Laser Treatments And Cures For Presbyopia
What Causes Presbyopia?
Whilst the precise underlying causes of presbyopia are not clear, the condition is associated with the natural process of ageing. Indeed, the initial symptoms of presbyopia usually present themselves in individuals aged between 40 and 50 years of age.
Suggested causes of presbyopia often relate to a loss of elasticity and flexibility in the muscles surrounding the lens of the eye. It is postulated that age related changes to the ciliary muscles, responsible for changing the shape of the less, result in a loss of power. The loss in muscle power, and subsequent difficulties in changing the shape of the lens, impairs the ability of the eye to focus on objects close to the individual.
However, whilst the precise cause/causes of presbyopia are subject to debate, it is clear that it does occur as a result of ageing.
One of the most common symptoms associated with presbyopia is difficulty reading, particularly fine print. As a consequence, many sufferers of presbyopia find it necessary to hold reading materials at further distances than were previously necessary, including an entire arm's length, in order to view print clearly.
Eyestrain and headaches resulting from long periods of reading are another symptom indicative of presbyopia. Additionally, individuals may experience general discomfort around their eyes when reading materials are situated too close.
Transitions in vision, such as when looking into the distance after viewing close objects, can also produce blurred vision.
The primary risk factor for the onset of presbyopia is age. Presbyopia is a natural part of the body's ageing processes, just like the appearance of wrinkles and prevalence of grey hair. Most people will begin to notice the signs and symptoms of presbyopia around the age of 40, with some individuals experiencing greater difficulty with their vision than others.
Nevertheless, presbyopia can, in rare circumstances, occur at an earlier age. It has been suggested that the risk of premature presbyopia is increased in individuals with specific medical conditions, such as diabetes and multiple sclerosis, or certain prescription and non-prescription drugs, such as antidepressants and diuretics.
With regards to ultimate prevention, there are currently no medically proven solutions available. Presbyopia is an inevitable part of ageing, and one which everyone will experience during the course of their lives to some extent.
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Presbyopia is not curable as such, in that the natural degradation of an individual's vision is inevitable. However, there are palliative treatment options available to correct the vision of presbyopia sufferers.
A common treatment solution is the use of corrective lenses, enabling individuals to effectively transition between distances. A popular choice in corrective lenses is a bifocal or varifocal lens. Both lenses provide corrected vision for the wearer at near and far distances, however the construction of these lenses differ.
Bifocal lenses are segmented, with the upper portion of the lenses devoted to allowing clear vision at far distances, and the lower portion providing clear vision at near distances. Varifocal lenses, on the other hand, do not feature a segmented construction, but rather allow a smooth transition in vision from top to bottom for far and near distances respectively. Generally, varifocal lenses are the more popular choice.
Alternatively, the use of contact lenses may be preferable to wearers over bifocal or varifocal lenses, due to their reduced size. Through a process known as monovision, wearers of contact lenses for presbyopia may chose to utilise separate lenses, one for far distance vision correction, and the second for near distance vision correction. Problems can occur with this procedure however, namely a degradation in the wearer's depth perception.
Treating Presbyopia With Laser Eye Surgery
Surgical options are also a possibility. Popular surgical options include variations of laser eye surgery. One of the available surgical processes is PresbyLASIK, in which an are utilised to alter the surface of the cornea. As a result of PresbyLASIK, the central area of the cornea is corrected for near distance vision, with the midperipheral area of the cornea corrected for far distance vision. Nevertheless, in low light conditions and extended periods of reading time, the individual is still likely to require the use of reading glasses.
Another laser based surgical option is laser blended vision, producing effects similar to that of monovision, previously discussed with regard to contact lenses. In laser blended vision surgery, the individual's dominant eye is corrected for far distance vision, with their non-dominant eye corrected for near distance vision. Through the brain's ability to merge the images of both eyes, the individual is able to clearly see at near and far distances without the need for corrective lenses.
Other, non-laser based, surgical options include the insertion of sclera expansion bands. The effect of this is to increase the distance between the ciliary muscles and the lens. It should be noted, however, that this form of surgery has produced neither predictable nor consistent results for patients.
Alternative treatments to surgery are also available in the form of enhancing the brain's image processing capabilities. The principle of neuroplasticity dictates that changes in the adult brain are possible, including changes with regard to the processing of images. Through perceptual learning (the repeated practice of a demanding task) improvements have been found in the visual processes of individuals suffering from presbyopia. Such treatment may be preferable to individuals who do not wish to undergo invasive surgery techniques, such as those discussed above.
Other suggested treatment methods also exist, based on exercising the ciliary muscles of presbyopia sufferers. However medical reviews have concluded that such exercises are ultimately ineffective in the treatment of presbyopia.
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