[Effect of pterygium operation on preoperative astigmatism. Prospective study].

High-grade corneal astigmatism is considered to be an indication for pterygium surgery. However, no prospective studies have been carried out to determine whether a pterygium operation really reduces preoperative astigmatism. Therefore, we prospectively examined 23 patients who were operated on for pterygia at the University Eye Clinic in Freiburg in 1991. Pre- and postoperative corneal astigmatism was measured by ophthalmometry or retinoscopy. Preoperative astigmatism after pterygium surgery was reduced or unaltered in 19 patients. In 4 patients, the postoperative astigmatism was increased. The mean preoperative astigmatism was 2.41 D in the horizontal meridian, the postoperative astigmatism 1.29 D. The reduction was statistically significant (P < 0.0001, Wilcoxon test). The higher the preoperative astigmatism, the higher the difference between pre- and postoperative astigmatism (r2 = 0.88, P = 0.0001). Our technique of pterygium surgery (free conjunctival transplant after polishing the cornea, limbus, and sclera) reduces preoperative astigmatism. Thus, high-grade astigmatism can be regarded as an indication for pterygium surgery.