退行性下眼瞼内反症の病態に基づいた外科治療法

Surgical Treatment for Involutional Lower-Eyelid Entropion Based on the Cause of Occurrence

はじめに

　形成外科医が診療する代表的な眼瞼疾患は眼瞼下垂である。その中で最も頻度の高い退行性（加齢性）眼瞼下垂は眼瞼挙筋腱膜の弛緩や変性が原因とされる。一方で，退行性下眼瞼内反症の発症機序も各組織の弛緩や変性によると考えられることから，下眼瞼は上眼瞼ほどダイナミックに動かないものの，下眼瞼内反症を眼瞼下垂のミラーイメージと捉えることが病態の理解に役立つ。

　本稿では，ともに退行性変化で生じる下眼瞼内反症と眼瞼下垂を対比しながら，病態とそれに基づいた外科治療法のバリエーションを著者の経験を交えて解説する。

　Ptosis is a representative eyelid condition treated by plastic surgeons. The most common type of ptosis is involutional (age-related) ptosis, which is believed to be caused by relaxation and degeneration of the levator aponeurosis. The mechanism of lower-eyelid entropion is also thought to be the relaxation and degeneration of various tissues, and although the lower eyelid does not move as dynamically as the upper eyelid, it is useful to understand the causes of lower-eyelid entropion by considering this condition as a mirror image of ptosis. The main surgical procedure for lower-eyelid entropion is thus advancement of the lower-eyelid retractors, which corresponds to a typical surgical procedure for ptosis, i.e., levator aponeurosis advancement. In this article I compare involutional lower-eyelid entropion and ptosis, and I explain the causes of lower-eyelid entropionʼs occurrence and variations in surgical treatment methods based on the cause(s), including a summary of my experience with such cases.