Jonas J B, Panda-Jonas S
Universitäts-Augenklinik, Universität Erlangen-Nürnberg, Germany.
Graefes Arch Clin Exp Ophthalmol. 1994 Sep;232(9):538-44. doi: 10.1007/BF00181997.
Autologous ipsilateral rotating keratoplasty is a special form of keratoplasty in which a nonprogressive opacification of the centre of the cornea is rotated towards the limbus and the clear peripheral cornea is rotated into the optical axis of the eye. This study was performed to find an equation for calculating the best size and location of the trephine for this special kind of keratoplasty.
Geometrical calculations were used to derive the formula.
We arrived at the following equation for the best diameter of the trephine: diameter(trephine) = 3/4 diameter(cornea)-1/2e(e = preoperative distance between corneal centre and nearest edge of opacity covering corneal centre). The postoperative diameter of the optical zone is: 2 x diameter(trephine)-diameter(cornea). A postoperative clear optical zone of half the corneal diameter is achieved if the opacity just touches but does not extend beyond the corneal centre. For a postoperative optical zone of at least 30% (40%) of the corneal diameter, the opacity is preoperatively not allowed to extend beyond the corneal centre for more than 20% (10%) of the corneal diameter.
This equation can be used for calculating the optimum size and location of the trephine for autologous ipsilateral rotational keratoplasty. For that purpose it is advisable to take photographs preoperatively.
自体同侧旋转角膜移植术是一种特殊形式的角膜移植术，其中角膜中央的非进行性混浊向角膜缘旋转，而透明的周边角膜旋转至眼的光轴。本研究旨在找到一个方程，用于计算这种特殊角膜移植术的环钻最佳尺寸和位置。
采用几何计算推导公式。
我们得出了以下环钻最佳直径的方程：环钻直径 = 3/4角膜直径 - 1/2e（e = 术前角膜中心与覆盖角膜中心的混浊最边缘之间的距离）。术后光学区的直径为：2×环钻直径 - 角膜直径。如果混浊刚好触及但未超出角膜中心，则术后可获得直径为角膜直径一半的透明光学区。对于术后光学区至少为角膜直径的30%（40%）的情况，术前混浊不允许超出角膜中心超过角膜直径的20%（10%）。
该方程可用于计算自体同侧旋转角膜移植术环钻的最佳尺寸和位置。为此，术前拍照是明智的。
