GOCOMMENTS
Best disease

Vitteliform macular dystrophy or Best disease was first described by Dr Frank Best at 1905. It’s about a disorder which is inherited by autosomal dominant type and affects young juveniles.

The disease is divided in five stages. A very common diagnostic tool, which gives us useful information, is called electroretinogram. In case of Best disease this examination is distorted, even in carriers who seem to be normal.

 

Best disease pathophysiology

The lesions of Best disease are limited to the eye. That means that the disorder does not provoke problems in other parts of the body. The problems that appear in the eye due to the disease, arise from lesions in a very sensitive part of the retina called retinal pigment epithelium (RPE). This layer is full of melanin and is the region where the photoreceptors of the retina are lying on. This layer also is very important for prohibiting any fluid from other tissues of the eye to pass in the retina. A malfunction of the RPE leads to an impaired and iron transport. Lipofuscin accumulates in the RPE cells and in the region under the RPE and especially around macula. Sometimes retinal photoreceptors (rods and cones) may be distorted or lost.

Prevalence of Best Disease

The prevalence of Best disease is estimated between 1/5.000 and 1/67.000 depending on which country carries the study.

Race

Best disease appears mostly in Europeans, Africans and in Spanish-speaking races.

Sex

It affects both men and women.

Age

Best disease usually appears at 6 years old (range 3-15 yo).
Usually it's difficult to diagnose the condition at early stages, because the visual acuity remains in adequate levels for many years. Atrophy may occur after 40 yo.
A special examination, called electroretinogram can diagnose the disease, even if there is no vision loss yet or the fundus image appears to be normal (there is no egg yolk spot).

Best disease morbidity

At early stages of the disease, the visual acuity is good. Even in case of egg yolk appearance at fundus, the visual acuity may be 10/10-4/10.
If the visual acuity becomes worse, the ophthalmologist may see a distorted egg yolk appearance (like an omelet).
In final stages of the disease (after the 4th decade of life) the visual acuity is extremely low and there is a geographic atrophy of the RPE, with possible appearance of neovascular choroidal membrane.
Several studies have shown that the majority of cases in adulthood, have adequate vision for reading and driving, in one eye at least (88% have 5/10 or more). Only 4% of these patients have visual acuity less than 1/10.

Clinical profile-Patient history

Many patients do not have symptoms at initial stages and any distortions of fundus are detected from the fundoscopy. Later, the vision may be distorted or blurred and these symptoms may become worse when there is atrophy on the RPE.

In case of carriers the examination is normal. These people do not have symptoms. However, the clinical findings are usually non symmetric and may affect both eyes.

Visual acuity of Best disease

1. Stage Previtelliform (before the yolk appearance at fundus examination) VA:10/10
2. Stage Vitelliform (yolk appearance at fundus examination) VA:10/10-4/10
3. Stage Pseudohypopyon : VA: 10/10-4/10
4. Stage Vitelliruptive (yolk's rupture appearance at fundus examination) VA:10/10-2/10
5. Atrophic stage: VA: less than 1/10
There are many cases, in which the disease does not evolve beyond the initial stages. Other patients have worse prognosis and their visual acuity is distorted faster, so that they have atrophic regions at the RPE very soon. Unilateral distortions may also be reported.

Unilateral fundus lesions/damages

1. Stage Previtelliform: Normal appearance or mild distortion at the RPE. The electroretinogram examinations is affected.
2. Stage Vitelliform: There is a 0,5-5mm round, raised yellow region with edema, usually described as egg yolk. The rest region of the retina is normal.

3. Stage Pseudohypopyon: The yellow substance is broken down and is accumulated in the subretinal space, where is forming a horizontal fluid. The yellow fluid can be moved in case of head movement (60-90min). This stage appears mostly in adolescent patients, but it has been also described in ages from 8-38 yo.

4. Stage Vitelliruptive : This stage resembles to omelet, because the yellow region is ruptured. In addition, at this stage, atrophic regions are noticed. Visual acuity may deteriorate.

5. Atrophic stage: At this stage, there is a replacement of the yellow region by atrophic regions of the RPE. Visual acuity is extremely weakened.

6. Choroidal neovascularization: Following the atrophic stage, choroidal neovascularization can be developed. This condition leads to a white subretinal fibrus tissue. Also, hyperopia is common in patients with Best disease.

 

 

 

Success Rates

Retinal detachment
Final restoration → 98,7%!

Μacular hole, final
restoration → 100%!

Epiretinal Membrane → Final Restoration 100%!
Lameral Hole → research in progress, results will be presented soon

 

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