Effect Of Pterygium On Corneal Astigmatism, Irregularity And Higher-Order Aberrations: A Comparative Study With Normal Fellow Eyes

To evaluate the effect of nasal pterygium on corneal astigmatism, irregularity and higher-order aberrations (HOAs).

Retrospective case-control study.

Patients who had unilateral nasal pterygium and normal fellow eye were included. Photography was used to measure the length, width, and area of the pterygium. Grading of the pterygium was categorized based on the relative translucency. Anterior segment optical coherence tomography was used to measure the thickness of the pterygium. Corneal astigmatism, irregularity and HOAs were analyzed using corneal topography. The left eye data were transformed by mirroring the vectors on the y-axis.

Fifty-nine patients were enrolled. The pterygium significantly increased with-the-rule corneal astigmatism and corneal irregularity. Trefoils, horizontal coma, and quatrefoils were significantly induced by the pterygium. In multiple linear regression analysis, pterygium-induced corneal astigmatic/irregularity values and horizontal trefoil/quatrefoil were significantly associated with the area of the pterygium. The length of the pterygium was an independent inducer of oblique trefoil/quatrefoil, while horizontal coma induced by the pterygium was independently associated with both its length and width. The thickness of the pterygium was not correlated with any optical parameters.

Nasal pterygium significantly induces corneal astigmatism, irregularity and some HOAs. These pterygium-associated changes in optical parameters could be predicted by the length, width and area of the pterygium and might provide surgeons with additional insight when making decisions about surgery.