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European Ophthalmic Review Highlights Treatment of Corneal Astigmatism at the Time of Cataract Surgery, What Can Be Promised George Beiko Assistant Clinical Professor, Department of Ophthalmology, McMaster University, Ontario, Canada Abstract The treatment of corneal astigmatism at the time of cataract surgery is commonplace. Corneal incisional surgery and toric intraocular lenses (IOLs) are routinely utilised; the role of each modality is understood and defined. Although technological advances have been made in the assessment of the cornea and in the execution of the treatment options, recent innovations in toric IOL designs may be more significant for the comprehensive ophthalmologist. Keywords Cataract surgery, corneal astigmatism, toric IOLs Disclosure: George Beiko has nothing to disclose in relation to this article. No funding was received in the publication of this article. Open Access: This article is published under the Creative Commons Attribution Noncommercial License, which permits any non-commercial use, distribution, adaptation and reproduction provided the original author(s) and source are given appropriate credit. Received: 27 November 2015 Published Online: 21 December 2015 Citation: European Ophthalmic Review, 2015;9(2):102–3 Correspondence: George Beiko, 180 Vine St, Ste 103, St Catharines, Ontario L2R 7P3, Canada E: Cataract surgery offers the ophthalmic surgeon an opportunity to treat corneal astigmatism. However, the question remains, what is reasonably possible and what is needed to attain this possibility? As an initial step, the question needs to be asked, how much astigmatism is significant? Employing adaptive optics and bench top studies, it has been shown that there is little visual benefit in reducing astigmatism to less than 0.50 D. 1 In terms of optical quality 1.00 D or greater of astigmatism results in decreased vision below 20/20 in 50  % of patients (Steve Schallhorn, review of 4,956 premium intraocular lens [IOL] cases, personal communication). However, the significance of residual astigmatism is probably best expressed in terms of when patients would be willing to undergo another procedure for correction of that astigmatism; 90 % of patients are unwilling to have further surgical intervention unless the astigmatism is greater than 1.00 D. 2 Thus, the majority of surgeons will offer management of astigmatism to patients with 0.75 to 1.00 D of corneal astigmatism. 3 Approximately 40 % of patients coming to cataract surgery have greater than 1.0 D of corneal astigmatism and could be considered as candidates for intervention. Accuracy in the treatment of astigmatism requires that the contribution of posterior corneal curvature and the drift of the astigmatism post- operatively with time be considered. Currently, the recommendation is to target an outcome with a small degree of with-the-rule astigmatism (0.25 to 0.50 D) when managing corneal astigmatism correction; this result will TOU CH MED ICA L MEDIA adequately compensate for both the posterior corneal astigmatism and any drift with time in the majority of cases. 4 Management options for corneal astigmatism include toric IOLs and incisional surgery. Incisional techniques range from cataract wound incision construction and placement, opposite clear corneal incisions, limbal relaxing incisions and astigmatic keratotomy. Comparing incisional techniques to toric IOLs, outcomes were similar in patients with corneal astigmatism up to 2 D. However, if the corneal astigmatism is greater than 2.25 D, toric IOLs result in better outcomes. 5 Although femtosecond lasers are touted as being more accurate in the performance of incisional correction of astigmatism, studies have found that the outcomes are not as dramatic. 6–11 Femtosecond corneal incisions are effective for astigmatism less than 2.0 D and, although they are statistically better, femtosecond lasers are clinically only 5  % more effective than manual incisions. 12 Intrastromal femtosecond laser incisions are minimally less effective than femtosecond astigmatic keratotomy, and can be used up to 1.50 D. The most common choice for ophthalmologists for correcting astigmatism continue to be toric IOLs. 13 When determining the power of a toric IOL, preoperative assessment with optical biometry and either corneal topography or tomography is essential. The use of intraoperative aberrometry has not shown any definitive advantage in this respect. Toric calculators allow for more accurate assessment of the amount of astigmatism to be corrected. Using a calculator based 57