Retinal thinning in epilepsy: A meta-analysis

Abstract

Background and objectives: Epilepsy has been linked with neurodegenerative changes, including neuronal and axonal loss. Epilepsy-related neuronal loss may be reflected on a retinal level as retinal thinning. Several Optical Coherence Tomography (OCT) studies have reported varied and contradicting results with regard to retinal thickness changes in epilepsy. We conducted a meta-analysis to elucidate retinal layer thickness changes in adult and pediatric epilepsy as assessed by OCT and to examine the relationship of these changes with disease, patient, and treatment-related factors.

Methods: Using PRISMA 2020 guidelines, PubMed, EMBASE, Cochrane Library databases were systematically searched for studies published between 2000 and 2024. The modified Newcastle-Ottawa Scale (NOS) was used to assess bias. Meta-analyses estimated the weighed mean difference (WMD) of peripapillary retinal nerve fiber layer thickness (pRNFLT) in adult patients with epilepsy exposed and not exposed to vigabatrin (VGB), and pediatric patients with epilepsy not exposed to VGB, compared to age-matched controls.

Results: Following the screening οf 1773 records a total of 18 cross-sectional studies of 1063 patients were included in the meta-analyses, categorized into three groups to enable comparisons. VGB-treated patients exhibited significant pooled pRNFL thinning compared to adults not exposed to VGB (WMD=-17.697 µm, 95 % CI:25.163 to -10.230, P < 0.001, n = 5). A significant pRNFLT reduction was also observed in adult patients with epilepsy not exposed to VGB, compared to controls (WMD=-6.655 µm, 95 % CI:8.77 to -4.53, P < 0.001, n = 10). Sectorial analysis showed that pRNFL thickness reduction was most pronounced in the superior and inferior quadrants and least extensive in the temporal quadrant. Pediatric patients with epilepsy exhibited a non-statistically significant trend toward pRNFL thinning. Meta-regression analyses did not reveal any significant patient or disease-related covariates.

Conclusions: In addition to VGB-related retinal thinning there is also considerable pRNFL thinning in adult patients with epilepsy with a predilection for the superior and inferior retinal quadrants. The potential clinical utility of OCT as a biomarker of neurodegenerative changes in adults with epilepsy and its plausible role in monitoring and prognostication merit further investigation.

Keywords: Epilepsy; OCT; Optical coherence tomography; RNFL; Retina; Seizures.