Definition of Optometry Terminology

Amblyopia: Vision is reduced (even with glasses) because the optic nerve has not fully developed.
Prevention: If you were prescribed glasses, wear them until at least 14 years of age to make ensure the optic nerves develop completely.

Astigmatism: The cornea is shaped like a football, resulting in distortion, and therefore, blurriness.

Bifocal glasses: Lenses with two different prescriptions. The upper part of the lens is to see far, the lower part is for near.
Bifocal lenses are not recommended when using a computer, because no part of the lens is allowing you to see intermediate distance.
​Bifocal glasses have lines running across the lens. Therefore, they are not the best options if you value aesthetic

Cataract: The lens becomes opaque (cloudy) and vision is blurry even with brand new glasses.
Prevention: Ultraviolet light can cause cataract formation. Wear sunglasses with 100% UV protection while outside during daytime. See Sunglasses Article.

Conjunctivitis: Infection and/or inflammation of the conjunctiva.

Farsightedness (also know as Hyperopia): Can see far, near is blurry. Caused by a cornea too flat, an eyeball too short, or both

Floater: Particle "swimming" inside the vitreous . Seen as a black or gray spot (or wiggly line) that moves when the eye moves.

Glaucoma: Eye disease affecting the optic nerve, resulting in loss of peripheral (side) vision.

Hyperopia (also know as Farsightedness): Can see far, near is blurry. Caused by a cornea too flat, an eyeball too short, or both

Keratoconus: Thinning of the cornea causing it to distort, which results in blurry vision, even with glasses or soft contact lenses.
Rigid gas permeable (hard) contact lenses must be worn to improve vision. If the keratoconus keeps progressing, contact lenses will not work anymore. Corneal transplant must then be performed.

Macular Degeneration: Disease affecting the macula. Central vision is lost.
Prevention: Take vitamins containing lutein, Meso-Zeaxanthin and Zeaxanthin as well as omega-3.
Wear sunglasses to protect your eyes from the sun's harmful ultraviolet rays. See Sunglasses Article.
Wear blue-blocking glasses to protect your eyes from the damaging blue light emitting from screens, such as cell phones, tablets, computers and TVs.
See Blue Light Glasses for more information.
​Quit smoking.

Monovision: One eye sees distance only, while the other eye is for near vision. Can be achieved by contact lenses or laser surgery.

Myopia (also know as Nearsightedness): Can see near, far is blurry. Caused by a cornea too steep, an eyeball too long, or both.

Nearsightedness (also know as Myopia): See above.

Nystagmus: Eyes move very rapidly and uncontrollable. Vision is poor, even with glasses.. Usually due to a macular disease.

Peripheral vision: Side vision

Presbyopia: Near blurry. The ciliary muscle is not pulling enough on the lens to focus near.

Progressive glasses: Lenses allowing you to see at all distances. Upper lens for far, middle for intermediate, lower for near.
Unlike bifocal and trifocal glasses, there are no lines in progressives lenses.

Pterygium: The sclera grows over the cornea, due to too much exposure to UV (ultraviolet), wind, dust and/or chemicals. See Sunglasses Article.

Retinopathy: Retinal disease which can lead to blindness. Usually caused by diabetes or high blood pressure.
Prevention: Retinopathy can usually be prevented by controlling diseases such as diabetes and high blood pressure.

Strabismus: Also known as crossed eye or lazy eye. One eye is either turned inward or outward.

Transitions lenses: Lenses that darken when exposed to ultraviolet. Regular glasses inside that turn into sunglasses outside.
Since Transitions need UV to darken, and windows block a good portion of UV, these lenses do not get very dark when inside a car. See Sunglasses Article.

Trifocal glasses: Lenses with three different prescriptions. Upper lens to see far, middle is for intermediate, lower is for near.
Trifocal glasses have lines running across the lens. Therefore, they are not the best option if you value aesthetics.