Ocular lesions in canine mucopolysaccharidosis I and response to enzyme replacement therapy.
ABSTRACT Mucopolysaccharidosis I (MPS I) is an inherited metabolic disorder resulting from deficiency of α-L-iduronidase and lysosomal accumulation of glycosaminoglycans (GAG) in multiple tissues. Accumulation of GAG in corneal stromal cells causes corneal opacity and reduced vision. The purpose of this study was to determine the extent of ocular GAG accumulation and investigate the effectiveness of intravenous enzyme replacement therapy (ERT) on corneal GAG accumulation in dogs.
Ocular tissues were obtained from 58 dogs with mucopolysaccharidosis I and four unaffected controls. Affected dogs received either low-dose ERT, high-dose ERT, or no treatment; some low-dose dogs also received intrathecal treatments. Histologic severity of corneal stromal GAG accumulation was scored.
Accumulation of GAG was found in corneal stromal cells and scleral fibroblasts but not in corneal epithelium, endothelium, ciliary epithelium, choroid, retina, retinal pigment epithelium, or optic nerve. Corneal GAG accumulation increased in severity with increasing age. Although low-dose ERT did not significantly reduce corneal stromal GAG accumulation in comparison with untreated animals, high-dose ERT did result in significantly less GAG accumulation compared with the untreated dogs (adjusted P = 0.0143) or the low-dose ERT group (adjusted P = 0.0031). Intrathecal treatments did not significantly affect GAG accumulation. Dogs that began ERT shortly after birth also had significantly less (P < 0.0001) GAG accumulation in the corneal stroma than dogs with a later onset of treatment.
These data suggest that high-dose, intravenous ERT is effective at preventing and/or clearing corneal stromal GAG accumulation, particularly if initiated early after birth.
- SourceAvailable from: Taha Y Ahmed[Show abstract] [Hide abstract]
ABSTRACT: PurposeTo describe the anterior segment optical coherence tomography (AS-OCT) characteristics of patients with ocular manifestations of mucopolysaccharidoses type I (Hurler), II (Hunter), and VI (Maroteaux-Lamy).Methods Prospective, observational study of nine consecutive patients with variants of mucopolysaccharidosis (MPS) attending the Paediatric Ophthalmology service at Manchester Royal Eye Hospital, UK. All patients underwent Visante AS-OCT imaging as part of their ophthalmic assessment.ResultsOcular involvement tended to be symmetrical. Angle-to-angle distance was significantly lower in MPS VI than in MPS I (P=0.04). Anterior chamber depth, angle opening distance, trabecular-iris space area, and scleral spur angle tended to be lower in MPS VI than in MPS I, but did not reach statistical significance. Corneal thickness in the central 0-2 mm zone was greater in MPS VI than in MPS I, approaching but not attaining statistical significance (P=0.07). The 2-5 and 5-7 mm zones were significantly thicker in MPS VI than MPS I (P=0.04, P=0.04). There was no difference in corneal thickness between MPS I and MPS VI in the peripheral 7-10 mm zone (P=0.57). Measurements of the patient with MPS II resembled the mean values of the MPS I group.ConclusionAS-OCT is valuable in quantifying anterior segment pathology in MPS. It suggests more crowded anterior segments and greater corneal thickness in patients with MPS VI than MPS I. AS-OCT is useful in evaluating the risk and mechanism of glaucoma in MPS patients, and may improve our assessment of the efficacy of systemic treatment.Eye advance online publication, 3 January 2014; doi:10.1038/eye.2013.281.Eye (London, England) 01/2014; · 1.97 Impact Factor
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ABSTRACT: The aim was to describe the confocal and histological findings of 2 corneas from a patient with an advanced case of type I mucopolysaccharidoses Hurler-Scheie disease (MPS IH-S). Both corneas from an MPS IH-S-affected patient were examined in vivo using confocal microscopy and then removed and processed for evaluation using light microscopy and transmission and scanning electron microscopy. Confocal microscopy evaluation showed basal epithelial cells with either diffuse or granular hyperreflectivity. Keratocytes were highly reflective determining a web-shaped stromal appearance. Endothelial cells were barely visible. The histopathological study demonstrated superficial cells with apical microfolds, small vesicles, and evident intercellular junctions. The wing cells showed either well-evident tonofilaments and small peripheral vesicles, or large paranuclear vesicles. The basal cells showed polygonal shapes, many small vesicles, and enlarged intercellular spaces. The Bowman layer was either normal or thinner and was formed by variably electron dense material. In the stroma, irregularly oriented lamellae, many vesicle-filled keratocytes, and intercellular granular material were present. The Descemet membrane was normal, whereas the corneal endothelium showed marked degenerative changes. The confocal alterations appeared consequent to the anomalous accumulation of material. The histopathological images gave a clue to better understand the corneal changes demonstrated by the confocal studies in MPS IH-S.Cornea 11/2013; · 1.75 Impact Factor
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ABSTRACT: The purpose of this review is to provide an update on ocular manifestations of mucopolysaccharidoses (MPS), to highlight diagnostic pitfalls in the evaluation of affected patients, and to briefly review etiopathogenesis, systemic manifestations, and therapeutic interventions in MPS. Advances in hematopoietic stem cell transplantation and enzyme replacement therapy for MPS have led to decreased morbidity and increased life-span of patients. Besides other causes, visual impairment because of corneal opacification, retinal degeneration, and optic atrophy remains a common cause of disability in MPS. The application of a standard ophthalmic evaluation protocol may serve as an important diagnostic and disease monitoring tool in patients. Diagnostic delays are not uncommon in patients with MPS. Given the early ocular involvement in MPS, ophthalmologists play a crucial role in early detection and follow-up of patients with MPS. Ophthalmic evaluation can be impeded by corneal opacification and patient cooperation. Altered corneal biomechanics confound intraocular pressure measurements. Recently developed therapies have made early detection increasingly important. Accurate diagnosis of specific MPS subtypes is of paramount importance for initiating appropriate therapy. Combined with advances in supportive care of ocular and systemic manifestations, the prognosis for patients with MPS has vastly improved.Current opinion in ophthalmology 07/2013; · 2.64 Impact Factor