Innovative IOL technology fills pipeline

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An array of IOLs under development and in clinical trials show promise for correcting presbyopia or addressing other limitations of existing pseudophakic lenses.

By Cheryl Guttman Krader; Reviewed by Jack T. Holladay, MD, MSEE

Houston-Multiple novel IOLs are in the pipeline that are designed to eliminate the problems remaining with current lenses, said Jack T. Holladay, MD, MSEE.

“Using various strategies, IOLs are being developed to eliminate refractive surprises and other aberrations, correct presbyopia without any optical compromise, avoid positive and negative dysphotopsias, and eliminate unwanted wavelengths,” said Dr. Holladay, clinical professor of ophthalmology, Baylor College of Medicine, Houston.

“Several of these lenses have already been implanted in human eyes,” Dr. Holladay said. “We can expect that some of them will become available to surgeons in the United States in the not-too-distant future.”

Three different companies, he noted, are pursuing different approaches for addressing refractive surprises and reducing unwanted aberrations.

• The Light Adjustable Lens (Calhoun) contains photosensitive silicone monomers IOL that undergo polymerization with exposure to ultraviolet light, resulting in shape changes. In human eyes, this technique has already been shown effective for adjusting sphere, cylinder, spherical aberration, and coma.

• Aaren Scientific is working on the development of IOLs that undergo in situ customization using a femtosecond laser to modify the refractive index of the polymer material.

• ClarVista Medical is pursuing a different approach with the development of a modular IOL (Harmoni). This dual-element platform includes a base component that is implanted in the capsular bag and an exchangeable optic that attaches to the base completely within the capsulorhexis and allows adjustments in spherical power, toricity, and multifocality.

The ‘holy grail’ of presbyopia

Novel IOL approaches for eliminating presbyopia are based on the use of optical, mechanical, and electrical strategies. The optical approach is represented by new extended depth of focus IOLs that use diffractive optics having a longer depth of focus that can be balanced in a way so that there are no compromises of distance acuity or contrast sensitivity.

The LiquiLens IOL (Vision Solution Technologies) is also based on an optical principle. This IOL contains two immiscible fluids and works on a gravity-dependent mechanism wherein the two liquids become axially juxtaposed with downward gaze, leading to an increase in power through the line of sight.

Several presbyopia-correcting lenses in development are using mechanical properties to change the power of the lens with accommodation. The Lumina accommodating IOL (Akkolens) is a dual-optic implant. Capsular bag contraction causes the optics to slide in opposite directions and results in an increase in total power.

Other lenses integrate mechanical properties with deformable optics. They include the FluidVision accommodating IOL (PowerVision), the DynaCurve (NuLens), and the FlexOptic IOL.

Also within this category are the injectable polymer IOLs, including the Smart IOL (Medennium), which is a rigid rod at room temperature, but transforms into a malleable capsular bag-filling gel inside the eye.

The Sapphire AutoFocal IOL (Elenza) is a novel system for presbyopia correction in which electrical current is used to change the index of refraction of a liquid crystal embedded within the IOL. The technology controlling the modification senses pupil constriction and lighting conditions in order to avoid initiation of the process if pupil constriction is related to the environment rather than a change in focal distance.

Curbing unwanted symptoms, wavelengths

Anti-dysphotopic IOLs include one design that features a groove on the periphery of the anterior optic surface that allows the optic to overlap the capsulorhexis. The result is that incoming light from the periphery is bent in a way that it will not lead to a scotoma or reflections. A lens with this design manufactured by Morcher received the CE mark in March 2013.

A second design, known as the bag-in-the-lens, was pioneered by Marie Tassignon, MD, PhD. It is intended for implantation in an eye with an anterior and posterior capsulorhexis and features flanges on the edge of the lens into which the capsule leaflets are placed. The design eliminates reflections, and in clinical trials so far, no patients have reported negative or positive dysphotopsias.

Elimination of dynamically unwanted wavelengths without compromising vision in low light conditions is being addressed through the creation of a photochromic IOL material developed by Medennium.

Jack T. Holladay, MD MSEE

E: holladay@docholladay.com

Dr. Holladay is a consultant to Alcon Laboratories and Elenza.

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