Correlation between size of pterygium and corneal astigmatism of patients receiving operation at Sichon Hospital, Nakhon Si Thammarat


  • Sarisa Supawimon โรงพยาบาลสิชล
  • Patchara Phosuwattanakul


corneal, astigmatism, pterygium


              Background: A pterygium is caused by the degeneration of the conjunctiva with more veins to grow and spread into the cornea. It covers the white part of eyes over the cornea due to astigmatism which can result in people vision and daily life.

              Objectives: To study correlative between size of pterygium and corneal astigmatism of patients and measure the size of pterygium that affects change of astigmatism significantly after surgery.

              Method: Observational Analytic Studies seek to address the research question. Participants were recruited from patient receiving treatment at Sichon hospital between January and December 2019. Patients were received pterygium and astigmatism measurement before surgery and after surgery at 1 month and 3 months. Data were analyzed using Spearman rank correlation coefficient, Pair t-test and Receiver Operating Characteristic (ROC)

              Results: In this study, 56 patients participated, 11 male (19.6%) and 45 female (80.4%) had pterygium, measured from the horizontal axis from the limbus, an average size of 3.48 millimeters, the average pterygium area was 11.04 square millimeters and it caused an astigmatism average 4.64 diopter. In addition, the pterygium area was positively correlated with astigmatism before and after surgery at a high level (0.80) with statistical significance (p-value<0.001) respectively. The compare levels of astigmatism before and after surgery at 1 month and 3 months was statistically significant decrease (p-value<0.001). Extension of pterygium exceeded 5.40 mm2 (89.47% of sensitivity, 55.56% of specificity) and 2.70 mm (79.0% of sensitivity, 55.6% of specificity) correlated a chance of reduction of astigmatism (2.01 diopter)

              Conclusions: The area of pterygium is positively correlated with astigmatism. In particular, pterygium surgery will effectively reduce the astigmatism of the cornea. Area of pterygium greater than 5.4 mm2 and 2.7 mm in horizontal size will affect the maximum reduction of astigmatism. This may be useful in patient selection for pterygium excision.


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How to Cite

Supawimon, S. ., & Phosuwattanakul, P. . (2020). Correlation between size of pterygium and corneal astigmatism of patients receiving operation at Sichon Hospital, Nakhon Si Thammarat . Region 11 Medical Journal, 34(4), 161–170. Retrieved from



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