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      Optimizing outcomes with toric intraocular lenses

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          Abstract

          Toric intraocular lenses (IOLs) are the procedure of choice to correct corneal astigmatism of 1 D or more in cases undergoing cataract surgery. Comprehensive literature search was performed in MEDLINE using “toric intraocular lenses,” “astigmatism,” and “cataract surgery” as keywords. The outcomes after toric IOL implantation are influenced by numerous factors, right from the preoperative case selection and investigations to accurate intraoperative alignment and postoperative care. Enhanced accuracy of keratometry estimation may be achieved by taking multiple measurements and employing at least two separate devices based on different principles. The importance of posterior corneal curvature is increasingly being recognized in various studies, and newer investigative modalities that account for both the anterior and posterior corneal power are becoming the standard of care. An ideal IOL power calculation formula should take into account the surgically induced astigmatism, the posterior corneal curvature as well as the effective lens position. Conventional manual marking has given way to image-guided systems and intraoperative aberrometry, which provide a mark-less IOL alignment and also aid in planning the incisions, capsulorhexis size, and optimal IOL centration. Postoperative toric IOL misalignment is the major factor responsible for suboptimal visual outcomes after toric IOL implantation. Realignment of the toric IOL is needed in 0.65%–3.3% cases, with more than 10° of rotation from the target axis. Newer toric IOLs have enhanced rotational stability and provide precise visual outcomes with minimal higher order aberrations.

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          Most cited references 93

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          Prevalence of corneal astigmatism before cataract surgery.

          To analyze the prevalence and presentation patterns of corneal astigmatism in cataract surgery candidates. University of Valencia, Valencia, Spain. Refractive and keratometric values were measured before surgery in patients having cataract extraction. Descriptive statistics of refractive and keratometric cylinder data were analyzed and correlated by age ranges. Refractive and keratometric data from 4,540 eyes of 2,415 patients (mean age 60.59 years +/- 9.87 [SD]; range 32 to 87 years) differed significantly when the patients were divided into 10-year subsets. There was a trend toward less negative corneal astigmatism values, except the steepest corneal radius and the J(45) vector component, in older groups (Kruskal-Wallis, P<.01). In 13.2% of eyes, no corneal astigmatism was present; in 64.4%, corneal astigmatism was between 0.25 and 1.25 diopters (D) and in 22.2%, it was 1.50 D or higher. Corneal astigmatism less than 1.25 D was present in most cataract surgery candidates; it was higher in about 22%, with slight differences between the various age ranges. This information is useful for intraocular lens (IOL) manufacturers to evaluate which age ranges concentrate the parameters most frequently needed in sphere and cylinder powers and for surgeons to evaluate which IOLs provide the most effective power range.
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            Correcting astigmatism with toric intraocular lenses: effect of posterior corneal astigmatism.

            To evaluate the impact of posterior corneal astigmatism on outcomes with toric intraocular lenses (IOLs). Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. Case series. Corneal astigmatism was measured using 5 devices before and 3 weeks after cataract surgery. Toric IOL alignment was recorded at surgery and at the slitlamp 3 weeks postoperatively. The actual corneal astigmatism was calculated based on refractive astigmatism 3 weeks postoperatively and the effective toric power calculated with the Holladay 2 formula. The prediction error was calculated as the difference between the astigmatism measured by each device and the actual corneal astigmatism. Vector analysis was used in all calculations. With the IOLMaster, Lenstar, Atlas, manual keratometer, and Galilei (combined Placido-dual Scheimpflug analyzer), the mean prediction errors (D) were, respectively, 0.59 @ 89.7, 0.48 @ 91.2, 0.51 @ 78.7, 0.62 @ 97.2, and 0.57 @ 93.9 for with-the-rule (WTR) astigmatism (60 to 120 degrees), and 0.17 @ 86.2, 0.23 @ 77.7, 0.23 @ 91.4, 0.41 @ 58.4, and 0.12 @ 7.3 for against-the-rule (ATR) astigmatism (0 to 30 degrees and 150 to 180 degrees). In the WTR eyes, there were significant WTR prediction errors (0.5 to 0.6 diopters [D]) by all devices. In ATR eyes, WTR prediction errors were 0.2 to 0.3 D by all devices except the Placido-dual Scheimpflug analyzer (all P<.05 with Bonferroni correction). Corneal astigmatism was overestimated in WTR by all devices and underestimated in ATR by all except the Placido-dual Scheimpflug analyzer. A new toric IOL nomogram is proposed. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
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              The AcrySof Toric intraocular lens in subjects with cataracts and corneal astigmatism: a randomized, subject-masked, parallel-group, 1-year study.

              To compare the AcrySof Toric intraocular lens (IOL) and an AcrySof spherical control IOL and to investigate rotational stability of the AcrySof Toric IOL (Alcon Laboratories, Inc., Fort Worth, TX) in subjects with cataracts and preexisting corneal astigmatism. Randomized, subject-masked, parallel-group, multicenter, 1-year study. We included 517 subjects (Toric IOL, n = 256; control IOL, n = 261). Unilateral implantation of an AcrySof Toric or AcrySof spherical control IOL (spherical powers, 12.00-25.00 diopters [D]; cylinder powers 1.50, 2.25, or 3.00 D for corneal astigmatism correction of 0.75 to < 1.50, ≥ 1.50 to <2.00, and ≥ 2.00 D with no upper limit, respectively). No limbal relaxing incisions were permitted. Visual acuity outcomes, IOL position, patient-reported spectacle use, and safety. One year postoperatively, best spectacle-corrected distance visual acuity of ≥ 20/20 was 77.7% (Toric IOL) versus 69.2% (control IOL). Uncorrected distance visual acuity of 20/20 or better was 40.7% (Toric IOL) versus 19.4% (control IOL; P<0.05). Mean absolute residual refractive cylinder was 0.59 D (Toric IOL) versus 1.22 D (control IOL; P<0.0001). Mean rotation was < 4° (range, 0°-20°) for the Toric IOL. Six-month spectacle freedom was 61.0% (Toric IOL) and 36.4% (control IOL; P < 0.0001). Complications in both groups were few and were as would be expected with cataract surgery. Favorable efficacy, rotational stability, distance vision spectacle freedom, and safety results support the use of the AcrySof Toric IOL for patients with cataracts and corneal astigmatism. Proprietary or commercial disclosure may be found after the references. Copyright © 2010 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.
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                Author and article information

                Journal
                Indian J Ophthalmol
                Indian J Ophthalmol
                IJO
                Indian Journal of Ophthalmology
                Medknow Publications & Media Pvt Ltd (India )
                0301-4738
                1998-3689
                December 2017
                : 65
                : 12
                : 1301-1313
                Affiliations
                Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
                Author notes
                Correspondence to: Dr. Jeewan S Titiyal, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences Ansari Nagar, New Delhi - 110 029, India. E-mail: titiyal@ 123456gmail.com
                Article
                IJO-65-1301
                10.4103/ijo.IJO_810_17
                5742958
                29208810
                4ac85c14-9b2e-4b05-93d1-614307b4f606
                Copyright: © 2017 Indian Journal of Ophthalmology

                This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.

                Categories
                Review Article

                Ophthalmology & Optometry

                astigmatism, cataract surgery, toric intraocular lenses

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