Ocular (eye) Terminology


Also called lazy eye. A condition where one or both eyes can not see 20/20, even with the best glasses, due to an eye turn, high refractive error or not wearing glasses as early as needed. These conditions cause the vision in one or both eyes to never fully develop correctly.


A refractive condition, like being near or far sighted, corrected by glasses or contacts, caused by the shape of your eye being more ‘football shaped’ than perfectly round. This causes light to focus in two places on the back of the eye ( the retina) so there are two different parts to your prescription in that eye.


Crusting and oily particles accumulate near the base of the eyelids and attract bacteria,
which causes inflammation of the eyelids, leading to irritation, itchiness, redness, and stinging or burning of the eye.


An involuntary blinking or spasm of the eyelids usually caused by too much caffeine, stress and lack of sleep.

Blocked tear duct

A condition which occurs when the eye’s drainage system for tears is either partially or completely obstructed. Tears cannot drain normally, causing a watery, irritated or chronically infected eye.


A cataract is a clouding of the crystalline lens of the eye, making it difficult for light to pass through and be focused properly. This can make it appear like you are looking through a cloudy windshield vision is not as crisp and clear as it used to be, more light is needed to read fine print and driving at night is more difficult. Most people have cataracts developing by the time they reach 60 although they can occur earlier for trauma, systemic diseases and heavy UV light exposure.

Color deficiency

Also known as ‘color blindness’, occurs when you are unable to see colors in a normal way. Most commonly people cannot distinguish between usually between greens and reds, and occasionally blues. This occurs mainly in males.


Often called ‘Pinkeye’, is caused by the inflammation of the conjunctiva, or clear membrane covering the white part of the eye and lining of the eyelids. Swelling, redness and a ‘gritty feeling’ are the most common symptoms. It is often viral and may be contagious. There are actually 20 different types of conjunctivitis – from fairly common strains that usually pose no longterm danger to you or your child’s vision – to types that are resistant to antibiotics. Call or see your doctor to treat pinkeye.


The transparent, multilayered front part of the eye that covers the pupil and iris. A few conditions that affect the cornea include: corneal abrasion, a scratch or scrape of the cornea; corneal laceration, a cut on the cornea; corneal ulcer, an open sore on the cornea usually caused by contact lens wear and potential sight threatening and keratitisa condition where the cornea becomes swollen or inflamed, making the eye red and painful and affecting vision.

Diabetic retinopathy

A common diabetic eye disease from changes in retinal blood vessels which causes bleeding in the retina and is a leading cause of vision loss in the U.S.

Dry Eye Syndrome

‘Dry eye’ is a condition where the eyes don’t produce enough tears or the right quality of tears to be healthy or comfortable. Symptoms include a dry scratchy itching, burning, redness, irritation, watering and often a feeling like there is a grain of sand under your eyelid.


Small specks that can look like a black spot, wiggly line, or clear worm or C-shaped membrane
moving slowly but noticeably in your field of vision. A floaters are caused by clumps of cells floating around in the vitreous, the jelly like sac in the back of the eye, floating around and casting shadows on the retina. Aging, eye injury and breakdown of the vitreous are the main causes of floaters. If you notice a sudden increase in the number you see, call your eye care professional.


Flashes of light that you see when the vitreous gel pulls or rubs the retina. They look like lightning flashes in the side of your vision and could be followed by a veil or curtain coming down over your vision. These could be signs of a retinal hole, tear or detachment, Follow up with your doctor immediately if you experience these symptoms especially after trauma to the head or body.


A common cause of preventable vision loss when excessive pressure within the eye damages the optic nerve. Treatable by prescription drugs or surgery. Glaucoma is a disease that damages the eye’s optic nerve and causes a loss in peripheral vision. It is a painless and slow process, often never evident until a significant amount of irreversible damage occurs, which is why early screenings are important. Glaucoma is a leading cause of preventable blindness in the U.S.

Hyperopia or Farsightedness

A refractive error, which means the eye does not bend or refract light properly. With hyperopia, typically distant objects look clear while close objects may appear blurred. Depending on your age and the amount of farsightedness you have, distance and near vision may be blurry or both may be clear. Far sighted people’s eye focus at a point far in the distance and the closer an object is the more work, or focusing, the eye has to do to make the image clear.


The pigmented (colored) membrane that lies between the cornea and the crystalline lens that controls the size of the pupil.


A condition when the normally round cornea becomes thin and develops a cone-like bulge.

Macular Degeneration

A group of conditions that include a deterioration of the macula. The part of the retina responsible for the sharp, central vision, causing a loss of central vision needed for sharp, clear eyesight. It is a leading cause of vision loss and blindness in those 65 years of age and older. Macular Degeneration is also called AMD or ARMD (age related macular degeneration).


Also known as nearsightedness, is a refractive error, which means the eye does not bend or refract light properly. With myopia, close objects look clear but distant objects appear blurred. ocular allergies: A reaction caused when your eyes are exposed to an allergen like pollen, your body releases histamines, like watering eyes and snot to try and rid itselg of these annoyances. The symptoms of eye allergies include red, itchy, watery, burning eyes and even swollen eyelids. However, red, itchy, eyes can also be caused by infections and other conditions such as dry eye . Many people suffer from both concurrently. To treat ocular allergies you need an antihistamine or mast cell stabilizer drop or a combo.

Ocular Migraine

Also called a retinal migraine,cause symptoms that include: Vision problems that affect one eye, such as flashing lights, blind spots in your field of visio n and a tunnel vision effect which may or may not be followed by a headache. A regular migraine with an aura, which can involve flashing lights and blind spots in the vision, is a more common problem. But in these cases, these symptoms usually appear in one side of your field of vision and in both eyes. Covering one eye and then the other can help you tell if your problem is affecting one eye or both. Suspected causes include spasms in blood vessels in the retina, the delicate lining in the back of the eye and changes that spread across the nerve cells in the retina.


A condition which affects everyone, beginning around age 40, in which the lens of your eye starts to lose it’s ability to focus and accommodate causing blurry vision up close and often affecting the distance vision as well. Symptoms include needing to hold things farther away to see clearly, eye strain and blurry vision up close. Presbyopia can be corrected with reading glasses, bifocal glasses, or progressive lenses.

Pingueculas and Pterygiums

Common, noncancerous growths on the conjunctiva (pinguecula) and/or cornea (pterygium) caused by exposure to ultraviolet (UV) light, dry eyes, wind and dust irritating the tissues over the years. UV protection and artificial tears help prevent these growths and slow their advancement over time.


Test to determine an eye’s refractive error and the best corrective lenses to be prescribed. It’s performed in the phoropter (the ‘big pair of glasses’ in the exam room) and is often referred to the ‘which is better 1 or 2’ test.


Part of the rear two thirds of the eye that converts images from the eye’s optical system into impulses that are transferred by the optic nerve to the brain. Consists of layers that include rods and cones.

Retinal tear/detachment

Occurs when the retina tears in one or more places. A detached retina is when the retina is lifted off the wall of the back of the eye.


The white part of the eye – composed of fibrous tissue that protects the inner workings of the eye. Strabismus: Commonly known as an ‘eye turn’, is a visual problem in which the eyes are not aligned properly and point in different directions. One eye may look straight ahead, while the other eye turns inward, outward, upward or downward.


A chalazion is a lump on the eyelid caused by enlarged oil producing gland in the eyelid. A stye is also a lump on the eyelid, usually caused by an infected eyelash follicle.

Ultraviolet radiation

Commonly referred to as “UV Rays”, these are light waves that consist of both UVA and UVB rays from the sun. Without proper protection, chronic exposure to UV rays can lead to various eye conditions and damage.

Visual Acuity

Assessment of the eye’s ability to distinguish objects clearly. the top number represents the number of feet from the object (usuually 20 feet) while the bottom number indicates the size of the object – the smaller the bottom number the small the object you can still see clearly from 20 feet away.

* Information from The Eyeglass Guide, The International Headache Society, geteyesmart.com and the American Academy of Ophthalmology was used in the making of this website.