A variety of approaches are commercially available or in development that allow refractive adjustments after cataract surgery, including changes in sphere, cylinder, asphericity, and multifocality
This article was reviewed by Burkhard Dick, MD
Available and emerging technologies are addressing the need for solutions to the persistent problem of refractive surprises after cataract surgery, according to Burk-hard Dick, MD, PhD.
Two multicomponent IOLs (PreciSight, InfiniteVision Optics; Harmoni Modular IOL, ClarVista) and the light-adjustable lens (LAL, RxSight) are now on the market in some countries, and four companies are developing approaches for inducing refractive index changes using a femtosecond laser, said Dr. Dick, professor of ophthalmology, Ruhr University, and chairman, The University Eye Hospital Bochum, Bochum, Germany.
Sharing his personal perspectives on the light-adjustable lens, Dr. Dick noted that there is now more than 10 years of clinical experience with this technology, and an upgraded version is now available commercially in Europe that is showing great success.
“A vast amount of experience underscores the value of this three-piece silicone lens whose refractive power can be changed within a few weeks after cataract surgery by specifically targeted UV irradiation,” he said. “I consider the light-adjustable lens a great option to improve refractive outcomes and advance patient care.”
The upgraded light-adjustable lens platform features added UV protection, is implanted with a proprietary injector that allows introduction through incisions ≤ (</=) 2.75 mm, and is adjusted with a new light delivery device. This offers improved ergonomics, a 10-fold reduction in retinal UV irradiance, and new optical patterns.
“The new platform allows for earlier noninvasive post-implantation adjustment and less lock-ins, and it can create an extended depth of focus pattern, induce negative asphericity, and be used to design individually adjustable mini-monovision,” Dr. Dick said.
The safety and performance of the new light-adjustable lens was investigated in a multicenter European study that enrolled 100 eyes of 50 patients with 0.5 to 3 D of preop keratometric astigmatism. The results demonstrated the safety and efficacy of the upgraded light-adjustable lens technology, Dr. Dick said.
“More than 70% of eyes achieved 20/20 or better UCVA, which represents a twofold improvement over the outcomes achieved with toric IOLs, and the accuracy to target refraction for spherical equivalent and cylinder was exceptionally high, matching LASIK outcomes,” he pointed out.
“In addition, the incidence of both glare and halo were very low.”
Multicomponent adjustable IOLs
Refractive adjustment with multicomponent adjustable IOLs is achieved by exchanging a front optic with a new component that corrects refractive error or better serves the patient’s vision goals. The two available technologies differ in design.
The PreciSight multicomponent IOL is a dual optic platform that is implanted into the capsular bag. In contrast, the Harmoni Modular IOL uses a scaffold that is implanted into the bag and a front exchangeable optic.
“My personal opinion is that because the multicomponent IOLs require a secondary procedure for power adjustment, they are best considered in situations where there is an increased likelihood of refractive change, such as in cases of pediatric cataract, progressive corneal pathology, or with vitreoretinal tamponade,” Dr. Dick said.
Laser-induced refractive index change
Laser-induced refractive index change (LIRIC) is caused by multiphoton absorption of ultrashort laser pulses and can be performed in silicone, hydrogel, or dye-doped polymers but also in the cornea.
Clerio Vision, one company developing LIRIC technology, is focusing on the development of a device for refractive index modification in the cornea that could supersede LASIK and is the first company to demonstrate LIRIC of a living human cornea.
The company is also working on a bench top customization device for contact lenses and investigating modification of IOL materials, according to Dr. Dick.
Perfect Lens is another company working in the LIRIC space. It focuses on developing a device for in vivo IOL adjustment.
Related: Striving for perfection: Creating the perfect IOL
Medicem is designing IOL material optimized for modification by a femtosecond laser and a device for in vivo IOL modification. To date it has found a material suitable for refractive index shaping that is expected to have potential for relatively high power change.
LicriEye (Merck) currently is developing polymers containing coumarin side groups to enable photo-induced adjustment of LIRIC. Its work is in an early stage of development.
Read more by Cheryl Guttman Krader, BS, Pharm
Burkhard Dick, MD
This article is based on Dr. Dick's presentation at the American Academy of Ophthalmology 2019 annual meeting. Dr. Dick is a consultant to RxSight.