Effect of needle type and injection technique on pain level and vitreal reflux in intravitreal injection

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.

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.

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.

The beveled scleral incision showed benefit in performing IVTs. The 29- and 30-gauge needles caused less pain.