Which is the larger gauge needle: 21 gauge or 23 gauge?

The correct answer is that a 21 gauge needle is larger than a 23 gauge needle. In the gauge system used for needles, a smaller gauge number indicates a larger diameter. The gauge system is somewhat counterintuitive: as the gauge number increases, the size of the needle decreases. Therefore, the 21 gauge needle, being of a lower gauge number, has a larger outer diameter compared to the 23 gauge needle.

This size difference is important in medical practices, including ophthalmic procedures, where the choice of needle size can affect the flow of fluids and the ease of injection. For instance, a larger gauge needle like the 21 gauge can be more suitable for drawing blood or injecting larger volumes of substances, while smaller gauge needles may be used for more delicate procedures where less trauma to the tissue is desired.