In NHS practice, only spherical correction is available. The intraocular lenses (IOL) we use in this situation are called monofocal. In most patients, these are perfectly sufficient, particularly if you have other eye conditions (such as a corneal surface or retinal problem). This lens gives patients without much astigmatism the best focus for distance (if this is what you want – some patients prefer to be short sighted). If you do opt for distance correction, then reading glasses will be needed for near vision. Equally, if you opt for near correction, then distance glasses will be needed to see far objects.
In the private sector, we can offer patients correction of their astigmatism and/or presybopia. If you have 1.5 dioptres or more of corneal astigmatism, I would strongly recommend a toric IOL to correct astigmatism. Lower degrees of astigmatism can be corrected with limbal relaxing incisions, but these are not accurate enough for the higher powers.
For patients who would like to be without glasses completely, presbyopic correction can be achieved with a bifocal IOL (commonly mis-called a multifocal IOL). There is always an element of compromise with these lenses as part of the light is focussed on near objects and part on far. So studies have shown a slight reduction in contrast discrimination with these lenses and all patients will temporarily notice haloes, starburst and ghosting. Having said this, most patients are delighted with the results as the brain almost always learns to filter out these optical side-effects. For patients with presbyopia and astigmatism, toric multifocals are available.
For most patients, better results are achieved by concentrating on getting good distance vision plus intermediate vision and accepting the need for reading glasses for very small print. I believe the best lens to achieve this is the http://www.tecnisiol.com/eu/tecnis-symfony-iol.htm“>Symfony intraocular lens.
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