Congenital aniridia is a rare condition in which the iris has not formed properly, so it is missing or underdeveloped. It affects both eyes. The amount of iris tissue missing varies from person to person. Many people with congenital aniridia also have a part of their retina that is not fully developed, and many have nystagmus.
People with congenital aniridia may be very light sensitive (photophobic) and report symptoms of glare. They may develop other eye problems such as glaucoma, cataract and corneal opacification. The degree of vision loss varies.
Treatment includes contact lenses with iris prints and tinted spectacle lenses.
Surgical implantation of an artificial iris device may be an option for some people with complete or partial congenital aniridia.
There are different devices available, including a solid acrylic ring or segment and a flexible silicone disc which can be custom-made for each patient. The implant has a defined pupil size, which offers a compromise between day and night vision.
The artificial iris implant is inserted using local or general anaesthesia. The exact details of the procedure vary according to the type of implant being used.
Flexible implants are rolled up and inserted through a cut about 3 mm long at the edge of the cornea, into the posterior chamber of the eye. They are then unfolded and fixed in the eye. If sutures are needed to hold the implant in place, a larger cut may be necessary. The implant insertion can be done on its own or at the time of cataract or lens fixation surgery.
Solid ring implants are typically inserted during cataract surgery along with an intraocular lens. In some patients, an iris reconstruction lens containing both an artificial iris and a lens is implanted. Depending on the condition of the eye, the lens and iris device may need to be sutured to the sclera.
The aim of artificial iris implant insertion is to improve visual acuity, reduce photophobia and glare, and improve the eye's appearance.