Multifocal and Monofocal IOLs: Visual Performance Comparison

What Are IOLs?

Intraocular lenses (IOLs) are synthetic corrective lenses that are implanted inside of the eye as a replacement for the eye’s natural lens These lenses are often made out of foldable, flexible acrylic, allowing them to seamlessly be integrated within the eye. Intraocular lenses are also surprisingly small – only about one-third the size of a dime.

The use of IOLs occurs most frequently during a cataract surgery, in which a clear intraocular lens replaces the naturally clouded lens otherwise known as a cataract. Intraocular lenses are also utilized during a refractive lens exchange, which is also referred to as clear lens exchange. People who are not good candidates for laser vision correction like LASIK, SMILE, or PRK might be good candidates for this type of surgery. Refractive lens exchange can significantly improve vision, and reduce the need for eyeglasses.

There are a wide variety of intraocular lenses available to fit a patient’s specific visual needs and lifestyle considerations. Two of the most common options are monofocal and multifocal intraocular lenses.

What Is The Difference Between Monofocal and Multifocal IOLs?

For over 50 years, monofocal intraocular lenses have been a viable option for people needing a lens replacement surgery as a result of cataracts. Because these are single focal-power lenses, a monofocal lens can be utilized for near, medium, or distant focus – but only one range can be selected. When light enters through this type of lens, it is bent to a specific focus point and can only be bent to one focus point at a time. These lenses will have the necessary prescription for the individual to achieve clear vision at a selected range. In most cases, monofocal lenses are used for distant focus, and then eyeglasses are utilized for reading or other up-close activities. It is ultimately up to the patient to decide which lens setting will improve their quality of life the most.

Patients who choose monofocal lenses can choose to have one lens selected for distant focus and the other eye for near or intermediate focus. This approach is referred to as monovision. While the vast majority of patients who choose to go the monovision route adapt well to their eyes being utilized for single (but different) ranges, a small percentage of people may feel off-balance and be unable to adjust appropriately for monovision to be effective. When this occurs, one lens can be exchanged to have the focus match the other eye creating more uniform (but less versatile) binocular vision.

There are 2 types of monofocal IOLs:  spherical and toric.  Spherical IOLs are lenses that are the simplest in design and do not have any astigmatism correction.  The position of these lenses in the eye does no matter as long as it rests in the location of the former natural lens.  For patients who will have astigmatism due to the shape of their cornea, an astigmatism correcting lens, also known as a toric lens, can be selected to neutralize the astigmatism.  People who have astigmatism will have blur at all distances unless it is corrected.  Toric monofocal IOLs, glasses, contacts and laser vision corrective surgery are all ways to correct astigmatism.

Monofocal IOLs provide the clearest vision at one distance. Multifocal intraocular lenses, meanwhile, are used to simultaneously improve near vision, intermediate vision, and distance vision. They utilize concentric rings of varying thickness, to allow the eye to focus images from all distances onto the retina. The patient’s brain registers the image that is most in focus depending on what distance the object is away from the eye. It often takes patients some time to adjust to the multifocal lenses. Some multifocal lenses correct astigmatism as well.  Your eye surgeon will be the best resource for you to know if this combination would benefit you.  The use of multifocal lenses following cataract surgery may mean a lower likelihood of needing additional glasses when compared to monofocal lenses.

While multifocal IOLs do have the added benefit of improving patients’ vision from multiple distances, there are several known adverse effects that may or may not influence your decision between the two types of intraocular lenses. Common side effects include glare, halo issues where the user sees rings around lights in their field of vision, and diminished contrast sensitivity, or ability to differentiate between objects. Halos, glare, and contrast issues typically provide more of a challenge for nighttime vision.

Which Is Better: Monofocal or Multifocal?

Like any other procedure, it is important to carefully consider your options when deciding between monofocal and multifocal intraocular lenses. Either lens will treat cataracts and improve your vision significantly, but there are a few key differences to understand before making a decision.

Monofocal and multifocal intraocular lenses have varying benefits and challenges, and there is no definitive answer for which is the best option between the two. Depending on differing individual needs, you and your doctor may determine that one type of lens more closely meets the specific needs of your eye health. Monofocal lenses allow only one focus region, meaning patients who opt for these will have improved distance vision, but will still need to use glasses for reading and to improve near or intermediate vision. Multifocal IOLs correct both cataracts and presbyopia, or farsightedness occurring usually in middle-aged individuals due to loss of elasticity of the lens of the eye.

Multifocal intraocular lenses are designed to correct vision up close, afar, and in between. This is accomplished through multiple specifically designed focus regions, ultimately even eliminating the need for glasses for many people. Following multifocal IOL implantation, it is expected for patients to experience an adjustment period during which they perceive halos, rings, and glares. This is normal, and as your eyes naturally adjust to the lenses, halos and glares diminish or disappear from your vision entirely.

People who have health problems in their eyes may not be good candidates for multifocal lenses.  Problems in the cornea, the retina, glaucoma and the need for prisms to correct eye alignment are among the conditions where multifocal lenses are used with caution.  Multifocal lenses are very sensitive to degradation in the optical quality of the eye such as dry eye or retina problems.

How Long Does It Take to Get Used to Multifocal Lens Implants?

People undergoing cataract surgery can expect a similar recovery process and period whether they choose monofocal or multifocal lenses. That being said, there is an additional adjustment period for multifocal intraocular lenses while your brain adjusts to the new neural pathways stimulated by the lens. It can take anywhere from weeks, months, and even years to adjust completely to multifocal lenses. Most patients adapt to the lenses without issue after time and can enjoy higher vision performance compared to their vision prior to surgery.

How Much Do Multifocal and Monofocal IOLs Cost?

It is important to consider costs when deciding whether monofocal intraocular lenses, multifocal IOLs, or a combination of both are the right choice for your eyes. Insurance and medicare typically cover simple monofocal IOLs, while multifocal lenses are generally considered an upgrade outside of insurance and come at an additional cost. Treatment could be costly if multifocal IOLs are deemed necessary in both eyes since each eye is a separate procedure.  Since multifocal lenses decrease the need for spectacle correction, there are some cost savings in future glasses purchases for either custom glasses or over-the-counter reading glasses.  You can discuss information regarding different types of lens implantations and costs with your local Texas eye surgeon .