A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z


A congestion of blood vessels.
Relative to an imaginary point centrally located within the eye; closer to this imaginary point.
The tilting of the upper part of the vertical meridian of the eye toward the mid-line of the face.
Intraocular Lens (IOL)

in-trah-AWK-yew-ler lenz

An artificial lens which is implanted in place of a damaged or diseased natural lens. Intraocular lenses are commonly used in cataract surgical procedures to replace the eye's clouded lens.

intraocular lens
lens implants
multifocal IOL

Additional keywords and misspellings:
IOL fake lens artificial intraocular lens

Intraocular Pressure (IOP)

in-trah-AWK-yew-ler PRESH-sher

The pressure inside the eye is created by the flow and drainage of the aqueous fluid (the clear fluid inside the eye) from the anterior chamber into the trabecular meshwork. An increase in pressure can result when the drainage passages become clogged or blocked. This can cause pressure within the eye to increase and damage the optic nerve.

What can be done?
A procedure called Tonometry is used to measure internal pressure of the eye. If the pressure is too high, the person may be diagnosed with glaucoma. Prescription eyedrops may be used to lower the pressure, and in severe cases, surgery may be necessary.

Since abnormal pressures usually don’t cause symptoms, it’s very important to have the pressure checked regularly.

Additional keywords and misspellings:
IOP glaucoma test pressure check tonometry interocular

Intraretinal hemmorhage

in-trah-REH-ti-nahl HEM-oh-rahj

Bleeding in the inner layers of the retina of the eye, often associated with Diabetic Retinopathy.

Incarceration of a portion of the iris in a wound at the limbus, either accidentally or as an operative procedure for management of glaucoma.
An inflammation of the iris and ciliary body; also known as anterior uveitis.
A paralysis of the iris sphincter and ciliary muscles resulting in pupillary dilatation and loss of accommodation.
The vibration of the iris with movement of the eye, indicating loss of lens support.


The colored "diaphragm" of the eye, which constricts and dilates the pupil to control the amount of light let into the eye.

iris diagram
human iris
Iris bombé
The bowing forward of the iris due to build up of aqueous humor in the posterior chamber (due to total or substantial posterior synechia).


A condition in which the iris becomes inflamed. It can be caused by an injury to the eye, juvenile rheumatoid arthritis, sarcoidosis, ankylosing spondylitis, Reiter's syndrome, syphillis or herpes zoster; often, there is no explanation. Some complications of this condition can be vision-threatening and include cataracts, macular edema and glaucoma. If untreated, blindness can occur in one or both eyes. Some complications of this condition can be vision-threatening and include cataracts, macular edema and glaucoma.

Additional keywords and misspellings:
eyeritis irtis

The Eye Encyclopedia is a collection of eye care terminology created by practicing optometrists and ophthalmologists. The information provided is not intended to be a substitute for regular medical care or to diagnose or treat any medical condition, and should be used only as a supplemental source of information. Please consult your doctor if you have any questions or concerns about your eye health.