J Korean Ophthalmol Soc.  2017 Sep;58(9):1023-1030. 10.3341/jkos.2017.58.9.1023.

Comparison of Corneal Higher-order Aberration before and after Excision of Pterygium

• Kim BJ
• Kim SW

• KMID: 2390064
• DOI: http://doi.org/10.3341/jkos.2017.58.9.1023

Abstract

PURPOSE
To investigate the types of corneal higher-order aberration (HOA) induced by pterygium, residual corneal HOA after pterygium surgery, and correlations between corneal HOA and the length of the pterygium.
METHODS
Fifty-three patients who underwent pterygium excision with conjunctival autograft were enrolled. Corneal HOA was measured by Pentacam® (Oculus Inc., Wetzlar, Germany) preoperatively and 3 months postoperatively in the 6-mm optical zone. Preoperative and postoperative HOAs of eyes with pterygium were compared with HOAs of the fellow eye to evaluate HOAs induced by pterygium and residual HOAs after pterygium surgery. Partial correlation analysis was performed to investigate the relationship between HOAs and the length of pterygium. A postoperative HOA less than 0.35 µm in size was defined as a favorable surgical outcome and the surgical indications were estimated using receiver operator characteristic (ROC) curve.
RESULTS
Horizontal coma, root mean square (RMS) of coma, oblique trefoil, horizontal trefoil, RMS of trefoil, and total HOA were significantly greater in the eye with preoperative pterygium. Three months after pterygium excision, only RMS of coma and total HOA remained significantly greater in eyes with pterygium. Vertical coma, horizontal coma, RMS of coma, and oblique tetrafoil were correlated with pterygium length. Pterygium excision when pterygium length was less than 1.6 mm led to favorable surgical outcomes.
CONCLUSION
Pterygium induced greater than third-order corneal HOAs and these HOAs were corrected via pterygium surgery. Longer pterygium length was associated with larger RMS of coma and larger coma RMS persisted after pterygium surgery. A pterygium length of 1.6 mm should be considered the cutoff for pterygium excision for reducing postoperative corneal HOA.

Keyword

Corneal aberration; Excision of pterygium; Higher-order aberration; Pentacam; Pterygium

MeSH Terms

Autografts
Coma
Humans
Lotus
Pterygium*

Figure

• 

  Figure 1 Preoperative slit-lamp photograph of the pterygium. Gray dashed lines were added to the image analysis for the measurement of length of pterygium. Length of pterygium (double-headed arrow): distance between the two vertical lines to the horizontal line passing through the corneal center (a), one line (b) tangent to the pterygium head and second line (c) tangent to the corneal limbus.

• 

  Figure 2 Receiver operator characteristic (ROC) curve for postoperative higher-order aberration under 0.35 µm versus length of pterygium. Std. = standard; Sig. = significance.

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