(presbyopia). The area of the pupil governs the amount of light that can reach the retina. The extent to which the pupil dilates decreases with age, leading to a substantial decrease in light received at the retina. In comparison to younger people, it is as though older persons are constantly wearing medium-density sunglasses. Therefore, for any detailed visually guided tasks on which performance varies with illumination, older persons require extra lighting. Certain ocular diseases can come from sexually transmitted diseases such as herpes and genital warts. If contact between the eye and area of infection occurs, the STD can be transmitted to the eye. With aging, a prominent white ring develops in the periphery of the cornea called arcus senilis. Aging causes laxity, downward shift of eyelid tissues and atrophy of the orbital fat. These changes contribute to the etiology of several eyelid disorders such as ectropion, entropion, dermatochalasis, and ptosis. The vitreous gel undergoes liquefaction (posterior vitreous detachment or PVD) and its opacities — visible as floaters — gradually increase in number. Eye care professionals, including ophthalmologists and optometrists, are involved in the treatment and management of ocular and vision disorders. A Snellen chart is one type of eye chart used to measure visual acuity. At the conclusion of a complete eye examination, the eye doctor might provide the patient with an eyeglass prescription for corrective lenses. Some disorders of the eyes for which corrective lenses are prescribed include myopia (near-sightedness), hyperopia (far-sightedness), astigmatism, and presbyopia (the loss of focusing range during aging). Macular degeneration Macular degeneration is especially prevalent in the U.S. and affects roughly 1.75 million Americans each year. Having lower levels of lutein and zeaxanthin within the macula may be associated with an increase in the risk of age-related macular degeneration. < Lutein and zeaxanthin act as antioxidants that protect the retina and macula from oxidative damage from high-energy light waves. As the light waves enter the eye they excite electrons that can cause harm to the cells in the eye, but they can cause oxidative damage that may lead to macular degeneration or cataracts. Lutein and zeaxanthin bind to the electron free radical and are reduced rendering the electron safe. There are many ways to ensure a diet rich in lutein and zeaxanthin, the best of which is to eat dark green vegetables including kale, spinach, broccoli and turnip greens. Nutrition is an important aspect