Astigmatism-oriented penetrating keratoplasty. A method for reducing astigmatism following keratoplasty?

Background. This pilot study examined whether astigmatism of donor corneas can be evaluated postmortem,and whether there is an effect on the astigmati sm following keratoplasty. Methods. The corneoscleral rims of donors were marked after measurement by a hand keratometer in the 12 o'clock position. We examined 38 patients afte r penetrating keratoplasty and divided them into three groups. The 12 o'clo ck position of the donor cornea was fixed in the same position as the recip ient (group A, n=12), or the donor corneas were transplanted with the axis in opposition to the axis of the recipient (group B, n=12) or in the same o rientation (group C, n=14). Development of postoperative astigmatism was co mpared with controls (group D, n=40). Results. in group B we found a new orientation of the astigmatism axis with in 2-4 months; in group C the axis maintained the original orientation of t he recipient. Mean postoperative astigmatism was 3.5 +/-1.5 dpt in group A, 2.1 +/-1.3 dpt in group B, 5.8 +/-1.6 dpt in group C, and 3.4 +/-1.5 dpt i n a roup D. After suture removal the axis orientation persisted in all grou ps. Conclusion. This study shows the possibility of evaluating corneal astigmat ism in donor eyes. The astigmatism of the donor cornea itself directly infl uences the postoperative axis of astigmatism in recipient eyes. Astigmatism after corneal grafting can be reduced by orienting the donor astigmatism a gainst the axis of the recipient.