To obtain a 1% iodine solution for eyelids and surrounding skin, which dilution should be used?

• A. 1:5
• B. 1:50
• C. 1:10
• D. 1:100

Answer: (C)

The main idea is figuring out how to dilute a stock solution to reach the desired final concentration. If you have a 10% povidone-iodine stock and you want a 1% solution, you dilute by a factor of ten. That means use one part of the 10% stock and add nine parts diluent (such as sterile saline or water). The math is 10% × (1/10) = 1%, so the correct dilution is 1:10.

This is important for eyelids and surrounding skin because the tissues are sensitive; using 1% reduces irritation while still providing antiseptic effect. Using a stronger dilution would result in more irritation (for example, about 2% with a 1:5 mix), while weaker dilutions would be less effective (for instance, around 0.2% with 1:50 or 0.1% with 1:100). Prepare with sterile technique and avoid direct application to the eye itself.