What is monovision? One eye for distance, one eye for near — who is suitable?
Explanation of monovision in glasses: mechanism, advantages and disadvantages, adaptation, and driving notes; does not replace an eye exam — prescribed by an ophthalmologist / refractionist.
Optometrist Vũ Văn Tiệp
March 28, 2026
Monovision (also known as single vision in some Vietnamese documents) is a way to adjust glasses or contact lenses where one eye is prioritized for clear distance vision, and the other eye is for clear near vision — the brain will learn to prioritize images from the eye suitable for each task (reading signs, reading medication labels, typing on a computer). This method is often considered for people over middle age when presbyopia occurs (difficulty seeing close when wearing glasses adjusted for distance), but do not want or are not used to progressive lenses, or do not accept the line of two lenses. Monovision is not “a solution for everyone”: some people adapt well, while others may experience dizziness, eye strain, or reduced depth perception — therefore, it is mandatory to test under control and prescribed by an ophthalmologist / refractionist. The article below explains the mechanism, advantages and disadvantages, comparison with progressive lenses, and driving notes; it does not replace an eye exam. For personalized advice, contact Kính Mắt Điện Biên Phủ, 529 Đường 3 Tháng 2, Quận 10.
Medical note: Do not self adjust the difference between the two eyes at home based on online readings. A discrepancy of 0.25–0.50 D can be the boundary between “usable” and “long-lasting discomfort.”
How does monovision work in practice?
In glasses, each eye wears a single lens but with different powers: usually, the dominant eye is adjusted for distance vision for driving, watching TV; the other eye accepts slightly blurred distance to read books, see the phone more clearly. The brain will filter information — similar to how many people use one eye for primary vision, one eye for secondary vision in daily tasks, but here it is optically intentional. The power difference (usually around 1.00–1.50 D for near, depending on the individual) is calculated and tested by the refractionist; there is no fixed chart for everyone.
Commonly mentioned advantages
- One pair of glasses instead of alternating between distance and reading glasses (for those who adapt well).
- No line between two lenses; appearance similar to single vision.
- The cost of lenses can be lower than some high-end progressive lenses (depending on the brand and coating).
- Some people adapt faster compared to a narrow progressive corridor.
Who is often discussed regarding monovision?
People over 40 with presbyopic symptoms, who have tried progressive lenses but are not used to the corridor, or whose work does not require rapid near-far switching every minute. People with fine occupations using both eyes (some engineers, artists) need to test thoroughly before finalizing.
Limitations and risks to know before choosing
- Depth perception (stereo) may decrease — affecting driving, climbing stairs, ball sports, playing tennis.
- Eye strain, headaches if the power difference is not suitable or if the brain adapts slowly.
- Intermediate vision (computer distance) may sometimes not be optimal compared to progressive lenses designed for intermediate zones.
- Not widely applicable for professional driving or individuals who require high binocular vision without testing.
Monovision compared to progressive and bifocal lenses
| Criteria | Monovision | Progressive | Bifocal |
|---|---|---|---|
| Adaptation | Brain chooses an eye; some may feel tired | Train to see in the corridor | Clear boundary far/near |
| Depth | May decrease | Usually better when adapted | Depends on viewing area |
| Aesthetics | Similar to single vision | No line | Has a line |
| Intermediate | Limited | Designed for computers | Two separate areas |
Read more about what progressive lenses are and which to choose: bifocal or progressive.
Monovision with contact lenses
In addition to glasses, monovision can also be applied in contact lenses (one eye for distance, one eye for near) — still requires examination, corneal measurement, and monitoring for dry eyes. This is a specialized branch; this article does not replace lens fitter consultation.
Driving and monovision: need to test in real conditions
If you drive a lot, please test glasses under conditions of headlights, rain, curved roads — not just reading in the clinic. If you experience dizziness or poor distance estimation, report immediately to adjust the power or switch options (progressive, bifocal).
Suggested process when working with a refractionist
Step 1: Measure fully for distance, near, ADD (if any). Step 2: Gradually test power difference within a safe frame. Step 3: Wear for a few days — keep a diary of driving, reading, computer use. Step 4: Re-examine for fine-tuning.
Can monovision replace an eye exam?
No. Conditions such as glaucoma, cataracts, retinal detachment are not directly related to choosing monovision but affect vision — screening is needed before complex lens adjustments.
“Mini monovision” or slight difference: talk to the refractionist
Some people only need a very small difference between the two eyes to reduce strain when reading short texts while still driving well — this is a fine-tuning area in the clinic, not a self-applied formula. If you hear the term mini monovision or modified monovision, ask the refractionist to explain the goal and how to evaluate after 1–2 weeks.
Monovision and screen work
Working in offices with two screens, online meetings, reading reports continuously creates a demand for intermediate and near vision. Monovision sometimes makes a range of viewing distances not sharp like progressive lenses optimized for computers — consider glasses for office workers or eye-relax / office progressive lines if suggested by the refractionist.
Commonly confused terminology: monovision is not “one-eye glasses”
Monovision does not mean wearing one eye or covering one eye. Both eyes remain open; the difference lies in the power on the lenses (or contact lens power) between the two sides. If you have heard the term dominant eye, that is part of the decision to test but should not self-derive the power at home.
Conclusion
Monovision is an option in the category of managing presbyopia when users want to avoid progressive or bifocal lenses, accepting the trade-off of optimal binocular fusion ability. Success depends on testing, power difference, and lifestyle needs (driving, sports, near work). Do not self copy powers from others. For measurements and advice in Ho Chi Minh City, see contact, articles, or foundational articles like what lenses are.
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