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Glossary

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Accommodation
An ocular adjustment for the sharp focusing of objects viewed at different distances is termed as accommodation.

Amblyopia
Amblyopia is defined as unilateral or bilateral partial loss of sight without any ophthalmoscopic sign.

Amsler Grid
It is a test featuring horizontal and vertical lines, usually white on black background, used to test central visual field defects like Macular Degeneration.

Aqueous
It is a clear watery fluid that bathes the inside of the front portion of the eye, providing nutrition to the cornea and the lens.

Age Related Macular Degeneration (ARMD)
It is an age related breakdown of the macula that causes a loss of central vision and even blindness in advanced cases. Watch Macular Degeneration video to learn more about this condition. 

Astigmatism
Astigmatism is a condition wherein the refraction varies in the different meridians of the eye, resulting in refractive errors.

Cataract
cataract is a cloudy or opaque area in the natural lens of the eye. As the opacity thickens, it prevents the light rays from passing through the lens and focusing on the retina.

Color Vision
It is the ability to perceive differences in color, including hue, saturation and brightness.

Conjunctivitis
Conjunctivitis, commonly known as “pink eye” or "red eye", is an inflammation of the membrane (conjunctiva) that covers the eye and lines the inner surface of the eyelid.

Convergence/Divergence
It is the turning of the eyes inwards or outwards so that they are both "aimed" towards the object that is viewed.

Cornea
The cornea is the curved transparent front surface of the eye that focuses light.

Depth Perception
The ability of the visual system to perceive the relative positions of objects in the visual field.

Diplopia
A condition in which a single object is perceived as two; commonly termed double vision.

Emmetropia
A medical term used for Normal vision.

Glaucoma
Is a symptomatic condition of the eye in which the intraocular pressure exceeds the tolerance of the affected eye. Glaucoma usually results in optic nerve damage and irreversible visual field defects.

Hyperopia
Hyperopia or Farsightedness is a refractive error where parallel rays of light come to a focus behind the retina. A patient with hyperopia can see objects in the distance with no problem, however there will be difficulty to focus clearly on near objects.

Intraocular Pressure
The fluid pressure within the eye created by the continual production and drainage of aqueous fluid in the anterior chamber.

Iris
The pigmented structure that gives our eyes their color.

Monovision
A situation where one eye, usually the dominant eye, is corrected for distance, and the other eye is corrected for reading.

Myopia
It is the dioptric condition of the eye in which parallel rays of light come into focus in front of the retina. A person with myopia can focus clearly on close up objects, but distance objects are blurry.

Ocular Hypertension
It is the condition of elevated fluid pressure. The normal pressure is about 10 to 20 mmHg, with the majority of people falling between 13 to 19. A pressure over 20 is considered suspicious and over 24 is cautiously concerned, which warrants immediate investigation. A reading over 30 is very urgent and potentially is an emergency situation.

Optic Nerve
It is the bundle of nerve fibers that connects the eye to the brain.

Ophthalmoscopy
It is an examination of the internal structures of the eye using an illumination and magnification system.

Presbyopia
Presbyopia is the aging eye condition when a person begins to experience difficulty in reading and focusing on close up objects. It is usually first noticed around the age of 45 years and is a progressive condition.

Pupil
The pupil is an aperture in the middle of the iris that determines the amount of light entering the eye.

Refraction
Determination of the optical refractive errors of the eye.

Refractive Error
Refractive error is the degree to which images received by the eyes are not focused on the retina.

Retina
The innermost layer of the eyeball. It is the tissue that transforms light into electrical impulses that are transmitted to the brain to create our sense of vision.

Retinal Detachment
The separation of the retina from its normal location covering the inner surface of the back portion of the eye. Watch Retinal Detachment video to learn more about this condition.

Strabismus
The medical term meaning a misalignment of the eyes. Strabismus is a lack of coordinated muscle movement or focusing ability between the eyes, causing the eyes to point in different directions.

Visual Acuity
The clearness of vision, which depends upon the sharpness of the retinal image.

Visual Field
The area of space visible to an eye in a given position of gaze. There is central visual field, which is directly in front of us, and peripheral visual field, which we perceive as our "side vision".

Vitreous
The gel like transparent fluid substance filling the posterior four fifths of the globe between the crystalline lens and retina.