Introduction: The cornea is the chief refractive element of the eye while the retina is a portion of the nervous system containing the photoreceptor cells which process and transmit the light information to the brain. Topiramate is one of the antiepileptic drugs that is mainly used for the treatment of seizure disorder and migraine. However, its administration may be associated with eye pain and blurred vision.
Aim of the Work: This study is aimed to explore the impact of topiramate on the structure of rat cornea and retina using different histological, and immunohistochemical techniques.
Material and Methods: Thirty adult male albino rats were used in this study and were divided equally into three groups: the control group and two experimental groups that were administered topiramate at doses of 100mg, and 200mg/kg B.W. orally once daily for 28 days. After the experimental duration, the rats were sacrificed, and the eyeballs were dissected for staining with H&E, and Masson's trichrome in addition to immunolabelling with anti-caspase 3, and anti-synaptophysin, which is before a presynaptic protein that is closely linked to synaptic activity in the retina.
Results: The cornea showed apoptotic vacuolated epithelial cells, disorganization and wide separation of scleral fibers, focal loss of Descemet`s membrane and endothelium, with a significant increase in corneal thickness and caspase 3 apoptotic index in 200 mg topiramate group. The retina revealed a wide separation between the retinal layers and loss of demarcation between the inner and the outer nuclear layer with cellular vacuolation that showed pyknotic hyperchromatic nuclei. In addition to, disorganized scleral fibers, congested blood vessels, a significant reduction in retinal thickness and synaptophysin intensity, and a significant increase in caspase 3 area percentage.
Conclusion: The present findings indicate that topiramate induced adverse effects on the eye structure and it is recommended to be used strictly under medical supervision.