Effect of fingolimod therapy on quantitative macular changes among patients with relapsing-remitting multiple sclerosis: a four-year follow-up study from Oman

PURPOSE: Fingolimod (FTY-720) is an immunomodulatory oral agent approved for the treatment of relapsing-remitting multiple sclerosis (RRMS); however, several clinical trials have shown that some recipients may develop macular oedema (ME) as an adverse reaction. As there are no studies assessing the long-term (> 1 year) effect of fingolimod on the macula, this study aimed to evaluate the quantitative effect of fingolimod therapy on central macular thickness (CMT) and total macular volume (TMV) over a four-year period. METHODS: This retrospective longitudinal cohort study was performed between January 2014 and December 2018. A total of 21 patients with RRMS receiving fingolimod therapy were recruited and followed-up over 4 years to assess CMT and TMV changes measured using spectral domain optical coherence tomography. A paired sample t-test was used to compare mean CMT and TMV values calculated at baseline prior to the initiation of fingolimod therapy with those observed at three, six, 12, 24, 36 and 48 months of treatment. RESULTS: None of the patients developed ME over the four-year study period. In addition, there was no significant difference in baseline mean CMT values and those observed at a four-year follow-up. Although mean TMV values remained constant initially, there was a significant decrease towards the end of the study period. CONCLUSIONS: Long-term fingolimod therapy did not result in significant CFT changes. While there was a reduction in TMV towards the end of the study, this is likely due to the degenerative effect of the disease itself on the nerve fibres of the retina.