The effect of haemopoietic stem cell transplantation on the ocular phenotype in mucopolysaccharidosis type I (Hurler)

Purpose To determine whether the ocular phenotype in patients with mucopolysaccharidosis type I (MPSI) Hurler is affected by the efficacy of previous haemopoietic stem cell transplantation (HSCT). Design A retrospective cohort study of patients with MPSI who had undergone treatment with HSCT. Methods Ocular phenotype was documented for each patient and compared to levels of biomarkers representing efficacy of previous transplantation. Main outcome measures: Assessment of visual acuity (VA), severity of corneal clouding and the presence of optic neuropathy or retinopathy. Biomarker assessment included dermatan sulphate/chondroitin sulphate (DS/CS) ratio and iduronidase enzyme level. Results Severe corneal clouding was significantly greater in patients with lower iduronidase levels (p = 0.023) and raised DS/CS ratio (R2 = 0.28 p = 0.043). Better VA was related to a higher iduronidase levels (R2 = 0.15, p = 0.004) and lower DS/CS ratio (R2 = 0.38, p = 0.001). Conclusion Improved ocular phenotypes in MPSI are associated with markers signifying efficacy of prior transplant. Early and effective HSCT may result in a better visual prognosis and reduction in ocular complications for patients with MPSI.