Aims: To measure spectacle dependence following bilateral monofocal intraocular lens (IOL) implantation and assess how it is predicted by postoperative refraction.
Methods: 300 cataract patients had bilateral phacoemulsification surgery with monofocal IOL implantation. A spherical equivalent of 0 to −0.5 D was targeted. Three months after surgery, patients answered a questionnaire and had a spectacle refraction. Refractions were converted into vector notation. Logistic regression was used to evaluate whether spectacle dependence for near and distance was related to overall refractive error, spherical error, signed spherical error and astigmatic error.
Results: 169 patients attended for assessment. 38 wore distance glasses, and 160 wore reading glasses either some or all of the time. The mean right spherical equivalent was −0.03 D, and the mean right cylinder was −0.64 D. Left outcomes were similar. Patients were 34 times more likely to always use distance glasses per dioptre of astigmatic error in the better eye (p<0.003), but there was no significant increase in the likelihood of wearing distance glasses with spherical error (odds ratio = 3.85, p>0.15). Similar effects were seen for both the better and worse eyes. Near-spectacle use was not dependent on astigmatic error (odds ratio = 0.22, p>0.12). It was only related to the signed spherical error in the worse eye with hypermetropic patients 6.74 times more likely to always wear spectacles per dioptre of positive spherical error (p<0.005).
Conclusions: Following bilateral monofocal intraocular lens implantation, small levels of overall refractive error, in either eye, particularly astigmatism, predict distance-spectacle dependence, whereas spherical ammetropia in the range of ±1.0 D does not. Hypermetropia in the worse eye, but not astigmatism, predicts reading-spectacle dependence.
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Competing interests None.
Provenance and Peer review Not commissioned; externally peer reviewed.
The Moorfields IOL Study Group: Study design: B Allan, C Bunce, F Fitzke, G Rubin. Recruiting surgeons: W Abdullah, B Allan, D Gartry, A Ionides, V Maurino, S Tuft, M Wilkins, R Wormald. Trial coordinator: N Dudley. Visual assessment technicians: K Bibi, E White. Data entry: W Xing, N Harris, S Mann. Data analysis: C Bunce, G Rubin, S Mann, W Xing, M Wilkins.