Monovision: correcting presbyopia while keeping one eye for near vision

After the age of 45, near vision begins to blur and reading glasses gradually become necessary. Among the solutions for reducing this dependence, monovision offers a simple approach: correcting one eye for distance vision and the other for near vision. Often mentioned but poorly understood, it does not suit everyone and relies on a prior tolerance trial. This guide explains how monovision works, who it is for, how it is carried out (laser or lens implants) and what its limits are.

UNDERSTANDING

What is monovision?

Presbyopia is the natural evolution of near vision from the age of forty onwards: the crystalline lens loses its flexibility and the eye struggles to focus on close objects. Monovision is a correction strategy that works around this loss of accommodation by dividing the distances between the two eyes. The dominant eye, known as the “leading eye”, is set to see clearly at distance, while the other eye is deliberately made slightly short-sighted to see clearly up close. The brain then selects, without conscious effort, the image best suited to whatever you are looking at.

This principle is not new: it has long been used with contact lenses, which is precisely what allows it to be tested before considering surgical correction. Monovision does not “repair” the lost accommodation. It offers a deliberate compromise: a little distance comfort traded for near comfort, while accepting a slight difference between the two eyes. The idea is long-standing and well established: the American Academy of Ophthalmology describes it as a common option for correcting presbyopia, sometimes called “blended vision”.

The role of the leading eye

Everyone has a leading eye, the one the brain spontaneously favours to aim or frame a view. In monovision, this is usually the eye corrected for distance vision, because distance is the most demanded range in everyday life (driving, getting around, recognising faces). The non-leading eye takes on near vision. Determining the leading eye is part of the prior assessment, because a poor choice would compromise comfort.

Full monovision or mini-monovision?

A distinction is made between “full” monovision, which creates a marked difference between the two eyes for maximum reading comfort, and mini-monovision, which deliberately limits this difference. Mini-monovision is often preferred today: it better preserves binocular vision and depth perception, at the cost of a slight top-up sometimes needed for very small print. The setting is decided case by case, according to each person’s visual priorities and tolerance.

Who is monovision suitable for?

Monovision may appeal to presbyopic people bothered by their dependence on reading glasses, whether they are otherwise short-sighted, long-sighted or emmetropic. It is particularly relevant for those who have already tolerated a difference between their two eyes well, for example with contact lenses. It is part of the range of solutions for reducing dependence on glasses in cases of presbyopia.

It is less well suited to people who are very demanding about sharp distance and near vision at all times, to those whose profession relies on fine depth perception or prolonged night vision (some professional drivers, for example), or to those who tolerate poorly the slightest difference between their eyes. It is precisely the role of the prior assessment and the contact lens trial to identify these situations before any decision is made.

One observation comes up often in consultation: it is not the measurements that decide, but the way each person experiences their presbyopia. A patient greatly bothered by their reading glasses will readily accept a slight night-time compromise; another, attached to perfect sharpness in all circumstances, will prefer to give it up after the trial. Neither of these choices is more valid than the other: they reflect personal priorities, which the discussion in consultation helps to clarify.

THE TRIAL

The tolerance trial with contact lenses

This is the key stage of monovision. Before considering a permanent correction, the result is simulated by fitting both eyes with contact lenses that reproduce the planned setting: one eye for distance, the other for near. The patient wears this setup for several days in their daily life, at work, while driving, while reading, in order to confirm that vision stays comfortable and that the brain adapts well. Nothing replaces this real-life trial.

This trial makes the choice concrete rather than theoretical. If it is well tolerated, monovision becomes a serious option. If it causes persistent discomfort (fatigue, a sense of unstable vision, discomfort while driving), it is better to give it up or reduce the difference between the eyes. This caution avoids unpleasant surprises after a procedure that is, by its nature, hard to reverse. In our experience, this stage clearly separates comfortable projects from those that need adjusting, or setting aside.

How is monovision carried out?

Two main routes exist, depending on age and the condition of the crystalline lens. The first reshapes the cornea with a laser; the second adjusts the power of the implants placed during cataract surgery. The principle remains identical in both cases: one eye set for distance, the other for near. The choice is a medical decision, made after a full examination.

With a laser (LASIK or PRK)

In a presbyopic person whose crystalline lens is still clear, monovision can be achieved through laser refractive surgery, by setting each eye to the desired distance. This approach relies on the same techniques as the correction of short-sightedness or long-sightedness; you can learn how it works on our dedicated LASIK page. As with any refractive surgery, a full pre-operative assessment checks eligibility, in particular the thickness and regularity of the cornea. Dr Tourabaly’s laser procedures are carried out at the Clinique Laser Victor Hugo.

During cataract surgery

When a cataract is present or the crystalline lens has lost its transparency, monovision can be achieved by choosing the power of the monofocal implants: one eye set for distance, the other for near. This is an alternative to multifocal or extended depth-of-field (EDOF) implants, whose logic we explain in detail in our article on choosing an EDOF implant and night-time halos. Cataract surgery and implant placement are carried out at the Clinique Sainte-Geneviève.

BENEFITS & LIMITS

Benefits and limits of monovision

Monovision has real strengths. It also involves compromises that are best understood before deciding, because they affect very specific everyday situations.

• Benefits: reduced dependence on reading glasses, a well-established technique, testable in advance with contact lenses, without a multifocal implant or its possible halos.
• Intermediate vision: the computer distance may call for a small top-up in some people, especially with full monovision.
• Depth perception: fine binocular vision is slightly reduced, which may matter for certain activities or professions.
• Night vision: prolonged night-time driving may be less comfortable; a pair of top-up glasses remains possible for these situations.
• Adaptation: it takes a few weeks and is not guaranteed in everyone, hence the importance of the prior trial.

No solution recreates the natural vision of a young eye: monovision, like multifocal implants, offers a compromise. The right choice depends on each person’s visual priorities, lifestyle and tolerance, which is discussed in consultation.

Intermediate vision, screens and daily life

Between distance and near lies a range that has become central: that of the computer screen, the dashboard or the label on a shelf, at around 60 to 80 centimetres. This is often where monovision shows its limits, especially in its full form, where the marked gap between the two eyes clearly favours close reading. Mini-monovision softens this point by keeping better continuity between distances.

In practice, most people adapt well after a few weeks. The brain learns to work with the two images and the initial discomfort fades. For prolonged tasks on screen, a light pair of top-up glasses, worn occasionally, is generally enough to restore optimal comfort — without giving up the independence gained for the rest of the day.

Lifestyle therefore weighs as much as the optical measurement. An avid reader, an IT specialist spending eight hours in front of two screens and a retired gardener do not have the same visual priorities. This is why the prior discussion explores real daily life before setting any adjustment at all. Numbers alone do not tell you whether a correction will be experienced as comfortable.

Monovision, multifocal implants: how to choose?

Faced with presbyopia, several strategies coexist: monovision, multifocal or EDOF implants, clear lens exchange, or simply progressive glasses. There is no universal “better” solution: each has its indications. Monovision appeals through its simplicity and its relative reversibility when carried out with a laser, while multifocal implants aim for near and distance vision in both eyes, at the cost of possible halos. Comparing these options in the context of one’s own life, with an ophthalmologist, remains the most reliable way to decide. Other avenues are presented in our article on solutions for presbyopia.

When should you seek a consultation?

If presbyopia disrupts your daily life and dependence on reading glasses weighs on you, a consultation allows you to review the options suited to your eye and your lifestyle. The ophthalmologist determines the leading eye, assesses the feasibility of monovision, offers a contact lens trial where appropriate and helps you compare it with the other solutions. Dr Moïse Tourabaly, former Chief of Clinic at the Hôpital National des Quinze-Vingts, sees patients in consultation to assess presbyopia and discuss correction strategies. You can find out more about his background and practice.

Sources

• American Academy of Ophthalmology (AAO) — patient information on monovision (blended vision) and presbyopia.
• Société Française d’Ophtalmologie (SFO) — reports and recommendations on presbyopia surgery.
• European Society of Cataract & Refractive Surgeons (ESCRS) — data on presbyopia correction and monovision.
• Haute Autorité de Santé (HAS) — quality of life and presbyopia correction during cataract surgery.