Abstract
Purpose: :
To examine the performance of patients implanted binocularly with refractive or a combination of diffractive-refractive intraocular lenses (IOL) in photopic and mesopic conditions.
Methods: :
Fifteen patients implanted with ReZoom refractive IOL in one eye and Tecnis ZM900 diffractive IOL in the other were examined 3 months after surgery. A further five patients implanted binocularly with ReZoom IOLs were assessed. Best distance corrected visual acuity at distance and near (logMAR chart), contrast sensitivity (Pelli-Robson chart) and binocular defocus curves from +1.5D to -5.0D in 0.5D randomised steps were measured in both photopic (85cd/m2) and mesopic (3cd/m2) conditions. In addition, monocular defocus curves were measured to assess binocular summation and binocular reading speed was assessed (MNRead) in photopic conditions.
Results: :
The visual performance (acuity, contrast sensitivity and reading speed) of implanted binocular refractive IOLs was similar to a refractive / diffractive combination in both photopia and mesopic conditions (p>0.05). Binocular summation of defocus curves in the two eyes implanted with multifocal IOLs increased visual acuity as expected (by 0.06±0.03logMAR binocular refractive; by 0.10±0.03logMAR refractive/diffractive combination). However, this increase was greater for the refractive/diffractive combination (p<0.001). Overall range-of-clear-focus was also increased with the refractive/diffractive combination, whereas the defocus profiles were similar between each eye and binocular vision in patients implanted binocularly with a refractive intraocular lenses; this improvement was not evident in mesopic conditions.
Conclusions: :
A ‘mix and match’ approach to multifocal IOL implantation enhances binocular summation and increases the range-of-clear-focus. This strategy is therefore recommended when implanting multifocal IOLs to minimise the effects of presbyopia.
Keywords: intraocular lens • presbyopia