Purpose: To compare retrospectively two different techniques of Xen implantation, which are transconjunctival (ab-externo) and standard (ab-interno) techniques.

Methods: Forty-three eyes of 43 patients with primary open-angle glaucoma (POAG) who had Xen implantation operation via transconjunctival (ab-externo) technique comprised Group 1. Of the 43 patients, 20 (46.5%) were males and 23 (53.5%) were females. Their mean age was 61.76 ± 8.81 (41-74) years. Forty-four eyes of 44 patients with POAG who had Xen implantation operation via standard (ab-interno) technique comprised Group 2. Of the 44 patients, 21 (47.7%) were males and 23 (52.3%) were females. The mean age of this group was 63.80 ± 9.78 (38-75) years.

Results: Regarding age and sex, there were no significant differences between the groups (p > 0.05). The mean postoperative 1st day, 1st week, 1st month, 3rd month, 6th month, and 12th month IOPs were significantly lower than the mean preoperative IOP in both groups (p < 0.05). The mean number of anti-glaucomatous agents used postoperatively was significantly lower than the mean preoperative number for both groups (p < 0.05). There was a significantly smaller need for needling in the transconjunctival group (p < 0.05).

Conclusion: Xen implantation is a safe and effective method of reducing IOP and anti-glaucomatous dependence. Potential postoperative complications can be resolved easily. There were no significant differences between the standard method and the transconjunctival method in respect of IOP and re-use of anti-glaucomatous agents. However, there was a significantly smaller need for needling in the transconjunctival group. We recommend further studies to investigate long-term results.

Keywords: IOP; Standard (ab-interno) technique; Transconjunctival (ab-externo) technique; Xen implantation.