Influence of different length corneal limbal incisions on the anterior and posterior corneal astigmatism after phacoemulsification / 中华实验眼科杂志

ABSTRACT

Background The different incisions in phacoemulsification,including the length,location and shape etc.,can cause surgery-induced astigmatism ( SIA ).But the SIA caused by 2.2 mm,3.0 mm corneal limbal incision after phacoemulsification,especially the change of posterior corneal surface astigmatism is still rarely reported. Objective This study was to investigate the anterior,posterior and total corneal SIA and compare their differences between phacoemulsification and foldable intraocular lens (IOL) implantation with 2.2 mm and 3.0 mm corneal limbal incisions. Methods Seventy-one eyes of 47 cases were randomly divided into two groups with matched age,visual acuity and astigmatism degree.Phacoemulsification and IOL implantation with 2.2 mm incision at the steepest corneal meridian was performed on the patients of 2.2 mm incision group,and the same surgery was adopted with 3.0 mm incision as 3.0 mm incision group.Corneal curvature radius and central corneal thickness were measured by Pentacam at 1 day before surgery and 1 week,1 month and 3 months after surgery respectively.The anterior and posterior corneal surface SIAs were calculated according to the flat axis and steep axis of corneal curvature and the air and the cornea refractive index.Based on the anterior and posterior surface SIAs,the total corneal SIA was then calculated using the vector analysis method.Jaffe/Clayman vector method was used to calculate the anterior and posterior and total corneal SIAs in the different time points,and the differences were compared between the two groups.Oral informed consent was obtained from each subject prior to the trial. Results The mean anterior and posterior surface corneal SIAs appeared to be lower in 2.2 mm incision group compared with 3.0 mm incision group at postoperative 1 day,1 week,1 month and 3 months but were not significantly different among groups at various time points ( anterior SIAP =0.290 ; posterior SIAP =0.740 ; total SIA0.434 ).The mean anterior corneal surface SIAs were significantly lower at the postoperative 3 months than those at postoperative 1 day,1 week in both groups(2.2 mm incision groupP=0.020,0.036;3.0 mm incision groupP=0.006,0.023 ).The posterior corneal surface SIAs were (0.70±0.43 ) D and (0.75 ±0.54 ) D at 1 day in 2.2 mm incision group and 3.0 mm inscision group,respectively,and significantly decreased posterior corneal surface SIAs were found in postoperative 1 week,1 month and 3 months compared with 1 day in both groups ( 2.2 mm incision groupall P =0.001 ; 3.0 mm incision groupP=0.028,0.044,0.032).The total corneal surface SIA showed significant differences between 1 day and 1 week,1 month,3 months after surgery ( 2.2 mm incision groupP =0.015,0.002,0.002 ; 3.0 mm incision groupP =0.049,0.007,0.016 ). Conclusions There are no significant differences in the anterior,posterior and total corneal surface SIAs between 2.2 mm and 3.0 mm incisions after phacoemulsification with IOL implantation.The SIA is gradually reduced with the prolongation of postoperative time.