Astigmatism is a refractive error like short-sightedness or long-sightedness, and may occur alone or, more commonly, in conjunction with one of these other vision errors. It results from an irregular shape to the front of the eye (the cornea) and means that light is focused differently depending on which direction it approaches the eye. The effect is blurred vision, and can be corrected by glasses, contact lenses or laser surgery, just like other focusing errors.
If the individual characteristics of a patients’ eyes are not taken into account, cataract surgery may often worsen astigmatism, and mean that patients need glasses to see well following their operation.
I assess each eye prior to surgery and aim to reduce astigmatism by a combination of selected placement of the surgical incision and additional incisions, called limbal relaxing incisions (see Surgical videos), if necessary.
In some cases I use special astigmatic or toric intraocular lenses in place of the standard lens for additional anti-astigmatic effect. Low or zero post-operative astigmatism is necessary if multifocal intraocular lenses are to be used. The net result is improved unaided vision, and a less strong glasses prescription, if one is required at all.