Corneal astigmatism after cataract extraction. A comparison of corneal and corneoscleral incisions

Abstract

Corneal astigmatism after cataract surgery by way of corneal incision (C, n = 62) and corneo-scleral incision (CS, n = 61) was followed for six months. Corneal incisions were closed by continuous nylon 10--0 (7--25 loops, median 14). Corneo-scleral incisions were sutured with single knots (2--10, median value 5). Keratometric results in the C and CS groups are compared. Concerning the degree of astigmatism, pre-operative median values were 0.5 and 0.7 D, respectively. After one week they were 4.5 and 3.0 D; after two weeks 3.3 and 3.0 D; after four months 3.0 and 2.0 D; after six months (final status) 1.5 and 1.7 D, respectively. The differences between C and CS were not significant. For both, astigmatism after cataract surgery did not quite return to pre-operative levels. Concerning the axis (weaker meridian) of corneal astigmatism, the C cases retained their pre-operative distribution, while the CS cases showed the classical shift towards against-rule astigmatism. Final corrected visual acuity was of the same order in the C and CS group. Due to frequent shifts, also of the axis, it is recommended by early (preliminary) glass prescription not to correct the astigmatism, but to give only the best spherical correction.