Monovision is a variation on the standard use of contact lenses to help people who don’t see as well close-up because of age-related changes to the eye. With monovision, one lens is prescribed to see better at a distance, and the other lens is prescribed to see better close-up. The result is a compromise between distance and close-up vision. Many people have good results with monovision, and are able to reduce their use of reading glasses. A monovision fitting tends to be more expensive and time-intensive than a fitting for standard contact lenses.
What Is Monovision?
The term “monovision” implies seeing with only one eye, but in fact that is not the case at all. Monovision refers to a method of treatment for a common age-related condition called presbyopia.
People with presbyopia have trouble focusing on objects close-up. By fitting one eye with a contact lens for close up vision and one for distance vision, people with presbyopia may be able to function without the need for additional reading glasses. Even though most people have two eyes that work together (binocular vision), one eye is usually dominant over the other. When looking at far away objects, the dominant eye is the one that is actually seeing more.
The reverse is true for focusing on objects that are closer. For monovision patients, the dominant eye will be fitted with the contact lens that is suited for driving or other activities that require focusing on objects far away. Closer objects may appear to be blurrier through this eye. The weaker eye is fitted with a contact lens that is used to see objects close up. This eye will be better able to see for reading or other close work. Distant objects will look blurrier through this eye. With one eye better able to focus on items close up and the other better able to focus on items far away, most people are able to rely less on their reading glasses. Monovision can be customized to the individual according to their daily activities or their profession. Overall, people who use monovision tend to adapt easily and see both distance and close-up items reasonably well.
Presbyopia and It’s Relationship to Monovision
Presbyopia is the inability to see objects close-up, such as small print. This condition starts to become evident in most people around the age of 38 to 48. People with presbyopia find it more difficult to read a book or a newspaper, and start to hold things farther away to make them easier to see. It may also be necessary to have brighter light in order to see. Presbyopia is the result of the lens of the eye losing its flexibility due to age. The lens is less able to focus on items close to the face. People with presbyopia may also notice that they develop eyestrain, or that their eyes become tired more easily. The loss of flexibility in the lens continues until about age 65, when the lens is at its greatest loss of flexibility and the presbyopia becomes stable.
Why Should I Use Monovision?
People who already wear contacts or glasses for an existing eye condition may need to use a different set of glasses to read or see objects close up. Many people are unhappy carrying multiple sets of glasses and switching between them, or using glasses to see close-up when they already wear contacts. Monovision can reduce the need for reading glasses, while still helping the patient to see items that are far away.
Why Should I Use Contacts For Monovision?
The good results that many people experience using contacts for monovision are not usually seen when a monovision Rx is tried with glasses. This is because the contact lenses sit on the eyes while the glasses are 12 mm in front of the eyes. A theoretical pair of monovision glasses sitting 12mm in front of the eyes can lead to motion/magnification changes that are exacerbated by an artificially large difference in prescription between the two eyes.
What Are The Types of Monovision?
Computer-monovision: This type of monovision uses less magnification in the eye that is used to see items close up. The result is that patients using this variation will be able to see at a mid-distance such as where a computer screen would sit, but still may need reading glasses to help with regular reading.
Objects that are far away tend to be in sharper focus because the eye used for close-up work has a lower power magnification. Computer-monovision works best for people who do not do a lot of reading or work at a computer distance on a daily basis, and want to retain better far vision than is seen with traditional monovision.
Modified monovision: Patients who choose this type of monovision wear one contact lens that is a bifocal. The lens with the bifocal is worn on the weaker eye, and is used to see close up. The other eye may wear a single-vision contact that corrects for whatever condition affects that eye. This helps to retain depth perception and clearer distance vision.
Surgical monovision: The effects of monovision can also be achieved with LASIK (Laser In Situ Keratomileusis) surgery. Instead of using contact lenses, LASIK surgery is used to adjust one eye for focusing on far-away objects, and one eye for focusing on close-up objects. This type of surgery is done on the cornea, and people who undergo LASIK surgery usually heal quickly and see a change in their vision right away. In most cases, an eye care professional will recommend using monovision contact lenses for a time before committing to a surgical solution.
What Is The Downside Of Monovision?
After an adjustment period of a week or two, many people have good results with monovision and are able to rely less on their reading glasses. However, monovision tends to sacrifice a certain amount of clarity and depth perception. Some people may feel that monovision does not provide clear enough vision for either distance or close-up viewing. There is a compromise between the two with monovision; vision may be clearer when using contacts for distance and eyeglasses for reading.
For some, however, monovision is more a lifestyle choice than a way to see as clearly as possible. Most people who have common age-related vision problems find that vision can be easily corrected with either contacts or glasses. But switching between glasses and contacts, or taking out glasses in a restaurant to read a menu (and thereby betraying both age and compromised eyesight) can be annoying, frustrating, or even embarrassing for some patients. One potential difficulty with monovision is some loss of depth perception. For some patients, good depth perception is important to either their daily tasks or their profession. If depth perception is too compromised, monovision may not be a good choice.