Acute visual dysfunction following Phenytoin induced Toxicity

Abstract

Aim: Acute Visual Dysfunction may be caused by Acute Phenytoin Toxicity Method: An 18 year old female with prior generalized tonic-clonic seizures developed blurred vision, diffuse corneal opacity (OD), and ankyloblepharon after Phenytoin administration for seizures. Colour vision was found to be normal with Ishihara pseudo-isochromatic charts and visual fields (Humphrey's automated perimeter) show gross concentric constriction in both eyes. Fundus examination revealed increased CD ratio in both eyes. Patient also developed multiple cutaneous maculo-papular lesions and Steven-Johnson syndrome like exfoliation of skin around lips and perioral area. Serum free-phenytoin concentration measured reveals toxic levels of Phenytoin with no other prior co-morbid retinopathy or optic nerve defect. Results: Phenytoin was withheld, and Leviteracetam administered for seizures and the patient experienced a partial recovery in skin lesions with administration of Prednisolone and in conjunction with reducing serum levels of Phenytoin. Two weeks later the skin lesions have partially subsided, perioral area healed but Bilateral Ankyloblepharon persists and surgical release may be advised. Conclusion: Phenytoin toxicity may cause acute visual dysfunction as previously unknown phenomenon.