Post-op IOL adjustment

Several technologies in development and on the market can help reduce residual refractive error.

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Burkhard Dick MD
Several new technologies are available or on the horizon for adjusting intraocular lens (IOL) power after implantation, according to Burkhard Dick MD .These include both invasive and non-invasive techniques for correcting residual refractive error, which is especially important for success in post-keratorefractive surgery eyes, and with premium multifocal and extended depth of focus IOLs. Invasive techniques Multi-component lenses require a second surgical procedure to adjust, Dr Dick said. Examples include the PreciSight (InfiniteVision Optics), in which the upper of a two-piece lens system can be changed, and the Harmoni (ClarVista), in which a central optic that is supported by a permanent scaffold can be changed. Monofocal, multifocal, toric and pinhole lenses can be exchanged in these devices, which are available outside the USA. Dr Dick believes these devices are most appropriate for patients likely to require a secondary IOL intervention, such as those with paediatric cataracts, progressive corneal pathology including keratoconus, or tamponades from vitreoretinal surgery. Non-invasive techniques Laser-induced refractive index change (LIRIC) technologies, in which a femtosecond laser is used to change the refractive power or inscribe Fresnel lenses in corneal tissue or an in vivo IOL, are getting close to market, Dr Dick said. Clerio Vision has successfully used LIRIC to write a -2.0 dioptre Fresnel lens in contact lenses as well as a live cat eye and has successfully induced refractive index changes in a living human cornea. A first-in-human study by Scott McRae MD inscribed a presbyopia-correcting pattern in corneas that significantly improved near vision, Dr Dick noted. Perfect Lens has successfully adjusted the power of IOLs implanted in living rabbits and has added or cancelled multifocality in a model eye. Merck has developed LicriEye, a polymer designed to accept reversible refractive index changes, though no commercially viable product has yet been presented. Medicem has developed a hydrogel IOL material that is specifically designed to accept high LIRIC power changes, Dr Dick said. Furthest along is the Light Adjustable Lens (LAL), which has gained FDA approval in the USA, with a 2.0 version on the market in Europe. The new lens and device reduce retinal UV irradiance by ten-fold and supports new optical patterns, including an expanded range of astigmatism correction and extended depth of focus, said Dr Dick, who helped develop the LAL. With nearly 30% of patients missing refractive targets by 0.75D or more, IOL adjustment technologies will improve patient outcomes, Dr Dick said. “We need something to adjust refractive power postoperatively for better patient care.”
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