Title: Clinical research of modulation transfer function caused by spherical and aspheric intraocular lenses tilt
Abstract: 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.
Key words:
Lenses, intraocular; Tilt; Decentration; Modulation transfer function; Phacoemulsification
Publication Year: 2010
Publication Date: 2010-12-25
Language: en
Type: article
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