Ocular System

Corneal clouding is a feature of all MPS I patients (Image 1) and can be progressive and obstruct vision.

Image 1 - Corneal clouding
Courtesy of J.E. Wraith, MD

Open-angle glaucoma, in which the trabecular meshwork is free from encroachment by the base of the iris, is also a common complication.^[1][2] The trabecular meshwork is usually engorged with glycosaminoglycans, and the sclera and cornea are thickened, causing shallow anterior chambers.

Retinal degeneration is common and can be assessed by electroretinogram. It results in decreased peripheral vision and night blindness; the exact etiology is unknown. Visual disturbances can progress to blindness from a combination of retinal pigmentary degeneration, optic nerve compression and atrophy and cortical damage.

Wearing brimmed hat or sunglasses can help individuals with corneal clouding. Patients should be routinely tested for glaucoma by assessing intraocular pressure; monitoring of retinal degeneration is also recommended. Corneal grafting may be helpful for some patients. However, patients with clear grafts may still have poor vision because of associated retinal and/or optic nerve disease.^[2][3]

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References:

1. Clarke, L.A. (1997) Clinical diagnosis of lysosomal storage diseases. In: Organelle Diseases. Clinical Features, Diagnosis, Pathogenesis and Management. Applegarth, D.A., Dimmick, J.E., and Hall, J.G. (eds.). Chapman and Hall Medical, London, p. 37.

2. Neufeld, E.F., and Muenzer, J. (2001) The mucopolysaccharidoses. In: The Metabolic and Molecular Bases of Inherited Disease. Scriver, C.R., Beaudet, A.L., Sly, W.S., Valle, D., Childs, B., Kinzler, K.W., and Vogelstein, B. (eds.). 8th edition, Vol. III. McGraw- Hill, Medical Publishing Division, p. 3421.

3. Caruso, R., M. Kaiser-Kupfer, et al (1986). Electroretinographic findings in the mucopolysaccharidoses Ophthalmology 93 (12).