Adjunctive Greater Occipital Nerve Block for Pain Control in Medically Refractory Acute Primary Angle Closure: An Observational Study.

Background: Acute primary angle closure (APAC) is an ophthalmic emergency characterized by abrupt elevation of intraocular pressure (IOP) and severe ocular pain and headache. While acute management prioritizes IOP reduction, supportive analgesic strategies during the preoperative waiting period in medically refractory cases remain insufficiently studied. We evaluated short-term changes in the pain intensity and safety of adjunctive greater occipital nerve block (GONB) in medically refractory APAC. Methods: This retrospective observational study included 34 patients with medically refractory APAC who received GONB during the preoperative waiting period. Headache intensity was measured using an 11-point Numeric Rating Scale (NRS) at baseline, 30 min, and 60 min. Longitudinal changes were analyzed using a linear mixed-effects model. Responder analyses were reported with 95% confidence intervals (Wilson method). No multivariable modeling or NNT estimation was performed in the revised analysis. Results: Baseline NRS was 7.8 ± 1.1, decreasing to 4.1 ± 1.5 at 30 min and 3.6 ± 1.3 at 60 min (both p < 0.001). The mean baseline-to-60 min change was -4.21 (95% CI, -4.88 to -3.54). Clinically meaningful pain relief (≥3-point reduction) at 60 min occurred in 79.4% (95% CI, 63.2-89.7%). In linear mixed-effects modeling, time remained a significant fixed effect (p < 0.001). Conclusions: Adjunctive GONB was associated with a rapid reduction in pain intensity in medically refractory APAC. These findings should be interpreted cautiously, given the uncontrolled design and concurrent treatment. Prospective controlled studies are warranted.