The Effects of Disease-Modifying Therapies on Optic Nerve Degeneration in Multiple Sclerosis.

Background: Retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) thinning are used as markers of subclinical retinal degeneration to evaluate the effect of disease-modifying therapies (DMTs) on disease progression in clinical trials of multiple sclerosis (MS). This study aimed to assess the available evidence regarding the effects of DMTs on retinal thinning in people with MS.

Methods: Databases were searched for studies reporting longitudinal optical coherence tomography (OCT)-derived annualized RNFL and GCIPL thinning in patients receiving DMTs treatment. The standardized mean differences (Hedges g) of RNFL and GCIPL thickness between the baseline and follow-up were used as the primary effect size measure. DMTs were divided into moderate (M-DMTs) and high (H-DMTs) efficacy therapies.

Results: Twenty-one studies including 2158 patients and 3685 eyes were included. Overall, significant annualized RNFL (g = -0.6715, p = 0.0077) and GCIPL (g = -0.31, p < 0.0001) thinning was observed at follow-up compared with baseline. Annualized RNFL thinning was only significant in the M-DMTs group (g = -0.6992, p = 0.0243). Annualized GCIPL thinning was significant in both M-DMTs (g = -0.38, p = 0.0006) and H-DMTs group (g = -0.19, p < 0.0001) but was significantly greater in the M-DMTs group compared with the H-DMTs group (g = -0.20, p = 0.0017). There was no difference in annualized GCIPL or RNFL thinning between RRMS and PMS, or between RRMS with and without ON history.

Conclusions: High-DMTs are more effective in reducing longitudinal thinning of RNFL and GCIPL compared with M-DMTs. GCIPL thinning could serve as a sensitive predictor for the surveillance of optic nerve degeneration and the assessment of DMT efficacy for both RRMS and PMS.