Effectiveness of Ultrathin 40-Gauge Needles for Intravitreal Injections

To compare pain perception and immediate post‑procedural complications of intravitreal injections (IVIs) performed with conventional 30‑gauge needles versus ultrathin 40‑gauge needles.

This single-center, retrospective crossover study reviewed consecutive patients who underwent serial IVIs for neovascular age-related macular degeneration, diabetic macular edema, retinal vein occlusion, myopic choroidal neovascularization, or other indications between April and October 2020. Each patient received one injection with a 30‑gauge needle and one with a 40‑gauge needle-either to the fellow eye on the same day or to the same eye 1-month apart. Injections (0.05 mL bevacizumab, ranibizumab, or aflibercept) were administered in an operating room by a single surgeon following the guidelines of Avery et al. Pain was recorded immediately postinjection on a visual analog scale (VAS). Subconjunctival hemorrhage (SCH) and vitreous reflux (VR) were graded 0 to 4.

Mean age was 69.3 ± 11.5 years; 69.0% were men. VAS pain scores were significantly lower with 40‑gauge needles than with 30‑gauge needles (2.33 ± 1.26 vs 4.02 ± 1.73; paired difference [mean ± standard error], -1.69 ± 0.33; p < 0.001). Median VR grade declined from 2 (interquartile range [IQR], 2-3) to 0 (IQR, 0-1) with 40‑gauge needles (p < 0.001). SCH grade did not differ between gauges (median [IQR], 0 [0-1]; p = 0.928). No injection-related adverse events occurred.

Using an ultrathin 40‑gauge needle for IVIs significantly reduces patient‑reported pain and VR without increasing subconjunctival hemorrhage. These findings support the integration of 40‑gauge needles into routine IVI practice to enhance long-term patient adherence and treatment efficacy.