If you’re preparing for cataract surgery or refractive lens exchange (RLE), one of the biggest decisions you’ll make is choosing the right type of intraocular lens (IOL). Two of the most common options are monofocal lenses and EDOF (Extended-Depth-of-Focus) lenses. On the surface, the choice might seem simple monofocals offer crisp distance vision, while EDOF lenses give you more range. But in reality, surgeons consider far more than just those two points before making a recommendation.
I want to help you understand how surgeons really make this decision, because the right IOL depends on you the way you use your eyes, your daily routines, your night-driving habits, your reading needs, your sensitivity to glare and even your personality. By the end of this article, you’ll have a much clearer picture of how ophthalmologists tailor lens recommendations, and you’ll feel better equipped to choose the IOL that offers the best long-term vision for your lifestyle.
Understanding the Two Main Lens Types
Before exploring how surgeons select the right lens for each patient, it’s important to understand the key differences between monofocal and extended depth-of-focus (EDOF) lenses. Each type offers distinct advantages depending on your visual priorities and lifestyle.
Monofocal lenses provide a single point of focus, usually optimised for clear distance vision. They offer excellent clarity and contrast, making them ideal for activities like driving, watching TV, or outdoor tasks. Reading or other near work typically requires glasses.
EDOF lenses, on the other hand, extend the range of clear vision from distance to intermediate. This creates a smoother transition between distances, which is particularly useful for computer work, cooking, or other mid-range tasks. Near vision may still require reading glasses, but many patients experience less dependency overall.
Understanding the basic benefits and limitations of each lens type is the first step in making an informed choice with your surgeon. The right selection balances your visual goals, lifestyle needs, and tolerance for glasses or minor visual side effects.
What Is a Monofocal IOL?
A monofocal intraocular lens (IOL) is designed with a single focal point, usually optimised for distance vision. It provides sharp, high-contrast clarity and excellent visual performance in a wide range of conditions, including low light. While monofocals deliver predictable, reliable vision and minimal glare or halos making them particularly effective for night driving most people will still need reading glasses for close-up tasks such as reading or detailed work.
What monofocals offer:
- Sharp, high-contrast distance vision
- Excellent clarity in low-light situations
- Minimal glare and halos
- Best performance for night driving
- Most predictable visual quality
Most people who choose monofocal lenses will still need reading glasses for close-up tasks.
What Is an EDOF IOL?
Extended Depth of Focus (EDOF) intraocular lenses are designed to stretch your range of focus, providing clear vision from distance to intermediate, with some functional near vision. Unlike multifocal lenses, EDOF lenses focus on creating a smooth visual experience rather than splitting light into multiple focal points.
Popular examples of EDOF lenses include the Alcon Vivity (non-diffractive) and Symfony IOL (diffractive). Both are engineered to deliver sharp distance vision, excellent intermediate clarity, and usable near vision for many everyday tasks.
One of the main advantages of EDOF lenses is that they tend to cause fewer visual disturbances than multifocal lenses, such as halos or glare. This makes them a good option for patients who want to reduce their dependence on glasses while maintaining high-quality vision across most daily activities.
Overall, EDOF lenses offer a balanced compromise between visual clarity and independence from spectacles, making them ideal for people seeking functional vision without the stronger side effects sometimes associated with trifocal lenses.
How Surgeons Decide: The Factors That Really Matter
Choosing an IOL isn’t just a clinical decision it’s a lifestyle decision. Surgeons match lens technology to your visual needs, your tolerance, your work habits and your daily activities.
Here’s what influences their recommendations.
1. Your Daily Visual Priorities
Surgeons want to understand how you use your eyes most of the day. If you spend a lot of time driving: Monofocal lenses may be preferred because they give the sharpest night-time clarity and least glare. If you spend hours at the computer: EDOF lenses are ideal because intermediate vision is one of their biggest strengths. If you read small print often: You may still need reading glasses with EDOF lenses, but some people manage well without for larger text.
2. Your Night Driving Habits
Your night driving habits play a key role in choosing the right lens. Monofocal lenses offer the best clarity in low-light conditions and carry the lowest risk of glare and halos, making them ideal for frequent night drivers. Non-diffractive EDOF lenses, such as Vivity, also perform well at night, while diffractive EDOF lenses may cause some halos. If you drive frequently after dark, your surgeon may recommend monofocals or non-diffractive EDOF lenses for safer, sharper night vision.
3. Your Sensitivity to Glare and Halos
Your sensitivity to glare and halos is another important consideration. Some people are naturally more affected by light scatter, so your surgeon may ask whether headlights bother you, reflections at night are troublesome, or bright sunlight feels uncomfortable. If you are sensitive, monofocals are the safest choice, and non-diffractive EDOF lenses may also be suitable. If you are not sensitive, diffractive EDOF lenses could be a good option.
4. Your Desire for Glasses Independence
Your desire for glasses independence is a key factor in selecting an IOL. Monofocal users typically still need reading glasses and may require intermediate glasses for computer work. EDOF users often don’t need glasses for intermediate tasks like using a computer but may occasionally need reading glasses for very close work, enjoying a more balanced range of vision overall. Your personal preference regarding glasses will strongly influence the final recommendation.
5. Pupil Size and Eye Anatomy
Pupil size and eye anatomy are important considerations when choosing an IOL. Monofocals are reliable for all pupil sizes. Diffractive EDOF lenses tend to perform best with medium pupils, while non-diffractive EDOF lenses work excellently with larger pupils. If your eye anatomy suggests a higher risk of visual artefacts from diffractive rings, your surgeon may recommend avoiding that technology.
6. Corneal Quality and Aberrations
Corneal quality and aberrations play a crucial role in IOL performance. If you have irregular astigmatism, higher-order aberrations, a history of LASIK/PRK/SMILE, or dry eye disease, your surgeon may recommend monofocals or non-diffractive EDOF lenses for the most reliable results. Diffractive EDOF lenses and multifocals require a very healthy, symmetrical cornea to achieve optimal performance.
7. Your Occupation
Your occupation can influence the best IOL choice. Monofocal lenses are well-suited for frequent drivers, pilots, night workers, and anyone who prioritises visual sharpness over range. EDOF lenses are ideal for office workers, freelancers on laptops, teachers, consultants, creatives, and anyone who moves frequently between devices and physical tasks, valuing versatility. Surgeons aim to match your lens choice to your typical workday.
8. Your Hobbies and Lifestyle
Your hobbies and lifestyle are important factors in selecting an IOL. Monofocal lenses suit golfers, cyclists, and others who enjoy outdoor sports that rely heavily on clear distance vision. EDOF lenses are better for gardeners, photographers, travellers, readers who prefer a wider range of vision, and anyone who frequently uses tablets or phones. The goal is to choose a lens that supports the activities you love.
9. Your Personality and Visual Tolerance
Your personality and visual tolerance can influence how well you adapt to different IOLs. If you value sharpness and predictability, you’ll likely adjust best to monofocals. If you’re easy-going about minor visual changes, you may adapt quickly to EDOF lenses. Visually perfectionist individuals might find EDOF lenses frustrating unless opting for a non-diffractive model. Surgeons typically consider your expectations before making a recommendation.
10. One Eye or Both?
Sometimes, using different lens types in each eye known as blended vision offers the best solution. Options include one monofocal lens for distance paired with an EDOF lens for a broader range, or an EDOF lens set slightly myopic in one eye to enhance near vision. Surgeons use blended vision to optimise your full visual range.
Comparing Monofocal and EDOF: What Surgeons Consider Side by Side
Distance Vision: Both Monofocal and EDOF lenses provide excellent distance vision.
Intermediate Vision: Monofocal lenses have limited performance, while EDOF lenses provide strong intermediate vision.
Near Vision: Monofocal users typically need glasses for near tasks, whereas EDOF lenses allow functional near vision.
Night Driving: Monofocal lenses are generally the best choice for night driving. EDOF performance depends on the lens type.
Glare and Halos: Monofocal lenses have minimal glare or halos. EDOF lenses vary: low for non-diffractive types, moderate for diffractive types.
Range of Focus: Monofocal lenses offer a narrow range of focus, while EDOF lenses provide an extended range.
Corneal Requirements: Monofocal lenses are more forgiving, whereas diffractive EDOF lenses need higher corneal quality.
Suitability for Large Pupils: Monofocal lenses perform very well; non-diffractive EDOF lenses are excellent.
Suitability for Perfectionists: Monofocal lenses are ideal for perfectionists; EDOF suitability depends on individual tolerance.
Case Examples: How Surgeons Decide in Real Life
Case 1: Heavy Night Driver with High Sensitivity
For a heavy night driver who is sensitive to glare and wants predictable clarity, the recommended IOL options are a monofocal lens or a non-diffractive EDOF lens if they also want some intermediate range of vision, as these lenses minimise halos and provide reliable low-light performance.
Case 2: Office Worker Using Screens 8 Hours a Day
For an office worker who spends around eight hours a day using screens, strong intermediate vision is essential for tasks like computer work, using a tablet, and managing documents. Since they don’t mind wearing glasses occasionally and do minimal night driving, an EDOF lens is the most suitable choice. The exact model should be selected based on their eye anatomy to ensure optimal performance, providing a comfortable balance between near, intermediate, and distance vision throughout the workday.
Case 3: Retired, Active, Outdoor Lifestyle
For a retired individual with an active, outdoor lifestyle who enjoys activities like golf, walking, and cycling and wants to avoid glare, monofocal lenses are the recommended choice. These lenses provide crisp, high-contrast distance vision, making outdoor and recreational activities safer and more enjoyable.
Case 4: Traveller Who Wants Freedom from Glasses
For a traveller who wants freedom from glasses, frequently uses a smartphone or camera, moves between different environments, and prefers minimal visual disturbances, the recommended options are a non-diffractive EDOF lens or a blended vision approach. These choices provide a versatile range of vision while reducing dependence on spectacles for daily activities and travel.
Why EDOF Lenses Are Becoming More Popular
EDOF lenses are increasingly chosen because they offer a balanced solution for everyday vision needs. They provide better intermediate vision than standard monofocals, making tasks like computer work, cooking, and shopping much easier without constantly relying on glasses.
Compared with multifocal lenses, EDOF lenses tend to produce less glare and fewer visual disturbances, which is especially helpful for night driving or working in bright environments. This makes them a more comfortable option for many patients.
For those seeking greater freedom in daily tasks, EDOF lenses strike a “happy medium.” They provide functional near vision while maintaining strong distance and intermediate clarity, reducing the need for spectacles for most activities.
Overall, the combination of visual quality, comfort, and convenience explains why EDOF lenses are becoming a popular choice for patients looking for a practical, versatile solution after cataract or lens replacement surgery.
Why Monofocals Remain the Gold Standard
Even with all the advanced lens options available today, monofocals are still the go-to choice for many people. If you prioritise sharp, reliable distance vision with minimal side effects, a monofocal lens could be the best fit for you.
Despite the rise of advanced lenses, monofocals remain the most widely implanted IOL because:
- They offer the sharpest distance vision
- They have the lowest side-effect profile
- They work for all pupil sizes
- They suit patients with corneal irregularities
- They offer exceptional night visibility
For people who prioritise crisp, reliable visual quality, monofocals remain unmatched.
Frequently Asked Questions:
1. What is the main difference between monofocal and EDOF lenses?
The primary difference lies in the range of focus each lens provides. Monofocal lenses are designed with a single focal point, usually set for distance vision, offering crisp and predictable clarity for faraway objects. EDOF lenses, on the other hand, extend the focal range, providing clear vision from distance to intermediate and functional near vision, which allows users to handle daily tasks like computer work or tablet use more easily without constantly relying on glasses.
2. Will I still need glasses if I choose a monofocal lens?
Yes, most people who opt for monofocal lenses will still require reading glasses for close-up tasks. While these lenses deliver excellent distance vision and superior night clarity, they do not provide the extended focal range that some other lenses, such as EDOF, offer. For activities like reading fine print, sewing, or smartphone use, glasses remain necessary.
3. Can EDOF lenses completely eliminate the need for glasses?
EDOF lenses can significantly reduce the reliance on glasses, especially for intermediate and some near tasks, but they do not always eliminate the need entirely. While many patients can perform computer work, tablet use, and casual reading without glasses, very close reading or prolonged fine-detail work may still require occasional spectacles. The degree of independence varies depending on the specific lens type and individual visual needs.
4. Which lens is better for night driving?
Monofocal lenses generally provide the sharpest clarity for night driving due to their minimal susceptibility to glare and halos. EDOF lenses can perform well in low-light conditions, particularly non-diffractive designs, but diffractive EDOF lenses may produce mild halos or light scatter that can be noticeable in certain nighttime scenarios. Surgeons often consider how frequently a patient drives at night when recommending an IOL.
5. How does pupil size affect lens choice?
Pupil size is an important anatomical factor. Monofocal lenses perform reliably across all pupil sizes, making them a flexible option. Non-diffractive EDOF lenses are particularly well-suited for larger pupils, providing a consistent extended range of vision. Diffractive EDOF lenses tend to work best with medium-sized pupils, as larger pupils can sometimes increase the perception of visual artefacts such as halos or glare.
6. Are there differences in how these lenses handle glare and halos?
Yes, glare and halos are managed differently depending on the lens design. Monofocal lenses have minimal glare or halos, making them ideal for patients sensitive to light scatter or reflections. Non-diffractive EDOF lenses also tend to produce low visual disturbances, whereas diffractive EDOF lenses may generate moderate halos under certain lighting conditions. Surgeons evaluate a patient’s sensitivity to light when making a recommendation.
7. Does corneal quality matter for lens selection?
Corneal health plays a significant role in lens performance. Monofocal lenses are more forgiving for patients with irregular corneas, previous refractive surgery, or higher-order aberrations. Diffractive EDOF lenses require a very regular and healthy corneal surface to function optimally. Non-diffractive EDOF lenses can accommodate some corneal irregularities but still need a relatively smooth corneal shape to deliver consistent visual quality.
8. Can I have different lenses in each eye?
Yes, surgeons sometimes recommend a blended vision approach, where one eye receives a monofocal lens for crisp distance vision and the other an EDOF lens to extend range. This strategy allows patients to benefit from the strengths of both lenses, improving intermediate and near vision while maintaining excellent distance clarity. Blended vision is particularly useful for patients who want a balance of spectacle independence and reliable night driving performance.
9. Which lens is better for active lifestyles or outdoor sports?
For activities that rely heavily on clear distance vision, such as golf, cycling, or driving, monofocal lenses remain a strong choice. They provide the most predictable clarity and the least susceptibility to glare. EDOF lenses can suit outdoor enthusiasts who also value versatility in intermediate vision for tasks like photography, gardening, or navigating digital devices, but individual tolerance to visual artifacts and lighting conditions must be considered.
10. How do personality and visual expectations affect lens choice?
A patient’s attitude and tolerance for minor visual compromises are often critical. People who prioritize perfect sharpness and predictability tend to adapt better to monofocal lenses, enjoying the reassurance of consistent distance clarity. Those who are flexible and willing to accept slight variations in vision for more independence from glasses often do well with EDOF lenses. Surgeons take the time to understand a patient’s expectations, daily routines, and lifestyle priorities to ensure the lens choice aligns with both visual and personal preferences.
Final Thoughts: Choosing the Safest Path to Multifocal Vision After a Monofocal IOL
Upgrading your vision after receiving a monofocal IOL is far more achievable than most people realise. Whether you want clearer near vision, sharper intermediate focus for computer work, or a fuller range without relying on glasses, there are several safe and effective options to choose from. The right pathway depends on your capsule clarity, whether you’ve had YAG treatment, your corneal health, and the type of visual freedom you want in daily life.
Modern techniques from trifocal and EDOF IOL exchange to reversible piggyback lenses and precise laser-based blended vision allow your surgeon to match the solution to your unique anatomy and lifestyle. Each method has its strengths, and the goal is always the same: to give you greater independence with the lowest possible risk. If you’re thinking about IOL replacement surgery in London, feel free to contact us at the London Cataract Centre. Our team can guide you through your options and arrange a thorough assessment tailored to your eyes.
References:
1. Chao, C.-C. & Chang, C.-K. (2022) ‘Difference in Quality of Vision Outcome among Extended Depth of Focus, Bifocal, and Monofocal Intraocular Lens Implantation’, Healthcare, 10(6), p. 1000. https://www.mdpi.com/2227-9032/10/6/1000
2. Kim, D.Y. et al. (2025) ‘Comparative Outcomes of the Next-Generation Extended Depth-of-Focus Intraocular Lens and Enhanced Monofocal Intraocular Lens in Cataract Surgery’, Journal of Clinical Medicine, 14(14), p. 4967. https://www.mdpi.com/2077-0383/14/14/4967
3. Atypon / Real‑World IOL study (2020) ‘Extended Depth of Focus Versus Monofocal IOLs: Objective and Subjective Visual Outcomes’, Journal of Refractive Surgery, 36(4), pp. 214–222. https://pubmed.ncbi.nlm.nih.gov/32267951/
4. Liu, J.R. et al. (2025) ‘Outcomes of a non‑diffractive extended depth of focus lens versus a monofocal IOL: Long‑term patient‑reported and clinical outcomes’ https://pmc.ncbi.nlm.nih.gov/articles/PMC11672098/ 5. Vision and patient‑reported outcomes with nondiffractive EDOF or neutral aspheric monofocal intraocular lenses. https://pubmed.ncbi.nlm.nih.gov/36728998/