All lenses placed during cataract surgery provide a range of acceptable focus surrounding a specific point.  This broader range can is called depth of field or depth of focus.  This is even true of the standard monofocal lenses, which are provided under your insurance at no extra cost.  

 

One presbyopia correcting strategy is to choose a slightly different focal distance for each eye using standard monofocal lenses (micro monovision).  This broadens your binocular depth of focus while allowing the eyes to continue working together.   Micro monovision will not completely free you from glasses for all tasks, but can provide significant glasses freedom at the range that is most important to you. 

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Three basic refractive paths can be considered:  Distance, Middle, and Near.  Each has unique advantages and disadvantages.  Which refractive path you choose depends on your goals.  The bottom line:  you can have a lot, but you can't have it all.  You have to choose your priorities for glasses-free vision.   This is explored in more detail below.

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Near Refractive Path  

 

Your eyes are focused like a camera at near.

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Advantages:  Good vision without glasses for reading and crafts such as knitting and artwork. 

Disadvantages:  You will need glasses for driving, watching TV and movies, and you may feel like your surroundings in a room are blurry if you don’t wear glasses.

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In summary, the upside of excellent reading vision is balanced by the downside of relatively blurred vision when looking around a room.  It is likely that you will need glasses to watch TV and drive.

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Middle Refractive Path 

 

Your eyes are focused around the optical midpoint between distance and near (approximately 1.0 – 1.5 meters away). 

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Advantages:  Good all around vision.  Many tasks at distance and near can be performed without glasses, but the most demanding tasks, such as driving at night and reading a book, will probably require glasses.   This is a popular choice for people who want to be glasses free for general tasks such as working around the house, shopping, and talking to people.

Disadvantages:  Although you may spend most of your day without glasses, you may need glasses for reading and driving. 

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Distance Refractive Path  

 

Your eyes are focused like a camera at distance.

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Advantages: Good vision without glasses for driving, hiking, skiing, watching movies.

Disadvantages:  You will need reading glasses for most close-up tasks, including computer work and reading a book.

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Summary

With micro monovision, the two eyes continue to cooperate with one another, but your brain naturally pays a little more attention to one eye depending on the situation at hand.   You may not even be aware of which eye is giving you the best focus at any given moment.  Depth of field is enhanced while retaining cooperation between the eyes.

 

The tasks that are important to you will help you determine whether you want to apply micro monovision to the Distance, Middle, or Near path.  Take a few minutes to fill out the refractive questionnaire to help you decide what might be best for you. 

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