During cataract surgery, the cloudy natural lens is replaced with an artificial lens called an intraocular lens (IOL). Monofocal and multifocal lenses are two common types of IOLs. They differ in how they work, and which patients they suit best.
What Is a Monofocal Lens?
A monofocal lens has one focusing distance. A magnifying glass is a useful comparison. It produces a clear image only when held at the right distance, and the image becomes blurry if the object is too close or too far away. A monofocal lens works in a similar way. It can be set for near, intermediate, or far vision, but only one of these at a time. Most monofocal lenses are set for distance vision, which helps with activities such as seeing street signs, watching television, or viewing objects far away.
Dr. David Robinson explains that monofocal lenses are the most commonly implanted type. Because they focus at one distance, they usually do not provide sharp computer or reading vision at the same time. Patients usually still need reading glasses, computer glasses, or progressive glasses for other distances. For some patients, switching between pairs of glasses can be frustrating. Standard monofocal lenses also do not correct astigmatism, which is an irregular curvature of the eye that can blur vision. Toric IOLs, which are designed to correct astigmatism, can be used for this purpose.
Some patients choose monovision, a technique in which one eye is set for distance and the other for near. The brain gradually adapts to combining the input from both eyes. Not every patient adjusts well, so monovision is generally considered mainly for patients who have already used monovision contact lenses successfully.
Advantages
- Lower cost and typically covered by insurance, although coverage varies by plan.
- Clear vision at the chosen distance.
- A long history of safe use.
- Lower risk of halos and glare than multifocal lenses.
Disadvantages
- Only one focusing distance.
- Glasses or contacts are often still needed.
- Monovision may be difficult to adapt to.
What Is a Multifocal Lens?
A multifocal lens has multiple focal zones that allow near, intermediate, and far vision at the same time. Intermediate vision is the range used for tasks such as looking at a computer screen or a car dashboard. Rather than focusing at a single distance, the lens divides light among several focal points, and the brain learns to select the appropriate focus for each task.
Advantages
- Patient satisfaction: A 2023 study reported that most patients remained satisfied three years after surgery.
- Many patients need glasses or contacts less often for reading, driving, or computer use.
- Possible long-term savings, because fewer pairs of glasses and prescription updates may be needed.
Disadvantages
- Higher cost, because these are premium lenses and insurance often does not cover the additional cost.
- Greater risk of halos, glare, and starbursts, especially around lights when driving at night.
- Possible reduction in contrast sensitivity, which is the ability to distinguish objects from their background, especially in low light.
- An adjustment period after surgery, during which some patients experience visual disturbances.
- Stricter eye health requirements, because multifocal lenses generally work best in a healthy eye.
How to Choose
Several factors help determine which lens is most appropriate. Lens selection is not only about choosing the newest or most advanced option. It involves matching the lens to the patient’s eyes, daily activities, and personal preferences.
Budget and coverage: Monofocal lenses generally cost less and are usually covered by insurance, although coverage varies by plan. Multifocal lenses often involve an additional out-of-pocket cost.
Lifestyle: For patients who want to reduce their dependence on glasses, multifocal lenses may be a better option. This may be most relevant for patients whose work or hobbies make glasses inconvenient. Patients who are comfortable using glasses for certain tasks, such as reading a menu in a dimly lit restaurant, may find a monofocal lens meets their needs.
Night driving: Halos, glare, and starbursts from multifocal lenses may affect night driving. These effects often lessen over time, although they may not resolve completely for every patient, and they should be considered.
Astigmatism: Both lens types generally perform best when astigmatism is corrected, either with a toric lens or another approach. A patient with significant astigmatism should discuss this with their eye doctor before choosing a lens.
Dr. David Robinson explains that the choice should be based on the patient’s daily activities and visual needs, not only on lens technology. The best lens is not necessarily the most expensive one. It is the one that best matches the patient’s eyes and goals. A lens that suits one patient may not suit another.
When Multifocal Lenses May Not Be Appropriate
Multifocal lenses divide incoming light among several focal points, which can slightly reduce contrast sensitivity, especially in low light. For most patients, this reduction is not noticeable. For patients with certain other eye conditions, it may be more significant.
Dr. David Robinson notes that patients with conditions affecting the retina, cornea, or optic nerve, such as age-related macular degeneration or glaucoma, may be better suited to a monofocal lens. These conditions can already limit vision, and the image from a multifocal lens may be further blurred or reduced in quality. An eye exam is needed to determine whether multifocal lenses are appropriate.
Other Options
Some lenses fall between monofocal and multifocal lenses. Extended depth of focus (EDOF) lenses are designed to provide a wider range of vision than a monofocal lens, particularly for intermediate tasks such as computer use, with a lower risk of halos and glare than many multifocal lenses. Reading glasses may still be needed for small print or in dim lighting. Patients interested in these options can discuss them with their eye doctor.
Comparison
| Feature | Monofocal | Multifocal |
| Focusing distances | One | Near, intermediate, and far |
| Need for glasses | More often | Less often |
| Cost | Lower; usually covered by insurance | Higher; premium lens, often with additional out-of-pocket cost |
| Halos and glare | Lower risk | Higher risk |
| Eye health requirements | Fewer | Stricter |
| Adjustment period | Typically short, except with monovision | Typically longer |
| Best for | Patients prioritizing cost or simplicity, or with certain eye conditions | Patients who want to reduce dependence on glasses |
Next Steps
Both lens types can provide good results, and neither is appropriate for every patient. An eye doctor can evaluate vision and overall eye health, explain how each option may affect vision in the short term and long term, and help select a lens that fits the patient’s needs and priorities.
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