Glossary
ASTIGMATISM
Astigmatism is a common optical condition which results in blurry vision. It results when the curve of your cornea is slightly irregular in shape. The visual condition resulting from two unequal, opposite meridians of the eye that produce two separate focal lengths and blurred image.
ACUITY
Clarity of vision.
ACCOMMODATION
The ability of the eye to adjust its dioptric power as the crystalline lens is contracted or relaxed to focus at variety of distances.
BLUE LIGHT FILTER
Blue light is a subset of light within the visible light spectrum; it’s emitted by the sun as well as screens on computers, phones, and other electronic devices. Our blue-light filtering lenses they filter out a higher percentage of blue light than any other optical lenses.
DIOPTER
A unit of measurement for refractive lens power. The focal length of a one diopter lens in one meter. In other words, it measures optical power.
EYES
Eyes are organs of the visual system. They provide animals with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and convert it into electrochemical impulses in neurons.
FOCAL LENGTH
The distance it takes a given lens to bring parallel beams of light to either a real or virtual point focus.
HYPEROPIA
Farsightedness. A condition of the eye that has parallel beams of light coming to focus behind the retina.
INDEX OF REFRACTION
The measure of a given lens material to bend light. It is equal to the redo between the speed of light in air divided by the speed of light in that given medium.
MYOPIA
Nearsightedness. A condition of the eye that has parallel beams of light coming to focus in front of the Retina.
OD
This abbreviation appears on your prescription. It stands for Oculus Dexter, which is Right Eye in Latin.
OS
This abbreviation appears on your prescription. It stands for “Oculus Sinister” which is Left Eye in Latin.
OU
Abbreviation for (Latin) Oculi Uterque – Both Eyes.
PLANO
Plano refers to a lens without a prescription. Just a plain.
PRESBYOPIA
The condition that requires the use of Bifocals for near vision because of aging and diminished power of accommodation.
PRESCRIPTION
A prescription is a formula for making the best pair of eyeglasses for you. An eyeglass prescription is an order written by an eyewear prescriber, such as an optometrist or ophthalmologist, that specifies the value of all parameters the prescriber has deemed necessary to construct and or dispense corrective lenses appropriate for a patient.
PROGRESSIVE
Progressive lenses are like two for one deal, offering multiple focal corrections all in the same lens (distance correction on top, intermediate in the middle, and reading correction on bottom). This means you can see your whole field of vision without switching between multiple pairs of glasses.
PUPILS
Pupil, in the anatomy of the eye, the opening within the iris through which light passes before reaching the lens and being focused onto the retina. The size of the opening is governed by the muscles of the iris, which rapidly constrict the pupil when exposed to bright light and expand (dilated) the pupil in dim light.
ULTRAVIOLET LIGHT
Ultraviolet light is a form of electromagnetic radiation that surrounds us, but it’s not visible with the human eye. Our main source of UV light is the Sun. If you’re overexposed to UV light, you can get a sunburn.
VISUAL ACUITY
Visual acuity (VA) commonly refers to the clarity of vision, but technically rates an examinee’s ability to recognize small details with precision. Visual acuity is dependent on optical and neural factors, the sharpness of the retinal focus within the eye.