Time to Keratometric Stability After Pterygium Excision and the Associated Factors: A Clinical Perspective

Abstract

Purpose

To determine the percentage of eyes with corneal astigmatic power stability and mean corneal keratometric power at 6-month post-pterygium excision, and to identify the time, and the associated factors, required to achieve stability.

Methods

This prospective observational study enrolled patients undergoing pterygium excision. Patients were evaluated for baseline characteristics and keratometric data before and every month after pterygium excision for six months using IOL Master 500^® (Carl Zeiss, Meditec). Clinically stable corneal astigmatic power and keratometric power were, respectively, defined as changes in these parameters of less than 0.25 and 0.27 diopters after two consecutive visits. Time to corneal astigmatic and keratometric power stability, as well as factors associated with the stability, were analyzed.

Results

Forty percent and 73.3% of eyes, respectively, demonstrated corneal astigmatic and corneal keratometric stability at six months post-operation. Within three months of reaching initial stability, the corneal astigmatic power and the mean keratometric power showed instability in 46.7% and 27.3% of patients, respectively. No patients with keratometric stability for more than three months became unstable during the study period. The extension of pterygium exceeding 3.0 mm was associated with a delay in time to corneal astigmatic stability (HRadjusted 0.41; 95% CI 0.19–0.89; P= 0.02).

Conclusion

According to the clinical relevance, 40% and 73% of patients, respectively, presented corneal astigmatic and keratometric stability within six months post-operation. Patients with a pterygium extension of more than 3 mm required a longer time for corneal astigmatic stability. It is recommended that keratometric stability be achieved for at least three months before commencing with additional procedures.

Keywords:

• pterygium
• corneal curvature
• keratometry
• astigmatism

Acknowledgments

This study was supported by Ratchapiseksompotch Fund (Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand, grant number RA57/049).

Disclosure

Ms Duangratn Niruthisard reports grants from Ratchadaphiseksomphot Endowment Fund, during the conduct of the study. The authors report no other potential conflicts of interest in this work.