Sperian Titmus V2 User Manual

Page 24
Titmus V4 / Titmus V2
Glossary of Eye Care Terms
A
Accommodation – eye’s ability to automatically change
focus from seeing at one distance to seeing at another.
Achromatic – being colorless or without color.
Amblyopia – the loss of vision without any apparent
cause. Also known as “lazy eye.”
Astigmatism – condition in which the cornea’s
curvature is asymmetrical (the eye is shaped like a
football or egg instead of a baseball). Light rays are
focused at two points on the retina rather than one,
resulting in blurred vision. Additional symptoms include
distorted vision, eyestrain, shadows on letters, squinting
and double vision.
B
Bifocals – two powers in one lens, usually for near and
distance correction.
Binocular vision – coordinated use of the two eyes.
C
Cataract – cloudiness or opacity of the crystalline lens,
preventing clear vision, often caused by aging.
Color deficiency – inability to recognize certain colors,
specifically shades of red and green. Often referred to as
“color blindness” and is usually hereditary.
Convergence – eyes’ ability to turn inward. People with
convergence insufficiency have trouble (eyestrain,
blurred vision, etc.) with near tasks such as reading.
Cornea – the clear part of the eye covering the iris and
pupil; it lets light into the eye, permitting sight.
Crossed eyes – see Esotropia.
D
Dark adaptation – increase in the sensitivity of the eye
to detect light in the darkness or dim light.
Depth perception – the ability to distinguish the relative
distance of objects in visual space.
Diopter – often written as “D.” The unit of measure of
lens power. A lens having one diopter of refractive
power will bring parallel rays of light to focus at a
distance of one meter.
Diplopia – also known as double vision; the perception
of two images yet being only one object.
Distance vision – the ability to see objects clearly at 20
ft. to infinity.
Divergence – the slight turning out to adjust the eyes to
a distant object.
E
Emmetropia – the normal refractive condition of the eye
in which there is clear focus of light on the retina.
Esophoria – a muscle condition in which both eyes are
open and each eye looks directly at a target, but, when
covering one eye, the covered eye turns inwards.
Esotropia – “crossed eyes,” a tendency of the eye to
turn inward toward the nose, when both eyes are open.
Exophoria – a muscle condition in which both eyes are
open and each eye looks directly at a target, but, when
covering one eye, the
covered eye turns outwards.
Exotropia – “wall eyes,” this is a tendency of the eye to
turn outward, away from the nose, when both eyes are
open.
F
Far Vision – distance vision.
Farsightedness – see Hyperopia.
Field of vision – the entire area which can be seen at
one time without shifting the head or the eyes.
Fixation – directing the eye so the image centers on the
fovea.
Fovea – area of clearest vision on the retina.
Fusion
– coordination of the images seen by each eye
into one picture.
G
Glare – bright light which causes discomfort and loss of
vision.
Glaucoma – condition caused by increased intraocular
pressure which damages the optic nerve.
H
Heterophoria – a squint due to a weak muscle.
Hyperopia – also called farsightedness. Condition in
which the length of the eye is too short, causing light
rays to focus behind the retina rather than on it,
resulting in blurred near vision. Additional symptoms
include eyestrain and squinting.
Hyperphoria – a tendency for one eye to deviate
upward.
Hypophoria – one eye in the line of sight depressed
relative to the other eye.
I
Intermediate vision — the area of vision between 20
and 40 inches.
Iris – the pigmented area behind the cornea that gives
color to the eye (e.g., blue eyes). The cornea controls the
amount of light entering the eye by changing the size of
the pupil.
L
Lateral Phoria – a Muscle Balance Test to define a value
for the balance of the eyes, in the horizontal direction,
that identifies Esophoria, Exophoria, and Orthophoria.
Lazy eye – see Amblyopia.
Legal blindness – the best-corrected visual acuity of
20/200 or less.
Lens – 1. The nearly spherical body in the eye, located
behind the cornea that focuses light rays onto the retina.
2. A device used to focus light into the eye in order to
magnify or minimizes images, or otherwise correct
visual problems. Eyeglass lenses, contact lenses, and
intraocular lenses are some examples.
M
Macula – part of the eye near the middle of the retina;
the macula allows us to see objects with great detail.

Sperian Titmus V2 Specifications

General

Brand	Sperian
Model	Titmus V2
Category	Medical Equipment
Language	English