Correlation of Surgically Induced Astigmatism and IOP Results After Canaloplasty
Purpose
To analyze the impact of surgically induced astigmatism on IOP results after canaloplasty.
Methods
Prospective nonrandomized evaluation of 57 consecutive eyes of 37 patients with open-angle glaucoma undergoing canaloplasty Best corrected visual acuity (BCVA), IOP by Goldman applanation tonometry, astigmatism value assessed with both auto kerato-refractometer and refractive corneal maps (AS-OCT SS-1000 CASIA), number of antiglaucoma medication used and secondary antiglaucoma procedure were assessed preoperatively and at 1 day, 7 days, 4 weeks, and 3, 6, 12 months postoperatively. In order to evaluate if there is any association between surgically induced astigmatism on IOP results, patients were divided into 3 groups according to surgically induced astigmatism value in the first postoperative day: group 1 (22 eyes) with astigmatism from 0 to <1.5 CYL, group 2 (19 eyes) with astigmatism from 1.5 to 3 CYL, group 3 (16 eyes) with astigmatism >3 CYL
Results
The mean preoperative IOP was: group 1 – 18.1mm Hg , group 2 – 21.75 mmHg, group 3 – 19.5mmHg . The mean IOP decreased to 14.3 mmHg, 13.8 mmHg, 11.8 mmHg at 12 months in group 1, 2, and 3 respectively. Mean astigmatism preoperatively was 0.6 CYL in group 1; 0.8 CYL in group 2 and 0.86 CYL in group 3. It was still in the same range at 1 week postoperatively. Thereafter the astigmatism underwent a spontaneous decline, reaching 0.75 CYL in group 1, 1.39 CYL in group 2 and 2.5 CYL in group 3 at 4 weeks. Six months after canaloplasty, mean astigmatism reached the preoperative range of 0.61 CYL in group 1, 0.82 CYL in group 2 and 0.98 CYL in group 3.
Conclusion
Patients with the highest postoperative astigmatism had the lowest IOP at 12 months. None of the patients from the group with the highest amount of postoperative astigmatism required antiglaucoma treatment or additional antiglaucoma procedures. The amount of surgically induced astigmatism on the first postoperative day correlate inversely with IOP at 12 months. Further studies are needed to fully assess that relation.