[Outcome of corneal astigmatism after pars plana vitrectomy with or without simultaneous cataract extraction]

Changes in corneal astigmatism induced by pars plana vitrectomy (PPV) (group I, 44 eyes) and PPV combined with no-stitch cataract surgery (group II, 20 eyes) were studied prospectively for a period of at least 3 months. The amount and orientation of the keratometric cylinder and the surgically induced astigmatism (according to the methods of Jaffe and Clayman or Naeser) were analysed. In the first postoperative week both groups exhibited a marked against-the-rule to oblique astigmatism (in group I up to 3.65 +/- 1.40 D, in group II up to 3.05 +/- 1.60 D, according to Jaffe). After 3 months this had declined in group I to 0.40 +/- 0.27 D, whereas a slight induced astigmatism (0.97 +/- 0.41 D) persisted in group II. Gas endotamponade did not significantly aggravate the postoperative astigmatism in either group. Computerized video-keratography generally revealed an asymmetric bowtie pattern during the first week. Our results show that PPV alone induces no appreciable long-term corneal astigmatism. Optical rehabilitation, however, can be delayed by a marked short-term postoperative astigmatism. PPV with simultaneous no-stitch cataract surgery, by contrast, was found to induce a persisting slight astigmatism against the rule.