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Vision Medical Terms

Get help understanding common medical terms related to vision.

Astigmatism

Is a common vision problem caused by an error in the shape of the cornea. With astigmatism, the lens of the eye or the cornea, which is the front surface of the eye, has an irregular curve. This can change the way light passes, or refracts, to your retina. This causes blurry, fuzzy, or distorted vision.


Blepharitis

Is inflammation of the eyelids. Blepharitis usually affects both eyes along the edges of the eyelids. Blepharitis commonly occurs when tiny oil glands near the base of the eyelashes become clogged, causing irritation and redness. Several diseases and conditions can cause blepharitis.


Cataract Extraction

Is a surgery to remove the cloudy lens from the eye. The surgeon makes a small incision (cut) on the surface of the eye near the clear part of the eye called the cornea. A small instrument is inserted into the incision and the cloudy lens material is removed from the eye.


Cataracts

Are the clouding of the lens of your eye, which is normally clear. Most cataracts develop slowly over time, causing symptoms such as blurry vision. Cataracts can be surgically removed through an outpatient procedure that restores vision in nearly everyone.


Cornea

Is the transparent part of the eye that covers the front portion of the eye. It covers the pupil (the opening at the center of the eye), iris (the colored part of the eye), and anterior chamber (the fluid-filled inside of the eye). The cornea's main function is to refract, or bend, light.


Cornea Disease

Is a serious condition that can cause clouding, distortion, scarring and eventually blindness. There are many types of corneal disease. The three major types are keratoconus, Fuchs' endothelial dystrophy and bullous keratopathy. Symptoms of corneal disease.


Corneal Scarring

The cornea is resilient and can typically heal from minor abrasions. However, major corneal damage can result in a corneal scar. These can be caused by improper use of contact lenses, deep scratches, lacerations, burns, and some diseases like shingles and syphilis.


Corneal Swelling

Also called corneal edema, is an inflammation of the outermost layer of the eye. The cornea is a clear layer of tissue that looks like a smooth, dome-shaped piece of glass.


Diabetic Retinopathy

Is an eye condition that can cause vision loss and blindness in people who have diabetes. It affects blood vessels in the retina (the light-sensitive layer of tissue in the back of your eye). If you have diabetes, it's important for you to get a comprehensive dilated eye exam at least once a year.


Dry Eye

Is a common condition that occurs when your tears aren't able to provide adequate lubrication for your eyes. Tears can be inadequate and unstable for many reasons. For example, dry eyes may occur if you don't produce enough tears or if you produce poor-quality tears.


Farsightedness

Also known as hyperopia, is a common vision condition in which you can see distant objects clearly, but objects nearby may be blurry. The degree of your farsightedness influences your focusing ability.


Corneal Transplant Surgery

A circular disk-shaped portion of your cornea is removed and replaced with a similarly sized portion of cornea from a donor. A cornea transplant (keratoplasty) is a surgical procedure to replace part of your cornea with corneal tissue from a donor.


Glaucoma

Is a group of eye conditions that damage the optic nerve, the health of which is vital for good vision. This damage is often caused by an abnormally high pressure in your eye. Glaucoma is one of the leading causes of blindness for people over the age of 60.


Glaucoma Tube Shunt Surgery

Also known as seton glaucoma surgery, involves placing a flexible plastic tube with an attached silicone drainage pouch in the eye to help drain fluid (aqueous humor) from the eye. This type of surgery is usually done after a trabeculectomy that failed.


Gonioscopy

Is using a goniolens (also known as a gonioscope) together with a slit lamp or operating microscope to view the iridocorneal angle, or the anatomical angle formed between the eye's cornea and iris. Its use is important in diagnosing and monitoring various eye conditions associated with glaucoma.


Keratoconus

Occurs when your cornea — the clear, dome-shaped front surface of your eye — thins and gradually bulges outward into a cone shape. A cone-shaped cornea causes blurred vision and may cause sensitivity to light and glare.


Laser Peripheral Iridotomy

Is a medical procedure which uses a laser device to create a hole in the iris, thereby allowing aqueous humor to traverse directly from the posterior to the anterior chamber and, consequently, relieve a pupillary block.


Macular Degeneration

Is an eye disease that may get worse over time. It's the leading cause of severe, permanent vision loss in people over age 60. It happens when the small central portion of your retina, called the macula, wears down.


Macular Holes

Is a small break in the macula, located in the center of the eye's light-sensitive tissue called the retina. The macula provides the sharp, central vision we need for reading, driving, and seeing fine detail. A macular hole can cause blurred and distorted central vision.


Macular Puckers

Is scar tissue that has formed on the eye's macula, located in the center of the light-sensitive tissue called the retina. The macula provides the sharp, central vision we need for reading, driving, and seeing fine detail. A macular pucker can cause blurred and distorted central vision.


Nearsightedness

Is a common vision condition in which you can see objects near to you clearly, but objects farther away are blurry. It occurs when the shape of your eye causes light rays to bend (refract) incorrectly, focusing images in front of your retina instead of on your retina.


Ophthalmology

Is the study of medical conditions relating to the eye. Ophthalmologists are doctors who specialize in the medical and surgical treatment of this organ.


Optic Nerve

Connects the eye to the brain. The optic nerve carries the impulses formed by the retina, the nerve layer that lines the back of the eye and senses light and creates impulses. These impulses are dispatched through the optic nerve to the brain, which interprets them as images.


Optometry

Is a health care profession that inv ies as well as prescribing the correction of refractive error with glasses or contact lenses olves examining the eyes and applicable visual systems for defects or abnormalit and the treatment of eye diseases.


Pink Eye

Is an inflammation or infection of the transparent membrane (conjunctiva) that lines your eyelid and covers the white part of your eyeball. When small blood vessels in the conjunctiva become inflamed, they're more visible.


Posterior Segment of the Eye

Is the back two-thirds of the eye that includes the anterior hyaloid membrane and all of the optical structures behind it: the vitreous humor, retina, choroid, and optic nerve.


Presbyopia

Farsightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age.


Pterygium Surgery

Is a procedure performed to remove noncancerous conjunctiva growths (pterygia) from the eye. The conjunctiva is the clear tissue covering the white part of the eye and the inside of the eyelids. Some cases of a pterygium produce little to no symptoms.


Refractive Eye Surgery

The most widely performed type of refractive surgery is LASIK (laser-assisted in situ keratomileusis), where a laser is used to reshape the cornea.


Retinal Detachment

Describes an emergency situation in which a thin layer of tissue (the retina) at the back of the eye pulls away from the layer of blood vessels that provides it with oxygen and nutrients. Retinal detachment is often accompanied by flashes and floaters in your vision.


Retinal Tear

Is a small break in this inner lining. Retinal tears can have many causes and can happen at any age. Aging, eye trauma, eye surgery or being drastically nearsighted may cause retinal tears or detachments. If not treated properly, a retinal tear may lead to retinal detachment.


Routine Eye Exam

An office visit for the purpose of checking vision, screening for eye disease, and/or updating eyeglass or contact lens prescriptions. Routine eye exams produce a final diagnosis, like nearsightedness, farsightedness or astigmatism.


Selective Laser Trabeculoplasty

Is a form of laser surgery that is used to lower intraocular pressure in glaucoma. It is used when eye drop medications are not lowering the eye pressure enough or are causing significant side effects. It can also be used as initial treatment in glaucoma.


Trabeculectomy

Is a surgical procedure to treat glaucoma. Glaucoma occurs when the fluid your eye produces, called aqueous humor, is unable to drain normally. This causes the intraocular pressure (IOP) to increase over time, possibly resulting in vision loss or blindness if left untreated.


Uveitis

Is a form of eye inflammation. It affects the middle layer of tissue in the eye wall (uvea). Uveitis (u-vee-I-tis) warning signs often come on suddenly and get worse quickly. They include eye redness, pain and blurred vision.


Watery Eye

Persistently or excessively. Depending on the cause, watery eyes may clear up on their own. Self-care measures at home can help treat watery eyes, particularly if the cause is inflammation or dry eyes.

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