This is a genetic eye disorder that causes the vision loss over a period of time. Among individuals with this condition, the small area at the center of the eye called the macula becomes affected. The macula is essential for the central vision and to recognize detailed vision such as reading or driving. As the result, the central vision becomes lost causing blurry or distorted vision although the side vision (peripheral) is not affected. There are two forms of this disorder; the early-onset also known as Best disease that develops in childhood and the adult-onset that occurs around mid-adulthood. The Early-onset (Best disease) can begin to affect the vision around the age of 3 to 15 although it generally does not cause a problem until later in life. It can either affect both the eyes or a single eye and the vision is not affected to the same extent in each eye. There are five stages of best disease; stage one where the macular appears to be healthy, at stage two (vitelliform stage) a blister appears on the macula with very slight vision changes, at stage three (pseudohypopynon stage) cysts can develop under the retina, at stage four (vitelliruptive stage) lesions can break up causing damage to the retina cells resulting in vision changes and stage five (atrophic stage) presents the scarring and damage of the retina cells resulting in serious vision loss. The symptoms of adult-onset type can begin between the ages 30 and 50 progressing to central loss of vision with time. Vitelliform macular dystrophy is inherited in an autosomal dominant pattern meaning the children of the affected parent have a 50% possibility of developing this disorder.
Symptoms
The symptoms vary among the affected cases and the initial symptoms include the inability to see fine details such as reading small prints. Also, the central vision can become blurred and the straight lines may appear to be distorted. The vision loss can occur in a one or both the eyes.
Diagnosis
The diagnosis is based on the examination of the eye and by dilating pupils that examine the macula. Some of the tests that are used to confirm the diagnosis include fluorescein angiogram which takes images of the blood vessels underneath the retina to determine the presence of damage. An optical coherence tomography provides the cross-sectional images of the retina and the electroretinography assesses the function of the retinal rod and cone. The electrooculogram test measures the response of the retina to light.
Treatment
There are no single treatment options for this disorder. Individuals with this condition should have a comprehensive eye examination once a year to prevent the development of complications. The low vision aids can be helpful for those with significant vision loss. In some cases, genetic counseling may be beneficial for the affected individuals and their families.
References
https://rarediseases.org/rare-diseases/best-vitelliform-macular-dystrophy/
https://ghr.nlm.nih.gov/condition/vitelliform-macular-dystrophy#inheritance
https://rarediseases.info.nih.gov/diseases/10909/adult-onset-vitelliform-macular-dystrophy