Skip to
  1. Homepage
  2. Rare diseases
  3. Search
Simple search

Simple search

(*) mandatory field


Other search option(s)

Best vitelliform macular dystrophy

Synonym(s) BMD
Best disease
Best macular dystrophy
Early-onset vitelliform macular dystrophy
Juvenile-onset vitelliform macular dystrophy
Polymorphic vitelline macular degeneration
Vitelliform macular dystrophy type 2
Prevalence 1-9 / 100 000
Inheritance Autosomal dominant
Age of onset Childhood
  • H35.5
MeSH -
MedDRA -


Disease definition

Best vitelliform macular dystrophy (BVMD) is a genetic macular dystrophy characterized by loss of central visual acuity, metamorphopsia and a decrease in the Arden ratio secondary to an egg yolk-like lesion located in the foveal or parafoveal region.


The prevalence is estimated to be between 1/5,000 and 1/67,000 in northern Sweden and Denmark respectively. Males are more affected than females (3:1).

Clinical description

Onset of BVMD is in childhood and sometimes in later teenage years (5-13 years). Affected individuals have normal vision at birth. BVMD then progresses through distinct stages that include an asymptomatic previtelliform phase (stage 1) followed by the formation of a yellow, egg yolk-like (vitelliform) lesion in the macula (stage 2). The contents become less homogenous and develop a "scrambled-egg" appearance (stage 2a). The lesion eventually develops a fluid, yellow-colored vitelline substance (pseudohypopyon or stage 3) and finally breaks down, leaving a scar that causes central visual acuity deterioration (20/200). This may be complicated by a subfoveal choroidal neovascular (CNV) membrane (rare in children). Anomalous color discrimination (mainly the protan axis) and metamorphopsia may be observed but patients retain normal peripheral vision and dark adaptation. Some affected individuals remain asymptomatic.


BVMD is characterized by atrophy of the retinal pigment epithelium (RPE) affecting photoreceptors with impaired central visual function. In most cases, BVMD is caused by mutations in BEST1 (11q12), encoding for bestrophin-1, a chloride channel expressed in RPE. A defect in this protein leads to accumulation of lipofuscin secondary to abnormal ion exchange.

Diagnostic methods

The clinical diagnosis is based on family history, visual-acuity testing and funduscopy (showing yellow, round deposits of lipofuscin at the center of the macula). Full-field electroretinogram (ERG) is normal. Electro-oculography (EOG) measures standing potential of the eye by recording the Arden ratio (AR; ratio of light peak/dark trough; normal value ≥1.8). AR is usually decreased in BVMD (1.0-1.3). High-resolution optical coherence tomography may identify abnormal accumulation of lipofuscin between photoreceptors and RPE. Diagnosis is confirmed by genetic screening of BEST1.

Differential diagnosis

Differential diagnosis of BVMD includes adult-onset foveomacular vitelliform dystrophy, age-related macular degeneration, autosomal recessive bestrophinopathy, autosomal dominant vitreoretinochoroidopathy, retinitis pigmentosa (see these terms) and Bull's-eye maculopathy.

Antenatal diagnosis

Prenatal diagnosis and preimplantation genetic diagnosis is possible for families in which the disease-causing mutation is known.

Genetic counseling

BVMD is inherited in an autosomal dominant manner with complete penetrance. Age of onset and severity of vision loss show inter- and intrafamilial variability.

Management and treatment

Management is symptomatic and includes use of low vision aids for individuals with significant deterioration in visual acuity. Annual ophthalmologic examination for persons of all ages is recommended. Smoking should be avoided as it increases the risk of neovascular macular degeneration. Photodynamic therapy using verteporfin, direct laser photocoagulation or anti-VEGF agents (bevacizumab) may be options for treating CNV. Transcorneal electrical retinal stimulation may be used to treat BVMD.


BVMD may progress to geographic atrophy and in some cases is complicated by development of CNV. 7-9% of patients never experience vision loss, but have an aberrant EOG with normal ERG.

Expert reviewer(s)


(*) Required fields.

Attention: Only comments seeking to improve the quality and accuracy of information on the Orphanet website are accepted. For all other comments, please send your remarks via contact us. Only comments written in English can be processed.

Captcha image

Detailed information

Summary information
Guidance for genetic testing
Article for general public
Clinical genetics review
Get Acrobat Reader
The documents contained in this web site are presented for information purposes only. The material is in no way intended to replace professional medical care by a qualified specialist and should not be used as a basis for diagnosis or treatment.