Down症候群に合併した円錐角膜―臨床像・電子顕微鏡像

Clinical features and ultrastructure of keratoconus in a case of Down syndrome

　Down症候群がある26歳女性が，12日前からの右眼充血と角膜混濁で受診した。左右眼とも-16Dの近視で，矯正視力は右0.3，左0.5であった。両眼に円錐角膜があり，右眼にはDescemet膜破裂による急性水腫があった。右眼は水疱性角膜症になり，初診から2年4か月後に全層角膜移植術が行われた。角膜の電子顕微鏡所見として，上皮基底膜の不整と一部消失，Bowman膜の厚さの減少と高電子密度物質の出現，実質膠原線維束の走行不整，実質細胞の多形化，Descemet膜の屈曲，内皮細胞の破壊があった。これらの所見は，臨床的にある角膜実質と上皮浮腫に一致した。

　A 26-year-old female with Down syndrome presented with hyperemia and opaque cornea in her right eye since 12 days before. Her visual acuity was 0.3 right and 0.5 left when corrected by-16 diopters each. Both eyes had keratoconus. The right eye had acute hydrops due to ruptured Descemet membrane. The right eye received penetrating keratoplasty for bullous keratopathy 28months later. The cornea showed following features by electron micro-scopy. Epithelial basement membrane was disoriented and interrupted. Bowman layer was thin containing high-density substances. Stromal cells showed polymorphism with disoriented collagen fibrils. Descemet membrane was tortuous. Endothelial cells were destroyed. These findings corresponded well to clinically observed stromal and epithelial edema.