Corneal astigmatism after micro-incision cataract operation

To evaluate the effect of micro-incision (2.2 mm) and small-incision (3.0 mm) coaxial phaco-emulsification on surgically induced astigmatism (SIA).

Cataract patients (n = 60, 60 eyes) were randomized into two groups: 30 eyes in the 2.2-mm incision group, 30 eyes in the 3,0-mm group. Phaco-emulsification was followed by intraocular lens implantation via the Monarch II injector with the C cartridge (Alcon Laboratories Inc., Fort Worth, TX, USA). Uncorrected distance visual acuity, corneal keratometry and corneal astigmatism and SIA were assessed 1, 7 and 30 days after cataract surgery.

At 1, 7 and 30 days postoperative, SIA of the 3.0-mm group was greater than SIA of the 2.2-mm (p < or = 0.05) only at first postoperative day, but SIA was similar between the 2.2-mm group and the 3,0-mm group at other follow-ups. Time wise, mean SIA at 30 days was greater than SIA at 90 days in the 3.0-mm group (p = 0.04), while SIA did less change with time for the 2.2-mm group. Postoperative uncorrected distance visual acuity tended to be better with the smaller incisions, but this trend did not reach statistical significance (p > or = 0.07) especially at letter follow-ups.

Incision size contributed to postoperative corneal astigmatism especially at earlier postoperative period. When incision size was reduced from 3.0 mm to 2.2 mm, SIA was reduced and refractive stabilization was faster. In longer period of time difference between 3,0 mm and 2,2 mm incision size groups decreases.