Ocular manifestations and management recommendations of lysosomal storage disorders I: mucopolysaccharidoses

Abstract

The mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by inborn errors of glycosaminoglycan (GAG) metabolism. These diseases are classified by enzyme deficiency into seven groups: type I, II, III, IV, VI, VII, and IX. GAG accumulation leads to characteristic clinical features. Some ophthalmic findings that are characteristic of MPS diseases include corneal clouding, retinal degeneration, decreased electroretinogram wave amplitude, optic atrophy, papilledema, and glaucoma. Current treatments such as hematopoietic stem cell transplantation and enzyme replacement therapy have increased the life span of many MPS patients and created the need to improve management of ocular symptoms. This article aims to provide a comprehensive review of ocular manifestations and treatment options for the various types of MPS.

Proteoglycan IMPG2 shapes the interphotoreceptor matrix and modulates vision

“…IMPG proteins are highly glycosylated, the excessive accumulation of IMPG1 covalently bound to ChS at the RPE-OS boundary can, over time, forms something akin to glial seal that, on time, overwhelms the RPE uptake capacity leading to the formation of subretinal lesions and visual impairment. This hypothesis is in line with the fact that patients with defects in the metabolism of GAGs due to abnormal matrix metalloproteinases develop retinopathy characterized by the accumulation of GAGs at the subretinal space (Ashworth, Biswas et al, 2006, Fenzl, Teramoto et al, 2015.…”

Variability in the ocular phenotype in mucopolysaccharidosis

“…Intracellular and extracellular deposition of GAGs occurs and can result in a wide range of systemic manifestations, including distinctive facial features; visual and hearing impairment; cardiorespiratory, skeletal and neurological problems and intellectual impairment 1. Quality of life in patients with MPS may be significantly affected by visual impairment secondary to corneal opacification; other ocular complications such as retinopathy, glaucoma and optic neuropathy may also contribute to visual loss 2. Previous studies have shown that the ocular phenotype varies in different MPS types, with corneal clouding being a prominent feature of MPSI (Hurler, Hurler-Scheie and Scheie), MPSIV (Morquio), MPSVI (Maroteaux-Lamy) and MPSVII (Sly) and retinopathy being a feature in MPSI, MPSII (Hunter), MPSIII (Sanfilippo A-D) and MPSIV 2–4…”

Rare diseases and sports: A pilot project to improve physical activity in patients with mucopolysaccharidosis

“…The implementation of exercises such as “Egg‐and‐Spoon Race” should be considered in the case of a majority participation of attendees with reduced mobility. The desired training of the reaction ability by “Shadow Fencing” could be too difficult, for example, by the condition‐induced corneal clouding in MPS type I, disk oedema/bilateral epiretinal membranes in MPS type II or restricted mobility through a wheelchair. “Everyday Squat” and “Boxing” seemed to be the physically most strenuous exercises for all participants.…”