Toric intraocular lens versus limbal relaxing incisions for corneal astigmatism after phacoemulsification. 2019

Jonathan C Lake, and Gustavo Victor, and Gerry Clare, and Gustavo Jm Porfírio, and Ashleigh Kernohan, and Jennifer R Evans
UNIFESP - Federal University of São Paulo, Ophthalmology, Rua Pedro de Toledo 650, 2nd floor, São Paulo, Brazil.

Cataract is the leading cause of blindness in the world, and clinically significant astigmatism may affect up to approximately 20% of people undergoing cataract surgery. Pre-existing astigmatism in people undergoing cataract surgery may be treated, among other techniques, by placing corneal incisions near the limbus (limbal relaxing incisions or LRIs) or by toric intraocular lens (IOLs) specially designed to reduce or treat the effect of corneal astigmatism on unaided visual acuity. To assess the effects of toric IOLs compared with LRIs in the management of astigmatism during phacoemulsification cataract surgery. We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register; 2019, Issue 9); Ovid MEDLINE; Ovid Embase and four other databases. The date of the search was 27 September 2019. We included randomised controlled trials (RCTs) comparing toric IOLs with LRIs during phacoemulsification cataract surgery.  DATA COLLECTION AND ANALYSIS: We used standard methods expected by Cochrane. We graded the certainty of the evidence using GRADE. Our primary outcome was the proportion of participants with postoperative residual refractive astigmatism of less than 0.50 dioptres (D) six months or more after surgery. We also collected data on mean residual refractive astigmatism. Secondary outcomes included: uncorrected distance visual acuity, vision-related quality of life, spectacle independence and adverse effects including postoperative lens rotation requiring re-alignment. To supplement the main systematic review assessing the effects of toric IOLs compared with LRIs in the management of astigmatism during phacoemulsification cataract surgery, we sought to identify economic evaluations on the subject. We identified 10 relevant studies including 517 people (626 eyes). These studies took place in China (three studies), UK (three), Brazil (one), India (one), Italy (one) and Spain (one). The median age of participants was 71 years. The level of corneal astigmatism specified in the inclusion criteria of these studies ranged from 0.75 D to 3 D. A variety of toric IOLs were used in these studies, in all but one study, these were monofocal. Studies used three different nomograms to determine the size and placement of the LRI. Two studies did not specify this. None of the studies were at low risk of bias in all domains, but two studies were at low risk of bias in all domains except selective outcome reporting, which was unclear. The remaining studies were at a mixture of low, unclear or high risk of bias. People receiving toric IOLs were probably more likely to achieve a postoperative residual refractive astigmatism of less than 0.5 D six months or more after surgery (risk ratio (RR) 1.40, 95% confidence interval (CI) 1.10 to 1.78; 5 RCTs, 262 eyes). We judged this to be moderate-certainty evidence, downgrading for risk of bias. In the included studies, approximately 500 eyes per 1000 achieved postoperative astigmatism less than 0.5 D in the LRI group compared with 700 per 1000 in the toric IOLs group. There was a small difference in residual astigmatism between the two groups, favouring toric IOLs (mean difference (MD) -0.32 D, 95% CI -0.48 to -0.15 D; 10 RCTs, 620 eyes). Although all studies favoured toric IOLs, the results of individual studies were inconsistent (range of effects -0.02 D to -0.71 D; I² = 89%). We considered this to be low-certainty evidence, downgrading for risk of bias and inconsistency. People receiving a toric IOL probably have a small improvement in visual acuity at six months or more after surgery compared to people receiving LRI, but the difference is small and probably clinically insignificant (MD -0.04 logMAR, 95% CI -0.07 to -0.02; 8 RCTs, 474 eyes; moderate-certainty evidence). Low-certainty evidence from one study of 40 people suggested little difference in vision-related quality of life measured using the Visual Function Index (VF-14) (MD -3.01, 95% CI -8.56 to 2.54). Two studies reported spectacle independence and suggested that people receiving toric IOLs may be more likely to be spectacle independent (RR 1.56, 95% CI 1.14 to 2.15; 100 people; low-certainty evidence). There were no cases of lens rotation requiring surgery (very low-certainty evidence). Five studies (320 eyes) commented on a range of other adverse effects including corneal oedema, endophthalmitis and corneal ectasia. All these studies reported that there were no adverse events with the exception of one study (40 eyes) where one participant in the LRI group had a central de-epithelisation which recovered over 10 days. We found no economic studies that compared toric IOLs with LRIs. Toric IOLs probably provide a higher chance of achieving astigmatism within 0.5 D after cataract surgery compared with LRIs. There may be a small mean difference in postoperative astigmatism, favouring toric IOLs, but this difference is likely to be clinically unimportant. There was no evidence of an important difference in postoperative visual acuity or quality of life between the techniques. Evidence on adverse effects was uncertain. The apparent shortage of relevant economic evaluations indicates that economic evidence regarding the costs and consequence of these two procedures is currently lacking.

UI MeSH Term Description Entries
D007910 Lenses, Intraocular Artificial implanted lenses. Implantable Contact Lens,Lens, Intraocular,Contact Lens, Implantable,Intraocular Lens,Intraocular Lenses,Lens, Implantable Contact
D011183 Postoperative Complications Pathologic processes that affect patients after a surgical procedure. They may or may not be related to the disease for which the surgery was done, and they may or may not be direct results of the surgery. Complication, Postoperative,Complications, Postoperative,Postoperative Complication
D012029 Refraction, Ocular Refraction of LIGHT effected by the media of the EYE. Ocular Refraction,Ocular Refractions,Refractions, Ocular
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001251 Astigmatism Unequal or irregular curvature of the CORNEA (Corneal astigmatism) and/or the EYE LENS (Lenticular astigmatism) resulting in REFRACTIVE ERROR. Corneal Astigmatism,Hyperopic Astigmatism,Lenticular Astigmatism,Mixed Astigmatism,Myopic Astigmatism,Oblique Astigmatism,Astigmatism, Corneal,Astigmatism, Hyperopic,Astigmatism, Lenticular,Astigmatism, Mixed,Astigmatism, Myopic,Astigmatism, Oblique,Hyperopic Astigmatisms,Mixed Astigmatisms,Myopic Astigmatisms,Oblique Astigmatisms
D014792 Visual Acuity Clarity or sharpness of OCULAR VISION or the ability of the eye to see fine details. Visual acuity depends on the functions of RETINA, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast. Acuities, Visual,Acuity, Visual,Visual Acuities
D015948 Keratoplasty, Penetrating Partial or total replacement of all layers of a central portion of the cornea. Keratoplasties, Penetrating,Penetrating Keratoplasties,Penetrating Keratoplasty
D016032 Randomized Controlled Trials as Topic Works about clinical trials that involve at least one test treatment and one control treatment, concurrent enrollment and follow-up of the test- and control-treated groups, and in which the treatments to be administered are selected by a random process, such as the use of a random-numbers table. Clinical Trials, Randomized,Controlled Clinical Trials, Randomized,Trials, Randomized Clinical
D018918 Phacoemulsification A procedure for removal of the crystalline lens in cataract surgery in which an anterior capsulectomy is performed by means of a needle inserted through a small incision at the temporal limbus, allowing the lens contents to fall through the dilated pupil into the anterior chamber where they are broken up by the use of ultrasound and aspirated out of the eye through the incision. (Cline, et al., Dictionary of Visual Science, 4th ed & In Focus 1993;1(1):1) Phacoemulsifications
D019654 Lens Implantation, Intraocular Insertion of an artificial lens to replace the natural CRYSTALLINE LENS after CATARACT EXTRACTION or to supplement the natural lens which is left in place. Implantation, Intraocular Lens,Implantations, Intraocular Lens,Intraocular Lens Implantation,Intraocular Lens Implantations,Lens Implantations, Intraocular

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