Advances in intraocular lenses used during cataract surgery
Eugenio Candal, Medical Director at Reliant Medical Group
Cataract surgery has come a long way since the first IOL was implanted in England in 1950. Sir Harold Ridley, a British ophthalmologist, found that a Royal Air Force fighter pilot injured in World War II retained a fragment of acrylic plastic (PMMA) which did not trigger any ignition. He then designed and implanted the first IOL made of a similar material. After facing much criticism in the ophthalmic community, he nevertheless persisted and continued to improve subsequent IOL designs. Ultimately, the FDA concluded that IOLs were “safe and effective” for use in cataract surgery in 1981. Cataract surgery is currently the most commonly performed procedure in the United States, where more 3 million patients undergo surgery each year.
The vast majority of cataract surgery patients receive a monofocal IOL, which improves uncorrected visual acuity at a distance. However, since the 1990s and early 2000s, new designs of IOLs, such as accommodating IOLs (which change shape in the eye to allow better intermediate vision), toric IOLs (to correct astigmatism ) and multifocal IOLs (to reduce presbyopia) have made IOLs progressive and substantial improvements in reducing the need for postoperative spectacle correction. With recent advances in technology, accommodating IOLs have become less commonly used.
One of the new multifocal IOLs, like the Panoptix IOL, is a diffractive multifocal lens. This design allowed patients to have excellent distance visual acuity (comparable to monofocal lenses), but in addition provides excellent intermediate and near vision. According to retrospective surveys of patients who underwent cataract surgery with this lens, patients were able to perform approximately 80% of their daily tasks without using glasses. The side effects of this IOL, by design, are the presence of nocturnal halos, glare and driving difficulties. Although the presence of halos has been reported quite frequently, neuro-adaptation occurs over time and the majority of patients tolerate these IOLs well. As with any multifocal IOL, there is always a small risk of requiring IOL exchange to manage patients with these nighttime problems.
“As with any multifocal IOL, there is always the small risk of requiring an IOL exchange to manage patients with these nighttime issues”
Another newer type of IOL is the Extended Depth of Field (EDOF) IOL. The Vivity IOL is an example of this type of lens. This type of lens allows patients to have excellent distance and intermediate vision, with functional near vision. The fact that this lens is non-diffractive provides patients with increased depth of field and an extended field of vision while significantly reducing the risk of dark circles and halos. This IOL may also be better tolerated in patients with other mild ocular conditions because the lens design is non-diffractive and does not split light rays. However, this IOL reduces contrast sensitivity.
While monofocal IOLs typically achieve 80-90% accuracy in refraction targets, a recently FDA-approved IOL, the Light-Adjustable Lens (LAL), has been shown to improve that number to 95-90%. 98%. The paradigm shift here is that the refraction target can be adjusted after cataract surgery. The IOL is made of a material that changes the power and shape of the lens in response to ultraviolet light. Once the lens is implanted at the time of surgery, a light scattering device is used to refine the refractive outcome during two separate visits, starting 3 weeks after surgery. These post-operative adjustments are made in the office, where a refraction can be performed before “locking in” the desired refraction target. A “mixed vision” result would improve uncorrected near and distance visual acuity.
In summary, the progress made over the past decades in IOL technology has been impressive. I am convinced that in the future, these technologies will continue to improve and that patients should continue to benefit from their quality of vision as well as their quality of life.