Effect of capsular tension ring on the accuracy of Barrett universal Ⅱ intraocular lens calculation formula in patients with high myopia

AIM: To evaluate the effect of capsular tension ring(CTR)on the stability and accuracy of Barrett universal Ⅱ intraocular lens(IOL)calculation formula in patients with high myopia and cataract.METHODS:Prospective study. A total of 40 cases(80 eyes)of high myopia and cataract that visited our hospital from January to June 2022 were selected. The patients were divided into CTR group and blank group by random number table method, with 40 eyes in each group. All patients were measured by IOL Master, and the actual implanted IOL power and predicted postoperative power were calculated according to Barrett universal Ⅱ formula. The uncorrected visual acuity(UCVA)and best corrected visual acuity(BCVA)at 6 mo after surgery were recorded, and the mean absolute error(MAE)was compared at 6 mo after surgery. Furthermore, the stability of postoperative refractive status and the relationship between the predicted postoperative diopter and CTR were evaluated.RESULTS:The UCVA and BCVA of the two groups were improved at 6 mo after operation(P>0.05), and there was no significant difference in UCVA and BCVA between the two groups at each time point(all P>0.05). After the implantation of IOL in 80 eyes based on the Barrett universal Ⅱ formula, the predicted postoperative diopter was -2.01±0.71 D, the actual postoperative diopter was -1.64±0.88 D, and the MAE was 0.37±0.98 D in the CTR group; in the blank group, the predicted diopter was -2.12±0.64 D, the actual diopter was -1.54±0.88 D, and the MAE was 0.58±0.31 D. The difference between the two groups was statistically significant(P<0.05). According to the axial length, CTR implantation can effectively reduce refractive error for any axial length(P>0.05). With the grouth of axial length, the MAE value increased. The postoperative MAE value of patients with axial length ≥30 mm was statistically different between the two groups(P<0.05).The proportion of hyperopic drift was 18%(7/40)in the CTR group and 30%(12/40)in the blank group, respectively, with a significant difference between the two groups(P<0.05).CONCLUSION: For patients with high myopia and cataract, the Barrett universal Ⅱ formula has high accuracy in predicting postoperative diopter. Intraoperative implantation of CTR can not only maintain the shape of the capsule bag, effectively prevent the intraoperative rupture of the suspensory ligament of the lens and make the IOL more neutral, but also is conducive to the early stability of postoperative diopter of cataract patients. It also provides more stable refractive results and reduces refractive drift. For myopic patients considering CTR implantation, it is recommended to increase the preoperative reserve diopter of -0.50 D to achieve the ideal refractive state.