Materials and Methods: The study included 40 eyes underwent trabeculectomy (n=20) and Ex-Press implant (n=20) due to uncontrolled glaucoma. Best corrected visual acuity (BCVA), intraocular pressure (IOP), and keratometry measurements were evaluated preoperatively and on postoperative months 1, 3 and 6 months. During the follow-up, keratometric astigmatism values and surgery-induced astigmatism (SIA) values calculated with Eğrilmez?s vector analysis program were analyzed using statistical comparisons.

Results: There were no significant differences in mean age, gender, laterality and glaucoma type (p>0.05) between study groups. Again, no significant differences were found in mean baseline BCVA (0,35±0,36, 0,46±0,33 logMAR), IOP (32,10±7,8, 37,10±8,3 mmHg), keratometry (43, 93±1,16, 43,71±0,61 D), and corneal astigmatism (1,10±0,61, 0,83±0,40 D) (p>0.05) values between trabeculectomy and Ex-Press implant groups. In the Ex-Press group, postoperative IOP reduction was significantly greater on month 1(14,10±4,2, 10,95±2,2 mmHg, p=0.013), but no significant difference was found between the two groups at remaining time points (p>0.05). Corneal astigmatism increased in both groups in the first month, but this increase was not statistically significant (p>0.05). There was no significant difference SIA vector size during the 6-months follow-up between groups (p>0.05). While oblique astigmatism was present in the trabeculectomy group at baseline, rule-compliant astigmatism was observed on postoperative month 6. In the Ex-Press group, the rule-compliant component persisted throughout follow-up period.

Conclusions: No significant difference occurred in IOP, visual outcomes, and astigmatism change after trabeculectomy and Express implantation. Keywords : Induced astigmatism, Trabeculectomy, Ex-Press, Vectorial analysis