Maloney R K
Department of Ophthalmology, Emory University, Atlanta, Ga. 30322.
Refract Corneal Surg. 1990 Sep-Oct;6(5):363-71.
Optical zone diameters in photorefractive keratectomy are small in order to minimize the depth of stromal tissue excision and, possible, the resultant stromal scarring. A small optical zone demands accurate placement on the corneal surface. This article reviews the principles that are important to location and measurement of the optical zone in photorefractive keratectomy. The ablated area should be centered on the cornea overlying the entrance pupil while the patient is fixating coaxially with the surgeon. An optical zone that is too small or decentered may decrease acuity, lessen contrast sensitivity, or produce glare, either on the fovea or on the perifoveal retina. The relationship between optical zone size and location and quality of vision is not yet known. Studies of this relationship will require videokeratography to locate the optical zone and its relationship to the entrance pupil, a capability that current videokeratoscopes do not possess.
为了尽量减少基质组织切除的深度以及可能由此产生的基质瘢痕形成，准分子激光原位角膜磨镶术（PRK）中的光学区直径较小。小光学区要求在角膜表面精确放置。本文回顾了在准分子激光原位角膜磨镶术中对光学区定位和测量很重要的原则。在患者与外科医生同轴注视时，消融区域应位于覆盖入瞳的角膜中央。过小或偏心的光学区可能会降低视力、减少对比敏感度或在中央凹或中央凹周围视网膜上产生眩光。光学区大小与位置和视觉质量之间的关系尚不清楚。对这种关系的研究将需要使用视频角膜地形图来定位光学区及其与入瞳的关系，而目前的视频角膜镜不具备这种能力。
