Aging and Cataracts
The natural lens of the eye changes as we age. Before we are born, the "hyaloid artery" supplies nutrition from the optic nerve to the lens. Just before we are born this artery atrophies, sometimes leaving a small spot on the back of the lens called a "polar" or congenital cataract, usually of no visual significance. These changes are responsible changes in the color, flexibility, shape and position of the lens. When we are young, the natural lens is extremely clear and flexible, allowing the ability to read only inches from the eye and to overcome moderate degrees of refractive error. This ability to focus is a result of the flexibility of the lens and the change in curvature as forces are put on the edges of the lens by "zonules," or small strings that are attached to it. As we approach the age of 40, the lens gradually hardens and eventually, the ability to read without bifocals or reading glasses is lost. This problem is called "presbyopia" and is often accompanied by small changes in refraction. The problem begins with only slight fuzziness when reading and gradually becomes more significant when it levels out at around age 50. At roughly that age, the lens often begins to yellow slightly and vision can change as the lens swells slightly and changes shape. Throughout our 50’s, slight changes in vision occur due to changes in the lens, and as it swells and narrows the outflow channel for fluid flowing through the eye, a form of narrow angle glaucoma can develop. As the yellowing worsens, so will vision until glare, reading problems, and diminished vision make removal of the cataract a practical necessity at around age 55 to 70. Cataracts develop in almost everyone sooner or later. According to a study by the American Academy of Ophthalmology, about one half of all people between the ages of 52 and 64 have a cataract.
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