Monovision (Correction of Interocular Difference with Contact Lenses or Surgery)

Key Points at a Glance

Key Points of This Condition

• Monovision corrects one eye for distance and the other for near, covering both distance and near vision through monocular vision.
• A critical drawback is impaired binocular stereopsis (depth perception), so it is not a method that can be actively recommended.
• It does not succeed in all cases, and may be particularly difficult in patients with orthophoria.
• Before surgery, a trial with contact lenses for 1–2 weeks should be performed to confirm adaptation in daily life before considering surgery.
• The basic principle is to set the dominant eye for distance and the non-dominant eye for near.

1. What is Monovision?

Monovision is a correction method in which one eye is corrected for distance and the other for near, covering distance and near vision through monocular vision.

Originally, “monovision” is mostly thought to develop when an anisometropic eye with one eye emmetropic (or near-emmetropic dominant eye) and the other moderately myopic (non-dominant eye) is left uncorrected during growth, resulting in impaired normal binocular vision. Its application to presbyopia correction is an intentional imitation of this physiological state.

As an option for patients troubled by presbyopia, it can be implemented via contact lenses, refractive surgery, or intraocular lenses (IOLs). Also, after refractive surgery or at presbyopic age, it is important to consider weaker correction or monovision taking into account not only distance vision but also intermediate to near vision.

Historical background and positioning of monovision:

Monovision was developed in the 1970s–1980s as a presbyopia correction method using contact lenses. Inspired by the observation that anisometropic individuals experienced functional distance and near vision even with contact lenses, it was later adopted in refractive surgeries such as LASIK and PRK. In cataract surgery, it is established as an alternative for patients who do not desire or are not suitable for multifocal IOLs. Since overcorrection leading to hyperopia can cause eye strain during near work, special attention is needed when designing correction for presbyopic ages.

Application Precautions

Not all cases succeed when attempting to apply this method for presbyopia correction. It may be difficult in patients with orthophoria. Also, because it has the critical drawback of impairing binocular stereopsis, careful consideration is needed for patients whose occupations require depth perception or who have binocular vision problems.

Q What is monovision correction?

A

It is a method where one eye is set for distance (emmetropia or distance correction) and the other eye for near (residual myopia or near addition), covering distance and near vision through monocular vision of each eye. The goal is to achieve distance and near vision without glasses. However, binocular stereopsis is reduced, which is disadvantageous for tasks requiring depth perception.

2. Indication Assessment

Characteristics of Good Candidates

Patients with the following characteristics are good candidates for monovision.

• Previous experience with anisometropia (e.g., long-term uncorrected myopia in one eye)
• Clearly identifiable dominant eye
• Relatively well-preserved binocular vision (stereopsis)
• No occupation or tasks requiring depth perception
• Demonstrated adaptation to monovision during contact lens trial
• Does not perform precise near work (e.g., fine craftsmanship, precision instruments) on a daily basis

Contraindications and Concerns

Monovision is not suitable or requires careful evaluation in the following cases.

• Poor stereopsis
• Occupations requiring depth perception (e.g., aircraft pilots, drivers, construction workers)
• Poor tolerance during contact lens trial
• Alternating fixation (unclear ocular dominance)
• Patients who routinely perform high-precision tasks
• Patients who do not wish to undergo reoperation if dissatisfied after surgery

3. Pathophysiological Background

Brain Adaptation Mechanisms

Monovision works because the visual cortex adapts to the difference in focus between the two eyes and preferentially uses the appropriate eye depending on viewing distance. If binocular rivalry does not occur, natural monovision is achieved.

The key to success is “binocular coordination and the brain’s adaptive capacity.” Prior experience with anisometropia, clear ocular dominance, and preserved binocular vision influence the prognosis.

Binocular Rivalry and Impact on Stereopsis

In normal binocular vision, small differences between the two eyes (binocular disparity) are used to perceive depth (stereopsis). In monovision, one eye is intentionally defocused, so binocular disparity information becomes incomplete, reducing stereopsis.

Mini-monovision (addition of +0.75 to +1.00 D) is a compromise that minimizes the impact on stereopsis while providing some near vision. It is an option for patients who need to maintain stereopsis (e.g., sports enthusiasts).

Full monovision (addition of +1.50 to +2.00 D) provides better near vision but causes more significant reduction in stereopsis.

Physiological Significance of the Dominant Eye

The dominant eye plays a central role in visual information processing. Setting the dominant eye for distance vision stabilizes information processing during distance viewing and increases the everyday acceptability of monovision.

Monovision Glasses (Application to Aniseikonia)

For myopic eyes, undercorrecting one eye can solve the problem of aniseikonia (monovision glasses). In cases of anisometropia, it is desirable that the difference in spherical power between the two eyes does not exceed 1.5 D. If it exceeds this, contact lens correction or intentional monovision setting may be useful in reducing aniseikonia.

4. Diagnostic and Indication Evaluation Tests

Standard Procedure for Indication Evaluation

The standard procedure for evaluating the indication for the monovision method is described below.

① Determination of the dominant eye

Success is more likely when the dominant eye is set for distance and the non-dominant eye for near.

• Hole-in-card test: Look at a distant target through a small hole in the center of a card and confirm which eye is used.
• Pointing test: Point at a distant target, then cover one eye; the eye that does not deviate from the target is the dominant eye.

② Stereopsis test

Quantitatively evaluate binocular stereopsis using TNO (random dot method) or Titmus (polaroid method). Preoperative stereopsis is related to the degree of stereopsis decline after monovision.

③ Refraction test and addition power setting

Set the addition power based on Sloan’s principle (reserve half of the accommodative amplitude as a reserve).

④ Trial fitting (CL trial)

Before surgery, simulate monovision with contact lenses for 1–2 weeks. Assess subjective acceptance in actual daily life (driving, reading, VDT work) before deciding on surgery. A trial using daily disposable CLs is easy to perform.

Test item	Purpose	Criteria
Dominant eye determination	Determine distance eye	Hole-in-card / pointing test
Stereopsis test	Binocular vision assessment	TNO / Titmus
CL trial	Real-life adaptation check	1–2 weeks of daily use
Refraction test	Add power setting	Sloan’s principle

Q What should I check before trying the monovision method?

A

It is recommended to perform a trial wearing of contact lenses (1–2 weeks) before surgery. Experience the monovision vision in actual daily life (driving, reading, computer work), and if it is deemed acceptable, surgery is indicated. Also, confirmation of the dominant eye and stereopsis testing are always performed preoperatively.

5. Standard Treatment Methods

There are three main methods for achieving monovision.

5-1. Monovision with Contact Lenses

This is the most reversible method and is also used for initial trials.

Standard settings:

• Dominant eye: ±0D (full distance correction)
• Non-dominant eye: +1.5 to +2.0D (near addition)

Prescription principles:

• When prescribing multifocal SCLs, confirm the dominant and non-dominant eyes; it often works better to set the dominant eye for distance and the non-dominant eye for near.
• Do not be constrained by age or addition power values; starting with a lower addition power often works better.
• If distance vision is poor, adjust the spherical power of the dominant eye toward distance; if near vision is poor, adjust the non-dominant eye toward near.
• Contrast sensitivity decreases in dark conditions, so caution is needed for night driving.

5-2. Surgical Monovision (Refractive Surgery)

A method of intentionally leaving one eye myopic through LASIK, PRK, etc. Mainly targeted at middle-aged and older patients with presbyopia.

Standard target refraction settings:

• Dominant eye: 0D (emmetropia)
• Non-dominant eye: -1.25 to -1.50D (intentional myopia)

Key points of preoperative evaluation:

• A successful preoperative trial with contact lenses is a prerequisite.
• Explain the possibility of enhancement surgery for postoperative dissatisfaction beforehand.
• Keep in mind that since most patients are myopic, overcorrection leading to hyperopia can cause eyestrain during near work.

Postoperative management:

• Evaluate vision 1 to 3 months after surgery.
• Confirm that both the distance and near eyes provide satisfactory vision at the desired distances.

5-3. Monovision with IOL (during cataract surgery)

A method of planning cataract surgery with one eye receiving a distance IOL and the other a near IOL (or set for residual myopia).

Setting considerations:

• Dominant eye: 0D (distance)
• Non-dominant eye: -1.50 to -2.00 D (near setting)

This is considered as an alternative for patients who do not desire multifocal IOLs or for whom multifocal IOLs are contraindicated (e.g., large higher-order aberrations, severe dry eye). Light-adjustable IOLs may also be an option for correcting postoperative refractive errors.

Monovision with Contact Lenses

Reversibility: High (returns to baseline when CLs are removed)

Dominant eye: ±0 D (full distance correction)

Non-dominant eye: +1.5 to +2.0 D (near addition)

Features: Ideal for trial. Easy to adjust.

Monovision with Surgery (LASIK/PRK)

Reversibility: Low (requires reoperation)

Dominant eye: 0 D (emmetropia)

Non-dominant eye: -1.25 to -1.50 D (intentional residual myopia)

Features: No CL needed. Successful CL trial is a prerequisite.

Monovision with IOL (Cataract Surgery)

Reversibility: Low (requires IOL exchange)

Dominant eye: 0 D (distance)

Non-dominant eye: -1.50 to -2.00 D (near setting)

Features: Alternative option for patients unsuitable for multifocal IOLs

5-4. Combination with reading glasses

While monovision is the basic approach, adding reading glasses for precise near work is also an option. For myopic patients, “monovision glasses” that use the undercorrected side for near vision under distance correction are a practical choice.

5-5. Management after cataract surgery

After cataract surgery with monovision setting, pay attention to the following:

Postoperative confirmation items:

• Check distance, near, and intermediate visual acuity in each eye
• Check binocular visual acuity and contrast
• Evaluate stereopsis (compared to preoperative)
• Patient’s subjective satisfaction with vision at intended distances

Management of postoperative refractive error:

• If deviation from intended refraction is mild, correct with glasses
• For large deviations, consider switching to a light-adjustable IOL (LAL)
• Reoperation (IOL exchange or LASIK enhancement) should be considered carefully

Relationship with smartphone/VDT use: In postoperative monovision patients, although accommodative load during smartphone use does not occur, convergence fatigue from prolonged near work can occur. Guidance on the working environment when using digital devices is provided as part of postoperative management.

5-6. Actual flow of monovision setting

Standard flow when conducting a monovision trial with CL:

1. Initial evaluation: Determination of dominant eye, stereopsis test, confirmation of full correction refraction values
2. CL trial prescription: Start with dominant eye ±0D and non-dominant eye +1.50D (daily disposable CL)
3. Follow-up after 1-2 weeks: Check satisfaction in daily life (driving, reading, PC work)
4. Adjustment: If dissatisfied, adjust the addition in ±0.25D increments
5. Final decision: If trial is successful, proceed to surgery
6. Preoperative final confirmation: Reconfirm with the patient the irreversibility of surgery, reduced stereopsis, and impact on depth perception

Success of the CL trial is the best predictor of postoperative satisfaction ¹⁾. If the trial is unsatisfactory, do not proceed to surgery and consider other presbyopia correction options (bifocal/multifocal CL, progressive addition lenses, etc.).

Postoperative follow-up plan

Recommended follow-up schedule after monovision surgery:

• 1 week postoperatively: Check corneal and intraocular status, measure subjective corrected visual acuity
• 1 month postoperatively: Confirm stability of refraction, evaluate patient satisfaction
• 3 months postoperatively: Finalize refraction, consider enhancement if necessary
• 6 months and 1 year after surgery: Check long-term progress, evaluate stereopsis, address complaints
• Every 2–3 years: Review addition power (adjust for progression of presbyopia)

If stereopsis decreases or dissatisfaction is strong after surgery, it is safer to first try adjusting correction with contact lenses (changing addition power or switching to multifocal CLs) before considering reoperation. Appropriate patient selection and thorough preoperative counseling are essential to maximize postoperative satisfaction.

Occupational considerations

Special attention is needed when applying to occupations that require depth perception and stereopsis:

Occupation	Points to note	Countermeasures
Car/train driver	May affect passing the depth perception test	Check employment regulations; consider mini-monovision
Pilot (aviation)	Depth perception required; monovision may be prohibited	Must check aviation medical examination standards in advance
Construction worker / high-altitude work	Reduced depth perception affects safety	Check work details in detail; consider alternative methods
Surgeons / Dentists	Requires stereopsis for precision work	Option to add reading glasses during surgery
Athletes	Reduced depth perception in ball sports and combat sports	Consider mini-monovision; individual assessment

Depth perception tests (driver’s license, some certifications) evaluate binocular stereopsis, so monovision may affect test results. If there are occupational risks, provide sufficient explanation and obtain consent before the procedure.

Relationship between Addition and Age

The addition required for presbyopia correction changes with age. As the addition increases, stereopsis decreases more noticeably, so regular reassessment based on age is necessary.

Age	Accommodative Amplitude (Approx.)	Monovision Addition (Approx.)	Characteristics
40–45 years	3–5 D	+1.00 to +1.50 D	Manageable with low addition
45–50 years	2–3 D	+1.50 to +1.75 D	Consider intermediate distance as well
50–55 years	1–2 D	+1.75 to +2.00 D	Full monovision required
55 years and older	0–1 D	+2.00 to +2.50 D	Additional reading glasses may be needed

Re-evaluation and adjustment of monovision are recommended every 2–3 years. As the addition increases, the degree of stereopsis reduction also increases, so it is important to consider switching to alternative methods (such as progressive addition lenses) early in patients with occupations requiring depth perception.

Patient satisfaction and QOL with monovision

Understanding the factors that affect patient satisfaction can improve appropriate patient selection and the quality of preoperative counseling.

Factors associated with improved satisfaction:

• Successful preoperative contact lens trial
• Preoperative experience with anisometropia (history of uncorrected monocular myopia)
• Clearly identifiable dominant eye
• Low frequency of nighttime driving
• Low need for precision work or sports
• Realistic patient expectations (no excessive expectations such as “no glasses needed at all”)

Factors associated with dissatisfaction:

• Decreased contrast sensitivity at night
• Perceived reduction in stereopsis during precision work
• Minor dissatisfaction during contact lens trial
• Equal vision in both eyes (no clear dominant eye)
• Postoperative refractive error (deviation from target)

In preoperative counseling, it is essential to emphasize that the goal is not “perfect vision” but “practical daily vision without correction,” and to form realistic expectations to maintain postoperative satisfaction.

Positioning as an option for presbyopia correction

The position of monovision within the overall picture of presbyopia correction is as follows.

Correction method	Main advantages	Main disadvantages	Indications
Progressive addition lenses	Full distance coverage, stereopsis maintained	Peripheral aberrations, adaptation required	Broadest indication
Multifocal contact lenses	No glasses needed	Slightly inferior visual quality	Contact lens wearers
Monovision (CL/surgery)	No glasses needed, maintains sharpness	Reduced stereopsis, individual variation in adaptation	Successful CL trial cases
Multifocal IOL	Full range, spectacle independence	Optical phenomena, high cost	During cataract surgery
Mini-monovision	Minimal impact on stereopsis	Limited improvement in near vision	Patients who value stereopsis

Monovision plays an important role as a “practical intermediate option” for patients who experience strong optical discomfort with progressive addition lenses, those who do not want to wear glasses, and those who are not candidates for multifocal IOLs. It must be remembered that careful patient selection using a contact lens trial is the key to success.

Advice for patients

If you are considering monovision, we recommend first trying it with contact lenses for 1–2 weeks. After checking how you see in actual daily life (driving, reading, sports, etc.), decide whether to consider surgery. If your occupation requires depth perception, please inform your doctor in detail about your job duties.

6. Pathophysiology

Detailed pathophysiology is described in section “3. Pathophysiological Background.” Additional information is provided below.

Anisometropia and aniseikonia

Monovision inevitably creates a refractive difference (anisometropia) between the two eyes. When the difference in spherical power exceeds 1.5 D, aniseikonia tends to become problematic. Aniseikonia is perceived as an abnormality in spatial perception (sensation of tilt or distortion).

Correction with contact lenses has less impact on aniseikonia compared to glasses, so a monovision CL trial is also useful for predicting surgical success.

Comparison with multifocal CLs

Multifocal CLs are also an option for presbyopia correction, but they differ from the monovision method in the following points:

Item	Monovision method	Multifocal CL
Mechanism of action	Monocular vision (one eye for distance, one eye for near)	Simultaneous vision (center for near, periphery for distance, etc.)
Image clarity	Clear at each distance	Inferior to single-vision CLs
Stereopsis	Decreased	Relatively maintained
Indications	After confirmation in CL trial	Trial comparison
Dark environment	Contrast reduction is more pronounced with multifocal CLs	Decreased contrast sensitivity

If multifocal CLs are not well tolerated, monovision with monofocal CLs (dominant eye for distance, non-dominant eye for near) combined with reading glasses is an option.

Trade-off between mini-monovision and full monovision

A smaller addition (+1.00 to +1.25 D) has minimal impact on stereopsis but limited improvement in near visual acuity, while a larger addition (+1.75 to +2.00 D) improves near visual acuity but significantly reduces stereopsis, presenting a trade-off ²⁾.

7. Latest research and future perspectives

For patients: Please read carefully

The following information is currently at the research stage or approved only in some regions, and is not standard treatment commonly available in Japan. It is reference information for professionals regarding future medical developments.

Evidence on patient satisfaction and success rates

When a monovision trial with CLs is conducted preoperatively, high postoperative patient satisfaction rates have been reported. Predictive factors for trial success include preoperative anisometropia experience, clear ocular dominance, and preserved binocular vision ¹⁾.

Consideration of optimal addition power

Determining the appropriate near addition is key to patient satisfaction. There is a trade-off: a low addition (+1.00 to +1.25 D) has minimal impact on stereopsis but limited improvement in near visual acuity, while a high addition (+1.75 to +2.00 D) improves near visual acuity but significantly reduces stereopsis ²⁾.

Rise of Mini-Monovision

Mini-monovision (addition +0.75 to +1.25 D) is gaining attention as a compromise that compensates for presbyopia while relatively preserving stereopsis. Evidence is accumulating, especially in IOL settings during cataract surgery ³⁾. Reports on mini-monovision using the new monofocal IOL (Eyhance ICB00) show that significantly better visual acuity is maintained in the intermediate to near vision range (−2.0 to −4.0 D) compared to the emmetropic group ⁵⁾.

Comparison of binocular defocus curves between emmetropic and mini-monovision groups (Eyhance ICB00 IOL)

Shimizu K, Ito M, Igarashi S, et al. Visual outcomes and spectacle independence of pseudophakic mini-monovision using a new monofocal intraocular lens. Sci Rep. 2022;12(1):22384. Figure 2. PMCID: PMC9755282. License: CC BY 4.0.

Binocular defocus curves after cataract surgery for the emmetropic group (blue line) and mini-monovision group (orange line) show that the mini-monovision group maintains significantly better visual acuity in the intermediate to near vision range (−2.0 to −4.0 D). This corresponds to the visual distance extension effect of mini-monovision discussed in the section “Latest Research and Future Prospects.”

Intermediate Vision in the Digital Device Era

With increased use of smartphones, tablets, and other devices, visual acuity at intermediate distances (50–80 cm) has become more important. In contrast to traditional monovision (distance + near), a micro-monovision approach that prioritizes distance + intermediate vision is also being studied ⁴⁾. In managing digital eye strain (DES), consideration for monovision patients is necessary, and the Tear Film & Ocular Surface Society (TFOS) has comprehensively summarized the impact of the digital environment on the ocular surface ⁷⁾.

Comparison with Multifocal IOLs

Studies comparing multifocal IOLs and monofocal IOL monovision show that multifocal IOLs provide superior vision at all distances, but have a higher incidence of optical phenomena such as halos and glare. Selection according to the patient’s lifestyle priorities is important ³⁾. A meta-analysis of 22 trials and 2,200 eyes comparing trifocal IOLs and EDOF IOLs showed that trifocal IOLs are superior in near visual acuity and spectacle independence ⁶⁾, providing a reference when considering multifocal IOLs as an alternative to monovision.

Selection Guide: Multifocal IOL vs. Monovision (Monofocal IOL):

Aspect	Multifocal IOL	Monovision (Monofocal IOL)
Vision at all distances	Superior (far to near)	Specialized for distance or near
Stereopsis	Relatively preserved	Decreased
Optical phenomena (halo/glare)	Frequent	Less frequent
Night vision	Risk of decreased	Relatively good
Spectacle independence	High	Moderate
Cost (selected medical care/out-of-pocket)	Expensive	Relatively inexpensive
Indications	Active lifestyle / multiple distance needs	Frequent night driving / cannot tolerate halos

For patients with severe dry eye, large higher-order aberrations, or concerns about reduced contrast sensitivity, monovision with a monofocal IOL is often more suitable than a multifocal IOL.

In the digital device era, screen time is increasing globally ⁸⁾⁹⁾, and even patients who have undergone monovision require attention to intermediate distance visual function. Particularly in patients with long screen time, accommodative fatigue is more likely to occur ¹⁰⁾¹¹⁾, and optimization of the work environment in addition to monovision settings is important ¹²⁾. The impact of increased screen time has also been reported in children and young adults ¹⁴⁾, and evaluation of digital device usage is essential across all age groups undergoing presbyopia correction ^13)15)16)17).

8. References

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3. Zhang F, Sugar A, Jacobsen G, Collins M. Visual function and patient satisfaction: comparison between bilateral diffractive multifocal intraocular lenses and monovision pseudophakia. J Cataract Refract Surg. 2011;37(3):446-453.

4. Evans BJ. Monovision: a review. Ophthalmic Physiol Opt. 2007;27(5):417-439.

5. Shimizu K, Ito M, Igarashi S, et al. Visual outcomes and spectacle independence of pseudophakic mini-monovision using a new monofocal intraocular lens. Sci Rep. 2022;12(1):22384.

6. Karam M, Alkhowaiter N, Alkhabbaz A, et al. Extended depth of focus versus trifocal for intraocular lens implantation: an updated systematic review and meta-analysis. Am J Ophthalmol. 2024;267:92-113.

7. Wolffsohn JS, et al. TFOS Lifestyle: Impact of the digital environment on the ocular surface. Ocul Surf. 2023;30:213-252.

8. Kaur K, et al. Digital Eye Strain- A Comprehensive Review. Ophthalmol Ther. 2022;11:1655-1680.

9. León-Figueroa DA, et al. Prevalence of computer vision syndrome during the COVID-19 pandemic. BMC Public Health. 2024;24:640.

10. Song F, Liu Y, Zhao Z, et al. Clinical manifestations, prevalence, and risk factors of asthenopia: a systematic review and meta-analysis. J Glob Health. 2026;16:04053.

11. Thakur M, Panicker T, Satgunam P. Refractive error changes and associated asthenopia observed after COVID-19 infection. Indian J Ophthalmol. 2023;71:2592-2594.

12. Pavel IA, et al. Computer Vision Syndrome: An Ophthalmic Pathology of the Modern Era. Medicina. 2023;59:412.

13. Barata MJ, et al. A Review of Digital Eye Strain: Binocular Vision Anomalies, Ocular Surface Changes. J Eye Mov Res. 2025.

14. Bhattacharya S, et al. Let There Be Light-Digital Eye Strain (DES) in Children as a Shadow Pandemic. Front Public Health. 2022;10:945082.

15. Lem DW, et al. Can Nutrition Play a Role in Ameliorating Digital Eye Strain? Nutrients. 2022;14(19):4005.

16. Anbesu EW, Lema. Prevalence of computer vision syndrome. Sci Rep. 2023;13:1801.

17. Downie LE, et al. TFOS Lifestyle: Impact of the digital environment on the ocular surface – Management and treatment. Ocul Surf. 2023;30:253-285.