Ophthalmological Findings in Mucopolysaccharidoses

Abstract

The mucopolysaccharidoses (MPS) are a heterogenous group of lysosomal storage disorders caused by the accumulation of glycosaminoglycans (GAGs). The accrual of these compounds results in phenotypically varied syndromes that produce multi-organ impairment with widespread systemic effects. The low incidence of MPS (approximately 1/25,000 live births) in conjunction with the high childhood mortality rate had limited the availability of research into certain clinical features, especially ocular manifestations. As the recent successes of hematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy (ERT) have greatly increased life expectancy in these patients, they have served as a focal point for the transition of research towards improvement of quality of life. Ophthalmological findings in MPS include corneal clouding, glaucoma, optic neuropathies, and retinopathies. While corneal clouding is the most common ocular feature of MPS (especially type I, IVA, and VI), its response to HSCT and ERT is minimal. This review discusses known eye issues in the MPS subtypes, diagnosis of these ocular diseases, current clinical and surgical management, noteworthy research progress, and ultimately presents a direction for future studies.

Keywords: corneal clouding; lysosomal storage disorder; mucopolysaccharidosis; ocular manifestations; ophthalmology.

Figure 1

Sagittal view of eye listing area of effect in MPS (mucopolysaccharidosis) subtypes. Modified from [2,3]. * mild, ** moderate, *** severe.

Figure 2

Corneal clouding in MPS I. The top picture (A) shows a 19-year-old patient. The bottom picture (B) shows a 38-year-old patient. No systemic treatment for both patients.

Figure 3

Retinitis pigmentosa in MPS II. Fundoscopy showing retinitis pigmentosa in a 39-year-old MPS II patient.

Figure 4

(A) Corneal clouding in MPS VI. (A) shows a 17-year-old male with enzyme replacement therapy (ERT). (B) shows an 11-year-old female with ERT. (C) shows a 38-year-old female with no systemic treatment.

Figure 4

(A) Corneal clouding in MPS VI. (A) shows a 17-year-old male with enzyme replacement therapy (ERT). (B) shows an 11-year-old female with ERT. (C) shows a 38-year-old female with no systemic treatment.

Figure 5

Dermatan sulfate (DS) degradation pathway. Enzymes are italicized. Disease process in blue. Asterisk indicates the location of the enzyme effect.