How do monofocal, EDOF and multifocal lenses differ?
A lens implant replaces the eye’s natural lens during cataract surgery. The implant’s power and your eye’s measurements determine its intended focus. The terms below describe different ways of managing focus.
- Monofocal: prioritises one main focus, usually distance. Reading glasses commonly provide the other distances. A monofocal can alternatively be targeted for near vision.
- EDOF: broadens the useful range, typically from distance into intermediate vision, such as a computer screen. Fine print often still needs glasses. Some designs give more near vision than others.
- Multifocal, including trifocal: provides more than one focus. A trifocal typically aims to cover distance, intermediate and near tasks, with a greater opportunity for reading without glasses.
These categories overlap. Enhanced monofocals offer a modest extension of focus, while some EDOF lenses use diffractive optics similar to multifocals. Others use different surface shapes or a small aperture. The exact model matters. A toric lens corrects astigmatism and can belong to all of these categories.
| Lens category | Main opportunity | Common compromise |
|---|---|---|
| Monofocal | Clear vision at the chosen focus | Glasses for other distances |
| EDOF | More intermediate vision without glasses | Fine print may need glasses; visual quality varies by design |
| Multifocal / trifocal | More opportunity for near as well as distance vision | More haloes or glare; contrast trade-offs; glasses still possible |
Why can’t one lens deliver everything without a trade-off?
There is a finite amount of light entering the eye. A monofocal lens concentrates useful light around one principal focus. A multifocal redirects portions into different focal orders or zones. When one image is in focus on the retina, contributions intended for other distances can form a blurred background around it.
An EDOF design reshapes the distribution of focus to make a longer useful range. Depending on the design, it may stretch a focal region, overlap neighbouring foci, modify aberrations or limit the aperture. It does not create extra light. A small aperture also reduces the light admitted and introduces its own diffraction considerations.
That is the optical version of sharing a cake: distributing what you have more widely changes what is available in any one place. Light is a wave, and diffraction and interference make real lens behaviour more complicated than cutting three equal slices.
Even a monofocal is not perfect: reflection, scatter, diffraction and the optics of the rest of the eye prevent all incoming light from becoming one infinitely sharp point. Better engineering can reduce avoidable losses or correct aberrations. It cannot make a fixed, passive, simultaneous-focus lens behave like a young natural lens that changes its focus for each task.
What is contrast, and why does it matter if I can read 6/6?
Visual acuity measures the smallest detail you can resolve, commonly with dark letters on a bright chart. Contrast sensitivity measures how faint a difference between light and dark you can detect. They answer different questions.
You may read the bottom of a high-contrast chart yet find a grey kerb, a face in dim light or small print on grey packaging less distinct. This is why a statement such as “the vision is 6/6” does not completely describe visual quality.
Out-of-focus light from a simultaneous-focus lens can reduce the difference between bright and dark features in the image. The effect may be more apparent in dim conditions or around bright lights. Pupil size, residual prescription, tear film, corneal shape and retinal health also influence the result.
The comparison below illustrates what a contrast difference can look like. It is not a prediction of how a particular implant will make you see.
What does modulation transfer function tell us?
Modulation transfer function (MTF) describes how well an optical system preserves the contrast of a pattern at different levels of detail. Think of progressively finer black-and-white stripes. Coarse stripes are easier to preserve; fine stripes place greater demands on the optics.
An MTF of 0.30 means that, under that test condition, the image retains 30% of the pattern’s input contrast. It does not mean the lens transmits only 30% of the light, that you lose 70% of your vision, or that 30% of patients are happy.
The graph shows measured distance-focus results from a 2025 optical-bench study: five samples each of Xact Mono-EDoF ME4, an enhanced monofocal, and Symfony ZXR00, a diffractive EDOF lens. In polychromatic light, ME4 measured 0.50, 0.29 and 0.17 at 25, 50 and 100 line pairs/mm; Symfony measured 0.35, 0.32 and 0.19. The curves cross, so a single number does not establish an overall winner.
These are laboratory results, not patient vision scores. The study used a 3 mm aperture and different model-cornea spherical aberration for the two lenses. It also found wavelength-dependent differences. They illustrate why a claim about “contrast” needs the test conditions, exact models and the part of the focus range being measured.
Do clinical studies show a loss of contrast with every EDOF lens?
Clinical results vary. The US regulatory study for AcrySof IQ Vivity, a non-diffractive EDOF design, found lower single-eye contrast sensitivity in dim light than its monofocal control at several tested detail levels. The graph below reproduces six-month median results without glare from 107 Vivity and 111 control participants.
At the finest tested pattern, 43% of the Vivity group and 21% of controls could not detect the reference pattern at any available contrast. That matters when interpreting the test’s lower limit.
Conversely, a 2026 study of 60 patients found no statistically significant contrast-sensitivity difference between Vivity and two enhanced monofocals, Eyhance and ISOPure, while Vivity provided better intermediate and near acuity.
It is therefore more accurate to discuss design-specific trade-offs than to quote one universal percentage of contrast loss. Binocular vision, lighting and the task being tested all matter.
Are haloes and glare the same as reduced contrast?
They are related aspects of visual quality, but not the same measurement. Haloes are rings around lights. Glare can make bright lights dazzling or wash out nearby detail. Starbursts are rays extending from a light source. A person may notice one effect much more than another.
Multifocal designs commonly produce more light phenomena than monofocals. A Cochrane review of older randomised trials found less spectacle dependence with multifocals, similar distance acuity, and more haloes and glare. Haloes were reported more often than with monofocals, with a relative risk of 3.58. The review combined varied, often older designs.
Some EDOF designs produce fewer troublesome haloes than some multifocals, but “EDOF” alone does not guarantee symptom-free night driving.
The brain may become less aware of some optical phenomena over time. This adaptation varies. Persistent symptoms deserve examination, particularly if they affect safe driving or daily activities.
Why can two people with the same lens feel differently?
Both the optical result and the person’s starting point matter. Someone looking through a dense cataract may experience a striking improvement after surgery even if their new implant has a modest optical trade-off. Someone whose previous vision was exceptionally crisp may be more aware of a small change.
Visual demands differ, too. A frequent night driver, photographer or person doing fine detail work may prioritise contrast and precision. Another person may value reading menus, using a phone and moving between a screen and the room without repeatedly changing glasses.
People differ in how much blur or a halo bothers them, and how strongly they value independence from glasses. This is a preference to understand, not a personality test that can reliably predict satisfaction. A demanding visual standard is not a character flaw.
One person’s “excellent near vision” may mean reading a phone in good daylight. Another means tiny print at 25 cm in a dim restaurant. Discuss the actual task, distance, lighting and whether glasses would be acceptable.
Why do short-sighted patients have different near-vision expectations?
Many short-sighted people can remove their distance glasses and read text that is held very close to their eyes. Before cataract develops, this can provide exceptionally clear near detail. Someone who was not short-sighted, or who was long-sighted, may have relied on reading glasses for years and have a different baseline for comparison.
Bringing the same print from 40 cm to 20 cm makes its angular size approximately twice as large. That helps explain why close reading can feel so detailed and illustrates the importance of viewing distance.
After a lens implant is targeted for distance, the eye’s previous unaided near focus is usually changed. A multifocal or EDOF may offer a useful new reading range without recreating the old habit of holding very small print extremely close.
For example, a simple optical approximation puts the unaided far point of a −3.00 dioptre myopic eye at about 33 cm. Actual usable near vision depends on cataract, astigmatism and other factors.
Tell your surgeon how you read now, with and without glasses. Discuss distance targets, retaining some near focus or monovision where appropriate. The desired focus is a separate decision from the implant’s optical category.
Is a monofocal lens a lower-grade option?
No. A well-chosen monofocal can provide excellent vision. Choosing one can be a deliberate decision to prioritise a crisp image at the chosen distance and use glasses for other tasks. It is not a second-hand or inferior treatment simply because another lens costs more or has a longer technology name.
In my own practice, where I treat eye doctors and their families, the majority have historically requested monofocal lenses. I am increasingly seeing interest in EDOF lenses as well.
My article on what intraocular lenses eye doctors choose for themselves discusses these preferences in more detail. An eye doctor's personal choice can be informative, but your eyes and priorities may be different.
How should I interpret lens marketing and early enthusiasm?
Lens implants are sophisticated medical devices sold in a competitive market. Manufacturers have good reasons to describe what makes their product different. A brochure can introduce a technology, but it cannot provide an individual recommendation.
Terms such as “premium”, “advanced”, “continuous vision” or “next generation” need translation into practical questions. At what distances was vision tested? In what lighting? Compared with which lens? How many people still used glasses? Were haloes present, and were they bothersome?
A new lens can have encouraging early results and enthusiastic support from respected surgeons before its limitations are fully characterised. Earlier generations of presbyopia-correcting lenses prompted published reports of dissatisfaction, with problems including residual prescription, dry eye and optical symptoms.
Longer follow-up helps assess persistent symptoms, stability of the lens material and the consequences of later eye disease. A six-month trial cannot answer every question about living with an implant for decades. Equally, difficulties with an older model do not prove a newer one will fail.
Look for independent studies, clear comparator groups, meaningful patient-reported outcomes and disclosure of funding or conflicts. A key opinion leader’s enthusiasm is useful context, but it is not a substitute for those data. New technology can be valuable without suspending the laws of optics.
Who may benefit most, and who needs particular caution?
EDOF and multifocal lenses can be excellent choices when the eye is suitable and the person understands the likely balance. Suitability involves more than having a cataract. The tear film, corneal regularity, astigmatism, pupil behaviour, macula, optic nerve and accuracy of the planned lens power all matter.
Dry eye can reduce visual quality and make measurements less reliable. Macular disease or glaucoma may already reduce contrast, leaving less tolerance for another optical compromise. Previous laser vision correction or other corneal surgery requires particular assessment. These reasons highlight why individual advice is important.
European cataract guidelines recommend selecting presbyopia-correcting lenses around ocular comorbidities, the desire for spectacle independence and realistic expectations. Your surgeon may recommend corneal mapping or an OCT scan of the macula when relevant.
- Describe your most important daily tasks and your usual reading distance.
- Explain how much night driving you do and how you feel about haloes.
- Decide whether occasional reading glasses would be acceptable.
- Ask what happens if the result misses the refractive target or you dislike the optical quality.
- Discuss whether the anticipated benefit is worth the remaining uncertainty for your eyes.
Removing a cataract can be life-changing. The improvement should be celebrated without turning it into a promise of perfect vision. Healthy eyes, careful measurements and realistic expectations improve the chances of a satisfying result.
What should optometrists discuss before and after surgery?
Before referral, record the patient’s habitual near distance, unaided near ability, occupational tasks, night-driving requirements and tolerance for glasses. A request for “the best lens” is the start of a conversation about priorities, not a specification.
Distinguish unaided from corrected acuity, and distance from intermediate and near performance. For research appraisal, look for lighting levels, contrast test and spatial frequencies, monocular versus binocular testing, pupil size, target refraction, follow-up and the exact comparator. A defocus curve describes the range of vision; it does not capture every aspect of contrast or dysphotopsia.
If someone is unhappy after surgery, a good high-contrast acuity score does not close the investigation. Check residual sphere and cylinder, the ocular surface, cornea, lens position, posterior capsule, macula and optic nerve as appropriate, and communicate with the surgeon. Dry eye, refractive error and other treatable problems may coexist with an optical-design complaint.
Do not assume that a more expensive lens, another procedure or simply waiting longer will solve the problem. In particular, discuss the plan with the surgeon before YAG capsulotomy if lens exchange is being considered, because opening the posterior capsule can make subsequent exchange more complex. See can a lens implant be replaced?
What questions should I ask about my lens choice?
Will an EDOF or multifocal lens guarantee no glasses?
No. Some people are very independent of glasses, but fine print, dim lighting or particular distances can still need them. Residual prescription and eye health also affect the result.
Does a low MTF number mean the lens wastes most of the light?
No. MTF measures contrast transfer at a specified level of detail and focus. It is not a light-transmission percentage.
Can an EDOF lens have contrast similar to a monofocal?
Yes, in some studies and test conditions. That does not establish identical vision in every situation. Consider the exact designs, test methods and benefit across the focus range.
Will I get used to haloes?
Some people become less aware of them; others remain bothered. Adaptation cannot be guaranteed, and persistent or worsening symptoms should be assessed.
Should I choose the newest lens?
Choose the lens with the best-supported balance for your eyes and priorities. Novelty alone does not establish superiority, and a monofocal remains an excellent option.
What is the most important message?
You can often enjoy a much wider range of useful vision, but you cannot assume it comes without any optical compromise. The best result is a choice you understand, made around the vision you value.
Why your friend’s cataract lens implant may not be right for you explains why eye health, personal priorities and the planned focus matter when comparing a friend’s result.
What is the best intraocular lens (IOL)? uses the car analogy to explain why the right implant depends on your eyes, lifestyle and priorities.
When should I seek urgent help after eye surgery?
Seek urgent advice from your surgeon or an urgent eye service for sudden loss of vision, increasing eye pain, marked redness, new flashes or a sudden increase in floaters, or a curtain or shadow across your vision. Do not assume these symptoms are a normal lens trade-off or wait for a routine review.
Sources
- de Silva SR et al. Multifocal versus monofocal intraocular lenses after cataract extraction. Cochrane Database Syst Rev. 2016;CD003169.
- US FDA. AcrySof IQ Vivity Extended Vision IOL: professional labelling, Table 22 and clinical trial results (2020).
- Baur ID et al. Ray Visualization and Through-Focus Optical Quality of Diffractive Enhanced Monofocal and Extended-Depth-of-Focus Intraocular Lenses. Clin Ophthalmol. 2025. doi:10.2147/OPTH.S520086.
- Baoud Ould Haddi I et al. Comparative Photopic and Mesopic Visual Performance of Enhanced Monofocal Versus Non-Diffractive Extended Depth-of-Focus Intraocular Lenses. J Clin Med. 2026;15:1368. doi:10.3390/jcm15041368.
- European Society of Cataract and Refractive Surgeons. ESCRS Recommendations for Cataract Surgery: final extended recommendations (accessed 10 October 2026).
- Gibbons A et al. Causes and correction of dissatisfaction after implantation of presbyopia-correcting intraocular lenses. Clin Ophthalmol. 2016.
- de Vries NE et al. Dissatisfaction after implantation of multifocal intraocular lenses. J Cataract Refract Surg. 2011;37:859–865.
- MacRae S et al. American Academy of Ophthalmology Task Force consensus statement for extended depth of focus intraocular lenses. Ophthalmology. 2017;124:139–141.
- Alarcon A et al. Optical and clinical simulated performance of a new refractive extended depth of focus intraocular lens. Eye. 2024;38(Suppl 1):4–8 (corrected October 2024).
- Wilkins MR, Allan B, Rubin G; Moorfields IOL Study Group. Spectacle use after routine cataract surgery. Br J Ophthalmol. 2009;93:1307–1312.
- Chen S. What intraocular lenses do eye doctors choose for themselves?