People with aniridia can develop other eye conditions as a result of their aniridia. Some of the more common conditions are outlined below however most people with aniridia will not develop all of these and some may not develop any at all.
A survey by Aniridia Foundation International found the following about 83 people, with an average age of 25, who have aniridia:
- 83% had nystagmus
- 71% had cataracts
- 53% had dry eye
- 46% had glaucoma
- 45% had keratopathy
- 41% had foveal hypoplasia
- 31% had strabismus
- 5% had retinal disease
- 2.4% had WAGR/11p deletion syndrome.
- 17% had delayed development
- The mean body mass index and the prevalence of obesity was significantly greater than in siblings without aniridia.
While the small sample size and other issues may well skew the results we hope they at least indicate the incidence of other conditions. More details about the survey results.
One of the functions of the iris is to expand or contract to adjust the amount of light entering the eye. Without a fully functioning iris, a person with aniridia cannot prevent a lot of light entering their eye on a sunny day or in a brightly lit room. Excess light can dazzle and cause glare making it difficult for them to see. For some it can also cause discomfort, pain, headaches or migraines.
People with aniridia often wear sunglasses and/or a hat outdoors. Some may choose to wear tinted spectacles indoors too. Good ambient lighting is required for people with aniridia to make the most of their vision, so rooms should still be well-lit. Light bulbs and windows may cause dazzle or glare but light shades and semi transparent blinds or curtains can be used to more evenly distribute the light without making the room dark.
This is an involuntary, quite rapid movement of the eyes up and down or side to side, giving the appearance of ‘wobbly eyes’. Some people with nystagmus find they can reduce the wobble when looking in a particular direction, known as their ‘null point’. There is currently no treatment for nystagmus.
People with aniridia are more likely to develop high pressure in their eye (known as intraocular pressure or IOP). This is caused when fluid fails to drain properly from inside the eye. Remnants of the under-developed iris can prevent this. If left untreated this can damage the optic nerve. This is known as glaucoma and it permanently reduces vision.
High IOP is often successfully treated with eye drops. Various surgeries can also be performed which help fluid to drain from the eye. It is important people with aniridia have their IOP checked regularly (typically at least once a year). This will normally be done by an ophthalmologist if they attend a hospital for regular check-ups but can also be done by an optician. For very young children the examination may have to be done under anaesthetic (known as an EUA) so in this case it may be done a little less often.
This is a specific form of cornea disease often seen in people with aniridia. The cornea is the clear window at the front of the eye which allows light in. Keratopathy is caused by a failure of limbal stem cells. These cells normally produce new cells to replenish the surface of the cornea and keep it healthy. When new cornea cells cannot be produced the eye tries to compensate with cells from the conjunctiva (the white of the eye). These cells are not as transparent and may contain blood vessels (known as cornea pannus).
In many people the keratopathy only forms a ring around the edge of the cornea which does not cause problems with vision, however if it progresses into the centre of the cornea vision can become hazy or blurry. The presence of keratopathy can make the eye feel dry, which can be relieved with lubricating eye drops. Patients with a limbal stem cell deficiency may take longer to heal if they damage their cornea. This can be painful and they may be advised to take antibiotics to avoid infection.
A cornea transplant will not permanently cure keratopathy as it does not address the underlying stem cell deficiency and the keratopathy will eventually re-occur. Current treatments aim to replace the stem cells with those from a healthy donor; this is known as a keratolimbal allograft (KLAL). This often improves vision but in some patients keratopathy does eventually recur. However this technique is still being developed and improved.
A condition where the patient cannot align both eyes to look in the same direction at the same time. Initially this would be treated by ensuring the patient has the correct glasses prescription and by using eye patches on the stronger eye to exercise the weaker one. If this is unsuccessful surgery is also an option.
Auditory Processing Disorder
[Central] Auditory Processing Disorder ([C]APD) affects learning has been linked to the same gene which causes aniridia. Below is a recording of expert Dr Doris Bamiou talking about it at our 2011 conference.