飞秒激光角膜基质内切割术治疗老视前后角膜生物力学特性的变化

摘要

Objective To investigate the changes of corneal biomechanics of intrastromal correction (INTRACOR) femtosecond technique to treat presbyopia.Methods A prospective,clinical self-control clinical trial was designed.Twenty-four presbyopic patients with emmetropia or mild hyperopia were enrolled in this study.The INTRACOR procedure was performed using the Technolas femtosecond laser in the nondominant eye.Uncorrected distance visual acuity (UCDVA),uncorrected near visual acuity (UCNVA) and spherical equivalent (SE) were recorded in preoperation and postoperative 12 months,and the quality of life of postoperative patients was evaluated.The corneal deformation parameters including highest concavity deformation amplitude (HC-DA),highest concavity peak distance (HC-PD),highest concavity radius (HC-R),non-contact intraocular pressure and the central corneal thickness (CCT) were measured using the Corvis ST visualization biomechanical analyzer in preoperation and postoperative 1 month,3,6 and 12 months,respectively.This study followed the Declaration of Helsinki.Written informed consent was obtained from each subject prior to entering study cohort.This study protocol was approved by Ethic Committee of Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine (No.SDZYYDXYKYYLL2011.06).Results Compared with preoperation,UCNVA of all 24 (100％) eyes was improved at 12 months postoperatively with minimal or no change in UCDVA.The mean spherical equivalent was (+0.35± 0.29)D and (-0.37 ± 0.29)D before and 12 months after operation,with a significant difference beteeen them (t=-7.39,P＜0.01).No significant differences were seen in the intraocular pressure,CCT and HC-PD values between preoperation and postoperative 1 month,3,6,12 months (F =1.273,1.347,2.434;all at P ＞ 0.05).Compared with preoperation,the postoperative 1 month,3,6,12 months HC-R values were significantly declined,HC-DA values were significantly increased,with significant differences between them (all at P＜0.05),and no significant differences were found in HC-R and HC-DA between the postoperative adjacent time points (all at P＞0.05).Corneal aspherical index (Q Value) was-0.28±t0.10 at 12 months postoperatively,which was increased compared with the preoperation,and the maximum value added value (diff-K) of the central corneal curvature was (2.55±0.81)D.Conclusions INTRACOR treatment of presbyopia can effectively improve near vision,increase postoperative corneal biomechanical maximum HC-R and HC-DA,negatively increase the corneal central curvature increased aspheric index,which suggests that corneal biomechanics of central cornea is weakened after intrastromal femtosecond presbyopic treatment,and the hyperprolate mutifocal corneal shape is formed under normal intraocular pressure.%目的 探讨飞秒激光角膜基质内切割术(INTRACOR)治疗老视前后角膜生物力学变化情况.方法 采用前瞻性自身对照研究设计.对老视患者24例24眼采用飞秒激光INTRACOR进行治疗,观察术前和术后12个月的裸眼远视力(UCDVA)(LogMAR视力)、裸眼近视力(UCNVA)(LogMAR视力)、等效球镜度(SE),并设计调查问卷评估术后患者生活质量.采用Corvis ST角膜生物力学分析仪检测患者术前和术后1、3、6、12个月的角膜生物力学参数,包括眼压、中央角膜厚度(CCT)、最大压陷时峰距(HC-PD)、最大压陷时曲率半径(HC-R)、最大压陷时变形幅度(HC-DA);采用Orbscan-Ⅱz角膜地形图检测角膜中央3 mm区屈光力和6 mm区非球面指数(Q值). 结果 术前和术后12个月UCNVA(LogMAR视力)分别为0.5(0.3,1.0)和0.2(0.0,0.4),差异有统计学意义(Z=-4.04,P＜0.01),术后12个月UCDVA与术前值比较,差异无统计学意义(Z=-1.61,P＞0.05).术后12个月SE为(-0.37±0.29)D,与术前的(+0.35±0.29)D相比,有轻度近视转换,差异有统计学意义(t=-7.39,P＜0.01).术前与术后1、3、6和12个月眼压、CCT、HC-PD比较,差异均无统计学意义(F=1.273、1.347、2.434,均P＞0.05);术前与术后1、3、6、12个月HC-R、HC-DA值比较,差异均有统计学意义(F=109.485、137.648,均P＜0.01),术后各时间点HC-R值均小于术前值,HC-DA值均大于术前值,差异均有统计学意义(均P＜0.05),术后各时间点HC-R值和HC-DA值两两比较差异均无统计学意义(均P＞0.05).术后12个月,角膜中央6 mm区非球面指数为-0.28±0.10,较术前的-0.16±0.09负性增加,中央区手术前后角膜最大曲率差异值(diff-K值)为(2.55±0.81)D. 结论 INTRACOR治疗老视可有效提高近视力,术后角膜HC-R减小,HC-DA增加,角膜中央曲率增加,非球面指数负性增加,提示手术降低了中央区角膜生物力学强度,角膜中央区前凸形成非球面多焦形态达到增加近视力目的.