Doyne honeycomb dystrophy
Most cases of Doyne honeycomb dystrophy are caused by a mutation or mistake on a single gene called EFEMP1. This causes the gene to ‘fold’ a protein wrongly, and stops it breaking down as it should. The protein then builds up to create ‘drusen’ inside the eye tissue and stops nutrients getting from blood vessels to the light-sensing cells that need them. As the cells waste and die, sight is lost.
How is it inherited?
Doyne honeycomb dystrophy is an autosomal dominant condition – if one parent has it, a child has a 50 per cent chance of developing it. It is equally common in men and women.
People with Doyne honeycomb dystrophy may notice problems seeing detail, distortion (for example, straight lines looking wobbly), gaps in the centre of their vision, and difficulty adapting to changes in light level. These are caused by drusen forming near the macula, and at the point where the optic nerve enters the eye. They start small and gradually grow together, forming a honeycomb pattern.
It usually develops in early-to-mid adulthood, although occasionally teenagers are affected. Once the drusen appear, people gradually lose their central vision, although peripheral (side) vision is not affected. Some people have more rapid sight loss caused by new blood vessels growing behind the macula.
Unfortunately there is currently no treatment for Doyne honeycomb dystrophy.
Anti-VEGF injections (commonly used to treat wet age-related macular degeneration ) have been trialled in a small number of patients who developed faulty blood vessels as a result of Doyne honeycomb dystrophy, but not enough to know whether it would be effective for everyone.
Photodynamic therapy has also been trialled: a drug is injected into the bloodstream, then a laser is used to activate it in the eye, sealing the leaky blood vessels. More research is needed before it can be recommended more widely.