Insulin syringe for anesthesia in ptosis surgery: a randomized, fellow eye-controlled clinical study

Unlike ordinary 30-gauge needles, insulin syringe needles are thinner and shorter and have a comparatively blunt tip. Therefore, insulin syringes may reduce injection discomfort, bleeding, and edema by minimizing tissue damage and vascular penetration. This study aimed to evaluate the potential benefits of using insulin syringes for local anesthesia in ptosis surgery.

This randomized, fellow eye-controlled study included 60 patients (120 eyelids), conducted at a university-based hospital. An insulin syringe was used on one eyelid, and a conventional 30-gauge needle was used on the other. Patients were instructed to score pain in both eyelids using a visual analog scale (VAS) ranging from 0 (no pain) to 10 (unbearable pain). Ten minutes after the injection, two observers scored degrees of hemorrhage and edema in both eyelids on five- and four-pointing grading scales (0-4 and 0-3) for each value, and the average score between the two observers was calculated and compared.

The VAS score was 5.17 in the insulin syringe group and 5.35 in the 30-gauge needle group (p = 0.282). Ten minutes after the anesthesia, the median hemorrhage scores were 1.00 and 1.75 (p = 0.010), and the median eyelid edema scores were 1.25 and 2.00 (p = 0.007) in the insulin syringe and 30-gauge needle groups, respectively (Fig. 1).

Injecting local anesthesia using an insulin syringe significantly reduces hemorrhage and eyelid edema, but not injection pain, before skin incision. Insulin syringes are useful in patients at high risk of bleeding because they can reduce the penetrative tissue damage caused by needle insertion.