COMPARISON OF PREOPERATIVE AND POSTOPERATIVE ASTIGMATISM FOLLOWING PTERYGIUM EXCISION WITH CONJUNCTIVAL AUTOGRAFT

BACKGROUND Pterygium is a common ocular surface disorder characterised by triangular fibrovascular subepithelial ingrowth of degenerative bulbar conjunctival tissue over the limbus onto the cornea in the interpalpebral area. It is usually present only on the nasal side. It can cause astigmatism by distorting the corneal topography and can also obscure the optical centre of the cornea in advanced cases. Excision of pterygium leads to statistically significant reduction in astigmatism, which improves vision significantly. Aims and Objectives- 1. To correlate the degree of pterygium-induced astigmatism with pterygium size. 2. To analyse the change in pterygium-induced astigmatism after its excision and autograft placement. MATERIALS AND METHODS This was a prospective observational study of 50 patients with primary nasal pterygium who underwent pterygium excision surgery with conjunctival autografting at Department of Ophthalmology, Mahatma Gandhi Medical College and Hospital, Sitapura, Jaipur from March 2017 to February 2018. Pterygium was graded into Grade I, II, III and IV according to its size and pre-operative keratometry readings were compared with findings on day 1, 1 week, 1 month and 3 months post-operatively. The data was compared using student's paired t-test. RESULTS As the grade of pterygium increased, the mean value of astigmatism caused by it also increased from 1.44 +/- 0.66 D in Grade I, 2.50 +/- 1.05 in Grade II and 3.65 +/- 0.56 in Grade III to 5.68 +/- 1.25 D in Grade IV. The mean change of astigmatism was 1.40 +/- 0.26 (p<0.0001) on 1st post-op day, 1.98 +/- 0.24 (p<0.0001) 1-week post-op, 2.54 +/- 0.24 (p<0.0001) 1-month post-op and 2.58 +/- 0.24 (p<0.0001) 3 months post-operatively. CONCLUSION Astigmatism induced is directly proportional to the grade of pterygium. Pterygium excision surgery reduced the pterygium-induced astigmatism significantly.