A comparative study of preoperative and postoperative changes in corneal astigmatism after pterygium excision by different techniques

Purpose:

To study the changes in corneal astigmatism before and after pterygium excision as well as with differences between various surgical techniques (bare sclera, conjunctival autograft, amniotic membrane graft).

Methods:

The study population included 71 patients with primary pterygium who underwent surgery. The surgical techniques used differed among the study population. All the patients were preoperatively assessed for visual acuity, anterior and posterior segments, autorefraction, and autokeratometry. After surgery, the patients were assessed for visual acuity, autorefraction, and autokeratometry on day 5, 1 month, and 3 months and the results were analyzed. Paired and unpaired t-tests were used to compare the variables. The probability level of 0.05 was considered as statistically significant.

Results:

The reduction in the mean preoperative astigmatism of 3.47 ± 1.74 Diopters (D) to 1.10 ± 0.78 D 3 months after surgery was statistically significant (P < 0.0001). Bare sclera, conjunctival autograft, and amniotic membrane graft techniques exhibited changes in astigmatism amounting to 1.85 ± 0.88 D, 2.55 ± 1.26 D, and 2.67 ± 1.44 D, respectively. Pterygium excision surgeries using amniotic membrane graft and conjunctival autograft techniques were more effective than pterygium excision surgery using bare sclera technique in reducing astigmatism.

Conclusion:

Pterygium excision results in significant reduction in astigmatism which leads to improvement in visual acuity. Amniotic membrane graft and conjunctival autograft are better surgical techniques than bare sclera as far as reducing astigmatism is concerned.