ASSOCIATION BETWEEN NEEDLE SIZE, POSTINJECTION REFLUX, AND INTRAOCULAR PRESSURE SPIKES AFTER INTRAVITREAL INJECTIONS
PURPOSE: To compare the effect of 30-gauge versus 32-gauge needle size on postinjection reflux and immediate postinjection intraocular pressure (IOP(immed_post)) spikes in eyes injected with anti-vascular endothelial growth factor agents. METHODS: This was a prospective interventional case series of 65 eyes of 54 consecutive patients in a clinical practice setting who received intravitreal anti-vascular endothelial growth factor therapy. All eyes had preinjection IOP, IOP(immed_post), postinjection reflux, and axial lengths recorded. RESULTS: There was a higher incidence of postinjection reflux in eyes injected with 30-gauge (53%) compared with those injected with 32-gauge (13%, P = 0.0007). Among 34 eyes injected with 30-gauge, 16 eyes without appreciable postinjection reflux had mean IOP(immed_post) of 44.3 +/- 7.48 mmHg and mean IOP(immed_post) elevation of 29.6 +/- 2.10 mmHg, which was significantly higher than the 18 eyes with reflux (mean IOP(immed_post) of 18.8 +/- 7.15 mmHg and mean IOP(immed_post) elevation of 4.5 +/- 1.74 mmHg, P < 0.0001). Among 31 eyes injected with 32-gauge, 27 eyes without appreciable postinjection reflux had mean IOP(immed_post) of 44.4 +/- 10.82 mmHg and mean IOP(immed_post) elevation of 29.5 +/- 1.99 mmHg, which was significantly higher than the 4 eyes with reflux (mean IOP(immed_post) of 21.3 +/- 8.54 mmHg and mean IOP(immed_post) elevation of 9.5 +/- 4.05 mmHg, P < 0.001). The differences in reflux and IOP between the two groups were unrelated to axial lengths (P = 0.451). CONCLUSION: Eyes receiving injections with 32-gauge needles had a lower incidence of postinjection reflux and higher mean IOP immediately after injection.