From the Center for Ophthalmic Optics and Lasers (Li, Yokogawa, Tang, Chamberlain, Zhang, Huang), Casey Eye Institute and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, USA; and the Department of Ophthalmology (Yokogawa), Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
From the Center for Ophthalmic Optics and Lasers (Li, Yokogawa, Tang, Chamberlain, Zhang, Huang), Casey Eye Institute and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, USA; and the Department of Ophthalmology (Yokogawa), Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
J Cataract Refract Surg. 2017 Apr;43(4):525-536. doi: 10.1016/j.jcrs.2017.03.004.
To analyze transepithelial phototherapeutic keratectomy (PTK) results using optical coherence tomography (OCT) and develop a model to guide the laser dioptric and depth settings.
Casey Eye Institute, Portland, Oregon, USA.
Prospective nonrandomized case series.
Patients with superficial corneal opacities and irregularities had transepithelial PTK with a flying-spot excimer laser by combining wide-zone myopic and hyperopic astigmatic ablations. Optical coherence tomography was used to calculate corneal epithelial lenticular masking effects, guide refractive laser settings, and measure opacity removal. The laser ablation efficiency and the refractive outcome were investigated using multivariate linear regression models.
Twenty-six eyes of 20 patients received PTK to remove opacities and irregular astigmatism due to scar, dystrophy, radial keratotomy, or previous corneal surgeries. The uncorrected distance visual acuity and corrected distance visual acuity were significantly improved (P < .01) by 3.7 Snellen lines and 2.0 Snellen lines, respectively, to a mean of 20/41.2 and 20/22.0, respectively. Achieved laser ablation depths were 31.3% (myopic ablation) and 63.0% (hyperopic ablation) deeper than the manufacturer's nomogram. The spherical equivalent of the corneal epithelial lenticular masking effect was 0.73 diopter ± 0.61 (SD). The refractive outcome highly correlated to the laser settings and epithelial lenticular masking effect (Pearson R = 0.96, P < .01). The ablation rate of granular dystrophy opacities appeared to be slower. Smoothing ablation under masking fluid was needed to prevent focal steep islands in these cases.
The OCT-measured ablation depth efficiency could guide opacity removal. The corneal epithelial lenticular masking effect could refine the spherical refractive nomogram to achieve a better refractive outcome after transepithelial ablation.
利用光学相干断层扫描（OCT）分析经上皮准分子光角膜切削术（PTK）的结果，并建立一个模型来指导激光的屈光度和深度设置。
美国俄勒冈州波特兰市 Casey 眼科研究所。
前瞻性非随机病例系列。
对有浅层角膜混浊和不规则的患者，采用飞点准分子激光进行经上皮 PTK，联合宽区近视和远视散光消融。OCT 用于计算角膜上皮透镜掩蔽效应，指导屈光激光设置，并测量混浊去除程度。使用多元线性回归模型研究激光消融效率和屈光结果。
20 例（26 只眼）患者因瘢痕、营养不良、放射状角膜切开术或先前的角膜手术导致混浊和不规则散光，接受 PTK 以去除混浊和不规则散光。未矫正的远视力和矫正的远视力分别显著提高（P<.01）3.7 行和 2.0 行，分别平均达到 20/41.2 和 20/22.0。实际达到的激光消融深度比制造商的图表预测值深 31.3%（近视消融）和 63.0%（远视消融）。角膜上皮透镜掩蔽效应的球镜等效值为 0.73 屈光度±0.61（标准差）。屈光结果与激光设置和上皮透镜掩蔽效应高度相关（Pearson R=0.96，P<.01）。颗粒状营养不良混浊的消融速度似乎较慢。在这些情况下，需要在掩蔽液下进行平滑消融，以防止局灶性陡峭岛屿的形成。
OCT 测量的消融深度效率可指导混浊去除。角膜上皮透镜掩蔽效应可改进球面屈光图表，以实现经上皮消融后的更好屈光效果。
