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Astigmatism gradually developing or remaining after cataract surgery is of concern for all cataract surgeons. Significant astigmatism may result even with small incisions and careful wound management. Current approaches vary widely. For this consultation section, 14 experts were asked to give their current thinking.
PROBLEM CASE
A male patient presents, age 65 years, who had cataract surgery with intraocular lens implantation in the right eye 2 years ago, the refraction is -50 -0.75 x 90, with a visual acuity of 20/20. The left eye had cataract surgery 1 year ago with a posterior chamber intraocular lens and the refraction is now + 2.00 -5.50 x 90 with a visual acuity of 20/25. His keratometry readings are 0 D, 42.00/43.00 x 180 and 0 S 39.25/45.50 x 180. Slit-lamp microscope examination shows the limbal wound to be well healed and shows no wound defect. The vision in the left eye corrects to 20/30. The patient complains of glare, eye fatigue, poor depth perception, and headaches. How would you manage this case?
Lee T. Nordan, MD La JoIIa, Calif
This patient has anisometropia due to the large degree of against-the-rule astigmatism in the left eye. The stated symptoms of headache, eye fatigue, etc are totally compatible with the patient's astigmatic anisometropia (the spherical equivalent is near zero), and these symptoms will probably be made worse with attempted spectacle correction.
In my hands, correction of the refractive error in the left eye would consist of an astigmatic keratotomy at 180°. As the astigmatic keratotomy flattens the steeper meridian at 180°, there is a commensurate steepening of the flatter vertical meridian. The patient, therefore, should end up with a refraction near emmetropia with loss of the anisometropia.
After cataract surgery, I consider the amount of astigmatism to be corrected by surgery to be equal to 60% of the measured amount since one can expect a larger effect on a postoperative eye than on an unoperated eye. In this case, the surgeon must design an astigmatic keratotomy to correct 3.3 diopters (5.50 x .60) of astigmatism which will correct 5.50 D of astigmatism in the postoperative Pseudophakie eye. For me, this astigmatic keratotomy will consist of two 4.0 mm transverse incisions with peripheral nonjoining radial incisions on either side...