最好是啦–Best disease

Best disease (Vitelliform macular dystrophy)

* AD
* Chromosome 11 上的VMD2 gene (bestrophin)
* 3-15 yrs onset, 40yrs 到atrophic stage
* 於診斷Best disease時，EOG特別重要！
=> 可能早期眼底正常，但EOG卻異常。

EOG – 測RPE function
Arden ratio 或 light-dark ratio 通常為 ≧1.85，若＜1.3代表abnormal
Best disease Arden ratio 100%異常（<1.5）

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臨床表現：

* 30%有ectopic lesion, 20%產生CNV
* ERG正常
* EOG的Arden ration 100%異常 (<1.5) normal 約1.8

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眼底檢查

* yellow or orange yolklike lesion in the macula
* well-delineate, atrophic macular areas with some yellowish marginal material

病理在RPE層，Lipofuscin堆積在RPE或sub-RPE space，有些會有photoreceptor loss

=> 病程中可能產生subretinal neovascular membrane

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Staging of Best disease

Stage 1. previtelliform,
Stage 2. vitelliform,
Stage 3. pseudohypopyon,
Stage 4. vitelliruptive (scrambled egg),
Stage 5. atrophic stage

一直到stage 4以前視力都還不錯，但在第四期開始惡化
直到stage 5(atrophy) VA≦20/200

魚目混珠之成人版：

「Adult-onset vitelliform lesion」 （和Best disease不一樣喔！）

* 40-60歲才開始
* AD (因為：ADult …）
* "RDS" gene - peripherin gene mutation
* 約1/3 disc 大小，雙側有yellow, round, subfoveal lesion
* EOG正常！有些cuticular drusen且有vitelliform exudative macular detachment
* 視力通常還好，但最後VA會因geographic atrophy, CNV, 或disciform scar而下降

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例題：下列何者EOG表現正常的比例最高？
1. carriers of Best's disease
2. Best's disease in the previtelliform stage
3. adult onset of foveomacular vitelliform dystrophy
4. Best's diseae in the vitelliform stage

答： (3) => adult onset of foveomacular vitelliform dystrophy之EOG正常。 (4)100異常， (1),(2)介於其中。