Wilson S E, Klyce S D, McDonald M B, Liu J C, Kaufman H E
LSU Eye Center, Louisiana State University Medical Center School of Medicine, New Orleans 70112.
Ophthalmology. 1991 Sep;98(9):1338-47. doi: 10.1016/s0161-6420(91)32127-4.
Computer-assisted analysis of corneal topography was performed in 17 normally sighted human eyes during the first year after excimer laser photorefractive keratectomy (PRK) for myopia. Laser ablation of the central cornea produced an optical zone with a smooth power transition to the peripheral cornea. Decentration of the ablation was noted in some eyes (less than 0.5 mm in 3 eyes, 0.5 to 1.0 mm in 10 eyes, 1 to 1.5 mm in 3 eyes, and 2.1 mm in 1 eye), suggesting that careful alignment of the laser beam is critical. Improved methods to align the ablation within the center of the entrance pupil are needed. In 12 of 17 eyes, the topographic pattern appeared to stabilize between 3 and 7 months after PRK. In the remaining five eyes, central ablation power changed by more than 0.5 diopters (D) between the 6- and 12-month examinations. Regression was more common and more pronounced in eyes with intended corrections more than 5 D, whereas the majority of eyes with intended corrections of 5 D or less showed good correspondence between the final change in central ablation power and the attempted correction. Two eyes had a loss of at least two lines of best spectacle-corrected visual acuity that was attributable to irregular astigmatism, decentration of the ablation, and/or corneal opacification.
对17只接受准分子激光屈光性角膜切削术（PRK）治疗近视的正常视力人眼在术后第一年进行了角膜地形图的计算机辅助分析。中央角膜的激光消融产生了一个光学区，其屈光力向周边角膜平稳过渡。在一些眼中观察到消融偏心（3只眼偏心小于0.5mm，10只眼偏心0.5至1.0mm，3只眼偏心1至1.5mm，1只眼偏心2.1mm），这表明激光束的精确对准至关重要。需要改进在入瞳中心内对准消融的方法。17只眼中有12只眼，角膜地形图模式在PRK术后3至7个月似乎稳定下来。在其余5只眼中，6个月和12个月检查之间中央消融屈光力变化超过0.5屈光度（D）。在预期矫正超过5D的眼中，回退更常见且更明显，而大多数预期矫正为5D或更低的眼在中央消融屈光力的最终变化与预期矫正之间显示出良好的对应关系。两只眼因不规则散光、消融偏心和/或角膜混浊导致最佳矫正视力至少下降两行。
