Kristian Naeser1, Jesper Ø Hjortdal, William F Harris. 1. Department of Ophthalmology, Randers Regional Hospital, Randers, DenmarkDepartment of Ophthalmology, Aarhus University Hospital, Aarhus, DenmarkDepartment of Optometry, University of Johannesburg, Johannesburg, South Africa.
Abstract
PURPOSE: To determine the optimal distribution of refractions in monofocal, pseudophakic monovision. METHODS: A previously reported mathematical method for describing defocus for a single eye (Acta Ophthalmol, 89, 2011, 111) is expanded to the binocular situation. The binocular distribution of refractions yielding the least defocus over the most extended fixation intervals is identified by mathematical optimization. The results are tested in a group of 22 pseudophakic patients. RESULTS: For the fixation interval 0.25-6.0 m, the optimal refractions are pure spheres of -0.27D for the distance eye and -1.15D for near eye. The mathematically derived defocus structure is confirmed in the clinical series. CONCLUSIONS: The reported mathematical method enables identification of the optimal distribution of refractions over any fixation interval. Monovision with refractions of approximately -0.25 and -1.25D may lead to spectacle independence for distance and intermediate vision. Binocular problems--such as monovision suppression, reduced stereoacuity and binocular inhibition--are likely to be minimal with the suggested anisometropia of 1.0D. This moderate monovision is fully reversible with spectacle correction, as the induced aniseikonia is minimal and it therefore represents a safe alternative to multifocal intraocular lenses (IOLs).
PURPOSE: To determine the optimal distribution of refractions in monofocal, pseudophakic monovision. METHODS: A previously reported mathematical method for describing defocus for a single eye (Acta Ophthalmol, 89, 2011, 111) is expanded to the binocular situation. The binocular distribution of refractions yielding the least defocus over the most extended fixation intervals is identified by mathematical optimization. The results are tested in a group of 22 pseudophakic patients. RESULTS: For the fixation interval 0.25-6.0 m, the optimal refractions are pure spheres of -0.27D for the distance eye and -1.15D for near eye. The mathematically derived defocus structure is confirmed in the clinical series. CONCLUSIONS: The reported mathematical method enables identification of the optimal distribution of refractions over any fixation interval. Monovision with refractions of approximately -0.25 and -1.25D may lead to spectacle independence for distance and intermediate vision. Binocular problems--such as monovision suppression, reduced stereoacuity and binocular inhibition--are likely to be minimal with the suggested anisometropia of 1.0D. This moderate monovision is fully reversible with spectacle correction, as the induced aniseikonia is minimal and it therefore represents a safe alternative to multifocal intraocular lenses (IOLs).