Advances in Intraocular Lenses Utilized During Cataract Surgery

Cataract surgery has advanced significantly since the first IOL was implanted in England in 1950. Sir Harold Ridley, a British ophthalmologist, had noted that a fighter pilot from the Royal Air Force wounded during World War 2 had a retained fragment of acrylic plastic (PMMA) which did not trigger inflammation. He subsequently went on to design and implant the first IOL made of a similar material. After facing much criticism in the ophthalmic community, he nevertheless persisted, and went on to improve the subsequent designs of IOLs. Ultimately, the FDA found IOLs to be “safe and effective” for the use in cataract surgery in 1981. Cataract surgery is currently the most commonly performed procedure in the US, where over 3 million patients undergo surgery annually.

The vast majority of cataract surgical patients receive a mono focal IOL, which allows for uncorrected visual acuity to be improved at one distance. However, since the 1990s and early 2000s, newer model IOLs, such as accommodating (which change shape within the eye to allow for improved intermediate vision), toric (to correct for astigmatism) and multifocal IOLs (to reduce presbyopia) have made progressive and substantial improvements in reducing the need for postoperative spectacle correction. With the recent newer technological advances, accommodating IOLs have become less commonly utilized.

One of the newer multifocal IOLs, such as the Panoptix IOL, is a diffractive multifocal lens. This design has allowed patients to have excellent visual acuity at distance ( comparable to mono focal lenses) , but additionally provides excellent intermediate and near vision. According to retrospective surveys in patients that have undergone cataract surgery with this lens, patients were able to perform approximately 80 percent of their daily tasks without using glasses. Side effects of this IOL, due to its design, are the presence of nighttime halos, glare and difficulty driving. Even though the presence of halos has been reported quite frequently, over time neuro-adaptation occurs and the majority of patients tolerate these IOLs well. As with any multifocal IOL, there is always the small risk of requiring IOL exchange to manage patients with these nighttime issues.

Another type of newer IOL is the Extended Depth of Focus (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 not diffractive provides patients with an increased depth of focus and extended range of vision while significantly decreasing the risk of rings and halos. This IOL may also be better tolerated in patients with other mild ocular pathology, since the lens design is not diffractive and does not split rays of light. However, this IOL does reduce contrast sensitivity.

While mono focal IOLs typically achieve an 80- 90% accuracy in refractive targets, a recently FDA approved IOL, the Light Adjustable Lens (LAL) , has been shown to improve that number to 95- 98%. The paradigm shift here is that the refractive 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. After the lens is implanted at the time of surgery, a light delivery device is utilized to refine the refractive outcome on two separate visits, starting at 3 weeks postoperatively. These postoperative adjustments are done in the office, where a refraction can be performed prior to “locking in” the desired refractive target. A “blended vision” outcome would allow for improved near as well as distance uncorrected visual acuity.

In summary, the advances over the last few decades in IOL technology have been impressive. I have no doubt that in the future these technologies will continue to improve and patients should continue to benefit in their quality of vision as well as quality of life.