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Monofocal Lens: The Most Common Intraocular Lens
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Most patients undergoing cataract surgery will get a monofocal lens, as this is the only lens covered by most insurance plans (including Medicare and Medicaid). For patients without insurance coverage, monofocal lenses also represent the most affordable option.
This “basic lens” provides very reliable vision outcomes. It offers very sharp vision with little halo or glare, but at a single focal point. Most patients with monofocal Ienses will still need to wear glasses for some activities after cataract surgery. This also applies to patients who got a monofocal lens as part of their Refractive Lens Exchange (RLE) procedure.
What is a Monofocal Lens?
A monofocal lens is a type of Intraocular lens (IOL) used during cataract surgery or refractive lens exchange (RLE). IOLs are artificial lenses that provide clear vision after the eye’s natural lens is removed as part of either procedure.
Monofocal IOLs are considered basic because they have a single corrective prescription. This means that they provide only one set focal point of clear vision, either distant, intermediate or near.
How does a Monofocal IOL Work?
A monofocal IOLs works by refracting (bending) light to focus on whatever the individual is looking at to the back of the eye. This provides a focused, clear image.
Monofocal lenses can correct refractive errors like myopia (nearsightedness), hyperopia (farsightedness), and even astigmatism. However, traditional monofocal IOLs are not designed to correct presbyopia (age related loss of near vision).
What are IOLs made of?
Most IOLs are made of silicone, acrylic, or other plastic compositions. They are also coated with a special material to help protect your eyes from dangerous ultraviolet light.
Monofocal IOLs and Glasses
Because vision will only be clear at the chosen focal point, patients will need one or two pairs of glasses to see clearly at other distances. However, some patients might be able to obtain a wider range of vision by using different lens powers for each eye. This procedure is known as monovision.
Monofocal Lenses for Distance Vision (most common)
Only near vision eyeglasses may be needed in this case. If the patient has astigmatism (nearsightedness), the monofocal lens will have to be toric (astigmatism-correcting) as cataract surgery by itself does not correct it.
Monofocal Lenses for Near Vision (less frequent)
Some people, for example those that spend a great deal of time reading, may want the monofocal IOL corrected for near vision. They will need to wear glasses for driving and other long-distance activities.
Monofocal Lenses for Intermediate Vision (rare)
Although uncommon, it is possible to have the monofocal IOL corrected for computer clarity (which is often mid-range; e.g. 30 inches). However, near vision and distance vision will be compromised.
Monovision: Using two different lens powers
Some people choose to select one monofocal IOL for distance in one eye, and near correction for the other eye. This technique is called “monovision”, or “blended vision”.
Monovision allows patients to see both far away and up close with both eyes open. The drawback is that there is no correction for intermediate range (for example, at arm’s length where a computer monitor is often situated). Another disadvantage is that each eye will see clearly at a different distance.
An alternative to monovision is “mini-monovision”, where one eye is set for distance vision, and the other for intermediate. In this case, patients will need glasses for tasks that require near vision.
Eye doctors will often have patients try monovision (or mini-monovision) with contact lenses first to see how patients respond to it prior to the cataract surgery or RLE. Doctors typically do not recommend taking IOLs out of eyes after surgery due to the increased risk of complications. So, it is recommended that patients are comfortable with their decision about the type of IOL they select prior to the surgery.
Monofocal Lens Options
The Monofocal IOL is the most common lens used during cataract surgery, as it is typically covered by insurance. The main disadvantage of traditional monofocal lenses is their limited range of vision, resulting in the need for glasses after surgery.
However, there are newer versions of the monofocal lens that allow viewing far away, intermediate and near objects. These premium monofocal lenses are designed to provide enhanced vision outcomes that were not previously possible with traditional monofocal lenses.
Premium Monofocal Lenses
Premium monofocal lenses include the Extended Depth of Focus (EDOF)IOL, accommodating IOLs, Light Adjustable Lenses and toric monofocal lens. Due to the more complicated design of these lenses, they are considered premium. The distinction between basic and premium IOLs is critical as insurance typically covers the cost of basic monofocal IOLs but not premium lenses.
Extended Depth of Focus IOLs (EDOFs)
These new extended depth of focus (EDOF) IOLs are a variant of monofocal IOLs which could allow satisfactory vision without the need for eyeglasses. EDOF lenses were FDA approved in 2016, so these are new IOL’s.1
Examples of EDOF IOLs are diffractive and pinhole. Diffractive based EDOF lenses bend incoming light to different focusing points. These IOLs may have reduced image quality and increased glare. Pinhole EDOF lenses improve vision quality by eliminating the more peripheral incoming light. Only central incoming light enters through a small aperture which results in less glare and distortions and a clearer image.
However, there are disadvantages. Pinhole EDOF lenses reduce the amount of light entering the eye, especially peripherally. This small aperture design may cut off peripheral vision and visual acuity may be reduced in low light conditions such as nighttime driving.
Accommodating IOLs
Another type of monofocal IOL is the accommodating IOL. The natural lens inside the eye is capable of changing shape, which increases its power allowing near objects to come into focus. A muscle in the ciliary body that surrounds the eye’s lens contracts to enable the lens to change shape. This mechanism which allows for the natural lens in the eye to focus on near objects is called accommodation.
The accommodating IOL attempts to allow clear near vision without the optical distortions and image degradation that may accompany EDOF and multifocal IOLs. Studies show that near vision is improved with these accommodating IOLs.2
Monofocal Toric Lens
Toric lenses are astigmatism-correcting IOLs. These lenses incorporate a special shape. to compensate for the irregular curvature of the cornea (the cause of astigmatism). Toric lenses are not covered by insurance, so any toric iol model will represent an additional expense.
Monofocal toric lenses cannot fully correct large amounts of astigmatism. So, if a patient has a significant amount of astigmatism and chooses a basic monofocal lens corrected for distance, they will still have some residual astigmatism and might need to wear eyeglasses.
Just like traditional monofocals, toric monofocal lenses are not designed to correct presbyopia (age-related loss of near vision). Patients with this condition might need reading glasses. If dealing with residual astigmatism, multiple pairs of glasses might be needed.
Light Adjustable Lenses
A new option in monofocal IOLs are light adjustable lenses (LAL). This newer type of monofocal IOL is the only type of IOL that can be customized after surgery.
Traditional IOLs typically are there to stay in your eyes. Once the procedure is done, replacing the lens implant is usually not recommended due to the higher risk of complications including loss of vision.3,4 The LAL eliminates a common reason why patients may want to exchange their existing IOL: dissatisfaction with their postoperative vision.
With an LAL, the eye surgeon can make adjustments to the IOL for any remaining refractive error after your eye heals from the cataract surgery. This involves a series of office-based light treatment procedures after the surgery. These adjustments can include correcting for residual astigmatism.
Choosing an LAL makes it unlikely eyeglasses will be needed after surgery for clear distance vision. The LALs can also be set for monovision to allow both near and distance vision without glasses.
Basic Monofocal Lenses
Traditional monofocal IOLs are considered basic lenses. Even if a patient chooses monovision, the lenses still typically fall into the basic IOL category.
Monofocal IOLs have the advantage of providing clear, sharp vision for a single point of focus (distance, intermediate or near). This may be preferred over EDOF and multifocal lenses due to the compromise of overall reduction in clarity and/or increased glare often associated with EDOF and multifocal IOLs.
Monofocal vs Multifocal Lens
Individuals who desire clear vision at all distances may prefer to invest in multifocal intraocular lenses instead of basic monofocal lenses. Multifocal IOLs are capable of clear vision for a multitude of different distance ranges. Multifocal lenses address near, far and intermediate vision at once. The disadvantage is that multifocal lenses can cause you to see glare and halos around lights.
Multifocal lenses have become popular in recent years. A multifocal IOL can offer vision correction for distance, intermediate and near ranges. Multifocal IOLs are somewhat similar to progressive eyeglasses or multifocal contact lenses in terms of how these lenses correct your vision. This type of IOL can correct general refractive errors as well as presbyopia.
Besides their limited vision range, traditional monofocal IOLs do not correct for presbyopia. For example, you would still have to wear reading glasses to see up close for distance corrected monofocal lens implants.
Monofocal Lenses and Cataract Surgery
A cataract develops when the natural, clear lens of the eye becomes cloudy. When the cloudiness of the lens becomes significant, vision is impaired.
During cataract surgery, an eye surgeon removes the natural, cloudy lens and inserts an artificial, clear lens containing a prescription to allow clear viewing. This provides a permanent solution to cataracts, but vision outcomes depend heavily on the type of IOL used. The best lens for your cataract surgery will depend on eye health, general health, personal preference, and lifestyle requirements. Monofocal lenses are a goof fit for many people, but it’s best to discuss your options with a surgeon before making the choice.
Cataract Surgery and Lens Replacement Surgery
Modern cataract surgery has now been around for decades.5 Due to recent advances in surgical techniques, the surgery is considered minimally invasive and takes typically less than 15 minutes. The ability to see without eyeglasses is appealing to many people. For these reasons, many people are interested in getting an IOL even though they do not have visually significant cataracts. This lens replacement surgery is known as Refractive Lens Exchange or RLE.
One of the main differences between cataract surgery and RLE is cost. Cataract surgery is considered medically necessary and covered by many insurances. RLE is elective and not typically covered by insurance. Cost of RLE should be discussed with your eyecare provider prior to undergoing the procedure.
What is Refractive Lens Exchange (RLE)?
Refractive Lens Exchange (RLE) is virtually the same procedure as cataract surgery. It replaces the eye’s natural lens with an artificial intraocular lens (IOL) to correct refractive errors like nearsightedness, farsightedness and astigmatism. The ideal candidate for RLE is over the age of 50, doesn’t have fully developed cataracts, and does not qualify for laser eye surgery.6
RLE is a relatively safe procedure which carries similar risks to standard cataract surgery. Risks associated with RLE include, but are not limited to, infection, bleeding, change in eye pressure, retinal detachment, and lens displacement.
Lens Options for Refractive Lens Exchange (RLE)
The IOL options for RLE are similar to lens options for standard cataract surgery which include various monofocal and multifocal options. However, many patients choose multifocal IOLs which usually reduces the need for eyeglasses after the surgery.
Monofocal Lens Price and Insurance Options
Cataract surgery using a basic monofocal IOL is usually covered by Medicare, Medicaid, and most major insurance companies.7 For patients paying out of pocket, the costs can vary often from $2000-$3000 per eye depending on various factors such as location and type of surgery facility.8,9 Premium IOLs are not covered by insurance and the patient may be responsible for all or part of the costs.
It is important to understand your insurance benefit and what it covers towards the surgery. Once you decide where you will have the surgery and what IOL you will go with, you may want to contact your insurance company to determine your specific benefits. The surgery center staff should be able to assist you.
References
- FDA Approves First Extended Depth of Focus IOL (2016 Jul 15). Retrieved from FDA approves first extended depth of focus IOL – American Academy of Ophthalmology (aao.org).
- Zhou H, Zhu C, Xu W, Zhou F. The efficacy of accommodative versus monofocal intraocular lenses for cataract patients: A systematic review and meta-analysis. Medicine (Baltimore). 2018 Oct;97(40):e12693. doi: 10.1097/MD.0000000000012693. PMID: 30290663; PMCID: PMC6200466.
- Abdalla Elsayed MEA, Ahmad K, Al-Abdullah AA, Malik R, Khandekar R, Martinez-Osorio H, Mura M, Schatz P. Incidence of Intraocular Lens Exchange after Cataract Surgery. Sci Rep. 2019 Sep 9;9(1):12877. doi: 10.1038/s41598-019-49030-2. PMID: 31501458; PMCID: PMC6733834.
- Hyeck-Soo Son, David F. Chang, Charles Li, Lynn Liu, Sidra Zafar, Flora Lum, Fasika A. Woreta. Visual Acuity Outcomes and Complications after Intraocular Lens Exchange An IRIS® Registry (Intelligent Research in Sight) Analysis. Ophthalmology. 2023 Oct 17;131(4):403-11.
- Houser, C. History of Cataract Surgery. EyeWiki. History of Cataract Surgery – EyeWiki (aao.org). Accessed July 26, 2024.
- Stephenson, M. A Review of Refractive Lens Exchange (2022 Nov 22). Retrieved from A Review of Refractive Lens Exchange (reviewofophthalmology.com).
- Terhorst, C. Factors to Consider in Choosing an IOL for Cataract Surgery (2022 Dec 12). Retrieved from Factors to Consider in Choosing an IOL for Cataract Surgery – American Academy of Ophthalmology (aao.org).
- Lett, B. Exploring Cataract Surgery Costs in 2024: A Clear Vision (2024 Jun 19). Retrieved from https://www.eyesurgeryguide.org/exploring-cataract-surgery-costs-in-2024-a-clear-vision.
- Cataract Surgery Cost: Insurance Coverage and Out of Pocket Expenses (2024 Jun 27). Retrieved from https://www.nvisioncenters.com/cataract-surgery/cataract-surgery-cost.
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