Surgeons may not need to consider the type of astigmatism a patient presents with when planning a surgical correction of astigmatism, according to a study published in the British Journal of Ophthalmology.
Researchers included 390 eyes of 390 patients with anterior corneal astigmatism who underwent phacoemulsification and 390 eyes of 390 healthy controls in a retrospective cohort study. They stratified participants according to astigmatism type (against-the-rule (ATR), with-the-rule (WTR), and oblique) and included an equal number of participants in each group (n=130 for all). Investigators obtained keratometry measurements at baseline (the day that surgically induced astigmatism stabilized) and during a follow-up visit conducted 8 years or more after the initial visit. The team classified changes in corneal astigmatism according to vertical/horizontal (Rx) and oblique astigmatism components (Ry), and compared changes in Rx and Ry values among eyes with and without surgery.
Researchers determined that mean corneal astigmatism changes (both Rx and Ry) exhibited a similar degree of ATR change from baseline to follow-up (0.2-0.3 D) and did not differ significantly between astigmatism types (P ≥.4566 for both Rx and Ry, all astigmatism types). These changes occurred regardless of whether the participants had surgery or not.
“Long-term corneal astigmatic changes towards ATR astigmatism occurred to a similar extent in eyes having ATR, WTR, oblique astigmatism and were comparable between eyes with and without surgery, suggesting that astigmatism type need not be considered when planning astigmatism correction,” according to the researchers.
The study was limited by a relatively short follow-up period.
Hayashi K, Sasaki H, Hirata A, Yoshimura K. Comparison of long-term astigmatic changes following cataract surgery among types of corneal astigmatism. Br J Ophthalmol. Published online March 17, 2022. doi:10.1136/bjophthalmol-2021-321026