Glossary of Eye Health Terms

A general term that denotes poor vision in an otherwise healthy eye, which cannot be corrected by eyeglasses or contact lenses. This condition is often referred to as "lazy eye". Learn More

Anisocoria simply means that one of your pupils is a different size than the other. Normally, your pupils adjust together to light, contracting in brightness and expanding in dim light. But in people with anisocoria, one pupil doesn’t quite keep up with the other. Learn More

Distorted vision typically caused by an irregular shaped cornea. When the cornea is not perfectly spherical in shape, two different points of focus may be formed in the same eye, creating distorted and blurred vision. Astigmatism often accompanies myopia (nearsightedness) or hyperopia (farsightedness). Astigmatism can be corrected with eyeglasses or contact lenses. Learn More

In this digital age, our devices expose us to a type of light that has garnered increasing attention—blue light. Understanding blue light is crucial in today's technology-driven society, where screens are universal and eye health is paramount. Learn More

Blepharitis is an inflammation along the rim or inside of the eyelids. While it can be a chronic condition, there are steps you can take to keep it under control. Learn all about how to identify and manage blepharitis here. Learn More

A condition of the crystalline lens, in which the normally clear lens becomes clouded or yellowed, resulting in blurred or foggy vision. Cataracts may be caused by aging, eye injuries, disease, heredity or birth defects. Learn More

Central serous chorioretinopathy (CSC) is a condition affecting the eye's retina that can cause blurred vision. This glossary will discuss the most common concerns about this eye condition. Learn More

Color blindness, also known as color vision deficiency, means that a person cannot tell the difference between certain colors because of a problem with the color-sensing ability of the cones in the retina. Learn More

Many people using a computer for long periods experience eyestrain, this is called Computer Vision Syndrome (CVS). CVS affects everyone who works on a computer and consists of symptoms such as headache, dry eyes, fatigue, blurred and double vision. Learn More

A common eye condition characterized by redness and swelling of the conjunctiva, the transparent layer that covers the white part of your eye and the inside of your eyelids. If you’ve ever experienced discomfort, itchiness, or a gritty feeling in your eyes, you might have been experiencing symptoms of conjunctivitis. Learn More

An open sore on the cornea of the eye. It is an urgent medical condition that requires immediate attention from an eye care professional. Learn More

A disease of the retina caused by high blood sugar. High blood sugar can damage tiny blood vessels in the retina. Learn More

Digital eye strain, also known as computer vision syndrome, is a common condition characterized by eye discomfort and vision problems resulting from prolonged use of digital devices such as computers, smartphones, and tablets. As technology advances, we spend extended periods in front of screens, increasing the prevalence of digital eye strain. Learn More

A diopter is a critical unit of measurement in optics that quantifies the refractive power of lenses used in eyeglasses and contact lenses. It indicates the degree to which a lens must bend light to properly focus it onto the retina, correcting visual impairments. Understanding diopters helps individuals and eye care professionals in choosing the right strength for corrective lenses for clear and accurate vision correction. Learn More

Dry eye is a persistent lack of sufficient lubrication and moisture in the eye, causing slight but regular irritation to ocular inflammation of the anterior (front) tissues of the eye. Learn More

Eye strain occurs when the eyes become tired from prolonged use, especially during activities demanding intense focus. In today’s digital world, where screen usage is becoming more frequent, understanding and managing this condition is more important than ever to maintain good eye health and overall well-being. Learn More

Floaters are what appear to be small specks or clouds moving in your field of vision. But they are actually small clumps of gel or cells inside the vitreous, the clear jelly-like fluid that fills the inside of your eye. They may look like strands, webs, specks, or other shapes, but they are shadows cast on the retina. Learn More

Have you ever heard of floppy eyelid syndrome (FES)? It’s a common, often under-diagnosed condition. In this glossary, we’ll tackle all the key concerns about the condition to help you understand what it is and how it’s treated. Learn More

Increased pressure in the eye, caused by abnormally high production of fluid or a decrease in the eye's ability to drain that fluid. Untreated, permanent damage to the optic nerve and possible blindness if untreated. Chronic glaucoma occurs gradually, is painless, and has few warning symptoms. Acute glaucoma is marked by sudden, severe pain in and around the eye, sharply decreased vision, nausea, and vomiting. Learn More

An eye infection caused by the herpes simplex virus (HSV), a viral infection that can affect different parts of the body. In this condition, the virus targets the cornea—the clear, protective layer at the front of the eye—leading to inflammation. Learn More

When you hear herpes zoster ophthalmicus (HZO), the word herpes might catch your attention—but this condition is all about eye health, not STIs. Here’s what you need to know about HZO, including how to manage it. Learn More

Condition in which the eye focuses light rays behind, rather than on, the retina, resulting in difficulty in seeing near objects clearly, while distant objects appear in focus. Learn More

Hypermetropia is a scientific name for farsightedness, the condition of seeing objects at a distance better than up close. Learn all about this common condition and how to manage it. Learn More

Involves the thinning and reshaping of the cornea, which is the clear, dome-shaped surface that covers the front of your eye. It results in a cone-shaped cornea, which deflects light as it enters the eye on its way to the retina, leading to impaired vision. This condition typically develops in the teenage years to early twenties and progresses for about a decade. Learn More

Lens coating enhances the performance and longevity of optical lenses by applying a thin layer of unique compounds that modify how light interacts with the lens. This upgrade is crucial for maximizing visual clarity, protecting the lenses and extending the benefits of your prescription glasses. Learn More

Pigmented area in the middle of your retina, the light-sensitive cell layer in the back of your eye. It enables clear central vision and much of your color vision. It also helps protect the retina by filtering excess blue light and ultraviolet light. This eye area is vital for activities requiring sharp vision, including driving, reading and recognizing faces. Learn More

Damage or breakdown of the macula, the central point of focus on the retina. It is usually caused by aging as the tissues in the eye thin and begins to break down. Symptoms include loss of color vision, a dark or empty area in the center of the visual field, or blurred vision in that area. Learn More

A condition that affects the tiny glands located along the edges of your eyelids. affects the tiny glands located along the edges of your eyelids. Learn More

Condition in which the eye focuses light rays in front of, rather than on the retina, resulting in near objects being seen clearly and distant objects being blurred. Learn More

Myopia control involves interventions designed to slow the progression of myopia. The objective is to minimize the degree of myopia and reduce the associated risks of vision complications in the future. Learn More

Nystagmus is the presence of repetitive, uncontrolled eye movements. It can have a variety of causes and can be a temporary or chronic condition. Learn all about its symptoms, treatment options and more. Learn More

Refers to any situation in which pressure in the eye is higher than normal. Learn More

A form of eye cancer that develops in your eye’s pigment-producing cells. Learn More

A medical doctor (M.D. or D.O.) who specializes in treating diseases of the eye and eye surgery. Learn More

One who fits, fabricates, and dispenses eyeglasses. An optician fills prescriptions for eyeglasses and other optical aids as specified by either optometrists or Ophthalmologist. Learn More

Curious about optic neuritis? It's more common than you might think. Around 5 per 100,000 people in the U.S. are diagnosed each year with new cases of the eye condition, mostly women. If you want to know what optic neuritis is, how it’s treated and other related concerns, this glossary has the answers. Learn More

A board certified doctor of optometry (O.D.), licensed to examine eye disease and other abnormalities of the eye, to administer certain medications, and to prescribe and dispense eyeglasses and contact lenses as well as other optical aids. Learn More

Although its name translates to “fear of light,” photophobia is actually a visual sensitivity to light, especially the sun and other bright lights. It causes a large measure of discomfort or pain. Photophobia is fairly common and associated with many different causes. Learn More

Loss of the eye's ability for "accommodation" (focusing on near objects) with age. Occurring in one's early forties, we often have to hold menus and books at arm's length in order to read. Presbyopia can be treated with eyeglasses. Learn More

The bulging of one or both eyes. It can accompany a variety of conditions, which call for different types of treatment depending on the underlying problem. Learn More

Also known as “surfer’s eye,” is a growth that occurs on the white of the eye due to extensive exposure to the sun and outdoor elements. Learn More

A condition where the upper eyelid droops down and sometimes covers part of the eye. It can involve one or both eyes and might be present at birth or develop later on. Learn More

A thin layer of tissue at the back of your eye that contains photoreceptors, or light-sensitive cells. When light reaches these photoreceptors, they convert it into neural signals, which are sent to your brain for visual recognition. The result is the image you see of the world in front of you. Learn More

The retina is a thin layer of cells on the back of the eye. It senses and sends light signals to the brain. Retinal detachment happens when the retina shifts or peels away from its normal position. Learn More

Retinitis pigmentosa (RP) was first described as a condition in 1853, but the name wasn’t used until 1857. Although "retinitis" suggests inflammation, it's actually a misnomer since inflammation plays a minimal role in the disease. This glossary will explain what retinitis pigmentosa is and address concerns about it. Learn More

Sometimes mistaken for pink eye, which inflames the thin, translucent layer covering the white of the eye and the inner eyelid, scleritis directly affects the sclera—the white part of the eye. Learn More

Misalignment of the two eyes, in which they point at different positions. Strabismus is more common in children and eyeglasses, vision training, and/or surgery can correct it. Learn More

a form of eye inflammation that impacts the uvea, the middle layer of the eye wall. Learn More

Refers to the clarity or sharpness of your vision, which is the ability to see and distinguish fine div and small objects at a standard distance. It’s usually measured using the Snellen chart, where you read letters that decrease in size from top to bottom. The results help your eye doctor determine if you need vision correction. Learn More

A visual field test evaluates the range and quality of your peripheral vision. Through visual field testing, your eye doctor can detect any issues with your field of vision, which may indicate an underlying health condition. Learn More