Predictive baseline thresholds for successful dual blade goniotomy combined with phacoemulsification in glaucoma patients

Purpose To define preoperative thresholds of intraocular pressure (IOP) and the number of IOP-lowering eye drops that may predict surgical success following Kahook Dual Blade goniotomy combined with phacoemulsification (Phaco-KDB) in patients with glaucoma and cataract. Methods This retrospective study analysed 307 eyes of 307 patients undergoing Phaco-KDB. Data on demographics, glaucoma type, IOP, number of IOP-lowering medications and complications were collected over 18 months of follow-up. Complete success was defined as IOP ≤ 21, 18, 15 or 12 mmHg without medications; qualified success allowed for ongoing topical IOP-lowering therapy. Logistic regression models were used to determine predictive thresholds. Results Mean baseline IOP was 18.6 ± 5.2 mmHg and decreased to 15.0 ± 4.4 mmHg at 18 months. The mean number of IOP-lowering medications was reduced from 2.2 ± 1.1 to 1.7 ± 1.4. For qualified success, the identified preoperative IOP thresholds were 27.2 mmHg for achieving ≤ 21 mmHg (AUC = 0.900, p < 0.001), 25.1 mmHg for ≤ 18 mmHg (AUC = 0.8604, p < 0.001), 19.8 mmHg for ≤ 15 mmHg (AUC = 0.7752, p < 0.001), and 13.5 mmHg for ≤ 12 mmHg (AUC = 0.7772, p = 0.0011). For complete success, the threshold IOP values were 20.6 mmHg for ≤ 21 mmHg (AUC = 0.7893, p < 0.001), 18.1 mmHg for ≤ 18 mmHg (AUC = 0.7365, p < 0.001), and 15.0 mmHg for ≤ 15 mmHg (AUC = 0.5890, p = 0.0109). No significant association was found between the number of preoperative medications and surgical outcome. Conclusions Preoperative IOP is a significant predictor of Phaco-KDB success. Our findings suggest that Phaco-KDB primarily stabilizes IOP at preoperative levels while reducing the need for IOP-lowering therapy, rather than achieving substantial additional IOP reduction.