Ophthalmic findings in a Hunter Syndrome patient on enzyme replacement therapy (P5.190)

Objective: To display the ophthalmic findings in a patient with Hunter Syndrome on enzyme replacement therapy (ERT). Background: Hunter Syndrome is a rare x-linked recessive enzymatic deficiency characterized by deposition of glycosaminoglycans (GAGs) in a multitude of organs. In the eye, this deposition can lead to optic nerve edema, uveal effusion, epiretinal membrane, retinal degeneration, and visual field defects. Although enzyme replacement therapy with idursulfase has led to improvements in morbidity and mortality, there has yet to be an investigation of the benefits of ERT on ophthalmic disease. Design/Methods: A case study of one 39-year-old man over three years while on ERT for Hunter Syndrome was performed. Results: A 39-year-old man with Hunter Syndrome presented to neuro-ophthalmology after four years of ERT with a complaint of a progressive bilateral visual field defect. Physical examination was relevant for bilateral optic nerve head elevation, and a myelinated nerve fiber-like appearance OS. Visual field testing revealed bilateral ring scotomata. Optical coherence tomography (OCT) of the maculae demonstrated diffuse bilateral retinal thinning. These findings remained stable at 2 and 4 month follow-up appointments. The patient was evaluated at several other institutions over the next three years, during which his fundus exam, visual field and OCT remained stable. Conclusions: The case presented demonstrates common ophthalmic findings in Hunter Syndrome: retinal degeneration, visual field defects, and optic nerve head elevation. The lack of improvement in this patient’s ophthalmic disease despite ERT is attributable to the fact that idursulfase cannot cross the blood-brain-barrier. Presently, an investigation of the utility of intrathecal idursulfase on central nervous system (CNS) disease in Hunter Syndrome is underway. A study of the ophthalmic response to intrathecal idursulfase would lead to a better understanding of the ophthalmic changes in Hunter Syndrome, and allow for a proper assessment of the potential vision improvement with CNS-targeted ERT. Disclosure: Dr. Jarstad has nothing to disclose. Dr. Meeker has nothing to disclose. Dr. Ko has nothing to disclose.