| Objective: 1.To analyze the reproducibility of keratometry and astigmatism measured by the VERION Digital Guidance System and the comparability of VERION with i Trace,Lenstar LS900 and manual keratometer.2.To observe the law of ocular rotation when patient from sited to supine position and after the negative pressure suction of femtosecond laser,and the difference in marking the horizontal position of cornea between VERION Digital Guidance System and manual marking method.3.To evaluate the accuracy of VERION system assisted cataract phacoemulsification combined with Toric IOL implantation.Methods: 1.The keratometry of 62 cataract patients were measured using four different devices.The steep keratometry(Ks),the flat keratometry(Kf),the astigmatic magnitude,the astigmatic axis,the cylinder at 0-degree meridian(vector component,J0)and the cylinder at 45-degree meridian(vector component,J45)from each machine were recorded and analyzed.Compare the three repeated measurements and the results of VERION system with other three devices to analyze the reproducibility and comparability of VERION system.2.Compare the anterior segment images of sited and supine position of 243 cataract patients and then record the angle and direction of ocular rotation.Compare the anterior segment images of sited with supine position(the first eye rotation)and supine position with suction of femtosecond laser(the second eye rotation),then record the eye rotation respectively;70 eyes implanted with Toric IOL were marked the corneal horizontal position with the manual marking method,comparing the difference of corneal horizontal axis between manual marking method and VERION system.3.60 eyes of 60 patients with Toric IOL were randomly divided into two groups.One group of patients were measured the preoperative measurements and intraoperative guidance using the VERION system,referred to as the VERION group;another group of patients measure the preoperative measurement with Lenstar LS900,intraoperative lens implantation guided by manual marking method,referred to as Lenstar group.Observed the result of actual axial of IOL,uncorrected visual acuity,corrected visual acuity and refraction of preoperative,postoperative a day,a week,a month,three months.Results: 1.Reproducibility: Intraclass correlation coefficients and Cronbach's alpha values were higher than 0.9 for Ks,Kf,the astigmatic magnitude,the astigmatic axis,J0 and J45 measured by the VERION system.Comparability: The results of Ks and magnitude of astigmatism of VERION were larger than the i Trace(P<0.05)in the paired-samples t test.There were no statistical differences for the rest of parameters.The Bland–Altman graphs revealed the 95% limits of agreement(LOA)of J0,J45 and the astigmatic axis between VERION and i Trace were-0.31~0.35 D,-0.25~0.31 D and-13.5~12.3° respectively;There were no statistical differences for all parameters except for J45 in the paired-samples t test between the VERION and Lenstar LS900(P>0.05).The Bland–Altman graphs revealed the 95% LOA of J0,J45 and the astigmatic axis were-0.25~0.31 D,-0.27~0.36 D and-13.5~11 ° respectively;There were statistical differences for the results of Kf and magnitude of astigmatism between the VERION and manual keratometer(P<0.05).The Bland–Altman graphs revealed the 95% LOA of J0,J45 and the astigmatic axis between VERION and manual keratometer were-0.38~0.35 D,-0.41~0.42 D,-12.6~16.4 ° respectively.2.In a total of 243 eyes,the average rotation were 3.8±2.9 degrees,range from 0 to15 degrees.There were 23 eyes(9.5%)rotated 1 to 2 degrees,83 eyes(34.2%)rotated 3 to 5 degrees,53 eyes(21.8%)rotated 6 to10 degrees,7 eyes(0.4%)rotated more than 10 degrees.The average of external rotation angle of the right eye were 4.3±2.6 °,the average internal rotation angle were 3.4± 2.5 °,the comparison between the two groups was statistically significant(P < 0.001).The average of external rotation angle of the left eye were 5.0±3.2 °,the average internal rotation angle were 3.2±2.5 °,the comparison between the two groups was statistically significant(P=0.003);The average difference between VERION and manual marking were 3.2±3.8 °,the difference were 3.0±3.7 ° on the nasal side and 3.5±3.9 ° on the temporal side.3.In group VERION,the UCVA after 2~3 months was 0.73±0.20,BCVA was 0.91±0.19.The result of Group Lenstar was 0.64±0.20 and 0.84±0.18.Comparing the preoperative UCVA,BCVA and postoperative UCVA,BCVA respectively,there were no statistically significant differences between the two groups(P > 0.05).The residual astigmatism of group VERION was 0.45±0.33 D,and the postoperative residual astigmatism was 0.60±0.27.The results of Group Lenstar were 0.2±0.13 D and 0.73±0.52 D.Comparing the degree of astigmatism of two groups of patients before and after surgery was statistically significant(P < 0.05).The expected residual astigmatism and actual residual astigmatism were compared between the two groups,and there were statistically significant difference(P < 0.05).The difference between the actual implantation axis 1 day after the surgery and the planed implantation axis of the group VERION was 3(1,5)degree.The maximum value was about 11 degrees.The result of Lenstar group was 3(2,8)degree and the maximum value were about 12 degrees.There was no statistically significant difference when compare the actual implantation axis of the IOL and the planed axis between the two groups(Z=-1.175,P =0.24).Conclusion: 1.The VERION system is a reliable system for the measurement of keratometry and astigmatism.The keratometry and astigmatic magnitude of the VERION system have a good agreement with the i Trace,Lenstar LS900 and manual keratometer.However,the astigmatic axis measurements are significantly different among the four devices.2.The human eye will have a mild to moderate rotation when the body change from sited to supine position.There is no obvious regular on rotational direction,but the range of external rotation is larger than the internal range.3.VERION system and manual marking method can be used to mark the corneal horizontal position accurately.However,since the VERION is only suitable for patients with a larger eye and a distinct feature of the anterior segment,the device does not apply to each patient.4.Whether using VERION system emerging or traditional Lenstar combine with manual marking method can guide Toric IOL implantation accurately,reduce the amplitude of postoperative astigmatism effectively and improve the visual quality of patients. |
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