IOLs: Choosing the best implant for cataract surgery

Intraocular lenses (IOLs) are medical devices that are implanted inside the eye to replace the eye's natural lens when it is removed during cataract surgery. IOLs also are used for a type of vision correction surgery called refractive lens exchange.

Before the use of intraocular lenses, if you had cataracts removed, you had to wear very thick glasses or special contact lenses in order to see clearly after cataract surgery, since no device was implanted in the eye to replace the focusing power of the natural lens.

The tiny, clear IOL replaces the natural lens inside your eye. [Image credit: By Frank C. Müller licensed under CC BY SA 3.0]

Today there is a wide variety of premium IOLs to choose from. The best intraocular lens for you depends on many factors, including your lifestyle and your specific visual needs.

The following is an overview of premium IOLs currently that are FDA-approved for use by cataract surgeons in the United States. These are considered "premium" intraocular lenses because they have advanced features beyond those found in basic single vision IOLs that are covered by Medicare and other types of health insurance.

During your preoperative exam and consultation, your cataract surgeon can help you choose the best IOL for your needs, as well as additional cataract surgery costs involved if you choose one of the following premium lens implants.

Aspheric IOLs

Traditional intraocular lenses have a spherical optical design, meaning the front surface is uniformly curved from the center of the lens to its periphery. Though a spherical IOL is relatively easy to manufacture, this design does not mimic the shape of the natural lens inside the eye, which varies in curvature from center to periphery. In other words, the eye's natural lens is aspheric ("not spherical").

Why is this important?

A spherical intraocular lens can induce minor optical imperfections called higher-order aberrations (HOAs), which can affect quality of vision, particularly in low-light conditions such as driving at night.

Premium aspheric IOLs, on the other hand, match more closely the shape and optical quality of the eye's natural lens, and thereby can provide sharper vision — especially in low light conditions and for people with large pupils.

Popular aspheric IOLs that are FDA-approved and available in the U.S. include: Tecnis (Johnson & Johnson Vision), AcrySof IQ (Alcon), and enVista (Bausch + Lomb).

Toric IOLs

Toric IOLs are premium intraocular lenses that correct astigmatism as well as nearsightedness or farsightedness.

Like toric soft contact lenses, toric IOLs can correct astigmatism because they have different powers in different meridians of the lens. They also have alignment markings on the peripheral part of the lens that enable the surgeon to adjust the orientation of the IOL inside the eye for optimal astigmatism correction.

Just prior to cataract surgery, the surgeon places temporary markings on the patient's cornea that identify the location of the most curved meridian of the front of the eye. Then, when the toric IOL is implanted during the cataract procedure, the surgeon rotates the IOL so the markings on the IOL are aligned with the markings on the cornea to insure proper astigmatism correction.

Prior to the development of toric IOLs, cataract surgeons had to perform a procedure call limbal relaxing incisions (LRI) to correct astigmatism during or after cataract surgery.

In LRI, small incisions are made at opposite ends of the cornea, very near the junction between the cornea and the surrounding white sclera. When these incisions heal, the cornea becomes more spherical in shape, reducing or eliminating astigmatism.

In some cases — even when a toric IOL is used — limbal relaxing incisions may be needed after cataract surgery to fully correct astigmatism. But typically in such cases, the amount of astigmatism remaining after implantation of a toric IOL is far less, making a better LRI outcome more likely.

LASIK and PRK also can be performed after cataract surgery to correct residual astigmatism, but toric IOLs decrease the likelihood of needing these additional surgical procedures.

FDA-approved toric intraocular lenses available in the U.S. include: Tecnis Toric (Johnson & Johnson Vision), AcrySof IQ Toric (Alcon), and enVista Toric (Bausch + Lomb).

Accommodating IOLs

Conventional spherical IOLs are monofocal lenses, meaning they are designed to provide clear vision at a single focal point (usually far away for good driving vision, for example). With conventional IOLs, typically you must wear eyeglasses or contact lenses in order to use a computer, read or perform other close-up tasks within arm's length.

Accommodating IOLs are premium intraocular lenses that expand the range of clear vision with both an aspheric design and flexible "haptics" — the supporting legs that hold the IOL in place inside the eye.

These flexible legs allow the accommodating IOL to move forward slightly when you look at near objects, which increases the focusing power of the eye enough to provide better near vision than a conventional monofocal lens.

Accommodating IOLs may not provide the same level of magnification for near vision that a multifocal IOL does. But many people find these premium IOLs greatly reduce their need for reading glasses or computer glasses after cataract surgery, while providing exceptionally clear distance vision similar to that offered by a monofocal IOL.

Popular accommodating IOLs available in the U.S. include Crystalens AO and Trulign Toric IOL, both made by Bausch + Lomb. (The Trulign Toric lens corrects astigmatism as well as presbyopia.)

Multifocal IOLs

Multifocal IOLs are another category of presbyopia-correcting IOLs that can decrease your need for reading glasses or computer glasses after cataract surgery.

Like multifocal contact lenses, these premium IOLs contain added magnification in different parts of the lens to expand your range of vision so you can see objects clearly at all distances without glasses or contact lenses.

Some studies have shown multifocal IOLs tend to provide better near vision than accommodating IOLs, but they also are more likely to cause glare or mildly blurred distance vision as a tradeoff.

Your cataract surgeon can help you decide if you are a good candidate for multifocal IOLs at your preoperative exam and consultation.

Laser cataract surgery often is recommended if you are interested in multifocal IOLs, because precise alignment of these lenses is very important to give you the best visual outcome at all distances.

Popular FDA-approved multifocal IOLs include: Tecnis Multifocal (Johnson & Johnson Vision) and AcrySof IQ ReSTOR (Alcon).

Monovision

An alternative to accommodating and multifocal IOLs for correcting presbyopia is monovision.

There is no such thing as a "monovision IOL." Monovision is the technique of fully correcting the refractive error of one eye and intentionally making the other eye mildly nearsighted.

In this scenario, the fully corrected eye sees distant objects clearly (but cannot see very well up close without glasses), and the mildly nearsighted eye sees very well up close without glasses (but not so clearly far away).

Monovision may sound odd the first time you hear about it, but this technique has been used very successfully with contact lenses for many years. And it is now being used frequently with cataract surgery to decrease a person's dependency on reading glasses and computer glasses after surgery.

Any combination of premium IOLs can be used for monovision cataract surgery.

When accommodating or multifocal IOLs are used for monovision, the term "modified monovision" often is used, since these lenses offer an expanded range of vision by nature of their design in addition to a prescribed monovision effect.

A different type of IOL for each eye

Sometimes, the best visual outcome after cataract surgery is achieved by using a different type of premium IOL in each eye.

For example, you may have more astigmatism in one eye than the other. If this is the case, your cataract surgeon may recommend a toric IOL in that eye, and perhaps an accommodating IOL in the other eye to also decrease your need for computer glasses.

Another scenario is for your cataract surgeon to recommend one brand of multifocal lens for one eye and a different brand for the other. This is because one brand may provide better computer vision and the other may provide sharper vision at a closer distance, for reading and other close-up tasks.

(For a first-hand account of having different multifocal IOLs implanted in each eye, read former AllAboutVision.com editor Marilyn Haddrill's account of her cataract surgery.)

Your cataract surgeon can fully evaluate your specific needs during your pre-op exam and consultation, and help you choose the best combination of premium IOLs for a successful visual outcome.

SEE RELATED: Alport syndrome

Cost of premium IOLs

Premium IOLs have additional features not found in conventional monofocal IOLs and cost more than conventional IOLs.

Unfortunately, health insurance companies do not consider these additional features as medical necessities. Therefore you will incur additional out-of-pocket expenses for your cataract surgery if you choose a premium IOL.

Medicare and private health insurance or vision insurance policies generally do cover the cost of cataract surgery, including the cost of a conventional monofocal IOL (though a deductible amount may be required, depending on your policy).

If you choose a premium IOL like one described above, typically you will have to pay the difference in cost between a conventional monofocal IOL and the premium lens implant. This out-of-pocket expense could range from $1,500 to $3,000 per eye or more, depending on the type of IOL and whether you opt for advanced laser cataract surgery as well.

To fully understand your cataract surgery costs and coverage, check the terms of your insurance policy carefully before you have surgery.

Also, ask plenty of cost-related questions at the business office of your eye doctor and cataract surgeon before consenting to surgery, to avoid unpleasant financial surprises afterward.

READ NEXT: What is aphakia?

Page published on Wednesday, February 27, 2019