| Objective: To study the relationship between pterygium size and preoperative and postoperative induced corneal astigmatism.Also to analyze the changing tendency of corneal astigmatism and the best corrected visual acuity after the operation and to provide the reference for clinical surgery.Methods: This thesis adopts the prospective study.On the basis of inclusive and exclusive criteria,this study was conducted on 56 eyes of 56 patients with unilateral primary pterygium who attended the three department of ophthalmology of the First Affiliated Hospital of Dalian Medical University Department from March to October in2014.The general information and medical history of all research-involved patients were collected.They were taken examinations of UCVA(Uncorrected Visual Acuity),BCVA(Best-spectacles corrected visual acuity),intraocular pressure,autorefraction,keratometry,slit lamp,anterior segment photography and so on.Meanwhile,the size of pterygum including extension,width and total area were calculated.The extension of pterygium is the distance from the middle to the top of limbal.The width is the chord extension of pterygium in limbal.The total area of corneal astigmatism was calculated according to the extension and width(calculation method: extension*width/2).The results of keretometry and autorefraction were used to record the size and shaft position of corneal astigmatism.All above objects accept the local infiltration anesthesia for the pterygium excision combined with conjunctival autograft transplantation that were operated by one skilled physician.The patients with UCVA,BCVA,surgery eyes,thevalue of control eyes and the shaft position were followed up after operation for one week,one month and three months.This study analyzed the relationship between pterygium size and preoperative corneal astigmatism,discussed the size of pterygium and postoperatively residual corneal astigmatism and knew about the tendency of the value of corneal astigmatism and BCVA from preoperation to postoperation for one week,one month and three months.The value of P<0.05 as discrepancy is of statistic significance.Results: The mean of the extension of pterygium onto cornea was a mean of 4.0±1.2mm.The width ranged with a mean of 5.1±1.0 mm.The total area ranged with a mean of 10.5±4.4 mm.The corneal astigmatism had the best correlation followed by pterygium extension,width and total area(correlation value: r=0.601,r=0.403,r=0.543).All the three values were statistically significant(P<0.05).The multiple linear regression showed that a stronger correlation was noted between pterygium extension and the corneal astigmatism(P<0.05).Both pterygium extension,total area and the corneal astigmatism after three months had a positive correlation,with respective r=0.506,r=0.422.All the three values were statistically significant(P<0.05).Pterygium width had no correlation with corneal astigmatism after surgery for three months(P>0.05).The multiple linear regression showed a stronger correlation was noted between pterygium extension and the value of corneal astigmatism(P<0.05).The three months corneal astigmatism has a strongly positive correlation with the preoperative value of corneal astigmatism,with respective r=0.414,The value was statistically significant(P<0.05).The preoperative value of corneal astigmatism was 3.0±1.9 D,and the postoperative values were respective 1.65±1.50 D,1.09±1.09 D and 1.02±1.11 D after one week,one month and three months.The value of corneal astigmatism had a obvious downturn.Compared with the value before surgery,that in three different periods had statistic significance(P<0.05).Compared with the value after operation for one month and three months,the differences were statistically significantly.However, when the postoperative figure for one month was compared with that of three months,the differences had no statistic significance(P>0.05).The BCVA was apparently rising after one week,one month and three month.When the BCVA in those three different stages were respectively compared with that before operation,all differences and statistic significance(P<0.05).When the BCVA after operation for one week was compared with that for one month and three months,the differences were statistically significantly.However,when the postoperative BCVA for one month was compared with that of three months,the differences had no statistic significance(P>0.05).Conclusion: 1.The corneal astigmatism has a strongly positive correlation with pterygium extension.2.The value of three months corneal astigmatism positively correlates with pterygium extension.3.The three months corneal astigmatism has a strongly positive correlation with the preoperative value of corneal astigmatism.4.The pterygium excision can improve corneal astigmatism and eyesight.The corneal astigmatism and BCVA will become stable after surgery for one month. |
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