Ocular Changes in Patients with Mucopolysaccharidosis I Receiving Enzyme Replacement Therapy: a 4-year Experience

Objective: To describe the progression of ocular changes in patients with mucopolysaccharidosis I receiving enzyme replacement therapy.

Methods: Three male and five female patients with mucopolysaccharidosis I were followed up for 4 years while undergoing enzyme replacement therapy with alpha-l-iduronidase (Aldurazyme). Visual acuity, corneal clouding, intraocular pressure, ophthalmoscopy, and optic disc measurements were performed yearly.

Results: Vision remained stable in 5 patients and deteriorated by at least 2 Snellen lines in 3 patients. Deterioration in 2 of these patients was related to progressive corneal clouding. Visual acuities improved in 1 patient after bilateral penetrating keratoplasties. In the third patient, deterioration was related to increasing papilloedema. All patients had typical corneal stromal opacities, however, to a variable extent. Two patients had already undergone corneal transplantation before recruitment in the study. Their grafts remained clear throughout follow-up. Of 2 patients with an elevated intraocular pressure, 1 developed intraocular pressure-related optic nerve damage. Vision remained stable in a patient with bilateral optic atrophy.

Conclusions: Ocular findings remain stable in most patients with mucopolysaccharidosis I receiving enzyme replacement therapy. However, enzyme replacement therapy does not seem to prevent progression of corneal or optic disc changes and, thus, the related worsening of visual function.