Variability in the ocular phenotype in mucopolysaccharidosis.

PURPOSE: Mucopolysaccharidoses (MPSs) are a heterogeneous group of lysosomal storage disorders. Ocular complications (such as corneal clouding, retinopathy and optic neuropathy) are common. Notably, there is a paucity of data on the effect of genotype and systemic treatments (enzyme replacement therapy or haematopoietic stem cell transplantation) on the ocular phenotype in MPS. We prospectively studied the ocular features of patients with MPSI (Hurler/Hurler-Scheie/Scheie), MPSIV (Morquio) and MPSVI (Maroteaux-Lamy), to evaluate the effect of different therapeutic interventions and to correlate the findings with genetic and biomarker data.

METHODS: Prospective observational cohort study. Study participants underwent detailed ocular examination including visual acuity; assessment of corneal clouding (Iris camera Corneal Opacification Measure score and Pentacam densitometry) and retinal and optic nerve imaging (optical coherence tomography and wide-field fundus imaging). Data on genotype, biomarkers and delivered therapies (type and length of treatment) were also collected for each patient where available.

RESULTS: Overall, 21 patients with MPSI, 4 patients with MPSIV and 3 patients with MPSVI were recruited. Corneal clouding scores were higher in MPSI compared with MPSIV and MPSVI. Retinopathy was evident in patients with MPSI only. Association was observed between corneal clouding and biomarkers in MPSI, MPSIV and MPSVI. However, no clear association was seen between genotype or treatment type and ocular phenotype.

CONCLUSIONS: The ocular phenotype in MPS is variable, with corneal clouding occurring in MPSI, MPSIV and MPSVI, and retinopathy in MPSI only. There was an association between corneal clouding and efficacy of systemic treatment as measured by biomarkers.