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Accommodating IOL pipeline looks promising as baby boomers age
Refractive surgeons can look forward to a number of accommodating IOL options for their patients in the future, explained Steven Dell, MD, who spoke at the Hot Topics Symposium during the American Society of Cataract and Refractive Surgery annual meeting.
Refractive surgeons can look forward to a number of accommodating IOL options for their patients in the future, explained Steven Dell, MD, who spoke at the Hot Topics Symposium during the American Society of Cataract and Refractive Surgery annual meeting.
The reason for this explosion in IOL technology is the potential market is growing fast. By 2020 the U.S. population over the age of 65 is expected to double from its current level. With increased wealth, patients will be able to consider IOL technology and will demand good near and intermediate vision. More individuals over age 50 are using computers and hand-held electronic devices, such as cell phones and PDAs, and this trend is expected to continue, Dr. Dell explained.
Current accommodating IOLs are of single-optic design, such as the Human Optics 1CU and the eyeonics crystalens. Another option available in Europe is the Kellan TetraFlex (Lenstec), an acrylic accommodating lens, which is in an FDA clinical trial. The mechanism of action of the lens is based on the movement of the optic.
Dual-optic accommodating IOLs are also under development. The Synchrony IOL (Visiogen) consists of a high plus lens in the front that is joined by spring haptics to the negative lens in the back.
"The plus lens is fixed at +32 D and the rear lens in the back is individualized for the patient's prescription," Dr. Dell said. This lens work by ciliary muscle contraction, which causes capsule bag laxity, and then the two lenses separate to create transient myopia, he said. The Synchrony IOL has been implanted in more than 50 eyes outside the United States.
Bausch & Lomb has developed the Sarfarazi Dual Optic Accommodating IOL, similar to the design of the Visiogen Synchrony device with a high plus lens in the front and a negative lens in the back. It can potentially provide about 3 D of accommodation, Dr. Dell said. With the Sarfarazi accommodating technology, human implants have been achieved outside of the United States.
The Smart IOL (Medennium), a hydrophobic acrylic lens, changes from its rod-type shape after implantation in the capsular bag.
"It has a high refractive index, meaning a small change in lens shape would be accompanied by a large change in accommodation. This lens is in the concept stage and no human trials have taken place yet," Dr. Dell said.The NuLens IOL (NuLens) has a unique design for implantation in the ciliary sulcus. Its flexible central gel-filled sac is subjected to pressure from the capsular diaphragm. Then its radius of curvature changes and provides accommodation, he said. This lens has been implanted only in primates to date.
The FluidVision Lens (PowerVision Inc.) is another unusual design with two fluid reservoirs at the haptic tips. These are connected by tubular haptics to a fluid-filled optic lens.
"Ciliary constriction causes zonular laxity. The reservoir changes shape with the fluid compressed down the tubular haptic and then the radius of curvature of the optic changes shape," Dr. Dell said.
Up to 10 D of accommodation are possible with this implant. So far, the lens has not been implanted in humans. Possible obstacles with the FluidVision Lens are capsular contraction and capsular rigidity issues, Dr. Dell said.
