Control of corneal astigmatism following cataract extraction by selective suture cutting
J. W. Kronish and R. K. Forster
Department of Opthalmology, Bascom Palmer Eye Institute, University of Miami School of Medicine, FL 33101.
We evaluated the ability of selective suture cutting to reduce
postoperative corneal astigmatism in 75 eyes of 68 patients who underwent
extracapsular cataract extraction with posterior chamber intraocular lens
implantation. Keratometric and refractive measurements were obtained before
and at selected intervals (3, 6, 10, 26, and 52 weeks) after surgery. The
number of sutures cut during the sixth week after surgery was based on the
degree of astigmatism (0.00 to 2.00 diopters (D), no sutures cut; 2.25 to
3.00 D, one suture cut; 3.25 to 4.00 D, two sutures cut; greater than or
equal to 4.25 D, three sutures cut). Our analysis demonstrated the
following: (1) a spontaneous reduction of 0.5 D in surgically induced
astigmatism in eyes without suture cutting, (2) an additional reduction of
1.2 D in postoperative astigmatism for each suture cut, and (3) attainment
of 75% to 93% of the total effect of suture cutting within four weeks. The
final astigmatism one year after surgery had increased by a mean of 0.9 D,
exhibited predominantly with-the-rule properties, and showed no significant
difference among the four groups of patients. Vector analysis revealed that
only small shifts in the axis of astigmatism occurred after suture cutting.
A strong correlation between the keratometric and subjective refractive
measurements during all postoperative examinations indicated that corneal
astigmatism is primarily responsible for postoperative astigmatism.
