Vision Screening Flashcards
most important measure of functional pathway
Visual acuity
Visual acuity is a measure of
functional pathway/ visual integrity
importance of visual acuity
report level of preservation or degradation and detect amblyopia and monitor the effectiveness of treatment
impairment of vision not due to organic damage or refractive errors
amblyopia
Child born with 20/100 vision (high refractive error) mut be treated within
7 years
Baby with congenital cataracts needs to be operated within
3 months
congenital cataract if not treated will lead to
irreversible amblyopia
congenital misalignments must be corrected within
2 years
congenital misalignment if not treated, will lead to
underdevelopment of stereopsis
disorders that may be brought about by use of steroids
retinal/optic disorders
intracranial hypertension may cause
papilledema
Types of Visual acuity
- recognition acuity
2. resolution acuity
most common measure of spatial vision and involve the resolution of featural differences in familiar
targets.
Recognition acuity
Detection of a target having two or more parts
Resolution acuity
(alternating black and white stripes
grating
Uses the alternating segments of black and white
stripes which must be presented to the patient to
determine their fixation preference in such patterns
Resolution acuity
A rhythmic jerk nystagmus occurring when one is
looking at constantly moving objects.
OPTOKINETIC NYSTAGMUS
small rapid jerky movement of the eye esp. as it
jumps from fixation on one point to another (as in
reading); can move from one visual stimuli to another
SACCADE
The adjustment of the eye for various distances
whereby it is able to focus the image of an object on the
retina by changing the curvature of the lens. The ability
of the eye to accommodate decreases with age.
- ACCOMMODATION
Tests vision of one eye; foveal fixation and quality
MONONUCLEAR FIXATION TESTING
Foveal fixation involves fixation using
macula
Fixation Preference Test; tests presence of amblyopia
binocular fixation
what is herring’s law
where one eye goes, the other eye
follows. Both eyes will elevate if the left eye is fixing
involuntary pursuit response to moving
stripes filling up most of the visual field
OKN (Optokinetic nystagmus)
types of fixation testing
mononuclear fixation binocular fixation OKN Forced choice preferential looking visual evoked response
Confirmatory test for suspected cortically-blind patients
VISUAL EVOKED RESPONSE (VER)
VER measures the
summed occipital cortical response to
pattern stimulus
Visual acuity assessment for verbal (preliterate) children
allen picture cards HOTV test Lea symbols Landolt rings tumbling E test
Visual acuity assessment for verbal (literate) children
Snellen chart
HOTV letters are chosen because
they don’t have laterality and are easily recognizable
figures included in lea symbols
apple square and circle
Discontinuous circles (letter Cs
Landolt rings
Low vision tests
count fingers
hand motion
light perception
total blindness
