Monovision Surgery

Presbyopia (Age-Related Farsightedness)

Presbyopia is a natural age-related condition that occurs in everyone, typically beginning between 40 and 50 years of age. Individuals with presbyopia have increasing difficulty seeing small objects at close range—for example, reading fine print, threading a needle, checking product prices, viewing the date on a watch, or applying makeup precisely. Early symptoms include blurred near vision in low light, improved clarity when holding objects farther away, or delayed refocusing when switching between near and far vision.

For people who previously had normal vision and never needed glasses, presbyopia eventually leads to difficulty reading, making reading glasses necessary. Individuals with myopia (nearsightedness) also develop presbyopia, although many are unaware because the symptoms can be masked by their existing myopia. Examples include:

1. Wearing glasses slightly weaker than their true prescription, resulting in slight blur at distance but easier near vision.
2. Mild myopes often notice they can read comfortably without glasses.
3. Higher myopes may push their glasses forward or require bifocal lenses.
   Misconception: “My nearsightedness is reversing as I get older.” This is incorrect. Presbyopia overlaps with myopia, causing confusion.
4. Contact lens users who wear full-correction lenses often find that near tasks become more difficult and must use reading glasses.
5. Some patients wear monovision contact lenses, correcting one eye for distance and the other for near vision—this concept is the basis of Monovision LASIK.

What Is Monovision?

Monovision is a refractive strategy used for patients 40 years and older who have presbyopia. One eye (the dominant eye) is corrected fully for clear distance vision, while the other eye (the non-dominant eye) is intentionally left slightly nearsighted, allowing for functional near vision. This approach provides good vision at both far and near distances for most daily activities without glasses—such as reading price tags, menus, or mobile screens.

How Monovision Works Visually

- Dominant Eye: Optimized for clear distance vision, but near vision may be limited.
- Non-Dominant Eye: Adjusted for better near vision, enabling comfortable reading of everyday text.
When used together, the brain blends the visual input from both eyes, allowing good functional vision at multiple distances.

Important Considerations About Monovision

Monovision offers many lifestyle advantages but has potential trade-offs:
- Distance vision may be slightly less sharp, especially in dim lighting or nighttime conditions.
- Near vision is functional for short tasks, but reading small print for extended periods may still cause eye strain or reduced clarity.

Occasional Use of Glasses with Monovision

• Night Driving. Low light may reduce distance clarity in the eye corrected for near tasks. A pair of driving glasses can improve confidence and safety—
  - Dominant eye: plano lens
  - Non-dominant eye: minus lens correcting residual myopia
• Prolonged Near Work. For long reading sessions, fine manual tasks, or extended computer use, reading glasses may be needed to reduce eye strain.
• These glasses are only for specific situations and do not harm the eyes or interfere with adaptation to Monovision.

Adapting to Monovision

• During the initial weeks—especially within the first week—vision may be unstable, and the full benefits of Monovision may not yet be noticeable. Some patients experience:
  - Blurred near and/or distance vision
  - Eye strain
  - Fatigue
  - Temporary difficulty reading
  - Mild headaches or dizziness
  Temporary glasses may be prescribed until the eyes stabilize. Adjustments to the prescription may be needed, particularly within the first 3 months, as the vision continues to settle. Patients choosing Monovision should remain relaxed and give their brain time to adapt. Once adaptation occurs, dependence on glasses decreases significantly.

Tips to Support Adaptation After Monovision

• Avoid covering one eye to “test” near or distance vision; the brain naturally learns to select the appropriate visual input.
• Some people may initially experience double vision, dizziness, eye strain, or discomfort—this is normal during early adaptation.
• These symptoms typically fade as the brain adjusts.

How Long Until You Know Whether Monovision Is Suitable?

If adaptation difficulties persist beyond 3 months, enhancement surgery may be considered to correct the residual myopia in the near-vision eye. However, after such enhancement, the patient will require reading glasses—similar to individuals with normal vision who develop presbyopia.