A Treatment for Presbyopia
Monovision is a treatment used to correct the condition of presbyopia, which is where, with age, the eyes become increasingly unable to focus on close objects. The exact cause is yet to be confirmed, though there is strong evidence to support reduced elasticity of the eye’s crystalline lens as being a main factor, as well as changes in the muscles that manipulate the lens causing it to move out of shape.
Presbyopia is a natural, unavoidable symptom of ageing, though the onset and severity of the condition can vary greatly between individuals. When younger, most people have a great ability to accommodate or ‘zoom in’ on a close object. As they age, this ability steadily reduces until it becomes particularly noticeable, usually after the age of 40, when distances shorter than arm’s length become problematic.
People generally notice the condition in low light environments when they struggle to read text, perhaps experiencing eye strain when reading or blurring of vision when shifting focus between distances. Strong light can cause the condition to be less noticeable, due to the iris becoming smaller. Reading, bifocal or varifocal glasses are often used to rectify the problem, allowing the user to focus on near objects, though this is a temporary solution and not always ideal if close up vision or shifting focus between near and far is regularly required.
People with a history of myopia (near-sightedness) may find that the onset of presbyopia may be reduced and that they can still focus on close objects well past 40, though this is not always the case.
Monovision can offer a more comprehensive and convenient solution to presbyopia than glasses, depending on the exact nature of the patient’s condition. In Monovision, one eye is treated to focus at near and the other at distance. After approximately one to two weeks, the brain adapts and learns to use the individual eyes to view near or distance objects respectively, without any noticeable awareness of using different eyes to do so.
Monovision Contact Lenses
There are two main treatments that provide Monovision. The first is through the use of contact lenses, where a lens on one eye corrects the distance vision and one on the other corrects the near vision. Here the eye that sees well up close will be a little blurred looking at a distance and the eye that sees distance will be a little blurred when viewing up close. However, when both eyes are open, vision will be comfortably clear and acceptable viewing any distance, with no noticeable lack of focus in either eye. Fitting Monovision contact lenses can be a more precise process than with regular lenses, so more time with the optician may be required.
If contact lenses provide an acceptable solution to an individual’s prebyopia, then they may be suitable for the second treatment, which is corrective surgery. LASIK or similar corneal or lens-based refractive surgery can be used to achieve the same effect as contact lenses, treating the one eye to focus on near and the other on distance. The surgery is generally very quick, mostly painless and very effective. This option removes the hassle of glasses or contact lenses and has an extremely high success rate.
Spectacles cannot provide effective Monovision treatment, as the wearer would need to always look through the centre of each lens for it to work and this is obviously not practical.
Monovision can be a highly effective solution to the problem of presbyopia, but may not suit all lifestyles or conditions. It is therefore always advisable to have a full consultation with a reputable and experienced eye specialist before committing to the treatment.