Letter to the Editor. Astigmatism after sutureless cataract surgery
I read the current Community Eye Health (Issue 48) with a lot of interest as these are the issues we deal with daily. An aspect which I feel needs further discussion is astigmatism after the sutureless surgery. Some claim that this gives more against-the-rule astigmatism and hence recommend that at least one suture will give more of a with-the-rule astigmatism. Question: is this true and is this of any consequence to the quality of life for the patient?
Editor’s note: A member of our editorial committee, Dr David Yorston, has kindly agreed to respond to this question.
Dr Githeko raises an interesting point. The sutureless wound leads to a flattening of the cornea in the direction of the wound. If it is placed superiorly, the cornea will be flatter along the vertical axis than along the horizontal. This causes “against the rule” astigmatism. Placing a suture might reduce this flattening effect. There is some evidence for this.There is some evidence for this. A 1995 paper from Berlin showed that a single suture reduced the astigmatism by 0.5D (Haberle H, Anders N, Drosch S, Pham DT, Wollensak J. See abstract on page 11 of this issue.)
However, the paper does not say if this increased the number of people with good unaided acuity. Dr Githeko asks the very pertinent question “is this of any consequence to the quality of life for the patient?” Using a stitch may reduce astigmatism, but, unless it reduces it enough to improve patients’ unaided vision, I don’t think it will improve their quality of life. On the other hand, using a stitch increases the risk of suture-related complications, such as erosion and irritation. Albrecht Hennig has pointed out that it also significantly increases the time taken to carry out the surgery, and adds to the cost.
The only way to be sure if the benefits of placing a suture outweigh the possible risks would be to perform a randomised trial.