What is Cone Dystrophy?
Cone dystrophy, also called retinal cone degeneration and retinal cone dystrophy refers to a group of rare eye disorders which affect the light-sensitive cone cells of the retina. The cone cells function best in bright light and are responsible for central vision, i.e., viewing fine details such as reading and face recognition and colour perception.
There are two types of cone dystrophy based on the progression of symptoms:
Stationary: Symptoms remain stable and are usually present since birth or early childhood.
Progressive: This develops during late adolescence or during adulthood. Symptoms gradually worsen with the passage of time.
What are the Causes of Cone Dystrophy?
Cone dystrophy occurs when the cone cells are damaged. It may be present since birth as a result of heredity. When the genes responsible for healthy cone cells undergo mutation, it may lead to cone dystrophy. While some people may develop cone dystrophy due to other causes such as an eye injury.
What are the Symptoms of Cone Dystrophy?
Symptoms of cone dystrophy vary from person to person. Yet, the common symptoms of cone dystrophy may include:
- Decreased central vision clarity and sharpness
- Photophobia: increased light sensitivity
- Reduced ability to see colours
Some people may develop complete inability to see colours while others may develop nystagmus: rapid, involuntary eye movements.
How is Cone Dystrophy Diagnosed?
You should visit an eye specialist/ophthalmologist for an eye check-up. They will check your medical history, clinical symptoms, and perform an electroretinogram (ERG): the diagnostic test to confirm cone dystrophy.
An ERG test is performed twice – once in a bright room and once in a dark room to determine whether the rod and cone cells are functioning properly.
During an electroretinogram (ERG), your doctor will administer eye drops to numb the eye. Then a special contact lens-electrode is placed on the eye. You will watch a set of flashing lights to stimulate the retina. Then, the electrical signals generated by the rod and cone cells are measured by your doctor. An absent or weak signal of cone cells indicates cone dystrophy.
What are the Treatments Available for Cone Dystrophy?
Cone dystrophy can be treated through conservative measures such as wearing tinted lenses or dark sunglasses in bright environments. Magnifying devices can also be used to assist in reading and other similar activities.