Identifying the predictors of needling after XEN gel implant

Purpose To identify factors associated with probability of needling after XEN implant. Methods Analysis of data from prospective case series of patients with standalone XEN implant or combined XEN + cataract. Primary outcome was to determine whether postoperative day 1 and week 1 intraocular pressure (IOP), type of glaucoma, and glaucoma severity affected probability and number of needling interventions required. Results A total of 149 eyes of 113 patients were included in the analysis. In the XEN alone group, mean IOP at day 1 and week 1 was 9.70 +/- 5.43 and 10.33 +/- 4.41 mmHg, respectively. Eyes with lower IOP on day 1 were less likely to require needling (Odds ratio; OR, 1.14; 95% CI, 1.02-1.28; p = 0.02). A similar association (OR, 1.15; 95% CI, 1.06-1.26; p = 0.001) was observed between day 1 IOP in and number of needling interventions. In the XEN + cataract group, mean IOPs at day 1 and week 1 were 13.75 +/- 7.52 and 11.81 +/- 5.36 mmHg, respectively. No significant association was noted between early postoperative IOP and probability or number of needling in this group. With IOP > 20 mmHg the probability of needling was similar to 80%. This number decreased to 35% if day 1 IOP was < 10 mmHg. Conclusion Postoperative day 1 IOP is a predictor for needling in patients undergoing standalone XEN implantation. These results suggest that surgeons should not wait too long to intervene via needling if IOP in the early postoperative period is in the high teens or above. Type or severity of glaucoma did not influence the probability of needling or number of needling interventions required.