SMILE术后1个月患者瞳孔中心和角膜顶点实际角膜基质透镜厚度与预计厚度的差异

Difference between the achieved and estimated corneal stromal lenticule thickness at the pupil center and corneal vertex one month after small incision lenticule extraction

目的探讨飞秒激光小切口角膜基质透镜取出术(SMILE)术后1个月患者瞳孔中心和角膜顶点实际角膜基质透镜厚度与预计厚度的差异。方法选取2021年1月至4月在西安高新医院眼科屈光门诊行SMILE的患者66例(132眼)作为研究对象。分别于术前和术后1个月应用眼前节三维成像分析系统Pentacam测量患者瞳孔中心角膜厚度和角膜顶点厚度,检测患者视力及等效球镜度。将术前Pentacam检查结果作为“A图”,术后1个月检查结果作为“B图”,(A图-B图)数据即可得出每个坐标的角膜厚度差值,角膜厚度差值中瞳孔中心的差值(ΔCT_(p))和角膜顶点的差值(ΔCTv)即为实际角膜基质透镜厚度。角膜基质透镜厚度误差(E)=预计角膜基质透镜厚度-实际角膜基质透镜厚度,其中预计角膜基质透镜厚度为VisuMax飞秒激光手术设计软件预计的角膜厚度(LT),瞳孔中心角膜基质透镜厚度误差E_(p)=LT_(p)-ΔCT_(p);角膜顶点角膜基质透镜厚度误差Ev=LTv-ΔCTv。分析实际角膜基质透镜厚度与预计厚度的关系。结果术后1个月所有患者均无角膜水肿及炎症反应发生,眼压正常;132眼患者裸眼视力均达到或超过术前最佳矫正视力。术后1个月132眼患者等效球镜度范围为-0.50~+0.50 D。患者ΔCT_(p)为43~133(86.83±16.81)μm,明显低于LT_(p)55~130(96.89±15.92)μm,差异有统计学意义(t=-17.71,P<0.01)。患者ΔCTv为43~131(86.95±16.66)μm,明显低于LTv55~130(96.89±15.92)μm,差异有统计学意义(t=-17.65,P<0.01)。患者E_(p)为-7~28(10.07±6.53)μm,Ev为-7~27(9.95±6.48)μm。实际角膜基质透镜厚度随着预计厚度的增加而增加。LT_(p)每增加1μm,ΔCT_(p)增加0.97μm y=-7.5+0.97x(R^(2)=0.85,P<0.01),x为LT_(p),y为ΔCT_(p);LTv每增加1μm,ΔCTv增加0.96μmy=-6.54+0.96x(R^(2)=0.85,P<0.01),x为LTv,y为ΔCTv。结论SMILE手术实际制作的角膜基质透镜厚度明显低于预计厚度,实际厚度与预计厚度呈线性关系;角膜顶点位置的检测结果与VisuMax手术设计软件所预计的角膜基质透镜厚度更接近。

Objective To evaluate the difference between the achieved and estimated corneal stromal lenticule thickness at the pupil center and corneal vertex one month after small incision lenticule extraction(SMILE).Methods A total of 132 eyes of 66 patients who underwent the SMILE procedure in the Ophthalmology Department of Xi’an Gaoxin Hospital from January to April 2021 were included.The corneal thickness at the pupil center and at the apex was measured by Pentacam preoperatively and 1 month postoperatively.Visual acuity and spherical equivalent were also measured.The achieved lenticule thicknesses at the pupil center(ΔCT_(p))and at the corneal vertex(ΔCTv)was calculated by subtracting the 1-month postoperative corneal thickness at the pupil center and at the corneal vertex(Figure B)from the corresponding preoperative values(Figure A).The difference between the estimated and achieved lenticule thickness was the error(E)of lenticule thickness.The estimated lenticule thickness was the corneal thickness(LT)provided by VisuMax surgical design software.The lenticule thickness error at the pupil center was denoted as E_(p)(E_(p)=LT_(p)-ΔCT_(p)),and the lenticule thickness error at the corneal vertex was denoted as Ev(Ev=LTv-ΔCTv).The relationship between the achieved and estimated lenticule thickness was analyzed.Results No corneal edema or inflammatory reaction occurred and intraocular pressure was normal in all patients 1 month after surgery.The postoperative uncorrected visual acuity of all eyes was close to or better than the preoperative best corrected visual acuity.One month after surgery,the range of spherical equivalent was-0.50-+0.50 D.ΔCT_(p) was significantly lower than LT_(p) 43-133(86.83±16.81)μm vs 55-130(96.89±15.92)μm,t=-17.71,P<0.01,andΔCTv was also significantly lower than LT_(p) 43-131(86.95±16.66)μm vs 55-130(96.89±15.92)μm,t=-17.65,P<0.01.The E_(p) was-7-28(10.07±6.53)μm,and the Ev was-7-27(9.95±6.48)μm.The achieved lenticule thickness increased with the increase of the estimated thickness.ΔCT_(p) increased by 0.97μm when LT_(p) increased by 1μm y=-7.5+0.97x(R^(2)=0.85,P<0.01),x was LT_(p),and y wasΔCT_(p).ΔCTv increased by 0.96μm when LTv increased by 1μm y=-6.54+0.96x(R^(2)=0.85,P<0.01),x was LTv,and y wasΔCTv.Conclusion The achieved lenticule thickness is significantly lower than the estimated lenticule thickness after the SMILE surgery.The achieved lenticule thickness is linearly related to the estimated lenticule thickness.The achieved lenticule thickness at the corneal vertex is closer to the estimated lenticule thickness than that at the pupil center.