Neural damage and neuroprotection with glaucoma development in aniridia.

Aniridia is a rare congenital disorder distinguished by the complete or partial absence of the iris. This panocular condition presents with a range of eye abnormalities, each to differing extents, such as cataract formation, keratopathy, and foveal and/or optic nerve hypoplasia [1,2]. Common symptoms such as cataracts may be clinically addressed by topical medication or surgical intervention [2]. However, there are no treatments available to reverse neural loss, which is most critical for vision [1-3]. Of particular importance are retinal ganglion cells (RGCs), neurons that project axons to form the optic nerve, and transmit visual information from the eye to central brain structures [4]. About 90% of aniridia patients were found to have underdeveloped fovea, the portion of the retina responsible for acute central vision, and recent data also suggests nerve fiber reduction throughout the retina [5,6]. Similarly, in a rodent model of aniridia, flat-mounted retinas show one-third fewer Brn3a-expressing RGCs than wildtype controls [7]. Optic nerve hypoplasia and associated retinal nerve fiber layer thinning have also been reported in approximately 10% of aniridia patients and may occur independently of foveal hypoplasia [8,9]. In both instances, patients suffer from varying degrees of vision loss [10].