Effect of Needle Type and Injection Technique on Pain Level and Vitreal Reflux in Intravitreal Injection

Purpose: To evaluate the amount of reflux and degree of pain with intravitreal injection (IVT) using 6 different types of syringes/needles and 5 techniques of scleral incision, including 3 modifications of a beveled scleral incision. Methods: This was a study conducted in 205 eyes of 205 patients. IVT of bevacizumab for retinal pharmacotherapy with 6 types of needles and 5 techniques of scleral incision. The severity of subjectively evaluated pain (0-10) and the width of the subconjunctival bleb arising from the vitreal reflux. Secondary outcomes were increase in intraocular pressure and complication rate. Results: The straight technique caused greater vitreal reflux than the beveled approaches, when compared individually or as a group (P < 0.01). No difference in the severity of pain was found among all 5 types of incisions (P > 0.05). There was greater reflux with 26- and 27-gauge needles in comparison to 29- and 30-gauge needles (P < 0.001); however, the width of the needle significantly affected the degree of reflux only when using the nonbeveled incision (P < 0.001). The patients injected with the 26- or 27-gauge needle experienced more pain matched to the 29- and 30-gauge needles (P < 0.001). No difference was found between the incision technique or width of subconjunctival reflux and the increase in intraocular pressure (P > 0.05). Postinjection events included transient mild uveitis, disease-related vitreous hemorrhage, foreign body sensation, conjunctival hemorrhage, and mild punctuate keratitis. Conclusions: The beveled scleral incision showed benefit in performing IVTs. The 29- and 30-gauge needles caused less pain.