[Changes of corneal topography and refraction after radial keratotomy and its combination with transverse incision]

In order to understand the changes of morphology and refractive power of cornea after radial keratotomy (RK) and its combination with transverse incision (T-incision), and the wound healing of the T-incision.

Corneal topography aided with a computer was used to analyze the changes of patients having undergone RK and RK combined with T-incision. The wound healing was analyzed, and the refractive powers of strong axis and weak axis of corneas were measured.

Corneal surface regularity index (SRI) and surface asymmetry index (SAI) became greater and greater along with the increase of myopia-astigmatism. The refractive powers of corneal visual area 3, 5, 7 mm decreased when getting closer to the center of the cornea. The refractive power of the strong axis in cornea with RK combined with T-incision obviously decreased more than that of RK. There was no such difference at weak axis between RK and RK combined with T-incision.

Corneal SAI and SRI will increase when myopia-astigmatism increases. The morphologic changes are from positive non-spherical lens before surgery to negative non-spherical lens after surgery. The increase of radius of curvature and the decrease of refractive power are due to incisions. These phenomena become clearer when the incision getting closer to the visual area or more incisions are performed. A T-incision less than 2 mm long along the strong axis of astigmatism not only can lessen refractive power of strong axis, but also can not affect RK results. This kind of T-incision does not delay the wound healing either.