Effects of Pterygium Excision on Corneal Curvatures
Abstract
Objective: To determine the difference in mean corneal curvatures before and after pterygium excision, by using automated refraction and keratometry.
Methodology: This quasi-experimental study was conducted at Eye Unit-I, Bahawal Victoria Hospital, Bahawalpur, from March 2010 to August 2010. Thirty patients with primary pterygium were analyzed before and after pterygium surgery for corneal curvature changes. Automated refraction and Automated keratometry were used to calculate the cylindrical error and the corneal surface power respectively. The mean and standard deviation were calculated for the corneal curvatures and the refractive cylinder before and after the operation. Paired sample t-test was used to compare the corneal curvatures and refractive cylinder before and after pterygium excision. P-value < 0.05 was considered significant.
Results: The preoperative cylindrical error decreased from 4.32 + 1.88 D to 2.11 + 1.96D postoperatively. Similarly, before surgery, the keratometry readings were 43.71 + 1.12 D in horizontal meridian and 44.94+ 1.41 D in vertical meridian. One week after the pterygium surgery these values were 44.45 + 0.85 D in horizontal meridian and 45.23 + 0.78 D in vertical meridian.
Conclusion: Pterygium excision brings a statistically significant change in corneal curvatures which leads to a decrease in cylindrical correction needed. This causes an improvement in subjective visual acuity in patients who have undergone pterygium surgery.
Methodology: This quasi-experimental study was conducted at Eye Unit-I, Bahawal Victoria Hospital, Bahawalpur, from March 2010 to August 2010. Thirty patients with primary pterygium were analyzed before and after pterygium surgery for corneal curvature changes. Automated refraction and Automated keratometry were used to calculate the cylindrical error and the corneal surface power respectively. The mean and standard deviation were calculated for the corneal curvatures and the refractive cylinder before and after the operation. Paired sample t-test was used to compare the corneal curvatures and refractive cylinder before and after pterygium excision. P-value < 0.05 was considered significant.
Results: The preoperative cylindrical error decreased from 4.32 + 1.88 D to 2.11 + 1.96D postoperatively. Similarly, before surgery, the keratometry readings were 43.71 + 1.12 D in horizontal meridian and 44.94+ 1.41 D in vertical meridian. One week after the pterygium surgery these values were 44.45 + 0.85 D in horizontal meridian and 45.23 + 0.78 D in vertical meridian.
Conclusion: Pterygium excision brings a statistically significant change in corneal curvatures which leads to a decrease in cylindrical correction needed. This causes an improvement in subjective visual acuity in patients who have undergone pterygium surgery.
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