Accommodation. The eye’s ability to change focus automatically from seeing at one distance to seeing at another.

Acute Angle Closure. See Glaucoma.

Age-Related Macular Degeneration. See Macular Degeneration.

Amblyopia. Also known as lazy eye. A failure of the eye to develop good vision. Patients with amblyopia lack the ability to blend the images of both eyes together (stereopsis). Crossed or turned eyes, congenital cataracts, cloudy cornea, droopy eyelid, unequal vision or uncorrected nearsightedness, farsightedness or astigmatism may cause amblyopia.

Anomalous Trichomat. The most common form of color vision deficiency. It characterizes a person with a deficiency in one pigment. See Color Vision Deficiencies.

Angle. A combination of structures in the front of the eye. If the angle space between the iris and the cornea is too narrow, it can lead to glaucoma.

Anterior Uveitis. Also known as iridocyclitis. The most common form of uveitis that affects the iris and ciliary body. It is characterized by symptoms including light sensitivity, blurred vision, redness around the iris, pain, small pupil, tearing and elevated intraocular pressure.

Aqueous. The clear fluid occupying the space between the cornea and the lens of the eye.

Argonne Laser Trabeculoplasty (ALT). A laser treatment for glaucoma patients who continue to experience high intraocular pressure after treatment with eye drops. The procedure stretches the pores and opens the outflow channels for fluid, which decreases eye pressure.

Astigmatism. A defect in the shape of the cornea, which causes blurred vision. Astigmatism can be corrected with glasses, contact lenses or refractive surgery.

Bifocals. Prescription lenses used to counteract presbyopia.

Binocular Vision. The ability of the eye to combine the images from each retina into one single image.

Biometry. Also known as A-Scan. A one-dimensional ultrasound image of the eye.

Blepharitis. Also known as inflamed eyelids. A common inflammatory condition that causes burning, itching or irritation of the eyelids.

Branch Vein Occlusion. See Vascular Occlusion.

Cataract Surgery. A common outpatient procedure in which a surgeon removes the natural lens in the eye and replaces it with a clear implant.

Cataracts. A clouding of the lens of the eye that causes blurry, hazy or distorted vision. Cataracts are a natural result of the aging process.

Central Vein Occlusion. See Vascular Occlusions.

Chalazion. A lump on the eyelid formed by retention of oil secretions and sometimes accompanied by inflammation.

Chorioretinitis. See Posterior Uveitis.

Choroid. The layer of blood vessels that lies between the retina and the sclera. The choroid nourishes the back of the eye.

Ciliary Body. A section of the eye between the iris and the choroid. Its main functions are accommodation, aqueous production and holding the lens in place.

Closed Angle Glaucoma. See Glaucoma.

Color Blindness. See Color Vision Deficiencies.

Color Vision Deficiencies. The inability to distinguish some colors and shades. Color blindness represents one, rare form of color vision deficiency, in which the retina is unable to distinguish any colors. More often patients have deficiencies with one of the three photosensitive pigments in the eye: red, green or blue (anomalous trichomats) or a complete absence of one cone pigment (dicromat). A person with normal color vision is known as a trichomat.

Comprehensive Color Vision Analysis. A variety of specialized tests used to diagnose the exact nature of color vision deficiencies.

Computer Vision Syndrome. Eye-related problems associated with the prolonged use of a computer, such as eyestrain and irritation.

Cone. A photosensitive receptor in the retina that enables people to see color.

Conjunctiva. The thin, transparent tissue that covers the outer surface of the eye.

Conjunctivitis. Also known as pink eye. An infection and inflammation of the conjunctiva, usually from an allergy, virus or bacterium.

Contact Lenses. Corrective lenses that are worn on the surface of the eye. They are used to correct myopia (nearsightedness), hyperopia (farsightedness), presbyopia and astigmatism.

Contrast Sensitivity Testing. A test used to measure a patient’s visual resolution, sometimes used to diagnose patients with low vision, special sports vision needs and, in some cases, cataracts.

Cornea. The clear, dome-shaped outer coating that covers the front of the eye. The cornea provides the eye’s focusing power.

Corneal Abrasion. A tearing or puncture of the cornea.

Corneal Transplant. A surgical procedure that removes a portion of a diseased cornea and replaces it with corneal tissue from another person.

Crossed Eyes. See Strabismus.

Diabetic Retinopathy. Changes in the retina due to diabetes. Adverse changes in the retinal blood vessels leads to weakening and eventually to more serious eye disorders. In its most advanced stages, diabetic retinopathy can lead to severe vision loss or blindness.

Dichromat. A person who has a color vision deficiency involving the complete absence of one cone pigment (red, green or blue). See Color Vision Deficiency.

Diffuse Uveitis. A type of uveitis that affects structures in both the front and back of the eye. Common symptoms include light sensitivity, blurred vision, redness around the iris, pain, tearing, floaters or elevated intraocular pressure.

Digital Ocular Imaging. A digital camera used for taking anterior and posterior images of the eye.

Dilation. A portion of a comprehensive eye examination during which eye drops are used to temporarily enlarge the pupil so that the eye professional can examine the structures in the back of the eye.

Drooping Eyelids. See Ptosis.

Dry Eye Syndrome. A chronic lack of sufficient lubrication and moisture in the eye(s) causing sensations of dryness, scratchiness or burning.

Edema. A swelling.

Endothelium. The inner layer of cells in the cornea.

Epithelium. The outer layer of cells in the cornea.

Exudative AMD. Also known as wet AMD. A less common form of age-related macular degeneration in which new blood vessels develop beneath the macula causing bleeding, scarring and loss of central vision.

Exudative Retinal Detachment. See Retinal Detachment.

Eye Movement Recording System (Visagraph). A computerized system used to evaluate eye movements for children and adults.

Farsightedness. See Hyperopia.

Flashes. The brief perception of light that can accompany an eye disorder, especially of the retina or brain.

Filtration. See Glaucoma Surgery.

Floaters. The sensation of spots appearing before the eyes caused by bits of optical debris, such as dead cells, usually in the vitreous.

Fluoroscein Angiography/Ocular Angiography. A diagnostic procedure used to diagnose and localize leaky blood vessels in the eye.

Focal Laser Treatment. An in-office laser procedure used to treat macular edema. During the treatment, a laser is used to seal off the leaky blood vessels and prevent further leakage.

Fovea. The center area of the retina that receives the focus of an object.

Glaucoma. A progressive disease caused by increased intraocular pressure (IOP) that results from an over-production of fluid or malfunction in the eye’s drainage structures. Glaucoma can lead to vision loss. The most common form is open angle glaucoma, caused by aqueous fluid building up in the anterior chamber. Closed angle glaucoma occurs when abnormal structures in the front of the eye, known as the angel, are too narrow. This results in a smaller channel for the aqueous to pass through. If aqueous becomes blocked, IOP increases.

Glaucoma Surgery (Filtration). A surgical procedure for severe glaucoma cases in which a new outflow channel is created to work in tandem with the existing channel.

Grid Laser Treatment. An outpatient laser treatment used for patients with diabetic retinopathy. During the procedure, leaky blood vessels over a diffuse area are sealed off.

Hordeolum. Also known as stye. A blocked gland at the edge of the eyelid that has become infected by bacteria.

Hyperopia. Also known as farsightedness. Difficulty seeing up close as a result of a flattened cornea, which focuses light behind the retina instead of on it.

Inflamed Eyelids. See Blepharitis.

Intermediate Uveitis. A form of uveitis affecting the ciliary body, vitreous and retina, which appears in both eyes. Floaters and blurred vision are common symptoms.

Intraocular Lens. A small plastic lens implanted into an eye after cataract surgery to replace the natural lens which is removed.

Intraocular Pressure (IOP). The pressure in the eye caused by the rate at which aqueous enters and leaves the eye. A build-up of intraocular pressure can cause glaucoma.

Iridocyclitis. See Anterior Uveitis.

Iris. The colored part of the eye. Tiny muscles inside the iris dilate (widen) or contract (narrow) the size of the pupil.

Iritis. An inflammation of the iris that can be caused by systemic disease (such as rheumatoid arthritis), systemic infections (such as measles or tuberculosis), trauma or unknown sources.

Ischemic. Oxygen-deprived.

Keratitis. An inflammation of the cornea.

Keratoconus. A condition in which the cornea develops a cone-shaped bulge that can result in blurring and distortion of vision.

Lacrimal System. The system in the eye responsible for the production and movement of tears.

Laser Peripheral Iridotomy (LPI). A laser treatment used to prevent glaucoma for patients with a narrow angle. In LPI, a laser is used to place a tiny opening in the iris in order to improve drainage.

LASIK (Laser-In-Situ-Keratomileusis). A laser treatment used to correct myopia (nearsightedness), hyperopia (farsightedness) or astigmatism.

Lazy Eye. See Amblyopia.

Lens. The lens focuses light on to the retina in the back of the eye.

Macula. A small, highly sensitive part of the retina responsible for detailed central vision.

Macular Degeneration. Also known as age-related macular degeneration. A disease affecting the central area of the retina (the macula), which over time can cause a partial or complete loss of central vision.

Monovision. A vision correction method for people with presbyopia in which one eye is corrected for near vision and the other for far vision. This can be accomplished through glasses, contact lenses or refractive surgery.

Myopia. Also known as nearsightedness. Difficulty seeing a distance caused by a misshaped cornea that focuses light in front of the retina instead of on it. Myopia is corrected with glasses, contact lens or refractive surgery.

Neovascularization. Abnormal growth of new, fragile blood vessels in the eye, which tend to hemorrhage causing blood to leak into the eye and decrease vision.

Non-exudative AMD. Also known as dry AMD. A common form of age-related macular degeneration that can lead to a reduction in central vision.

Ocular Angiography. See Fluoroscein Angiography.

Ocular Electrophysiology. Diagnostic test that measure the performance of electrical impulses in the eye. It is most often used to diagnose certain hereditary macular or ocular conditions, which can lead to vision loss.

Ocular Health. The health status of the tissue and structures outside and on the surface of the eye.

Open Angle Glaucoma. See Glaucoma.

Ophthalmologist. Physician and surgeon specializing in the structure functions and diseases of the eye.

Optic Nerve. The optic nerve transmits electrical light impulses from the retina in the back of the eye to the brain.

Optical Coherence Tomography (OCT). A non-invasive technology that creates a high-resolution color image of the eye using light and light rays instead of ultrasound. OCT is used to measure the thickness of the macula, the tissue make-up of the nerve fiber layer or to analyze individual layers of the retina.

Optician. A maker or dealer of optical items. Someone who reads prescriptions for vision correction, orders lens and dispenses glasses and contact lenses.

Optometrist. A doctor of optometry who examines the eyes and associated structured to determine the health of the eyes. An optometrist prescribes glasses or contact lenses and medications for eye illness.

Orbits and Plastics. A variety of devices used to repair problems with muscles around the eye (such as droopy eyelids).

Pachymetry. A diagnostic test used to measure the thickness of the cornea.

Pan Retinal Photocoagulation (PRP). A type of laser treatment used in cases of diabetic retinopathy to destroy oxygen-deprived retinal tissue outside of the patient’s central vision.

Pan Uveitis. A form of uveitis affecting structures in both the front and back of the eye. See Uveitis.

Photodynamic Therapy (PDT). A relatively new laser treatment used to stop the growth of new blood vessels for some patients with macular degeneration.

PRK (Photorefractive Keratectomy). A laser treatment used to remove corneal tissue to correct myopia (nearsightedness), hyperopia (farsightedness) or astigmatism.

Photosensitive Pigments. The elements in the cone of the eye that enable us to see color.

Pink Eye. See Conjunctivitis.

Posterior Uveitis. Also known as retinitis or horioretinitis. A form of uveitis involving the retina, choroid and optic nerve. Blurred vision and pain (if the optic nerve is affected) are the primary symptoms. See Uveitis.

Posterior Vitreous Detachment (PVD). A normal separation of the vitreous from the retina due to age. It is often accompanied by Floaters and Flashes.

Presbyopia. A difficulty focusing that many people notice around the age of 40. It is correctable using prescription glasses, contact lenses or bifocals.

Ptosis. Also known as droopy eyelids. A condition in which the upper eyelids sag. It can be present at birth or caused later. If needed, ptosis can be treated with orbits and plastics.

Pupil. The black circular opening in the center of the iris. It regulates the amount of light entering the eye.

Refraction. An examination of visual acuity to determine whether a correction is needed. Correction can be treated using corrective lenses (glasses or contacts) or refractive surgery, such as LASIK or PRK.

Retina. A very thin layer of light-sensitive tissues that line the inner part of the eye. It is responsible for capturing the light rays that enter the eyes, and along with the optic nerve, converting them to light impulses and sending them to the brain for processing.

Retinal Detachment. Separation of the retina from the tissue beneath it, known as Retinal Pigmented Epithelium (RPE). There are three types of retinal detachments. Rhegmatogenous detachment occurs when fluid seeps underneath and causes the retina to separate from the RPE. Traction retinal detachment occurs when strands of scar tissue create traction on the retina, pulling it loose. The least common form of retinal detachment is called exudative retinal detachment and occurs when fluid collects between the retina and RPE, usually due to inflammation or tumor.

Retinal Pigmented Epithelium. A layer of pigmented cells that nourishes and supports the retina.

Retinal Vein Occlusion. See Vascular Occlusion.

Retinitis. See Posterior Uveitis.

Rhegmatogenous Detachment. See Retinal Detachment.

Sclera. The tough, opaque tissue that serves as the eye’s protective outer layer.

Short Wavelength Automated Perimetry (SWAP). A specialized field of vision test that uses a yellow background instead of the traditional white background.

Stereofundus Photography. A film-based technology used to photograph the back of the eye.

Stereopsis. The ability to blend the images of both eyes together. Stereopsis allows us to appreciate depth and judge distances.

Strabismus. Also known as crossed eyes. A misalignment of the eyes caused when one or more eye muscles function improperly. The causes the eye to turn in, out, up or down relative to the other eye.

Strabismus Surgery. Strabismus surgery is used to realign the muscles that control eye movements. The need for surgery depends on which way the eye is turning, the severity of the turned or crossed eye, and whether or not improvements can be made through glasses or vision therapy.

Stroma. The cornea’s middle layer, made up of collagens and cells, which makes up most of the cornea.

Stye. See Hordeolum.

Subconjunctive Hemorrhage. A condition in which a small blood vessel under the conjunctiva breaks and bleeds, causing a red, bloody patch to appear on the white of the eye.

Test of Variables of Attention (TOVA). A computerized test used to diagnose and treat children and adults with attention disorders.

Trabecular Meshwork/Canal of Schlemm. The passageway in the eyes for aqueous fluid to leave the eye.

Traction Retinal Detachment. See Retinal Detachment.

Trichomat. People with normal color vision. See Color Vision Deficiencies.

Ultrasonography. A diagnostic test using ultrasound technology specially calibrated for the eye. It provides a picture of the back of the eye when it cannot be seen by an eye professional.

Uveitis. Inflammation of the uvea, the middle layer of the eye. Different forms of uveitis are related to inflammations to different combinations of structures in the eye, including the iris, ciliary body and choroid.

Vascular Occlusion. Also known as Retina Vein Occlusion. A condition in which a retinal vein becomes obstructed by a blood vessel, which results in a hemorrhages in the retina. This can lead to swelling and lack of oxygen in the retina. The sudden onset of blurred vision or a missing area of vision characterizes a Branch Vein Occlusion. A Central Vein Occlusion results in severe loss of central vision.

Visagraph. See Eye Movement Recording System.

Vision Therapy. An individualized program of treatment for binocular vision dysfunctions, including eye turns, eye tracking difficulties, eye teaming and focusing problems.

Visual Evoked Potentials (VEP). A diagnostic test used to evaluate vision for infants and nonverbal children.

Visual Efficiency Examination (VEE). A series of diagnostic tests performed on children or adults who complain of discomfort when reading or doing work at close range.

Visual Information Processing Evaluation. A series of diagnostic tests most often done on children who are having trouble with schoolwork or individuals who have experienced head trauma.

Vitrectomy. A surgical procedure used to treat patients with severe diabetic retinopathy who have vitreous hemorrhage bleeding in the center of the eye. Blood and vitreous are removed from the eye and replaces with a clear saline solution.

Vitreous. A thick, transparent and colorless substance that fills the center of the eye behind the lens. It is comprised mainly of water and gives the eye its form and shape.

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