Postoperative Corneal and Surgically Induced Astigmatism following Superior Approach Manual Small Incision Cataract Surgery in Patients with Preoperative Against-the-Rule Astigmatism.

Edmund Arthur,David Ben Kumah,Frank Yeboah Asiedu,Eugene Appenteng Osae,Ahmed Abdul Sadik,Felix Agyemang Mireku,Reynolds Kwame Ablordeppey

doi:10.1155/2016/9489036

Edmund Arthur, David Ben Kumah + Show 5 more

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https://doi.org/10.1155/2016/9489036

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Abstract

The aim of the study was to report postoperative corneal and surgically induced astigmatism (SIA) in patients with preoperative against-the-rule (ATR) astigmatism who underwent superior approach manual small incision cataract surgery (MSICS). 58 eyes of 58 cataract patients with preoperative ATR astigmatism were involved in this study. All patients had operable cataracts and underwent superior approach MSICS. Keratometric (K) readings were taken prior to surgery and at 12 weeks after surgery. Centroid values of SIA, preoperative astigmatism, and postoperative astigmatism were calculated using Cartesian coordinates based analysis. Wilcoxon signed rank test was used to compute statistical significance between mean preoperative and postoperative corneal astigmatism. Cohen's d was used as effect size measure. Centroid values of 1.42 D × 179, 2.48 D × 0, and 1.07 D × 1 were recorded, respectively, for preoperative astigmatism, postoperative astigmatism, and SIA. Wilcoxon signed rank test indicated that mean ± SD postoperative corneal astigmatism (2.80 ± 1.40 D) was statistically significantly greater than preoperative corneal astigmatism (1.49 ± 1.34 D), Z = −6.263, p < 0.0001. A high Cohen's d of 1.32 was found. Our results suggest statistical and clinically significant greater postoperative corneal astigmatism than preoperative corneal astigmatism for ATR astigmatism cataract patients who underwent superior approach MSICS.

Highlights

Cataract poses both a significant socioeconomic burden and a public health concern as it is the leading cause of blindness worldwide [1] and a major cause of visual disability throughout the African continent [2,3,4,5]
With an on-axis incision, there is a reduction in the corneal power of the steeper meridian because of the flattening effect of the incision leading to minimal postoperative corneal astigmatism
For patients with ATR astigmatism who have a flatter vertical corneal meridian, it would be expected that a superior approach manual small incision cataract surgery (MSICS) would flatten the already flatter vertical meridian leading to high postoperative corneal astigmatism

Summary

Introduction

Cataract poses both a significant socioeconomic burden and a public health concern as it is the leading cause of blindness worldwide [1] and a major cause of visual disability throughout the African continent [2,3,4,5]. The current treatment for cataract is surgery [6, 7] and while phacoemulsification remains the more advanced and technically superior method of cataract surgery, manual small incision cataract surgery (MSICS) is the most popular surgical management option for cataracts in developing countries [8,9,10,11]. This is mainly because of the low cost, short surgical time, reduced dependence on technology, and equivalent visual outcome to phacoemulsification [8,9,10,11]. Corneal or keratometric SIA is the vector difference between the preoperative corneal or keratometric astigmatism and the postoperative astigmatism [15]

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