Mucopolysaccharidoses and the eye

The mucopolysaccharidoses (MPSs) are a group of disorders caused by inherited defects in lysosomal enzymes resulting in widespread intra- and extra-cellular accumulation of glycosaminoglycans. They have been subdivided according to enzyme defect and systemic manifestations and include MPS IH (Hurler), MPS IS (Scheie), MPS IH/S (Hurler/Sheie), MPS II (Hunter), MPS III (Sanfilippo), MPS IV (Morquio), MPS VI (Maroteaux-Lamy), MPS VII (Sly) and MPS IX (Natowicz). The mucopolysaccharidoses have a spectrum of systemic manifestations, including airway and respiratory compromise, skeletal deformities, intellectual and neurological impairment, cardiac abnormalities, and gastrointestinal problems. Ocular manifestations are common in the mucopolysaccharidoses and may result in significant visual impairment. Corneal opacification of varying severity is frequently seen, as well as retinopathy, optic nerve swelling and atrophy, ocular hypertension, and glaucoma. New treatment modalities for the systemic manifestations of the mucopolysaccharidoses include bone marrow transplant and enzyme replacement therapy, and have resulted in an improved prognosis in many cases. This article reviews the systemic and ocular manifestations of the mucopolysaccharidoses, as well as new treatment options, and discusses the ophthalmic management of mucopolysaccharidosis patients.