Outcome of Cataract Surgery in Nigeria: Visual Acuity, Autorefraction, and Optimal Intraocular Lens Powers-Results from the Nigeria National Survey

Imam, AU; Gilbert, CE; Sivasubramaniam, S; Murthy, GVS; Maini, R; Rabiu, MM; (2011) Outcome of Cataract Surgery in Nigeria: Visual Acuity, Autorefraction, and Optimal Intraocular Lens Powers-Results from the Nigeria National Survey. Ophthalmology, 118 (4). pp. 719-724. ISSN 0161-6420 DOI: https://doi.org/10.1016/j.ophtha.2010.08.025

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Objective: To describe presenting and corrected visual acuities after cataract surgery in a nationally representative sample of adults. Another objective was to describe refractive errors in operated eyes and to determine the optimal range of intraocular lens (IOL) powers for this population. Design: Cross-sectional, population-based survey. Participants: Adults aged 40 years and more were selected using multistage stratified sampling and proportional to size procedures. A sample size of 15 027 was calculated, and clusters were selected from all states. Methods: Individuals who had undergone cataract surgery were identified from interview and examination. All had their presenting visual acuity (VA) measured using a reduced logarithm of the minimum angle of resolution chart and underwent autorefraction. Corrected VAs were assessed using the autorefraction results in a trial set. An ophthalmologist conducted all examinations, including slit-lamp and dilated fundus examination. Causes of visual loss were determined for all eyes with a presenting VA <6/12 using the World Health Organization recommendations. Biometry data were derived from 20 449 phakic eyes using the SRK-T formula after excluding those with poor VA or corneal opacities. Main Outcome Measures: Presenting and corrected visual acuities in pseudo/aphakic individuals and autorefraction findings; biometry profile of Nigerian adults. Results: Data from 288 eyes of 217 participants were analyzed. Only 39.5% of eyes had undergone IOL implantation at surgery. Only 29.9% of eyes had a good outcome (i.e., >= 6/18) at presentation, increasing to 55.9% with correction. Use of an IOL was the only factor associated with a good outcome at presentation (odds ratio 9.0; 95% confidence interval, 4.3-18.9; P = 0.001). Eyes undergoing cataract surgery had a higher prevalence and degree of astigmatism than phakic eyes. Biometry data reveal that posterior chamber IOL powers of 20, 21, and 22 diopters (D) (A constant 118.0) will give a postoperative refraction range of -2.0 D to emmetropia in 71.4% of eyes, which increases to 82.6% if 19 D is also included. Conclusions: Postoperative astigmatism needs to be reduced through better surgical techniques and training, and use of biometry should be standard of care. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article Ophthalmology 2011;118:719-724 (C) 2011 by the American Academy of Ophthalmology.

Item Type: Article
Faculty and Department: Faculty of Infectious and Tropical Diseases > Dept of Clinical Research
Research Centre: The International Centre for Evidence in Disability
International Centre for Eye Health
Centre for Global Non-Communicable Diseases (NCDs)
PubMed ID: 21055820
Web of Science ID: 289075200017
URI: http://researchonline.lshtm.ac.uk/id/eprint/895


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