| Objective: To evaluate the effect of phacoemulsification combined with limbal release incision(LRI)on preoperative corneal astigmatism by vector analysis,and to observe the effectiveness and safety of improving uncorrected visual acuity.To compare the efficiency and accuracy of astigmatism correction between Donnenfeld nomogram and Nichamin nomogram,in order to select and improve the LRI nomogram which is more suitable for Chinese people,and provide reference foundation for clinical management of corneal astigmatism.Methods: This investigation was a prospective intervention randomized controlled study.Patients with regular corneal astigmatism(0.75D?3.0D)in the ophthalmology ward from October 2018 to December 2019 were collected and divided into Donnenfeld nomogram and Nichamin nomogram according to the Donnenfeld nomogram and Nichamin nomogram designed before limbal release surgery.The depth and arc length of preoperative LRI arc incision were planned according to these two diagrams,and phacoemulsification combined with limbal release incision was performed.Corneal topography and visual acuity were examined before operation,1 month and 3 months after operation.The changes of uncorrected visual acuity,corneal astigmatism and axial direction,as well as intraoperative and postoperative complications were observed.The magnitude and axial position of astigmatism before and after operation were decomposed into X-axis and Y-axis components by Alpins vector analysis,and the evaluation indexes of these vector analysis were calculated,including surgical astigmatism(SIA),correction index(CI),success index(SI),flattening index(FI),calibration coefficient(CA)and so on.The experimental data and correction evaluation indexes of the two groups of LRI were compared to evaluate the effect and accuracy of correction of corneal astigmatism.The visual acuity,astigmatism and correction evaluation indexes of Donnenfeld group and Nichamin group at the same time after operation were compared by nonparametric test and ttest,and the eye and sex distribution were compared by chi-square test.The visual acuity and astigmatism of the two groups were compared by independent sample Mann-Whitney U test.Results: 1.A total of 64 cases(64 eyes)were included in the statistics,with an age of(72 ±12)years.There were 33 eyes in Donnenfeld group(D group),17 eyes in male and 16 eyes in female,and 31 eyes in Nichamin group(N group),including 14 eyes in male and 17 eyes in female.There was no significant difference in age and sex distribution,eye difference,preoperative uncorrected visual acuity,preoperative best corrected visual acuity and preoperative astigmatism between the two groups(P(29)0.05).2.The UCVA(logMAR)of group D before operation,1 month after operation and 3 months after operation were 0.63±0.25,0.16±0.11,0.11±0.86 respectively.There was significant difference in UCVA between preoperation and 1 month after operation(P(27)0.001),and there was significant difference between pre-operation and 3 months before operation(P(27)0.001).The UCVA of group N before operation,1 month after operation and 3 months after operation were 0.64±0.21,0.19±0.11,0.12±0.96 respectively.There was significant difference between pre-operation and 1 month after operation(P(27)0.001),and there was significant difference between preoperation and 3-month(P(27)0.001).There was no significant difference in UCVA between group D and group N before operation,1 month and 3 months after operation(all P(29)0.05).The postoperative uncorrected visual acuity in group D and group N was significantly improved as compared with that before operation.3.The astigmatism of Donnenfeld group was 1.62±0.45 D,0.80±0.24 D,0.67±0.26 D before operation,1 month and 3 months after operation.There was significant difference between preoperation and 1 month and 3 months after operation(all P(27)0.001).In Nichamin group,the astigmatism was 1.54±0.41 D,0.79±0.25 D,0.60±0.26 D before operation,1 month and 3 months after operation.There was significant difference between pre-operation and 1-month and 3-month after operation(all P(27)0.001).There was no significant difference between group D and group N before operation,1 month and 3 months after operation(all P(29)0.05).The astigmatism of the two groups decreased significantly 1 month and 3 months after operation compared with that before operation,and the corneal astigmatism of the two groups tended to be stable till 3 months after operation.4.The concomitant astigmatism(WTR)of Donnenfeld group changed from 4 eyes(12.1%)before operation to 10 eyes(30.3%)3 months after operation,and the(ATR)of retrograde astigmatism changed from 27 eyes(81.8%)before operation to 8 eyes(24.2%)3 months after operation.In Nichamin group,compliance astigmatism changed from 5 eyes(16.1%)before operation to 13 eyes(41.9%)3 months after operation,and reverse astigmatism changed from 24 eyes(77.4%)before operation to 6 eyes(19.4%)3 months after operation.The axial position of astigmatism in group D and group N was(55.91±68.65)° and(115.61±69.38)°,respectively,with significant difference(P(27)0.003),and the axial shift(AS)was(49.55±47.70)° and(68.68±53.69)° respectively 3 months after operation,and there was no distinct difference(P(29)0.05).Three months after operation,compared with those before operation,the number of cases of concomitant astigmatism and oblique astigmatism increased significantly,while the number of cases of reverse astigmatism decreased significantly in both groups.5.The astigmatism vector analysis of corneal astigmatism in Donnenfeld group: surgical induced astigmatism(SIA)was 1.52±0.59,correction index(CI)was 0.87±0.23,success index(SI)was 0.38±0.12,flattening index(FI)was 0.54±0.28,calibration coefficient(CA)was 1.24±0.36.The astigmatism vector analysis of corneal astigmatism in Nichamin group: surgical astigmatism(SIA),correction index(CI),success index(SI),flattening index(FI)and calibration coefficient(CA)were 1.36±0.58,0.95±0.28,0.41±0.12,0.68±0.37 and 1.16±0.39 respectively.There was no distinct difference in SIA,CI,SI,FI and CA between Donnenfeld group and Nichamin group(all P(29)0.05).No complications such as corneal penetration,posterior capsule rupture,incision leakage,incision rupture or poor healing,corneal infection,IOL dislocation,Cystoid macular edema and endophthalmitis occurred after operation.Conclusion: 1.The efficiency and accuracy of corneal astigmatism correction of Donnenfeld nomogram and Nichamin nomogram are similar,and both can effectively correct anterior corneal astigmatism.2.Phacoemulsification combined with limbal release incision is a simple,effective,economical and safe method to correct regular corneal astigmatism before cataract surgery,which could effectively improve the postoperative uncorrected visual acuity and improve the visual function of patients. |
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