The ocular surface in aniridia

In aniridia, ocular surface alterations arise after several years, in distinction to congenital anomalies such as absence of the iris and cataract. In patients with aniridia, the cornea is transparent at birth and gradually loses transparency from 18 to 20 years of age due to the formation of a superficial vascular pannus determined by limbal stem cell deficiency. It is currently not clear whether this process is due to congenital anomalies of the limbal stem cells or to alterations of their regulation. In its early stages, limbal stem cell deficit usually causes problems related to the corneal epithelium such as: recurrent erosions and persistent epithelial defects leading to reduced visual acuity, pain and photophobia. In the following stages, with the absence of corneal epithelium, the ocular surface is covered by conjunctiva-derived epithelium. The conjunctival epithelium determines chronic inflammation that induces symptoms such as burning sensation and photophobia. In the later stages, the conjunctival epithelium may completely cover the cornea causing severe visual impairment. In the initial stages, treatment is focused on ocular surface lubrication. When corneal opacity is present, different treatments such as keratoplasty, keratoprosthesis, allogenic limbal stem cell transplantation and transplantation of oral mucosa epithelium autologous stem cells have been experimented.