柯氏症 Coats disease

A montage of fundus image in a case of Coat's disease showing central and peripheral exudation.

柯氏症又稱為滲出性視網膜炎(exudative retinitis)或是視網膜末梢血管擴張症(retinal telangiectasis)，是一種非常少見的兒童視網膜疾病，可以造成視力減退甚至失明，目前認為與雷伯氏粟粒狀動脈瘤(Leber's miliary aneurysm)可能是同一種疾病。柯氏症的發生原因仍不明，雖然懷疑與某些基因有關，但已知是不會遺傳到下一代，且有極少部分的人在發病過程中，病症會自行停止惡化。

柯氏症一般僅侵犯單眼，大多在十歲以內發作(男性約佔70%)，主要的病灶是視網膜毛細血管異常擴張及增生(主要是因為血管內皮細胞異常)，導致血漿滲漏到視網膜下，結果造成視網膜下膽固醇沉積與視網膜剝離，嚴重時還會併發新生血管型青光眼、葡萄膜炎、白內障、甚至眼球萎縮。柯氏症一般可分為五期：一、只有視網膜毛細血管異常擴張；二、視網膜毛細血管異常擴張合併滲出液；三、滲出型視網膜剝離；四、全部視網膜剝離合併青光眼；五、已失明。

柯氏症的主要症狀是視力模糊、閃光及飛蚊現象，患者可能會被觀察到有斜視及白瞳孔的現象(主要是因為膽固醇沉積或是視網膜剝離所造成)，因此必須與視網膜母細胞瘤作鑑別診斷。柯氏症在三期以前，可考慮利用雷射或是冷凍治療的方式，破壞視網膜的異常毛細血管，以阻止病情惡化。當柯氏症達到四期時，往往會嚴重到需要剜除眼球。

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Coats disease is a telangiectatic neovascular disease of the retina of unknown etiology that frequently affects unilateral eyes of young males.

George Coats[1] in 1908 described the histopathological features of enucleated eyes with massive exudation. He divided the morphology into 3 groups:

"Group I demonstrated massive subretinal exudate alone,

group II consisted of eyes with massive subretinal exudate, intra and subretinal hemorrhage, and retinal vascular dilatations, and

group III included eyes with subretinal exudate and retinal arteriovenous malformations."[2] Later, Von Hippel recognized group 3 as a separate entity called angiomatosis retinae.

A large study of 117 patients[3] took the definition of Coats disease as 'idiopathic retinal telangiectasia and intraretinal or subretinal exudation without appreciable signs of vitreoretinal traction.'

資料來源：
http://blog.udn.com/jnwu/2917728
http://eyewiki.aao.org/Coats_disease