Until recently, only single focus lenses were available. These lenses can be chosen to provide a single sharp focus, usually distance or near, sometimes intermediate. Monofocal implants provide the best quality of vision, but will usually require spectacles for some activities after surgery (to change the focus).
Some patients choose to have both eyes corrected for distance after cataract surgery, and wear reading glasses for close vision. Others who want to be less dependent on glasses, can choose to have monovision (“blended vision”) where one eye is corrected for distance focus and the other eye corrected so it is focused for close work. This gives a better range of focus with both eyes working together, and the brain usually learns to adapt to this by enhancing the clear image, and suppressing the blurred image. Many cataract patients would have been using monovision in contact lenses already, and sometimes we will recommend trying it first with contact lenses.
Multifocal lens implants are designed to maximise independence from spectacles after surgery. Multifocal implants are best used in individuals who want the best chance of not needing spectacle correction after their cataract surgery, and who have no other significant ocular health problems. Multifocal implants have the ability to focus distance, intermediate and near simultaneously. There are several different lens options available, which can be tailored according to the visual requirements.
Mutlifocal implants are not recommended if there is irregularity or disease of the cornea or macula, or if there are very high visual quality requirements. Multifocal lenses will produce more scattering of light than a monofocal implant, resulting in increased glare and haloes, which usually diminish with time as the brain adapts to the vision. Dr Sharma is selective about using multifocal implants in the right candidates, and about choosing the best option for your visual requirements.
Also known as toric implants, these lenses compensate for blurred or distorted vision caused by astigmatism. Toric lenses are available in both monofocal (single-focus) and multifocal intraocular lenses, and can be customised to treat very high levels of astigmatism as seen in cases after corneal transplantation or keratoconus. Dr Sharma will usually recommend that astigmatism is corrected at the time of cataract surgery if this is possible. Part of the diagnostic workup for cataract surgery involves detailed measurements of your cornea in order to get the best measurements to plan correction of the astigmatism.