Aristotle delivered one of the first theories for presbyopia. From his work we also get the term itself, formed from the prefix “presbys,” which means old man in ancient Greek, and the suffix “ops,” meaning eye. In De Generatione Animalium (On the Generation of Animals), Aristotle stated, “…a reason why old men have not keen sight, the skin of the eye like the rest of the skin wrinkling and becoming thicker in old age.”
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By Tina Lahti
Aristotle’s reference to “the skin of the eye” turned out to be very close to biological truth for two reasons. First, during development, the lens of the eye is formed on the surface ectoderm, so is the skin. Second, when it comes to both the skin and eyes, many problems that were once simply associated with aging, are now known to be linked to sun exposure.
The sun, specifically high-energy light from the sun, is known to be damaging to human tissue. Ultraviolet light is classified as a known carcinogen. Exposure to UV light kills biological cells. This is why UV light is used for sterilization. Under controlled conditions, it can quickly and effectively kill microorganisms. In human skin and eyes, cellular damage is less likely to happen all at once and more likely to happen over time. As a result, problems related to exposure to solar radiation often masquerade as aging.
It is estimated that 90 percent of skin aging is caused by exposure to the sun. The link between solar radiation and cataracts has been well established. We’re starting to learn more about the association of sun exposure and age related macular degeneration. Now scientists are beginning to theorize there may also be a connection between sunlight and presbyopia.
The onset of presbyopia tends to occur earlier among people who live closer to the equator. For example, the age of onset of presbyopia in India (10 to 30 degrees latitude) is 37 years of age. In England (51 to 54 degrees), it is 43. This is speculated to be due to higher exposure to both UV light and higher ambient temperatures. The crystalline lens absorbs both solar UV and infrared (heat) radiation.
Researchers in Australia are now asking if presbyopia may be the first stage of cataracts. They note that progressive hardening of the center of the lens may be the reason for both conditions, and in both cases the development of a chemical barrier with age stops antioxidants from reaching cells. This impedes the body’s natural ability to repair them.
Perhaps the most interesting link between presbyopia and cataracts is non-surgical treatments being investigated for the treatment of cataracts are also expected to have a positive effect on presbyopia. Several companies are investigating use of pharmaceuticals, generally eye drops or injections, to treat both at once.
It may be a long time before there is an eye drop that cures presbyopia. Good sun protection for the eyes is available right now. When you encourage your patients to invest in a high-quality pair of sunglasses, you may be helping them protect their vision in ways we are just beginning to understand.