A chalazion is the medical term for a slowly developing lump on the eyelid that occurs due to an oil gland blockage. At first, the eyelid may appear to be red, tender and swollen. After several days, the chalazion will form on the eyelid, appearing as a slow growing lump. While it is initially painless

An eye occlusion is a blockage in one of the arteries or veins supplying blood to the retina and/or optic nerve. These blockages can cause severe and sudden vision loss. Contact your eye care professional immediately if you experience sudden vision loss, and follow up right away with your family doctor.

Visual perception refers to a set of skills used to collect and interpret visual information taken in from our environment. The visual information gathered is combined with our other senses, allowing us to derive meaning from what we see. Through the process of merging visual data with our other senses,

Also known as demyelinating optic neuritis, optic neuritis refers to the inflammation of the optic nerve due to the loss of or damage to a protective covering called myelin, which surrounds the optic nerve. The myelin is essential to the function of the optic nerve. A more general term, optic neuropathy,

Pronounced SHOW-grins, Sjogren's syndrome is a disorder of the immune system, or an autoimmune disease, which causes the body's immune system to attack and harm the body's glands. Your glands are responsible for the production of saliva, tears, and other lubrication necessary for the proper function

Glaucoma is the second leading cause of blindness in the United States, making it an important public health priority. Although there are several factors that cause glaucoma, all types of glaucoma are characterized by damage to the optic nerve. This damage prevents the brain from receiving appropriate

Uveitis refers to the inflammation of the eye's middle layer, which consists of the iris, ciliary body, and choroid. Several fungal, viral, or bacterial infections lead to uveitis, as do certain autoimmune (systemic) and inflammatory conditions. In most cases of uveitis, however, the exact cause is unknown. Types

The human visual system is a complex network including the eye, ocular nerves, and key brain areas that process visual information. Under most circumstances, we use information from both eyes to create a single visual image. This ability to converge information from both eyes is called binocular vision.

Almost everyone uses computers in the modern world, whether for recreation, employment, education or any combination of the three. Unfortunately, our increased use of computers in almost every aspect of our lives -- even using a smartphone to make a telephone call -- requires our eyes to read a computer

Commonly called crossed eyes, strabismus is a condition in which eyes do not work together, failing to maintain proper alignment. While one eye focuses on an object, the other does not. The failure of the eyes to work together causes double vision, and if untreated can lead to an extreme reduction of

Approximately 11% of school-aged children have been diagnosed with attention deficit/hyperactivity disorder (ADHD), according to recent studies. The central symptoms of ADHD -- difficulty sustaining attention, poor control of behavior, hyperactivity -- make it difficult for children to succeed in school.

Similar to a bruise under the skin, a subconjunctival hemorrhage happens when a small blood vessel located between the sclera (white portion of an eye) and the conjunctiva (lining on the surface of an eye) breaks and covers the sclera with blood. Unlike broken blood vessels located under the skin which

Many body parts begin to change as you age, and your eyes are no exception. One of the most common age-related eye changes is the development of cataracts. Although cataracts do not occur exclusively in older adults, they affect approximately half of all Americans by age 80. What Are Cataracts? Cataracts

Glare and halos are both eye symptoms that some people experience around bright lights. Halos show up as bright circles around a light source. Glare is light that interferes with your vision, making it difficult to see or sometimes making your eyes water. These symptoms can show up at any time of the

Characterized by a yellowish raised part of the scleral conjunctiva (the lining of the white part of the eye), a pinguecula usually develops near the cornea (colored part of the eye), but does not extend past it. Similar to a callus on the skin, changes in tissues lead to the buildup of calcium, fat,

The eye has many parts that work together to create vision. The eyes themselves are only part of “seeing.” The brain is also involved. The eyes, though, begin the complex process of vision by gathering, focusing and passing on visual information to the brain. To help you learn how the eye works,