About vitelliform macular dystrophy
Vitelliform macular dystrophy is an inherited eye disorder that can cause progressive vision loss. It causes build-up of fatty yellow pigment (lipofuscin) in the macular area. This, in turn, can damage the light sensitive cells responsible for clear central vision. Sight loss can be variable and can affect central vision in one or both eyes.
There are two main forms of vitelliform macular dystrophy. These are Best vitelliform macular dystrophy (Best disease) and adult-onset vitelliform macular dystrophy, also known as adult-onset foveovitelliform macular dystrophy. They are different clinical entities but have overlapping features and genetic changes.
Best disease onsets in childhood and the severity of vision loss can vary widely.
Adult-onset vitelliform macular dystrophy presents between 40-60 years. It generally causes mild vision loss that worsens slowly over time.
Genetics of vitelliform macular dystrophy
Vitelliform macular dystrophy is typically inherited in an autosomal dominant pattern. This means children of an affected parent have a 50 per cent chance of receiving the gene. Family members who inherit the same genetic mutation may not experience the same changes. Other inheritance patterns are also possible.
Researchers have linked a number of genes, including BEST1 and PRPH2, to vitelliform macular dystrophy. Research on how these gene mutations cause the disorder is continuing.
Further information and genetic counselling is available from specialist clinics and your GP will be able to advise you about local genetic services. If you have vitelliform macular dystrophy, you may also wish to be entered onto the Australian Inherited Retinal Disease Register and DNA Bank. This facility is located at Sir Charles Gairdner Hospital in Perth.
Progression of vitelliform macular dystrophy
Vitelliform macular dystrophy causes a fatty yellow pigment (lipofuscin) to build up in the macula area, forming a lesion that has the appearance of an egg yolk.
Over time, the accumulation of lipofuscin can damage the light sensitive cells that are needed for clear central vision. As a result, people with this disorder often lose their central vision. Sight may become blurry or distorted. Vitelliform macular dystrophy typically doesn’t affect side (peripheral) vision or the ability to see at night.
Diagnosis of vitelliform macular dystrophy and Best disease
Vitelliform macular dystrophy has characteristic changes in the macula that your eye health professional can detect during an eye examination.
Your eye health professional may order additional scans including optical coherence tomography (OCT) to investigate the layers of the retina and electrooculography (EOG), which assesses the electrical response of the retina when stimulated by light.
You may also be referred to genetic testing. This will help confirm your diagnosis, inform prognosis and your eligibility for therapies and trials. This may have implications for your family members, so we advise discussing this with a genetics counsellor.
There is currently no effective treatment for vitelliform macular dystrophy, but scientific research, both traditional and genetic, may provide useful treatments for the future.
Infrequently, there is development of new blood vessels under the retina. This is known as neovascularisation and it’s similar to what happens with the ‘wet’ form of age-related macular degeneration. This can lead to a rapid loss of central vision. In most cases, it can now be treated very effectively with a series of injections of an anti-VEGF drug into the eye.
Using an Amsler grid
Since eye injections with anti-VEGF are most effective when given soon after the formation of the new blood vessels, if you have vitelliform macular dystrophy it’s recommended you self-monitor your vision.
You can do this at home, using an Amsler grid. These are available free from Macular Disease Foundation Australia. Any sudden changes in the appearance of the Amsler grid should be promptly checked by your ophthalmologist. It could be a sign of neovascularisation.
There is no specific evidence regarding the effect of diet or vitamin supplements on the progression of vitelliform macular dystrophy. However, an eye-healthy diet, as recommended for age-related macular degeneration, may be beneficial. This includes eating fish two to three times a week, plenty leafy greens and other fruit and vegetables, a handful of nuts a week, and where possible, eating low glycaemic index (GI) carbohydrates in preference to high GI.
It’s also recommended you use sunglasses with good ultraviolet blocking abilities outside and not smoke.
Managing vision loss from vitelliform macular dystrophy and Best disease
If you experience vision loss as vitelliform macular dystrophy progresses, a key priority is maintaining quality of life and independence. A low vision assessment is an essential way to regain control of your situation and get started to ensure you can live well with vision loss.