How Eyeglasses Help
Myopia is a refractive defect in the eye where light produces image focus in front of the retina. Persons with myopia see near objects in focus but those further away are blurred. An optometrist commonly treats myopia through the use of eyeglasses with corrective lenses in a negative power. Contact lenses are also commonly used to correct this condition.
Hyperopia is a defect of vision where light produces image focus behind the retina. Persons with hyperopia have difficulty focusing on near objects. An optometrist commonly treats hyperopia through the use of eyeglasses with corrective lenses in a positive power.
Presbyopia is a condition characterized by diminished ability to focus on near objects as a person's age increases. The crystalline lens loses flexibility over time. This hardening lessens the lens's capacity to focus. Optometrists commonly treat presbyopia with reading glasses or eyeglasses with multi-focal lenses. These eyeglasses are commonly referred to as trifocals, bifocals or no-line bifocals (also known as progressives).
Dry Eye (Keratitis sicca)
Dry eye is an eye disease caused by a decrease in tear production or an increase in tear film evaporation. Common causes of reduced tear production include clogged tear glands, some medications, and dry environments. An optometrist can recommend several treatments for dry eye, as left untreated, severe cases can lead to corneal scars, damaged ocular tissues, or vision impairment. Eyeglasses, as opposed to contacts, are often recommended since contact lenses can lead to dryness.
Astigmatism is a refractive defect of the eye in which an abnormally curved cornea allows focusing to fall along different meridians of the eye. A person with astigmatism will have difficulty distinguishing fine details. Astigmatism can occur with myopia or hyperopia. An optometrist can treat astigmatism with eyeglasses or toric contact lenses; however, many patients report better vision correction with eyeglasses including lenses with an anti-glare treatment.
A cataract is a cloudy area over or in the crystalline lens in the eye, and can vary in its severity. Severe cases are treated with surgery. Often times eyeglasses are made during the surgery process or between the procedure on each eye to assist in vision correction until the healing is complete. It is not uncommon to have eyeglasses remade or changed during this time period.