| Objective:To explore relationship between the normal strehl ratio(SR) values and Modulation transfer function(MTF) at anterior corneal surface and total corneal at different pupil diameters in normal population.Method:This was a retrospective case analysis study.200patients (400eyes) with myopia who will undergo LASIK surgery ranged from December2010to March2011were selected from Department of Ophthalmology in Beijing Military General Hospital. The SIRIUS3D topography system(CSO Co., Ltd. Italy. Software Version:phoenix1.2) and three-dimension anterior segment analysis system were utilized for data acquisition.The degree of astigmatism of the anterior corneal surface/total corneal is controlled to less than1.00D in the results of corneal topography examination of all patients,and we measured the SR values of total aberrations and the SR values of total higher-order aberrations, the corresponding RMS value and MTF values at anterior corneal surface/total corneal. The SR values at100’SR and200’SR were selected for the study.Use single-factor ANOVA to compare the SR values of total aberrations and SR values of total higher-order aberrations at the anterior corneal surface/total corneal at different pupil diameters (3.0mm,5.0mm,6.0mm,7.0mm),Pearson correlation analysis was applied to study the relationship between the SR values of total aberrations and SR values of total higher-order aberrations at the anterior corneal surface/total corneal and the corresponding RMS values, and the relationship between SR values of the total aberrations at the anterior corneal surface/total corneal and corresponding MTF values.Result:The subjects with different pupil diameters(3.0mm,5.0mm,6.0mm,7.0mm)’s exam results of anterior corneal surface were as following:100’SR value of total aberrations is (0.46±0.13)-(0.14±0.03)(F=1400.294, P=0.000);100’SR value of total higher order aberrations is (0.69±0.15)-(0.17±0.04)(F=2475.324, P=0.000);200’SR value of total aberrations is (0.45±0.13)-(0.16±0.04)(F=1004.5, P=0.000);200’SR value of total higher order aberrations is (0.70±0.15)-(0.20±0.05)(F=2103.583, P=0.000);and in the total cornea group with different pupil diameters(3.0mm,5.0mm,6.0mm,7.0mm):100’SR value of total aberrations is (0.49±.12)～(0.15±0.04)(F=1689.295,P=0.000),100’SR value of total higher order aberrations is (0.62±0.17)～(0.16±0.04)(F=1604.966, P=0.000),200’SR value of total aberrations is (0.47±0.12)～(0.18±0.04)(F=1160.711, P=0.000)200’SR value of total higher order aberrations is (0.62±0.18)～(0.19±0.05)(F=1300.205, P=0.000).So in the groups of the anterior corneal surface and total cornea,the SR values reduce with the increase of the pupil diameter.The correlation between the SR values and corresponding RMS value decreases gradually with the increase of pupil diameter. Among them,in the group of the anterior corneal surface:when the pupil diameter is3.0mm,the correlation between200’SR value of total aberrations and corresponding RMS value is maximum(r2=-0.862,P<0.05),when the pupil diameter is7.0mm,the correlation between100’SR value of total aberrations and corresponding RMS value is minimum(r2=-0.474,P<0.05);In the group of total corneal,when the pupil diameter is3.0mm,the correlation between200’SR value of total aberrations and corresponding RMS value is maximum(r2=-0.681,P<0.05),when the pupil diameter is7.0mm,the correlation between200’SR value of total aberrations and corresponding RMS value is maximum(r2=-0.457,P<0.05).When the pupil diameter is small, the SR value of total aberrations is more related to higher frequency region of MTF. When the pupil diameter is big, the SR value of total aberrations is more related to lower frequency region of MTF. Among them,in the group of the anterior corneal surface:when the pupil diameter is3.0mm, there is a correlation between100’/200’SR value of total aberrations and the high frequency region of corresponding MTF(55Hz,60Hz)(P<0.05),when the pupil diameter is5.0mm, there is a correlation between100’SR value of total aberrations and the high frequency region of corresponding MTF(55Hz,60Hz)(P<0.05), while the correlation of the200’SR values of the total aberrations with all12spatial frequencies (5、10、15、20、25、30、35、40、45、50、55、60Hz) of corresponding MTF are higher (P<0.05),when the pupil diameter is7.0mm,the correlation between100’/200’SR value of total aberrations and the low frequency region of corresponding MTF (5、10、15Hz) are higher (P<0.05);In the group of total cornea:when the pupil diameter is3.0mm,there is a correlation between100’/200’SR value of total aberrations and the high frequency region of corresponding MTF(50Hz,55Hz,60Hz)(P<0.05),when the pupil diameter is5.0mm, there is a correlation between100’/200’SR value of total aberrations and all12spatial frequencies (5、10、15、20、25、30、35、40、45、50、55、60Hz) of corresponding MTF (P<0.05),which have a higher correlation with the low frequency region of corresponding MTF (5、10、15Hz),when the pupil diameter is7.0mm,the correlation between100’/200’SR value of total aberrations and the low frequency region of corresponding MTF (5、10、15Hz) are higher (P<0.05).Conclusion:The SR values of total aberrations and the SR values of total higher-order aberrations at normal anterior corneal surface/total corneal are negatively correlated with pupil diameter.There is a certain correlation between SR values and the corresponding RMS values and MTF values. |
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