角膜前面放射状切開術を受けたヒト角膜の組織学的検索

Histological findings of two eyes following anterior radial keratotomy

　角膜前面放射状切開術（anterior radialkeratotomy,ARK）を受けた2症例（3眼）を組織学的に検索し，以下の様な結論を得た．

（1）症例1で同一眼でも，切開線の深さに30％程の差が認められた事より，切開線の深浅の差が術後の屈折量定の困難さや，乱視の発生に関与していると考えられた．切開線の非対称さも乱視の発生の原因の一つであると考えられる．

（2）ボーマン膜の断裂，離開，実質創への上皮陥入，角膜実質のcollagen lamellaeの断裂および乱れ，実質細胞の創附近での集合，実質内のepithelial inclusion cyst等がglareと羞明の原因であると推測した．

（3）屈折効果を高める目的で再切開を受けた症例2の角膜は，1回の切開に比べより強いdamageが角膜に観察され，そのwound healingには，より長い年月が必要であろうと思われた．

（4）症例1では両眼とも切開線に一致して角膜の裏面に突出（ridge）が認められた事より，切開線の裏面直下は他の部分に比較し，stressが加わりやすく，構築上脆弱であると思われた．

（5）症例1の両眼に偶然であるが，デスメ膜の後面にabnormalなcollagen layerが認められた．

（6） ARKの角膜内皮細胞への影響に関し，若干の考察を加えた．

We performed histological examination on 3 corneal specimens with past history of anterior radial keratotomy (ARK). Two eyes were obtained from a 31-year-old Caucasian male who underwent ARK bilaterally 3 months before death. A third corneal specimen was obtained from a 35-year-oldCaucasian male in whom ARK had been performed twice with an interval of 5 months. The anterior layer of the cornea was obtained for histological examination during homoplastic keratomileusis to cure blurring of vision and photophobia 5 months after the second ARK.

In the eyes from the first case, the incisions ran-ged in depth from 48% to 63% of the full thickness of the cornea in the right eye, and from 69% to 98% in the left eye. This variation seemed to demon-strate the difficulties in making incisions of precise and predictable depths. Conversely, incisions of varying depths may be related to variations in postoperative refraction and astigmatism seen after ARK.

All the 3 corneas showed disruption of Bowman'slayer, epithelial ingrowth, epithelial inclusion cysts, disrupted collagen lamellae, and infiltration of fi-broblastic keratocytes near the wound. These fea-tures appeared to be related to the glare and photo-phobia often seen after ARK.

The pair of corneas from the first case showed protrusions of the posterior corneal surface into the anterior chamber beneath the incisions, signs of endothelial stress, and abnormal collagen fibrils in the Descemet's membrane, the last of which appar-ently predated the ARK surgery. In the second case, incisions that were further deeped during the secondsurgery showed more severe histological damages than incisions made by a single cut.

It would seem reasonable to avoid this type of surgery especially in eyes with corneal guttata, family history of Fuchs' dystrophy, early-onset cataract, or uveitis.

Rinsho Gamka (Jpn J Clin Ophthalmol) 41(3) : 217-224, 1987