Elsevier

American Journal of Ophthalmology

Volume 156, Issue 6, December 2013, Pages 1112-1119.e2
American Journal of Ophthalmology

Original article
Axis Difference Between Corneal and Internal Astigmatism to Consider for Toric Intraocular Lenses

https://doi.org/10.1016/j.ajo.2013.06.039Get rights and content

Purpose

To evaluate the axis difference between corneal and internal astigmatism in patients with cataract, because if the axis of corneal astigmatism is opposite to the axis of internal astigmatism, the amount of refractive astigmatism will increase after cataract surgery owing to disappearance of the neutralizing effect of the crystalline lens on corneal astigmatism.

Design

Retrospective cross-sectional study.

Methods

One hundred eighty patients (180 eyes) who underwent cataract surgery were enrolled. Preoperative refractive, corneal, and internal astigmatism were measured using a wavefront analyzer and retrospectively analyzed. On-axis was defined as an axis difference between corneal and internal astigmatism of 180 ± 10 degrees. Opposite-axis was defined as an axis difference between corneal and internal astigmatism of 90 ± 10 degrees. The remaining cases were defined as oblique-axis.

Results

Corneal and internal astigmatic vectors showed a tendency to have the opposite direction. An on-axis difference was seen in 10.0% of patients (18 eyes), oblique-axis in 69.4% of patients (125 eyes), and opposite-axis in 20.6% of patients (37 eyes). Of all eyes, 10.0% had an opposite-axis difference with more than 1.00 diopter (D) of both corneal and internal astigmatism. The percentage of eyes with an opposite-axis difference between corneal and internal astigmatism had a tendency to increase as corneal and internal astigmatism increased (P = .030 and P = .003, respectively).

Conclusions

A total of 10.0% of all eyes with cataract had an opposite-axis difference with more than 1.00 D of both corneal and internal astigmatism. In these cases, surgical techniques to reduce corneal astigmatism, such as a toric intraocular lens, should be recommended to increase patient satisfaction.

Section snippets

Study Population

This retrospective cross-sectional study included 180 eyes from 180 consecutive patients who underwent cataract surgery with implantation of an IOL at our institute between May 24, 2011 and May 30, 2012. Patients whose corneal and internal astigmatism could be measured using a wavefront analyzer (KR-1W; Topcon, Tokyo, Japan) were included. Patients with best-corrected visual acuities (BCVA) less than 20/40 in the operated eye after cataract surgery, prior ocular surgery (such as pars plana

Results

A total of 180 eyes from 180 patients who underwent uncomplicated cataract extraction with implantation of an IOL in the bag were included in this study. Of the 180 patients, 61 were men and 119 were women. The mean (± SD) age was 66.1 (± 10.6) years (range, 39-93 years). The laterality, mean preoperative corneal power, anterior chamber depth, axial length, and predicted refraction are given in Table 1.

The mean cylinder power and J0, and J45 components for the preoperative refractive, corneal,

Discussion

The present study tried to evaluate the axis difference between corneal and internal astigmatism in patients with cataract. Corneal and internal astigmatic vector showed a tendency to have opposite directions. Corneal astigmatism can be reduced by several surgical techniques at the time of cataract surgery. It is important to select the proper patients who can be satisfied with these surgical techniques by reducing corneal astigmatism. Patients who have an opposite-axis difference between their

Youngsub Eom, MD, is a clinical instructor of the Department of Ophthalmology at the Korea University College of Medicine. Dr Eom graduated from Korea University Medical School in 2007, where he completed his ophthalmology residency in 2012. His special interests are optics, visual function and cataract and refractive surgery.

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Youngsub Eom, MD, is a clinical instructor of the Department of Ophthalmology at the Korea University College of Medicine. Dr Eom graduated from Korea University Medical School in 2007, where he completed his ophthalmology residency in 2012. His special interests are optics, visual function and cataract and refractive surgery.

Jong-Suk Song, MD, PhD is an associate professor at the Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea. He is currently Secretary of the Korean Society of Cataract and Refractive Surgery (KSCRS). His research interests include corneal endothelium, ocular imaging, phakic IOL and premium IOL.

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