macula: small area of the retina that contains specialized light-sensitive cells that provide detail and allow for performance of fine tasks and reading.
multifocal: term that describes a type of lens (spectacle or contact lens) that has more than one focal area such as bifocal, trifocal, or progressive ("no-line bifocal") lenses.
myopia: nearsightedness; close objects are in relative focus while distant objects are blurred. Light is focused on a point that lies in front of the retina.
ocular hypertension: a condition of elevated pressure within the eye (intraocular pressure) that may lead to glaucoma.
ophthalmologist: a doctor of medicine (M.D.) or doctor of osteopathy (D.O.) who specializes in both the medical treatment and surgical care of the eyes and the visual system. Ophthalmologists must complete four or more years of medical school, one year of internship, and three or more years of specialized training and experience.
optician: state licensed professionals who interpret and fill a prescription from an optometrist or ophthalmologist for corrective eyewear. An optician is trained in the selection and fitting of eyeglasses and contacts (with special license). Qualifications for licensure include successful completion of a 2 year college program in optical science or a 2 year apprenticeship under a licensed optician or optometrist, followed by a state license examination. Opticians must also attend continuing education classes each year to maintain their license.
optometrist: doctors of optometry (O.D.) who specialize in the examination of the eyes and the visual system as well as the diagnosis and treatment of certain ocular diseases, injuries, and other health problems. An optometrist can prescribe many ophthalmic medications, but cannot perform surgery. They may, however, participate in pre-operative and post-operative care relating to eye surgery. Optometrists must complete four years of post-graduate optometry school.
photochromic lenses: spectacle lenses that undergo a chemical reaction when exposed to the ultraviolet (UV) wavelengths in sunlight. The reaction causes molecules within the lens to absorb light which causes them to darken.
polarized lenses: spectacle lenses that contain a polarizing filter that eliminates glare providing superior visual acuity and enhanced color perception while reducing eye strain and fatigue.
presbyopia: condition that arises when the lens in the eye becomes less flexible, making it difficult to bring close objects into focus and requiring special correction via bifocal or multifocal lenses or contacts. Often becoming noticeable by the age of 40-45, presbyopia is not a disease, but simply a natural part of the aging process.
progressive lenses: also referred to as "no-line bifocals"; multifocal lenses which provide visual correction for all distances. The different levels of correction are presented gradually over the lens. Typically, distance vision is corrected in the upper half of the lens, the middle area is for intermediate distances, and the lower part of the lens provides an increasing amounts of correction for close objects.
PRK: Photorefractive Keratectomy; a procedure in which a small section of the corneal surface is removed with a laser in order to modify its refractive properties and provide correction for problems with visual acuity.
pupil: the adjustable opening at the center of the iris that allows variable amounts of light into the eye. The pupil will expand or dilate in response to low light conditions in an attempt to bring more light into the eye and will reduce in size when intense light is present.
