How and when to use the latest intraocular lenses

Every year, the American Academy of Ophthalmology (AAO) says, nearly 4 million Americans undergo cataract surgery for vision correction where the clouded lens is replaced with an IOL. With intraocular lens technology growing increasingly complex, now is a critical time for ophthalmologists to learn more about IOLs and ways to optimize managing patients who have received IOLs or are considering the procedure.

In addition to correcting cataracts, implanting an intraocular lens can also resolve other vision problems. As the AAO explains, “An IOL can not only restore vision lost to cataracts, but may also correct refractive errors such as nearsightedness (myopia), farsightedness (hyperopia), astigmatism, or presbyopia.”

The main types of IOLs are:

Each type of intraocular lens used during cataract surgery performs with different strengths and has its own contraindications. It is important to know what each type of intraocular lens does and who the ideal candidate is for each so that you can select the right IOL for your patient.

Monofocal intraocular lenses let patients see at a single distance and are often set at a long-distance range, requiring patients to continue using glasses for short-distance activities such as reading if needed. Ideal candidates for traditional monofocal IOLs are patients who understand and accept that they will need to continue to wear corrective lenses at some distances post-surgically.

A new type of monofocal IOL, the Light Adjustable Lens (LAL), now allows for non-invasive post-surgical adjustments using UV lights and vision tests to customize the prescription and correct refractive errors after the eye heals. LAL IOLs can accommodate astigmatism and can allow for both near and far vision without glasses. The AAO explains that LALs are not suited for patients with pre-existing macular disease, nystagmus, a history of herpes eye infection, or — because of the nature of the UV light-adjusting treatments — those on retino-toxic or UV-sensitive medications.

Multifocal IOLs, as the name suggests, allow the patient to see at different focal lengths. These intraocular lenses are made using refractive, diffractive, or combination designs to, as Liberdade C. Salerno et. al explain in “Multifocal intraocular lenses: Types, outcomes, complications and how to solve them,”

“Enhance outcomes of cataract surgery improving near vision [versus the results from using monofocal IOLs] by dividing light in different focuses, which changes the vision physiology because of the light dispersion that happens when it enters into the eye.”

Multifocal IOLs can present complications such as haloing, but Salerno and their fellow researchers recognized in the 2017 article that “new and more sophisticated multifocal IOLs [aim] to improve patient expectations across all distances, and [possibly decrease] low incidence of photic phenomena, such as halos and glare.” The ideal candidate for use of multifocal IOLs is a person with cataracts who does not want to continue wearing glasses after the surgery. This excludes patients with comorbidities such as severe dry eye, irregular astigmatism, and macular degeneration, or a problematic condition that would cause the multifocal IOL to dislocate.

Though Salerno’s paper predicted that this “depth of focus” revolution would come in the form of multifocal lenses, extended depth-of-field IOLs have emerged as a distinct type of IOL that borrow multifocal optical concepts. Unlike multifocal lenses, EDOF IOLs, explains Dr. Piotr Kanclerz et. al in “Extended Depth-of-Field Intraocular Lenses: An Update,”

“Create a single elongated focal point, rather than several foci, to enhance depth of focus [and] aim to reduce photic phenomena, glare, and halos, which have been reported in [multifocal] IOLs. [...] Frequently, EDOF IOLs are combined with [multifocal] optical designs; for this reason, EDOF IOLs are commonly a subject of confusion with optical multifocality concepts.”

The ideal EDOF IOL patient will not necessarily mind wearing glasses if necessary and may seek to correct existing presbyopia at the same time as the cataract(s).

Accommodating IOLs are more flexible than other intraocular lenses, using the eye’s ciliary muscular contractions to change the lens’s shape and refractive power. AIOL designs are categorized as single-optic, dual-optic, or deformable surface. Ideal AIOL candidates demonstrate good ciliary muscle function and would like strong near and distance vision.

Toric IOLs are suggested for patients who have cataracts and astigmatism as it corrects both, except in cases of irregular astigmatism resulting from ectasia or corneal scarring. Ideal patients will want to treat both conditions simultaneously but will not have any of the additional contraindications for toric IOLs, including glaucoma implants, zonular instability, poor pupillary dilation, posterior capsular dehiscence, and previous vitreoretinal surgeries.

As with any implanted medical device, intraocular lenses can cause complications. As a clinician, it’s important to be aware of the kinds of challenges that IOL implantees can face and to proactively mitigate potential side effects by selecting the right lens for the patient’s needs.

Clinicians must proactively research each type of intraocular lens in depth to understand the relevant potential side effects of IOLs. Multifocal IOLs can cause glare, halos, and lower contrast sensitivity. EDOF IOLs can present “a decrease of retinal image quality” in certain circumstances as well as an increased risk of contrast reduction and halos. AIOLs can cause “limited amplitude of accommodation and high rate of posterior capsular opacification.”

Understanding the potential benefits and complications of each kind of intraocular lens is critical for providing your cataract surgery patients with the best care possible. Relevant intraocular lens CME courses can help you learn about new technologies and treatment modalities in cataract surgery — including how to manage patients who are unhappy with their IOL results — so you can inform your clinical decisions with the most modern findings.

Here is a short list of available continuing education courses on IOLs:

Want additional continuing education on eye health? Search for more online CME audio lectures in ophthalmology available right on your phone or desktop through AudioDigest.org.

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