Vitelliform macular dystrophy is a group of macular dystrophies characterized by yellowish deposits containing lipofuscin in the subretinal space, generally located in the center of the macula.
There are 4 genes involved to date in this group of entities, which can be divided into:
- Vitelliform macular dystrophy associated with BEST1 (Best’s disease; vitelliform macular dystrophy type 2): it is characterized by its onset generally in childhood, although the diagnosis is reached in adulthood or even already entering old age on many occasions. In the early stages, subretinal deposits cause characteristic macular lesions that resemble the appearance of the yolk of an egg. Subsequently, the affected area becomes pigmented, changing the appearance of the lesion in the fundus of the eye. The disorder is progressive and can lead to vision loss. A defining characteristic of Best’s disease is an alteration of the electrooculogram with a low Arden index, between 1.1-1.5, and without presenting aberrations in the electroretinogram.
- Adult-onset foveomacular vitelliform dystrophy (adult vitelliform macular dystrophy; vitelliform macular dystrophy type 3): Entity associated with PRPH2, is characterized by a yellowish subretinal lesion similar in appearance to that observed during the yolk or vitelliform phase of Best’s disease. Patients report symptoms from the fourth or fifth decade of life with a decrease in visual acuity and mild metamorphopsia. Electrooculographic tests show a normal or only slightly reduced Arden ratio. The prognosis is relatively favorable since most patients retain reading vision throughout life.
- Vitelliform macular dystrophy-4, associated with IMPG1 and vitelliform macular dystrophy-5, associated with IMPG2: both forms are characterized by a late-onset moderate visual impairment and also, normal or almost normal results in electrooculography.
