Monovision is a term for when only one eye is seeing at a time. This can occur if one eye is damaged or removed, but more commonly, this is an intentional change made to allow clear vision at multiple distances. Ways to achieve monovision include using contact lenses, LASIK, or through cataract surgery. There are both benefits and negatives to monovision correction.
When both eyes are functioning and seeing clearly, the brain will use the images of the two eyes together to create an interpretation of the vision. Since there are two slightly different images — one from each eye — there can be depth appreciation.
Binocular vision is very important for judging distances and establishing proper spatial relationships since it allows for depth perception or “3-D vision.”
Alternatively, monovision does not have both eyes produce a clear image at any distance and therefore will not have depth appreciation as well as with binocular vision. If both eyes are present and functional, there will be some degree of depth awareness even though one eye is presumably creating a blurred image.
Monovision is not commonly used on anyone under the age of forty because at that young of age, the eyes should be able to see at all distances clearly with one prescription power.
Over forty, the eye begins to struggle to focus up close and things are harder to read. This creates a need for reading glasses or bifocals when the distance prescription power is different from the near prescription power.
An alternative to reading glasses is to have monovision correction.
Monovision is a great option for anyone wanting to avoid glasses who is unable to see well and comfortably with multi focal contact lenses.
The most common way to correct vision with monovision is using contact lenses.
Since contact lenses come in a wide array of prescription powers and are easy to differentiate between the two eyes, they are an ideal method for monovision correction.
The dominant seeing eye will be corrected for the distance power and the fellow eye will be corrected for the near prescription power.
Depending on the prescription, one eye may not require a contact lens and only one lens may be worn for monovision.
When pursuing LASIK surgery, monovision may be a consideration if a near prescription is needed or will be needed soon.
Similar to contact lenses, one eye is corrected with LASIK to the distance prescription power and the other eye is either left uncorrected or LASIK is performed to correct for a near power.
Cataract surgery is often used as a way to get rid of the need for glasses.
Monovision correction with cataract surgery is more difficult and may have results that are less favorable than other methods.
If expectations are managed and the possibility of needing contacts or glasses after the surgery is understood, monovision correction can be considered.