复杂性放射状角膜切开并发白内障术后屈光误差1例

A case of refractive error after cataract surgery in a complex patient with previous radial keratotomy

74岁男性,因“双眼视物模糊5年,加重1年”就诊。患者25年前曾行双眼高度近视放射状角膜切开术(RK)。双眼最佳矫正视力:右眼0.4(﹣6.00/﹣4.00×65°),左眼0.3^(﹣2)(﹣6.00/﹣4.00×70°)。裂隙灯检查示双眼角膜不规则RK瘢痕,瞳孔圆,直径约2 mm,晶状体混浊。诊断为双眼并发性白内障,并行左眼白内障超声乳化联合人工晶状体(IOL)植入术,手术顺利,无并发症。术前根据IOLmaster 500的结果,使用Haigis公式计算出IOL度数为5.00 D,预计术后近视﹣1.50 D。术后第20天,左眼裸眼视力0.4,矫正视力+6.50/﹣1.50×5°→0.2,等效球镜+5.75 D,屈光误差超过7 D。讨论体会:对于RK术后的患者,特别是角膜存在不规则RK瘢痕的患者,我们要采用多种方法测量角膜曲率,特别是使用Pentacam角膜地形图测量,同时选择合适的IOL计算公式。对于角膜不规则的患者,使用以瞳孔为中心,实际瞳孔大小区域内的角膜曲率SimK参数,结合Barrett True K公式,计算的IOL度数最为准确。

A 74-year-old man presented with“vision loss in both eyes for 5 years and worsening for 1 year”.The patient underwent radial keratotomy(RK)for the treatment of high myopia 25 years ago.Best corrected visual acuity was 0.4(﹣6.00/﹣4.00×65°)in the right eye and 0.3^(﹣2)(﹣6.00/﹣4.00×70°)in the left.Slit lamp examination revealed a clear central cornea with peripheral irregular corneal scar due to RK,round pupil with a dimeter around 2 mm.and opaque lens in both eyes.The patient was diagnosed with bilateral complicated cataract and had undergone phacoemulsification combined with intraocular lens(IOL)implantation for the left eye successfully without complication.Based on the biometry obtained with IOLmaster 500 and the target refractive diopter(D)set at﹣1.50 D,the IOL power calculated by Haigis formula was 5.00 D.Twenty days after surgery,his uncorrected visual acuity of the left eye was 0.4,and the best corrected visual acuity was 0.2(+6.50/﹣1.50×5°).Therefore,the postoperative spherical equivalent refraction was+5.75 D and the refractive error was more than 7 D.For patients who underwent RK,especially those with irregular corneal incisions,the corneal curvature should be measured by different methods,particularly using Pentacam.In addition,we should choose appropriate IOL calculation formulae.For patients with small pupils,the calculation of IOL power will be more accurate by using Barrett True K formula combined with the SimK within the zone of actual pupil diameter centered on the pupil axis.