Contact Lenses and Presbyopia (Monovision)
If you thought presbyopia and the loss of your reading vision meant the end of contact lenses think again. If you are over 40 your eyesight is probably changing. You may have difficulty reading or doing simple tasks up close. As we mature the eye becomes less capable of focusing from far to close objects. This is a common condition called presbyopia and it affects nearly everyone by the age of 50. The crystalline lens of the eye thickens throughout life making it harder and less flexible over time. The progressive loss of elasticity in the lens makes tasks like reading small print and computer work much more difficult. Distance vision however is usually unaffected.
But if you thought presbyopia and the loss of your reading vision meant the end of contact lenses think again. An option available for new presbyopes who are just starting to notice more difficulty with near tasks is monovision. This contact lens fitting technique results in the dominant eye (the eye you would use to focus a camera) being focused for distance vision while the non-dominant eye is focused for near to intermediate vision. Monovision has an extremely high success rate especially for people who have never worn reading glasses or bifocals. Either soft contacts or rigid gas permeable lenses can be used. Although monovision is a popular option a major disadvantage is that for some people it compromises depth perception. In addition since each eye is more or less independent your head position may have to be continually adjusted.
Monovision usually requires a longer period of adaptation. Because depth perception is altered with monovision additional correction may be needed for driving and operating heavy equipment. Under these circumstances driving glasses to correct the reading eye for distance and improve binocular vision are recommended. Similarly some wearers may require an additional near vision correction in the distance eye to allow prolonged or concentrated reading. A variant of monovision called modified monovision puts a bifocal contact lens in one eye and a single-vision contact lens in the other eye. This can give better depth perception for driving while still permitting near vision for reading.
Monovision certainly isn’t appropriate for everyone. However when paired with the right person it can be a great fit. Monovision is ideal for people with an active lifestyle. However since it is a compromise most people’s vision isn’t perfectly crisp up close or far away. Instead it offers the best of both worlds. If you’re considering refractive surgery as a permanent form of monovision it might be best to consider a trial period with contact lenses before making a decision. When helping you to decide whether monovision is right for you your optometrist may ask a number of questions. You may be asked to describe your usual lifestyle or daily activities and from this your practitioner will be able to recommend a solution most suited to your needs.
