Optometric Terms Flashcards
“A pattern”
a horizontal deviation may be different in upgaze versus downgaze
an “A pattern” deviation shows more eso in upgaze
abduction
movement of the eyes away from the nose
accommodation
the act of focusing the eyes to provide an image clear enough for interpretation
the stimulus to accommodation may come from blur on the retina, or perceived awareness of the proximity of a target
when looking at near objects, accommodation is said to be
“stimulated”
when looking at far objects, accommodation is said to be
“relaxed”
Accommodation is part of the what system?
“idenitifcation system” it tells us the “what is it?” of what we are looking at
accommodative amplitude
the range of distance or lens power over which the patient can stimulate focus to maintain clarity
accommodative insufficiency
a patient who shows a reduced accommodative amplitude
accommodative flexibility
ease with which accommodation can be changed from one distance to another
accommodative infacility
a patient who has reduced accommodative flexibility
accommodative spasm
difficulty releasing (relaxing) accommodation
acquired brain injury (ABI)
- refers to damage to the brain acquired after birth
- It usually affects cognitive, physical, emotional, social or independent functioning
- It can result from TBI (i.e. accidents, falls, assaults, etc.) and nontraumatic brain injury (i.e. cerebral palsy, stroke, brain tumors, infection, poisoning, hypoxia, ischemia, or substance abuse)
visual acuity (VA)
- clearness or sharpness of sight
- the ability to resolve or discriminate contours and to tell when there is a separation of the contour from its background
In the US, visual acuity is usually represented as
A fraction which identifies the size of the smallest letters resolved at the testing distance used
numerator: testing distance used (typically 20’)
denominator: size of the letter read
adduction
movement of the eyes toward the nose
afterimage
a visual sensation that persists after the original light stimulation has ceased
alternating
switching from one eye to the other (in relation to strabismus, it means that either eye may fixate while the other eye deviates)
amblyopia
visual condition in which there is a low or reduced central visual acuity that cannot be “corrected” by traditional refractive means (eg. glasses or contact lenses)
and which is not attributable to disease, injury, or pathology
Amblyopia is said to exist when
there is a set level of acuity, typically 20/40 or worse
or when a difference of 2 or more Snellen acuity lines between the eyes is present
Behaviorally, amblypoia is looked upon as
a dysfunction that hinders a patient’s ability to gather, process, analyze, and respond to visual information in a meaningul way
functional ambloypia
(amblyopia ex anopsia) usually one or more of the following conditions is present before the age of 6:
- significant anisometropia
- constant unilateral esotropia or exotropia
- significant isometropia
- significant unilateral or bilateral astigmatism
- image degradation
Binocular competition in an amblyopic patient causes
adaptations to be made via neural suppression, leading to reduced VA and dysfunctions in the amblyopic eye in such skills as:
- ocular motility
- fixation
- accommodation
- spatial sense
- speed of perception
Vision therapy has a high rate of success for patients with functional amblyopia by improving:
visual acuity and developing abilities in the visual functional areas that are commonly affected by this condition
- ocular motility
- fixation
- accommodation
- spatial sense
- speed of perception
anaglyph
used to provide a stereoscopic 3D effect, when viewed with special anaglyph glasses (each lens a different color, usually red and green or red and blue)
Images are made up of 2 color layers, superimposed, but offset with respect to each other to produce a depth effect. The picture contains two differently filtered colored images, one for each eye. When viewed through anaglyph glasses they produce a unified stereoscopic image