October 3rd, 2008
C-8162 Refractive Surgery - Presbyopic LASIK and Multifocal Intra - Ocular Lenses
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Presbyopia is the loss of the ability for the eye to accommodate or change focus from viewing a distant object to viewing an object up close. This loss of functionality is due to a gradual loss of amplitude of accommodation that is provided by th crystalline lens. The loss of accommodation is a slow progressive process that begins from birth. At age 8. the average amplitude of accommodation is 14.00 to 16.00 diopters (D): it declines to 10.00 + 2.0 D by age 25. to 6.00 + 2.00 D by age 40. and to 1.00 D + by age 60 (figure 1). However, the effect of accommodation loss is only felt from the age of approximately 45 as it is at this stage when the residual focusing power of the crystalline lens cannot provide sufficient near vision. A person unable to maintain 3.00 D of accommodation for any length of time is considered to have symptoms of presbyopia occurs in100% of the population and as longevity increases, presbyopes now represent one of the largest groups of patients suffering from a refractive error.
Author: Professor Dan Reinstein