Center of Optometry (T.G., B.G., D.L., W.L., N.L., Q.H., and R.W.), Tianjin Medical University Eye Hospital, Tianjin, China; Tianjin Medical University Eye Institute (T.G., B.G., D.L., Q.H., and R.W.), Tianjin, China; The School of Optometry & Ophthalmology (T.G., B.G., D.L., W.L., N.L., Q.H., and R.W.), Tianjin Medical University, Tianjin, China.
Eye Contact Lens. 2019 Nov;45(6):372-376. doi: 10.1097/ICL.0000000000000580.
To investigate the lens decentration (LD) of orthokeratology (ortho-k) and the association between pretreatment corneal topographic parameters and LD of the ortho-k.
Fifty right eyes of 50 myopes wearing ortho-k lenses were included in the prospective study. Corneal topography was conducted pretreatment to get topographic corneal parameters, including flat-K (K1); steep-K (K2); corneal astigmatism (CA), CA at 0 to 3 mm (3 mm-CA), 3 to 5 mm (5 mm-CA), 5 to 7 mm (7 mm-CA); surface asymmetry index (SAI); surface regularity index; the curvature of best-fit sphere; the diameter of cornea (DC); the distance from the corneal center to the corneal vertex (CCCV); flat eccentricity (E1), steep eccentricity (E2), and E1/E2 (E ratio); and the corneal curvature differences between the nasal and temporal quadrants at 0 to 3 mm (3 mm-Knt), and the corneal curvature differences between the superior and inferior quadrants at 0 to 3 mm (3 mm-Ksi), 5 mm-Knt (at 3-5 mm), 5 mm-Ksi (at 3-5 mm), 7 mm-Knt (at 5-7 mm), and 7 mm-Ksi (at 5-7 mm). The relationship between these cornea topographic parameters and LD of the ortho-k was tested using stepwise multiple linear regression models.
The mean magnitude of LD was 0.51±0.23 mm (0.06-1.03 mm). According to the stepwise analysis, 4 factors were associated with the overall LD (P<0.01): SAI (β=0.252), CCCV (β=0.539), 5 mm-CA (β=-0.268), and 3 mm-Ksi (β=-0.374); 5 factors were associated with the horizontal LD (P<0.01): DC (β=0.205), CCCV (β=0.881), 3 mm-CA (β=-0.217), 5 mm-Knt (β=0.15), and 3 mm-Ksi (β=-0.18); and 3 factors were associated with the vertical LD (P<0.01): SAI (β=0.542), 5 mm-CA (β=-0.188), and 3 mm-Ksi (β=-0.213).
Lens decentration is most common, but in most cases, the amount of LD is moderate and acceptable. The magnitude of LD can be predetermined by topographic corneal parameters. Surface asymmetry index, CCCV, 5 mm-Knt, and 3 mm-Ksi may be more preferable parameters in terms of the assessment of LD of ortho-k.
研究角膜塑形术(ortho-k)的晶状体偏心(LD)以及术前角膜地形图参数与 ortho-k 的 LD 之间的关系。
本前瞻性研究纳入了 50 名右眼近视患者,共 50 只眼,他们均佩戴角膜塑形镜。在治疗前进行角膜地形图检查,获取角膜地形图参数,包括:平 K 值(K1);陡 K 值(K2);角膜散光(CA),0 至 3 毫米(3 mm-CA)、3 至 5 毫米(5 mm-CA)、5 至 7 毫米(7 mm-CA)的角膜散光;表面不对称指数(SAI);表面规则指数;最佳拟合球的曲率;角膜直径(DC);角膜顶点至角膜中心的距离(CCCV);平偏心距(E1)、陡偏心距(E2)和 E1/E2(E 比);以及 0 至 3 毫米时鼻侧和颞侧象限的角膜曲率差异(3 mm-Knt),0 至 3 毫米时上方和下方象限的角膜曲率差异(3 mm-Ksi)、5 毫米时鼻侧和颞侧象限的角膜曲率差异(5 mm-Knt)、5 毫米时上方和下方象限的角膜曲率差异(5 mm-Ksi)、7 毫米时鼻侧和颞侧象限的角膜曲率差异(7 mm-Knt)以及 7 毫米时上方和下方象限的角膜曲率差异(7 mm-Ksi)。使用逐步多元线性回归模型测试这些角膜地形图参数与 ortho-k 的 LD 之间的关系。
LD 的平均幅度为 0.51±0.23 毫米(0.06-1.03 毫米)。根据逐步分析,有 4 个因素与整体 LD 相关(P<0.01):SAI(β=0.252)、CCCV(β=0.539)、5 mm-CA(β=-0.268)和 3 mm-Ksi(β=-0.374);5 个因素与水平 LD 相关(P<0.01):DC(β=0.205)、CCCV(β=0.881)、3 mm-CA(β=-0.217)、5 mm-Knt(β=0.15)和 3 mm-Ksi(β=-0.18);3 个因素与垂直 LD 相关(P<0.01):SAI(β=0.542)、5 mm-CA(β=-0.188)和 3 mm-Ksi(β=-0.213)。
晶状体偏心是最常见的,但在大多数情况下,LD 的幅度是适度的,可以接受的。LD 的幅度可以通过角膜地形图参数来预测。表面不对称指数、CCCV、5 mm-Knt 和 3 mm-Ksi 可能是评估 ortho-k 的 LD 更可取的参数。