Amblyopia |
“Dimness of vision,” amblyopia is a common visual impairment. It is commonly referred to as “lazy eye;” this condition can occur when there is considerable difference in refractive error between the two eyes of an individual. If uncorrected, amblyopia may lead to irreversible vision loss. This condition is not usually correctable by a spectacle lens. |
Ametropic |
Imperfection in the refractive powers of the eye so that images are not brought to a proper focus on the retina; includes hyperopia, myopia and astigmatism. |
Anisometropia |
A condition in which the two eyes have different refractive errors requiring a different lens correction for each eye. |
Astigmatism |
A defect in curvature of the cornea or lens of the eye. As a result, a ray of light is not sharply focused on the retina but is spread irregularly. |
Asymmetry |
Unequal size, shape, position or brightness between the right and left eyes related to eye lids, pupils, crescents, corneal reflext and red reflext. |
Blur Circle |
A blurred image of the light reflecting back off the retina in the eye with a refractive error. The reflected blurred image is detected by the camera as a bright white crescent. |
Cataracts |
Partial or complete loss of the transparency of the crystalline lens or its capsule. |
Corneal Light Reflection |
The pinpoint image of light reflecting back off the cornea, also known as the Hirschberg Corneal Light Reflex. |
Curvilinear |
Consisting of or bounded by curved lines following the edge of the pupil. |
Esotropia |
One eye is turned inward; often called “cross-eyed.” |
Exotropia |
One eye is turned outward; often called “walled-eyed.” |
Fixate |
To focus one’s gaze on an object. |
Hyperopia |
Farsightedness; a person can see distant objects more clearly than close objects. A refractive error in which the eyeball is too short from front to back or the refractive power of the eye too weak, so that parallel rays of light are brought to a focus behind the retina. Farsightedness, a condition requiring convex (plus) lens to correct. |
Hypertropia |
One eye turned upward. |
Lazy Eye |
See amblyopia. |
LED |
Light Emitting Diode, different colored lights often used on electronic displays for indication of an operation or active function. |
Media Opacity |
Any obstruction or opacity in the visual pathway within the eye. This can be caused by corneal scars, cataracts, etc. |
Misalignment |
A muscle inbalance where the two eyes are not aligned either horizontally, vertically or both. See strabismus. |
Myopia |
Nearsightedness; a person can see near objects clearly while distant objects appear blurred. A refractive error in whch the eyeball is too long or the refractive power too strong, so that parallel rays of light are focused in front of the retina. Nearsightedness, a condition requiring a concave (minus) lens to correct. |
Null Interval |
Area of camera insensitivity to minimum degrees of refractive error (+0.50 of hyperopia to -1.00 of myopia.) |
Ocular Media |
The eye’s clear cornea, pupil, crystalline lens and vitreous fluid which transmits light to the retina or intermembrane of the eye. |
Peripheral Edge Effect |
Small crescents seen around the edge of the pupil which are often due to an edge effect in the pupil or a lens aberration. This effect can be present on the PhotoScreener™ film image and is not a cause for failure. |
Ptosis |
The drooping of the upper eyelid and asymmetry of lid height. |
Red Reflex |
The retinal or fundus reflection of the eye’s interior caused by illumination. The red reflex captured by the PhotoScreener™ will appear gray with the special high speed, black and white film used. |
Refractive Error |
A defect in the eye that prevents light rays from being brought to a sharp focus exactly on the retina. The amount of myopia, hyperopia or astigmatism present in the eye. |
Retina |
The sensory membrane that lines the eye, receives the image formed by the lens, is the immediate instrument of vision, and is connected with the brain by the optic nerve. |
Shutter |
A camera attachment that exposes the film or plate by opening and closing an aperture. |
Strabismus |
The two eyes are not directed at the same point: misalignment of the eyes. |
Strobe |
A device that uses a flashtube for high-speed illumination. Also referred to as a flash or camera flash. |
