3 or greater was predicted by pRNFL thickness of 88 μm or less (HR, 4.0; 95% CI, 1.8-3.3; P<0.001) and by GCIPL thickness less than 77 μm (HR, 5.1; 95% CI, 1.6-4.2; P<0.001).
Time to progression independent of relapse activity (PIRA) was also predicted by pRNFL thickness of 88 μm or less (HR, 3.1; 1.7-5.4; P<0.001) and by GCIPL thickness less than 77 μm (HR, 4.1; 95% CI, 2.3-7.3; P<0.001). Dr. Bsteh said it was “very encouraging” to see that this was independent of other risk factors, such as age, MRI lesion load, and disease-modifying treatment. PRFNL and GCIPL thickness did not predict inflammatory activity.
Dr. Bsteh concluded that PRNFL/GCIPL may be a cross-sectional marker of neuro-axonal damage and could potentially inform treatment. However, OCT availability is limited and requires quality control. Dr. Bsteh also pointed out that changes in retinal layer thickness are not specific for MS, but can be influenced by other factors, including diabetes mellitus and glaucoma. Moreover, OCT is not applicable if there is myopia of more than four to six diopters or retinal comorbidities.
