Frangieh G T, Kwitko S, McDonnell P J
Doheny Eye Institute, University of Southern California School of Medicine, Los Angeles 90033.
Arch Ophthalmol. 1991 Apr;109(4):506-10. doi: 10.1001/archopht.1991.01080040074030.
Computer-assisted photokeratoscopy was used to evaluate the topographic characteristics of corneas preoperatively and postoperatively in seven patients who underwent surgery for correction of postkeratoplasty astigmatism. The steep hemimeridians were typically separated by an angle other than 180 degrees (mean, 162.5 degrees) and the flat hemimeridians were often not orthogonal to the steep hemimeridians. Asymmetry of power (1.5 or more diopters) between these two major hemimeridians was also observed in three patients. Relaxing incisions were placed in the two steep hemimeridians and compression sutures were placed in the flat hemimeridians. The mean percent of reduction of astigmatism (vector-corrected) was 81.1%. The amount of keratometric astigmatism, and the degree of asymmetry of the hemimeridians were not correlated with the percent of reduction of astigmatism after placement of the relaxing and compression sutures. Computer-assisted topographic analysis may prove useful in planning transverse keratotomies centered on the steep hemimeridians and in placement of compression sutures in flat hemimeridians.
采用计算机辅助角膜地形图检查法，对7例接受角膜移植术后散光矫正手术患者的角膜术前和术后的地形特征进行评估。陡峭的半子午线通常以非180度的角度分开（平均为162.5度），而平坦的半子午线通常与陡峭的半子午线不垂直。在3例患者中还观察到这两条主要半子午线之间的屈光力不对称（1.5屈光度或更大）。在两条陡峭的半子午线上做松解切口，并在平坦的半子午线上放置压迫缝线。散光减少的平均百分比（矢量校正）为81.1%。角膜散光量和半子午线的不对称程度与放置松解缝线和压迫缝线后散光减少的百分比无关。计算机辅助地形分析可能在规划以陡峭半子午线为中心的横向角膜切开术以及在平坦半子午线上放置压迫缝线方面证明是有用的。
