角膜塑形镜塑形后眼客观视觉质量变化

Objective optical quality after orthokeratology

目的 探讨角膜塑形镜矫治前后眼客观视觉质量变化.方法 本研究采用前瞻性、自身对照设计.选取2013年1至6月在青岛眼科医院行角膜塑形镜矫治的近视眼儿童患者25例（48只眼）,采用双通道客观视觉质量分析系统（OQASⅡ）测量矫治前、矫治1周、1个月及3个月客观视觉质量参数,包括客观散射指数（OSI）、调制传递函数（MTF）截止频率、客观对比度视力、客观泪膜质量变化;并采用角膜地形图检测角膜散光及e值.采用单因素方差分析对组内数据进行统计学比较,如差异有统计学意义,同时行LSD校正进行两组间对比.结果 矫治前及矫治1周、1个月、3个月球镜度数分别为（-3.65 ±1.75）、（-0.30 ±0.64）、（-0.08 ±0.20）、（-0.05±0.22）D,柱镜度数分别为（-0.39±0.39）、（-0.65±0.57）、（-0.79±0.56）、（-0.81±0.53）D,UCVA分别为3.97±0.51、4.95±0.12、5.00±0.06、5.00±0.05,组内比较差异均有统计学意义（F=79.9,6.1,74.4;P＜0.05）.角膜地形图指标e值矫治前后分别为0.37±0.24、-0.23±0.42、-0.29±0.39、-0.30±0.37,矫治后e值变为负数,且与矫治前差异有统计学意义（F=33.3,P＜0.01）.3 mm范围角膜散光度数矫治前后差异无统计学意义（F=0.06,P≥0.05）.MTF截止频率分别为（36.6±12.0）、（34.2±8.9）、（27.9±12.6）、（27.7±11.6）周/度,矫治后MTF截止频率下降,1个月、3个月时与矫治前有统计学差异（P＜0.05）.OSI为0.59±0.47、0.99±0.66、1.47±1.17、1.49±1.03,矫治后OSI上升,与矫治前有统计学差异（P＜0.05）.100％、20％及9％对比度视力矫治后虽有轻微下降,但与矫治前相比差异无统计学意义（F=0.68,1.58,2.19;P≥0.05）.客观泪膜质量OSI均值1.27±1.12、2.09±1.67、2.07±1.12、2.10±1.33,矫治后上升,与矫治前有统计学差异（F=3.13,P＜0.05）.结论 患者配戴角膜塑形镜3个月内,柱镜度数增大,角膜中心散光度数不变;e值变负,OSI上升,MTF截止频率及客观泪膜质量下降;该变化在矫治1个月内随矫治时间延长而明显,1个月后较稳定.经短期角膜塑形治疗,在塑形效果显现的同时亦可引起眼屈光系统光学质量下降,但下降程度轻微.

Objective To determine the changes of objective optical quality after orthokeratology.Methods Prospective,self-controlled study.Optical quality,including objective scatter index （OSI）,modulation transfer function （MTF） cutoff frequency,contrast visual acuity （CVA） and objective tear film quality,was assessed with the OQAS Ⅱ instrument before and 1 week,1 month,and 3 months after orthokeratology.Parameters of corneal astigmatism and e value from topography were also assessed.The data was analyzed using one-way ANOVA.Results Cylinder refraction was （-0.39 ± 0.39） D,（-0.65 ±0.57）D,（-0.79 ±0.56）D,and（-0.81 ±0.53）D,respectively,at the four timepoints,and there was a statistically significant difference between before and after therapy （P 〈 0.05）.Uncorrected visual acuity was 3.97 ±0.51,4.95 ±0.12,5.00 ±0.06,and 5.00 ±0.05,respectively.The e value was 0.37 ±0.24,-0.23 ± 0.42,-0.29 ± 0.39,and-0.30 ± 0.37,respectively.The negative values after therapy were significantly different from the value before therapy （P 〈 0.01）.The corneal astigmatism in 3 mm diameter was （1.27 ±0.75） D,（1.06 ±0.69） D,（1.11 ±0.68） D,and（1.15 ±0.67）D,respectively.There was no significant difference in astigmatism between before and after therapy （P≥0.05）.After therapy,the OSI increased from 0.59 ± 0.47 before therapy to 0.99 ± 0.66 at 1 week,1.47 ± 1.17 at 1 month,and 1.49 ± 1.03 at 3 months.The difference between pre-and post-therapy OSI values was statistically significant （P 〈0.05）.The MTF cutoff frequency decreased from （36.6 ± 12.0） cpd before therapy to （34.2±8.9） cpdat 1 week,（27.9±12.6） cpd at 1 month,and （27.7±11.6）cpd at 3 months after therapy.The difference in MTF cutoff frequency between before and 1 month after therapy was statistically significant （P 〈0.05）.The 100% CVA,20% CVA,and 9% CVA all declined after therapy,but there was no statistically significant difference between before and after therapy.The OSI of tear film quality was 1.27± 1.12,2.09 ± 1.67,2.07 ± 1.12,and 2.10 ± 1.33,respectively,and the difference was statistically significant between before and after therapy （P 〈 0.05）.Conclusions After 3 months of orthokeratology,the corneal central astigmatism remained,and the e value became negative,while OSI increased,and MTF cutoff frequency and tear film quality declined.The alteration was more and more obvious along with the therapy within 1 month,and was not significant within the following month.After short-term corneal reshaping,the ocular optical quality declined in some degree,but the loss was acceptable.