球面与非球面人工晶状体的倾斜度对调制传递函数的影响

目的 比较白内障超声乳化联合后房型人工晶状体（IOL）囊袋内植入后,不同IOL的倾斜度对调制传递函数（MTF的影响.方法 回顾性病例系列研究.年龄相关性白内障患者75例（75眼）,其中男39例,女36例,年龄为50～75岁,平均（64.6±6.3）岁.按照植入IOL的类别分两组,非球面ZA9003组40例（40眼）,球面AR40E组35例（35眼）.术后2个月进行随访,散瞳至8 mm后,用Pentacam眼前节成像系统采集Scheimpflug图像,分析IOL的倾斜度与偏心值,i-Trace采集5 mm瞳孔直径下的各空间频率（5、10、15、20、25、30 c/d）MTF值.两组再根据倾斜度大小以0.5°为组距分为小、中和大3个倾斜度组.采用SPSS 17.0软件对倾斜度与偏心值进行Pearson相关分析,两种IOL组间的倾斜度与偏心值进行独立样本t检验,多个倾斜度组间及其所对应的空间频率下的MTF值采用单因素方差分析,球面与非球面IOL的倾斜对MTF的影响用中心调整后的数值进行Kolmogorov-SmirnovZ检验.结果 所有IOL的倾斜度与偏心值无显著相关性（r=0.183,P=0.051）.ZA9003组和AR40E组患者IOL的平均倾斜度分别为（0.93±0.71）°、（1.12±0.73）°,平均偏心值为（0.13±0.10）mm、（0.18±0.12）mm,两组差异均无统计学意义（P＞0.05）.ZA9003组小、中、大倾斜度组的平均倾斜度分别为（0.28±0.15）°、（0.78±0.12）°、（1.67±0.60）°,AR40E组分别为（0.38±0.20）°、（0.71±0.12）°、（1.77±0.56）°,组间差异均有统计学意义（P＜0.05）.ZA9003组小、中、大倾斜度组的平均偏心值为（0.09±0.05）mm、（0.11±0.08）mm、（0.16±0.12）mm,AR40E组分别为（0.15±0.06）mm、（0.13±0.15）mm、（0.16±0.08）mm,组间差异均无统计学意义（P＞0.05）.在5 mm瞳孔直径下,ZA9003组与AR40E组各倾斜度组在各空间频率下的MTF值差异均无统计学意义（P＞0.05）.ZA9003与AR40E组各倾斜度组的各空间频率的MTF值经中心调整后比较,在小倾斜度组和中倾斜度组之间差异均无统计学意义（P＞0.05）,在大倾斜度组只有在空间频率为20、25 c/d时两种IOL的MTF值差异才有统计学意义（Z=2.465、1.017,P＜0.05）,其他空间频率下差异均无统计学意义（P＞0.05）.结论 在现在的手术技术条件下,非球面IOL对大倾斜度所造成的视觉质量改变在一些空间频率下比球面IOL敏感.但是,无论是球面还是非球面的IOL的倾斜都不足以引起人眼视觉质量的明显改变.

Clinical research of modulation transfer function caused by spherical and aspheric intraocular lenses tilt

Objective To compare tilt and decentration of different intraocular lens (IOL)and modulation transfer function (MTF) caused by different IOL tilt after phacoemulsification and IOL implanted in the bag. Methods It was a retrospective clinical case series study. Seventy-five eyes of 75 patients with age related cataract were examined 2 months after phacoemulsification and IOL implantation. Among which 39 cases were male and 36 cases were female. The age range 50-75years, mean (64.6±6.3)years. According to the type of IOL we divided into 2 groups, ZA9003(aspheric) and AR40E (spherical). There were 40 cases in the ZA9003 group and 35 cases in the AR40E group. The patients were followed up and dilated to 8 mm pupil size 2 months later, and their decentration and tilt of the IOL were quantified using a video photography system (Pentacam,Oculus) and image-analysis. The inter MTF at 5, 10, 15, 20, 25, 30 c/d spatial frequencies were measured by i-Trace application under 5 mm pupil size. According to the class wides of 0.5° of tilts, we divided the tilt and decentration into 3 groups: small tilt, middle tilt and big tilt. At first,we analysed the correlation between tilt and decentrtion. Then, among the 3 groups of each IOL, we compared the differences of decentration and tilt and MTF at 5, 10, 15, 20, 25, 30 c/d spatial frequencies which corresponding to them with ANOVA test. We also compared the visual quality caused by different tilt of spherical and aspheric IOL with Kolmogorov-SmirnovZ test after doing central adjustment. Results The correlation between IOL tilt and decentration was not significant (r=0.183, P=0.051). The mean tilt of ZA9003 and AR40E groups were (0.93±0.71)°, (1.12±0.73)°, and the mean decentration were (0.13±0.10)mm, (0.18±0. 12)mm, there were no significant differences (P＞0.05). The mean tilt of the 3 groups of ZA9003 were (0.28±0.15)°, (0.78±0.12)°, (1.67±0.60)°; and the mean tilt of the 3 groups of AR40E were (0.38±0.20)°, (0.71±0.12)°, (1.77±0.56)°; there were significant differences among the tilt of the 3 groups of each IOL (P＜0.05). The mean decentration of the 3 groups of ZA9003 were(0.09±0.05)mm, (0.11±0.08)mm, (0.16±0.12)mm; and the mean decentration of AR40E were (0.15±0.06)mm, (0.13±0.15)mm, (0. 16±0.08)mm; there were no significant differences among the decentration of the 3 groups of each IOL (P＞0.05). There were no significant differences in MTF of all spatial frequency corresponding to the different tilt groups of each IOL under 5 mm pupil size (P＞0.05). After doing central adjustment of the MTF of each groups of the two IOL, there were no significant differences between ZA9003 and AR40E in small tilt group and middle tilt group (P＞0.05). There were significant differences in big tilt group at the spatial frequencies of 20 and 25 c/d (Z=2.465, 1.017, P＜0.05), but not in the other spatial frequencies.Conclusion With the modern technique, the visual quality changes in aspheric IOL caused by the big tilt at some spatial frequencies is more sensitive than in spherical IOL. However, the tilt of both spherical and aspheric IOL can not change the visual quality significantly.