Møller-Pedersen T, Vogel M, Li H F, Petroll W M, Cavanagh H D, Jester J V
Department of Ophthalmology, Aarhus University Hospital, Denmark.
Ophthalmology. 1997 Mar;104(3):360-8. doi: 10.1016/s0161-6420(97)30307-8.
The authors establish, for the first time, observer-independent quantification of stromal thinning, epithelial thickness, and corneal haze after excimer laser photorefractive keratectomy (PRK) using a unique, new form of in vivo confocal microscopy.
Rapid, continuous z-scans of high-resolution confocal images, termed confocal microscopy through focusing (CMTF), were performed in the central corneal area of 17 patients before and 1 month after PRK for low- to moderate-grade myopia (-2.88-9.13 diopters [D]). Corneal, epithelial, and stromal thickness measurements and an objective haze estimate were obtained from each CMTF scan by digital image analysis.
Epithelial thickness averaged 51 +/- 4 microns before and 45 +/- 10 microns 1 month post-PRK (P < 0.005), whereas stromal thinning ranged from 20 to 154 microns, representing a direct estimate of the actual photoablation depth. Corneal thickness averaged 560 +/- 36 microns before PRK and 462 +/- 52 microns at 1 month. The change in corneal thickness correlated closely with the change in spherical equivalent refraction (r = 0.94, P < 0.0001); linear regression analysis revealed a value of 14.3 microns corneal thinning per diopter of correction. A significant correlation was found between the objective CMTF haze estimate and a clinical haze grading obtained by slit-lamp examination (r = 0.73, P < 0.001).
Confocal microscopy through focusing is a new, powerful in vivo tool that enables quantitative, unbiased evaluation of PRK procedures over time by providing epithelial and stromal thickness analysis, photoablation depth assessment, and unbiased haze measurement. The method is uniquely valuable in the pre- and postoperative assessment of PRK patients and for determining the optimal treatment strategy, especially in assessing refractive and visual outcomes in individual cases.
作者首次使用一种独特的新型活体共聚焦显微镜，建立了与观察者无关的准分子激光屈光性角膜切削术（PRK）后基质变薄、上皮厚度和角膜混浊的量化方法。
对17例低度至中度近视（-2.88至-9.13屈光度[D]）患者在PRK术前和术后1个月，在角膜中央区域进行快速、连续的高分辨率共聚焦图像z扫描，即通过聚焦的共聚焦显微镜（CMTF）。通过数字图像分析从每次CMTF扫描中获得角膜、上皮和基质厚度测量值以及客观混浊估计值。
PRK术前上皮厚度平均为51±4微米，术后1个月为45±10微米（P<0.005），而基质变薄范围为20至154微米，直接估计了实际光凝深度。PRK术前角膜厚度平均为560±36微米，1个月时为462±52微米。角膜厚度的变化与等效球镜度的变化密切相关（r = 0.94，P<0.0001）；线性回归分析显示每矫正1屈光度角膜变薄14.3微米。在客观CMTF混浊估计值与裂隙灯检查获得的临床混浊分级之间发现显著相关性（r = 0.73，P<0.001）。
通过聚焦的共聚焦显微镜是一种新型、强大的活体工具，通过提供上皮和基质厚度分析、光凝深度评估和无偏混浊测量，能够对PRK手术进行随时间的定量、无偏评估。该方法在PRK患者的术前和术后评估以及确定最佳治疗策略方面具有独特价值，特别是在评估个体病例的屈光和视觉结果时。
