In contrast to typical RP (known as the rod-cone dystrophies), which results from the loss of rod cells and later the cone cells, cone-rod dystrophies reflect the opposite sequence of events, where cone cells are primarily first affected with later loss of rods.
What are the symptoms of cone rod dystrophy?
The cone cells are initially involved, as previously mentioned, and difficulty with the clarity of vision, colour vision problems and light sensitivity can be some of the earliest symptoms experienced. This is followed by a progressive loss of rod cells, which leads to night blindness and loss of side vision. The age of onset, progression and severity of cone-rod dystrophies can vary greatly from one person to another, even among individuals with the same type of cone-rod dystrophy. It is therefore very difficult to predict what an individual’s vision will be like at a specific time in the future. Some forms of cone-rod dystrophy are inherited; other forms appear to occur spontaneously for no apparent reason (sporadically).
Cone-rod dystrophies have many similarities to RP following varied inheritance patterns, including autosomal dominant, autosomal recessive, and X-linked.
What treatments are available?
Maximising an individual’s remaining vision is a crucial first step to take. There are many new low vision aids, including telescopic and magnifying lenses, providing plenty of choice for users at all stages of sight loss. This technology has also removed many barriers to education and employment.
There are, currently, no proven or effective cures for cone-rod dystrophies. However scientists have identified more than 20 genes that can have mutations which cause these conditions. It is likely that many more mutations in many more genes will be identified in the coming years..
Despite the lack of current treatments for cone-rod dystrophies, general eye check-ups are important. People with these conditions are still at risk for other kinds of eye problems that can affect the general population and may be treatable. Patients with cone rod dystrophies tend to develop cataracts at an earlier age than the overall population. Regular visits to your eye doctor can also make you aware of current advances as we learn more about these conditions.