Common Ocular Terms and Eye Conditions


 Acuity  Unit of measure of the eye’s ability to distinguish an objects details and shape It is assessed by the smallest identified object at a specified distance.


“Lazy Eye” Decreased vision in one or both eyes without damage to the eye or visual pathway. Uncorrected by glasses.


Astigmatism is an imperfection in the curvature of the cornea. Instead of being spherical in shape, like a ping pong ball, an eye with astigmatism is shaped more like an egg or football. This shape results in distorted images, as light rays are prevented from meeting at a common focus. People with astigmatism experience blurry or distorted vision regardless of how close or far away an object is.


Inflammation of the eyelids, usually with redness, swelling and itching.


Opacity/Cloudiness of the crystalline lens that may prevent a clear image from forming on the retina. Usually requires surgical removal when vision is reduced.


The thin transparent mucous membrane lining the inner surface of the eyeball, excluding the cornea.


Inflammation of the mucous membrane covering the white of the eye and inner eyelid surfaces. Can be acute, allergic, atopic, and bacterial. Characterized by discharge, grittiness, redness and swelling


Transparent front segment of the eye that covers the iris, pupil, anterior chamber. Provides most of the eye’s optical power.

Corneal Abrasion

An injury, scraped area of the corneal surface, accompanied by some loss of corneal epithelial tissue.

Crystalline lens

Transparent biconvex lens that help bring rays of light to focus on the retina thus allowing a more in-depth eye exam, also used to treat Iritis.

Diabetic Retinopathy

Diabetic Retinopathy is a diabetes complication that affects the eyes. It occurs when high blood sugar levels cause damage to blood vessels in the retina. These blood vessels can swell and leak. Or they can close, stopping blood from passing through. Sometimes abnormal new blood vessels grow on the retina. All of these changes can steal your vision.


Is a widening of an opening, such as the pupil.

Dry eye syndrome

Pathological condition that causes corneal and conjunctival dryness due to a deficiency in tear production. Treated with moisturizing drops/gels

Eye strain

Symptom of discomfort while using the eyes for visual tasks


Eye floaters appear as small spots that drift through your field of vision.They tend to dart away when you try to focus on them.They might annoy you, but they shouldn’t interfere with your sight. Once you get them, they usually don’t go away. But you usually notice them less over time.


Interior surface of the eyeball, including retina, optic disc, macula and posterior pole.


Characterized by an increased intraocular pressure resulting from damage to the optic nerve fibres and changes in optic cup size. Most common cause of preventable vision loss.


Hyperopia is commonly called farsightedness. People with hyperopia can see more clearly objects in the distance than at close up.

Intraocluar len

(IOL) Artificial lens surgically implanted during cataract surgery to replace the natural crystalline lens.

Intraocular pressure

(IOP)Fluid pressure inside the eye, which is measured using a tonometer.


Keratoconus is a progressive eye disease in which the normally round cornea thins and begins to bulge into a cone-like shape. This cone shape deflects light as it enters the eye on its way to the light-sensitive retina, causing distorted vision.

 Macular Degeneration

a degenerative condition affecting the central part of the retina (the macula) and resulting in distortion or loss of central vision. It occurs especially in older adults, in which case it is called age-related macular degeneration.


Myopia is commonly called nearsightedness. People with myopia can see more clearly objects close up rather than in the distance.


Optical coherence tomography (OCT) is a non-invasive imaging test. OCT uses light waves to take cross-section pictures of your retina, showing distinct layers.

Ocular Migraine with Aura

This is a migraine that involves visual disturbances with no headache. During an ocular migraine with aura, you may see flashing or shimmering lights, zigzagging lines, or stars. Some people describe psychedelic images. It may also cause blind spots in your field of vision.


Presbyopia is an age-related condition when the eye’s lens doesn’t change shape as easily as it once did, making it more difficult to read or see things at close up. This is commonly noticed around the age of 40.


Refraction is the way light changes direction as it passes from one medium to another.

Retinal Detachment

A retinal detachment is when the retina pulls away from the surrounding tissue. This is an emergency situation because if prompt medical attention is not given, permanent vision loss can occur.


Strabismus is where the eyes are not aligned properly and point in different directions. This condition may affect one or both eyes.

Visual Field

The visual field refers to the total area in which objects can be seen in the side (peripheral) vision as you focus your eyes on a central point.