We report on our investigation into
astigmatism in 40 eyes following a corneal
cataract incision closed with a continuous 10/0
nylon monofilament
suture (
Ethilon). Immediately after surgery there was
astigmatism caused by the
nylon suture (
suture-induced
astigmatism), its severity depending on the tightness of the
suture. It ranged from 1 to 10-5 dioptres, the mean value 4-09 dioptres with a standard deviation of +/-2-5. Removing the
nylon suture eliminated this
astigmatism and within a few weeks the
corneal astigmatism correction in 48% of eyes returned to the preoperative level. In 80% of eyes the difference between the final postoperative
corneal astigmatism (4 months after removing the continuous
suture) and the preoperative
astigmatism was 0-75 dioptres or less and the maximum change was 1-5 dioptres. In 40% of eyes the axis of the cylinder changed from a horizontal to an oblique axis but did not change from a with- to against-the-rule axis. The degree of
astigmatism remained constant while the
suture was in place and in 50% of eyes was equal to or less than 3 dioptres. The mean of the spherical equivalents was 11-31 dioptres with a standard deviation of +/-1-25. A spectacle correction 14 days after operation prescribed either as the mean spherical equivalent (11-50 dioptres) or according to the patient's refraction will give satisfactory vision until the
suture is removed 4 months after operation. The degree of
astigmatism following a corneal section and continuous
nylon suture compares very favourably with
astigmatism following other suturing techniques for
cataract.