PVP (also known as povidone) is a water-soluble polymer similar to medical and industrial dextran (as shown above). Although there have been rare reports of severe allergic reactions, povidone is generally considered safe. The pH of povidone-iodine solution is about 5 and the acidity decreases with dilution. 10% povidone-iodine is composed of 90% water, 8.5% povidone and 1% iodine and iodide.
Povidone-iodine can act on a variety of bacteria, fungi, protozoa and viruses. Povidone is hydrophilic and has an affinity for cell membranes. It acts by transporting diatomic free iodine directly to the surface of the target cell. For cataracts, povidone-iodine mainly acts on the plasma membrane and cytoplasm, and can take effect within a few seconds.
1. Use of 5%-10% povidone-iodine
Globally, the concentration of povidone-iodine used on the ocular surface is generally 5%-10%
Shimada et al. reported a scheme in which 0.25% povidone-iodine was repeatedly used in cataract surgery, with 2-3 drops dripped every 20-30 seconds.
For corneal ulcers, 1.25% povidone-iodine can be used 4 times a day.
To prevent neonatal ophthalmia, 2.5% povidone-iodine can be used once. There are no reports of using povidone-iodine in the anterior chamber.
During vitreoretinal surgery, 0.025% povidone-iodine can be added to the perfusion solution for endophthalmitis.
