Sonographic ocular findings in patients with mucopolysaccharidoses I, II and VI

Ophthalmological complications in patients with mucopolysaccharidosis (MPS) are clouding of the cornea, glaucoma, optic neuropathy, and degeneration of the retina. These changes may impair visual function to the point of total loss of vision.

To document the ophthalmological changes demonstrated by grey-scale US in patients with MPS.

A total of 65 patients with MPS (18 type I, 12 type II, 35 type VI) including a subgroup of 30 undergoing enzyme replacement therapy (ERT) were studied by US of the globe and optic nerve.

Average scleral thickness at the posterior pole of the globe measured 2.02-2.58 mm (normal range 1.4-1.7 mm), the average diameter of the optic nerve and its sheath measured 5.35-6.71 mm (normal <4.5 mm). All medians were statistically significantly different from those of healthy volunteers. Concomitantly there was hypermetropia of up to 7.5 dioptres. During a mean follow-up of 3.1 years there was no distinct progression in scleral or optic nerve complex thickness.

The optic nerve sheath and sclera were clearly thickened in comparison to normal values. Many morphological changes in the eye and optic nerve were already present at the time of the initial clinical diagnosis, and thus seem to develop very early in the course of the disease. ERT in our patients did not seem to alter the US characteristics of the globe or optic nerve.