Steep Axis Incision Versus Temporal Incision in Microcoaxial Cataract Surgery

Woong-Joo Whang; Yong-Soo Byun; Choun-Ki Joo

doi:10.3341/jkos.2011.52.1.29

Journal List > J Korean Ophthalmol Soc > v.52(1) > 1008989

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Whang, Byun, and Joo: Steep Axis Incision Versus Temporal Incision in Microcoaxial Cataract Surgery

Original Article

J Korean Ophthalmol Soc 2011;52(1):29-33.

Published online: 7 September 2011

DOI: https://doi.org/10.3341/jkos.2011.52.1.29

Steep Axis Incision Versus Temporal Incision in Microcoaxial Cataract Surgery

Woong-Joo Whang, MD, Yong-Soo Byun, MD, Choun-Ki Joo, MD, PhD

Department of Ophthalmology, Seoul St. Mary's Hospital, The Catholic University of Korea School of Medicine, Seoul, Korea

Address reprint requests to Choun Ki Joo, MD, PhD Department of Ophthalmology, Seoul St. Mary's Hospital #505 Banpo-dong, Seocho-gu, Seoul 137-701, Korea Tel: 82-2-2258-1188, Fax: 82-2-533-3801, E-mail: ckjoo@catholic.ac.kr

Received 14 June 2010 Revised 25 August 2010 Accepted 9 December 2010

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose

To determine if a difference exists in surgically-induced astigmatism (SIA) and the mean change in keratometric astigmatism in patients who underwent microcoaxial cataract surgery (MCCS).

Methods

A prospective study including 193 eyes with astigmatism of greater than 0.5 diopters was performed. The eyes were randomized into two groups: (1) 95 eyes with steep axis incision, and (2) 98 eyes with temporal incision. A 2.2-mm microcoaxial phacoemulsification was performed. The UCVA, BCVA and corneal topography (Orbscan II, Bausch & Lomb) were measured preoperatively and three months postoperatively. Surgically induced astigmatism was calculated via vector analysis, and the mean change in keratometric astigmatism was also calculated.

Results

There were no significant differences in UCVA or BCVA between the two groups three months postoperative. The mean SIA was 0.45 ± 0.27 diopters in the steep axis incision group and 0.30 ± 0.17 diopters in the temporal incision group. In the steep axis incision group, the mean keratometric astigmatism showed a mean reduction of 0.31 ± 0.37 diopter (WTR: 0.37 D; oblique: 0.35D; ATR: 0.16 D), while the mean keratometric astigmatism showed a mean increase of 0.06 ± 0.29 diopters (WTR: 0.15 D increased; oblique: 0.11 D increased; ATR: 0.13 D reduced) in the temporal incision group. There were statistically significant differences in SIA and change in astigmatism between the two groups (p = 0.002, p = 0.000).

Conclusions

In MCCS, steep axis incision achieved superior astigmatism correction in patients having with-the-rule or oblique astigmatism of greater than 0.5 diopters.

Keywords: Clear corneal incision, Microcoaxial cataract surgery, Steep axis incision, Surgically-induced astigmatism

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Figure 1.

UCVA and BCVA in the 2 groups.

Figure 2.

SIA (surgically induced astigmatism) and change in cylinder (absolute value of preoperative cylinder– absolute value of postoperative cylinder) shows statistically sigsigicant difference between 2 groups). In change in cylinder, positive result indicates decrease in astigmatism and negative result indicates increase in astigmatism.

^*Mann-Whitney U test.

Table 1.

Demographics and preoperative data in each group

	(1) Steep axis incision	(2) Temporal incision	^* p value
Eyes	95	98	
With-the-rule	50 (52.6%)	48 (49.0%)	
Oblique	22 (23.3%)	30 (30.6%)	
Against-the-rule	23 (24.2%)	20 (20.4%)	
Ages (mean year ± SD)	70.77 ± 9.52	67.52 ± 10.28	0.750
Preoperative visual acuity (logMAR)			
UCVA	0.79 ± 0.43	0.77 ± 0.50	0.309
BCVA	0.61 ± 0.30	0.63 ± 0.35	0.665
Mean tophographic cylinder (mean power ± SD)	1.02 ± 0.47	0.96 ± 0.69	0.125

UCVA=uncorrected visual acuity, BCVA = best corrected visual acuity.

^* Mann-Whitney U test.

Table 2.

Surgically indeced astigmatism according to preoperative astigmatism in both (1) steep axis incision group and (2) temporal incision group

	With-the-rule	Against-the-rule	Oblique	^† p value
(1) Steep axis incision	0.52 ± 0.28	0.26 ± 0.12	0.47 ± 0.25	p<0.05
(2) Temporal incision	0.31 ± 0.25	0.25 ± 0.15	0.34 ± 0.27	p = 0.11
^* p value	p<0.05	p = 0.77	p<0.05	

^* Mann-Whitney U test

^† Kruskal-Wallis H test.

Table 3.

Change in cylinder according to preoperative astigmatism in both (1) steep axis incision group and (2) temporal incision group. Change in cylinder: absolute value of preoperative cylinder– absolute value of postoperative cylinder. Positive result indicates decrease in astigmatism and negative result indicates increase in astigmatism

	With-the-rule	Against-the-rule	oblique	^† p value
(1) Steep axis incision	0.37 ± 0.19	0.16 ± 0.15	0.35 ± 0.18	p<0.05
(2) Temporal incision	−0.15 ± 0.26	0.13 ± 0.18	−0.11 ± 0.24	p<0.05
^* p value	p<0.05	p = 0.83	p<0.05	

^* Mann-Whitney U test

^† Kruskal-Wallis H test.

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