Progressive lenses are also designed to counter presbyopia – a condition that usually develops around the age of 40
Bifocal lenses used to be the only option for people with presbyopia who also require a correction for myopia,.
Single vision lenses have the same focal power throughout the entire lens and can be used to correct myopia, hyperopia, and astigmatism.
An Optical Dispenser is a professional who interprets optical prescriptions and supplies, clients, with frames and lenses. They also assist in the fitting of contact lenses.
Myopia, or nearsightedness, is a refractive error, which means that the eye does not bend or refract light properly to a single focus to see images clearly. In myopia, close objects look clear but distant objects appear blurred.
Hyperopia (farsightedness), is a refractive error, which means that the eye does not bend or refract light properly to a single focus to see images clearly. In hyperopia, distant objects look somewhat clear, but close objects appear more blurred.
Astigmatism is a vision condition that causes blurred vision due either to the irregular shape of the cornea (the clear front cover of the eye), or sometimes the curvature of the lens inside the eye. An irregular shaped cornea or lens prevents light from focusing properly on the retina, the light sensitive surface at the back of the eye. As a result, vision becomes blurred at any distance. Astigmatism frequently occurs with other vision conditions like nearsightedness (myopia) and farsightedness (hyperopia). Together these vision conditions are referred to as refractive errors because they affect how the eyes bend or “refract” light.
Presbyopia is the gradual loss of your eye's ability to focus on nearby objects. It's a natural, often annoying part of aging. Presbyopia usually becomes noticeable in your early to mid-'40s and continues to worsen until around age 65. To correct this defect, a person is prescribed bifocal or progressive lenses.
Keratoconus is an eye disease that affects the structure of the cornea. The cornea is the clear tissue covering the front of the eye. The shape of the cornea slowly changes from the normal round shape to a cone shape. The eye bulges out. This causes vision problems. The cause is unknown, but the tendency to develop keratoconus is probably present from birth. Keratoconus is thought to involve a defect in collagen, the tissue that provides strength to the cornea and gives it its shape. The earliest symptom is subtle blurring of vision that cannot be corrected with glasses. (Vision can most often be corrected to 20/20 with rigid, gas-permeable contact lenses.) Over time, you may have eye halos, glare, or other night vision problems. Most people who develop keratoconus have a history of being nearsighted. The nearsightedness tends to become worse over time. As the problem gets worse, astigmatism develops. Contact lenses are the main treatment for most patients with keratoconus. Wearing sunglasses outdoors after being diagnosed may help slow or prevent the disease from becoming worse.
The Ophthalmologist is a medical doctor who specializes in the treatment of eye diseases. He is trained to provide medical, surgical and/or optical treatment. The Optometrist is trained to examine your eyes, fit and supply glasses and contact lenses. They also recognize signs of eye diseases and will refer patients to the ophthalmologist. The Optician is trained to fit and supply glasses prescribed by the Ophthalmologist or Optometrist.