Purpose: To compare the effectiveness of topical and subconjunctival anesthesia in intravitreal injection administrations.
Methods: Twenty-eight patients from a university clinic with bilateral diabetic macular edema were prospectively randomized to receive intravitreal injection of 4 mg triamcinolone under topical anesthesia for one eye and subconjunctival anesthesia for the other eye by using lidocaine 4%. Patients were asked to grade the pain they experienced during administration of both anesthesia and intravitreal injection by using a 4-point pain scale: from 0=no pain to 3=severe pain. Complications that developed during both procedures were recorded.
Results: The mean pain score experienced during subconjunctival injections was 0.78+/-0.62, whereas no anesthesia-related pain was reported in the topical group. The mean pain score experienced during intravitreal injection was 1.64+/-0.67 in the topical and 0.85+/-0.52 in the subconjunctival group (p<0.001). The mean total pain scores of both procedures were 0.82+/-0.34 in the topical and 0.82+/-0.51 in the subconjunctival group (p>0.05). Nine eyes (32%) developed subconjunctival haemorrhage after subconjunctival injection, whereas no anesthesia-related complication developed in the topical group. Subconjunctival haemorrhage was also observed in 5 eyes (18%) in the topical group and in 11 eyes (40%) in the subconjunctival group (p>0.05) after intravitreal injection.
Conclusions: Although subconjunctival anesthesia provides better pain control during intravitreal injections, its application is more painful and leads to subconjunctival haemorrhage. Moreover, the mean total pain scores are similar in both methods. Therefore, topical anesthesia may be more suitable for daily practice.