He suggested that finer suture which remain in situ without irritation, causes wound compression and increases vertical curvature hence astigmatism with the rule. Larger sutures allows the wound to gape thus reduces vertical curvature hence astigmatism against the rule.
This can be explained by the wound compression by the sutures, irrespective of the suture technique as well as reactionary tissue edema, resulting in steepening of the vertical meridian, hence astigmatism with the rule.
A self-sealing corneal tunnel incision measuring 4.0 to 4.1 mm in external diameter and 6.5 to 7.0 mm in internal diameter (stretch incision) was performed on the steeper axis and the results suggested that surgical induced astigmatism (SIA) following superior incisions in cases of astigmatism with the rule
(n = 29) amounted to 1.93 +/- 0.97, while lateral incisions in cases of astigmatism against the rule (n = 29) led to an IA of 1.35 +/- 0.73.