Application of (lamellar) keratoplasty and limbal stem cell transplantation for corneal clouding in the mucopolysaccharidoses - a review

Corneal clouding or opacification is a prominent feature of mucopolysaccharidosis (MPS), particularly in MPS I and VI. In patients with marked corneal clouding and visual impairment, penetrating keratoplasty may be considered to improve the patient's vision, functional capacity and quality of life. In MPS, glycosaminoglycans mainly accumulate in the corneal stroma and not in Descemet's membrane or the endothelium, therefore deep anterior lamellar keratoplasty (DALK) may be preferred in these patients over penetrating keratoplasty. Although there are only limited data on the use of DALK in MPS (I and VI) patients, the results are generally favourable. Nonetheless, when deciding on whether to perform keratoplasty in patients with MPS, the risk of general anaesthesia due to potential concomitant cardio-pulmonary problems and cervical spine instability, the potential presence of other ocular manifestations that also impair vision (e.g. glaucoma, retinal degeneration and optic atrophy) and/or complications such as allograft rejection and the risk of re-opacification of the graft, all need to be taken into consideration. Limbal stem cell transplantation, which can be combined with keratoplasty, also holds potential promise in the treatment of these complex cases. A review of the indications, local and systemic risks, techniques of lamellar andpenetrating keratoplasty, and the potential of limbal stem cell transplantation is provided in the context of corneal opacity in MPS.