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Veerendranath Pesala, Prashant Garg, Shrikant Bharadwaj, Visual Optics Group; Optimizing binocular vision of pseudophakes with uncorrected astigmatism. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1522.
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© ARVO (1962-2015); The Authors (2016-present)
Uncorrected astigmatism improves monocular near acuity of pseudophakes, but with an associated loss in distance vision. The impact of uncorrected astigmatism on binocularity of these eyes however remains unknown. This study determined combinations of astigmatism in the two eyes that simultaneously optimize binocular distance and near resolution acuity and stereoacuity of bilateral pseudophakes with monofocal IOL implants.
Binocular distance (3m) and near (40cm) logMAR acuity and random-dot stereoacuity (40cm) was measured in 13 emmetropic pseudophakes with 10 different combinations of astigmatism induced in random order before the two eyes. Three strategies were chosen such that one eye had I) no astigmatism or II) 1D simple myopic or III) 1D simple hyperopic astigmatism at 90° while the fellow eye had a) the same error or that with b) orthogonal axis (180°) or c) different magnitude (2.5D) or d) opposite polarity (-1D).
For all combinations of induced astigmatism, the mean (±1SEM) distance logMAR acuity (0.03±0.03) did not deteriorate significantly from the best-corrected condition (-0.08±0.02) (p=0.32). Near logMAR acuity and stereoacuity were in-between the uncorrected (NVA: 0.59±0.05; Stereo: 232.9±33.9arc sec) and best-corrected (NVA: 0.18±0.02; Stereo: 60.9±10.2arc sec) conditions for all myopic astigmatic combinations (Ib & c and IIa - c) and same or worse than the uncorrected condition for hyperopic astigmatic combinations (Id, IId & IIIa - c) (p=0.003 to 0.36 for all). All outcomes variables were closest to their respective best-corrected values for combination IIc (OD: ±/+1.0x90°; OS: ±/+2.5x90°; DVA: 0.12±0.02; NVA: 0.38±0.03; Stereo: 82.6±8.05arc sec), followed by IIa (OU: ±/+1.0x90; DVA: 0.04±0.02; NVA: 0.43±0.05; Stereo: 104.5±13.5arc sec) and Ib. Stereoacuity was worse with orthogonal axes (IIb) than with parallel axes of myopic astigmatism (IIa) in the two eyes (p=0.002).
Binocular near logMAR and stereo acuity of bilateral pseudophakes can be simultaneously optimized without hindering distance vision using combinations of myopic astigmatism in the two eyes. Leaving such combinations uncorrected after cataract surgery may be a viable alternative to sphero-cylindrical bifocals in optimizing the overall binocular visual experience of the patient. Combinations with astigmatism with orthogonal axes in the two eyes or with hyperopia deteriorate near vision of pseudophakes.
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