Air and liquid provide bifocality in new IOL

ATHENS — A pseudoaccommodative IOL that creates bifocality through air and liquid is currently approaching a phase 3 clinical trial, according to a surgeon speaking here. The new concept in creating multifocality holds "tremendous promise and may prove to be a breakthrough in bifocal IOL technology," said Meenakshi Gupta, MD.

The IOL consists of a coaxial plano-convex lens combination. The anterior lens has a convex surface with a refractive power of 20 D within the eye. The posterior lens, which also has a convex anterior surface, has a power of about 3 D in air. "The little space in between these two lenses is sealed around the periphery and filled to about two-thirds with liquid and one-third with air," Dr. Gupta said.

When the eyes are directed horizontally for distance vision, the liquid occupies the space in between the lenses' optical zones and neutralizes the 3 D power of the posterior lens. When the eyes swivel down by 30° to 40° for near vision, the fluid level remains horizontal and the air occupies the space in between the optical zones, leading to restoration of the additional 3 D power of the posterior lens. The resulting total power of the lens for near is 23 D, Dr. Gupta said.