What Is Monovision LASIK?

How Does the "Dominant Eye" Test Determine the Surgical Plan?

The success of monovision depends entirely on which eye is set for distance. The surgeon identifies the patient's "Master Eye", the one the brain uses for spatial orientation, and treats it for perfect 20/20 distance vision. The non-dominant eye is then "intentionally" left slightly nearsighted (usually around -1.50 diopters) to provide reading power. If the eyes are accidentally swapped the patient will experience chronic dizziness and a feeling of instability. Data indicates that using a "Cross-Finger" test or a "Point-and-Stare" test is 99 percent accurate in identifying the correct dominance for the laser plan.

What are the Primary Success Data Trends for Monovision Adaptation?

Clinical data indicates that approximately 75 percent of the population can successfully adapt to Monovision LASIK. Statistics show that the brain requires an average of two to four weeks to "neuro-adapt" to the mismatched images. Data suggest that patients who have a "higher" difference between the eyes (more than 2.00 diopters) have a 30 percent higher rate of "failure" or dissatisfaction. This has led many surgeons to recommend "Mini-Monovision" where the difference is smaller which provides a smoother transition and better comfort for digital screen use.

Why Is the "Contact Lens Trial" Mandatory Before Surgery?

Because Monovision LASIK is permanent surgeons require every patient to undergo a "Monovision Simulation" using contact lenses. The patient wears one distance lens and one reading lens for one week to "live" with the vision. Statistics show that patients who "pass" the contact lens trial have a 95 percent satisfaction rate after surgery. Conversely if a patient feels "nauseous" or "unbalanced" during the trial they are not a candidate for the surgery, preventing a permanent and expensive visual error.

What are the Specific Impacts of Monovision on "Depth Perception"?

By design Monovision LASIK reduces 3D "Stereopsis" because the two eyes are never focused on the same point at the same time. This is a critical data point for patients who are pilots, athletes, or surgeons who require high-level depth perception for their jobs. Data indicate that while monovision patients can drive safely they may be 10 percent slower at judging distances during high-speed tasks. Clinicians must provide this "performance data" to the patient before surgery to ensure that the "convenience" of reading is worth the minor loss in athletic performance.

How Do Clinicians Handle Monovision "Night Glare" Issues?

A frequent side effect of monovision is "ghosting" or "doubling" of lights at night. This occurs because the "near" eye creates a blurred shadow around the clear headlights being seen by the "distance" eye. Data suggest that nearly 15 percent of monovision patients choose to have a "distance-only" pair of glasses in their car for night driving. This "night-set" of glasses merges the two eyes for perfect 3D vision in the dark while allowing the patient to remain "glasses-free" for 90 percent of their daytime hours.