Determination of maximal incision length for true small-incision surgery.

We studied induced astigmatism in cadaver eyes to determine how small a limbal incision must be to avoid a long-term corneal flattening induced by limbal incisions along the meridian of the incision. We performed scleral pocket incisions (2.0 to 5.5 mm in 0.5-mm increments) on 12 fresh human cadaver globes, recessing the incisions 0.5 mm to simulate the natural wound sliding that causes corneal flattening. We found that with increasing incision length there was a nearly linear increase in corneal flattening. The maximal incision length that minimized induction of corneal flattening in excess of 0.25 diopters was 3.0 mm.