Effects of steep meridian incision on corneal astigmatism in phacoemulsification cataract surgery

Abstract

Choosing the corneal incision based on the preoperative steep meridian significantly decreased keratometric astigmatism at the temporal, superotemporal, and superior locations. Thus, it is desirable to place the corneal incision on the steep meridian in eyes with corneal astigmatism higher than 0.50 D.

The location of incision in cataract surgery and its impact on induced astigmatism

“…Studies on this subject are divided into two categories: studies which only demonstrated the results of cataract surgery with on-axis incisions and studies that compared this method with other methods. In a study of 95 eyes with on-axis incisions, Rho and Joo [21] found significant changes in the three superior, superotemporal, and temporal groups, but the greatest change was observed with the superior approach; the recommended incision site in this study for corneal astigmatism over half a diopter was the steep meridian. Altan-Yaycioglu et al [46] showed that cataract surgery performed at the steep meridian for patients with more than 0.75 D corneal astigmatism has the least changes with temporal incisions, and SIA was higher with nasal incisions.…”

“…Factors affecting astigmatism and SIA in cataract surgery include the type, length, and location of incision and suturing techniques [12 && ,13 && , [14][15][16][17][18][19][20][21][22][23][24][25]. Thus, different incision sites (on-axis, superior, superonasal, superotemporal, and temporal), limbal relaxing incisions (LRI), and toric intraocular lenses (IOL) are astigmatism correction strategies in cataract surgery.…”

“…Thus, different incision sites (on-axis, superior, superonasal, superotemporal, and temporal), limbal relaxing incisions (LRI), and toric intraocular lenses (IOL) are astigmatism correction strategies in cataract surgery. To date, the efficiency of these methods has been evaluated in different studies [16,21,23,[25][26][27][28][29][30][31][32][33]. Among astigmatism correction methods, the choice of incision site is the oldest method.…”

Cataract surgery audit at an Australian urban teaching hospital

“…It has been reported that superior corneal incisions induce greater corneal astigmatic change than temporal incisions. 9,10 Overall results from a study by Rho and Joo showed the surgically induced astigmatism (SIA) centroid (or summated vector mean) was 0.46 D at 92°in the superior incision group and 0.28 D at 79°in the temporal incision group. 10 Although the power of these vectors suggests less SIA for temporal incisions, the axes of the SIA are both near vertical.…”

“…9,10 Overall results from a study by Rho and Joo showed the surgically induced astigmatism (SIA) centroid (or summated vector mean) was 0.46 D at 92°in the superior incision group and 0.28 D at 79°in the temporal incision group. 10 Although the power of these vectors suggests less SIA for temporal incisions, the axes of the SIA are both near vertical. This is intuitively correct for temporal incisions (SIA being expressed, by con-vention, as a steepening effect) but appears anomolous for superior incisions.…”