To report ocular findings of a mucolipidosis type II patient with novel mutation.

A 10-year-old boy visited our pediatric genetic metabolic clinic for evaluation of his overall developmental delay and short stature. The boy was diagnosed with mucolipidosis type II (I-cell disease) using plasma enzyme assay and DNA sequencing of the GNPTAB gene mutation. An ophthalmologic investigation was then performed, and a depressed nasal bridge, broad nose, and swelling in the upper lid of both eyes were noted. The best corrected visual acuity was 0.32 and 0.1 and the intraocular pressure was 35 mmHg and 24 mmHg in the right and left eyes, respectively. The anterior chamber angles of both eyes were normal and mild cornea opacity in both eyes was observed. Fundus examination revealed retinal atrophy with folds in both eyes, as well as optic disc edema and optic atrophy in the right and left eyes, respectively. Atherosclerotic changes in the retinal vessels and cystoid macular edema in the left eye were observed, and ocular ultrasound revealed increased posterior sclera thickness in both eyes.

Ocular manifestations of mucolipidosis type II are not currently well-known, and differentiation from other metabolic disorders may be difficult. An ophthalmic work-up can assist in diagnosis, and regular ophthalmic examinations should be used to maintain visual function in mucolipidosis patients.