Induced astigmatism and its decay with a frown incision.
Forty consecutive patients selected for cataract extraction by phacoemulsification were studied to evaluate prospectively the amount of and changes in surgically induced astigmatism from a 5 mm to 6 mm pocket incision with the external opening made convex against the limbus (frown incision). All incisions had an internal corneal valve and were closed by a single X-stitch to counteract the relaxing effect of the pocket in the 90-degree meridian. Surgically induced astigmatism calculated by simple subtraction was 0.64 +/- 0.90 diopters (D) (P < .0001) on the first postoperative day, 0.03 +/- 0.58 D (P = .75) six weeks after surgery, and -0.18 +/- 0.44 D (P = .01) six months after surgery. Calculated from polar equivalents, the induced astigmatism on the first postoperative day was 0.98 D +/- 1.03 D (P = .0001), after six weeks -0.11 D +/- 0.64 D (P = .30), and after six months -0.28 D +/- 0.49 D (P = .0009). On the first postoperative day 42% of eyes had less than 0.5 D of induced astigmatism, 68% had less than 1.0 D, and 79% had less than 1.5 D. After six weeks the respective percentages increased to 61%, 97%, and 97% and after six months to 84%, 100%, and 100%. The distribution of patients with against-the-rule, oblique, and with-the-rule astigmatism preoperatively was nine, 20, and 11, respectively, and 11, 19, and nine after six months. The amount of astigmatism induced from the 5 mm to 6 mm frown incision did not differ from that found in previously published studies of smaller incisions (to about 4 mm).(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Ophthalmology, Hjørring Hospital, Denmark.
J
J
Nielsen
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control*; D002387:Cataract Extraction / Q000009:adverse effects*; D003315:Cornea / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011446:Prospective Studies; D013536:Suture Techniques