Retinal nerve fiber layer thickness as a marker of neurodegeneration in epilepsy

The relationship between epilepsy and neurodegeneration has recently been a subject of debate, particularly regarding whether neurodegeneration is a cause or a consequence of epilepsy. Given that the retina is an extension of the brain and closely connected to it, retinal layer thickness can serve as a biological marker of neurodegeneration. The aim of this work was to measure retinal nerve fiber layer (RNFL) thickness in patients with epilepsy in comparison to healthy controls, and to study the impact of epilepsy duration and seizure frequency on RNFL thickness in those patients.

This case-control study was conducted on 53 patients matched clinical definition of epilepsy established by the International League Against Epilepsy (ILAE) 2017, and 50 healthy controls. Cognitive assessment using Montreal cognitive assessment scale (MOCA), and measurement of RNFL thickness using Spectral domain Optical Coherence Tomography (SD-OCT), were done to all included patients and controls.

The peripapillary RNFL thickness (superior, inferior & average) were all significantly reduced in both eyes in epileptic patients compared to healthy controls (p-value <0.05). There was a statistically significant difference between epileptic patients and controls regarding MOCA score. There was no statistically significant impact of seizure control, history of status epilepticus, anti-epileptic drugs, seizure frequency, or disease duration on RNFL thickness.

There was a statistically significant reduction of the retinal nerve fiber layer thickness in epileptic patients in comparison to healthy controls. Epileptic patients had significant impairment in cognitive functions in comparison to healthy controls.