Shine the Light on Aniridia Facts
- First described by Barratta in 1818, Aniridia = absence of iris (in Greek)
- According to a study in Denmark, the condition affects 1 in 96,000 newborns
- 30% of children with sporadic Aniridia develop Wilms Tumour before the age of 5 years old
- Glaucoma is a huge risk for aniridics and causes raised eye pressure and can lead to blindness
- Eyes appear ‘black in colour’
- Fovea and optic nerve hypoplasia (underdevelopment of these mean messages are not correctly received by the brain for vision)
- Leads to worsening eyesight and often blindness
- Severe photosensitivity (bright light causes huge problems), headaches, the need for hats outside or dark glasses, shade is paramount
- Corneal pannus – scarring of the cornea, reducing vision to seeing only differences between light and dark eventually, due to lack of working stem cells
The science bit……
by Dr Julie Daniels, Cells for Sight Campaign, Moorfields Eye Hospital
Aniridia is an eye disease that can lead to blindness by affecting several parts of the eye. From the outset the vision is often reduced by the fact that the area of central vision, the macula does not develop fully. This is known as macular hypoplasia. However despite this, patients with Aniridia develop sufficient vision to navigate safely, recognise friends and family, read with the help of special reading aids and have sufficient eyesight to live a very fulfilling life.
However there are two conditions that can threaten the precious eyesight that these patients are so reliant on. These are glaucoma and Aniridia related keratopathy.
- Glaucoma, which is a build up of pressure in the eye, occurs in up to 50% of patients, usually starting in childhood. With early diagnosis and proper treatment, the vision can be preserved. Therefore vigilance and early treatment are paramount.
- Keratopathy is a condition usually occuring in early adulthood (20s) but can occur in mid to late childhood. The cause is not fully understood but we believe that the stem cells that are responsible for keeping the front clear window of the eye (the cornea) transparent start to malfunction. This causes the cornea to lose its clarity and instead become opaque. As a result the patient cannot see through the cornea and vision becomes progressively poorer. Also, because the skin on the surface of the cornea is unhealthy, it tends to break down, causing painful ulcers.
Until recently, treatment for Aniridia related keratopathy has aimed to relieve discomfort using contact lenses and eyedrops. Recently, the Cells for Sight Transplantation and Research Programme has treated several adult patients with Aniridia using stem cell therapy. The early results are promising but far from perfect. It is possible in some cases for vision to be improved from perception of hand movement to reading the larger letters on an eye test chart. However, this outcome may not be enduring and has not been experienced by all patients treated. This could be for many reasons. Our early data suggest that defective communication between different cell types in the cornea play a significant role in this disease. To prevent Aniridia-induced corneal blindness it would in the future be necessary to treat children. Therefore it is imperative that we have a better understanding of the basic biology of disease progression in Aniridia in order to improve our existing therapeutic strategy and to develop novel therapies that may preserve or improve vision for longer.