Suppression Tests: worth 4 dot and 4BO test Flashcards
what is Worth’s 0 degree of fusion
no sensory fusion- suppression/monocular vision (may also have diplopia)
What two tests can be used when central suppression scotoma is suspected
Worth a-Dot and 4-Prism Base Out tests
what is Worth’s 1st degree of fusion
simultaneous fusion- diplopia/confusion
what is Worth’s 2nd degree of fusion
flat fusion/superimposition- no diplopia, no stereo, has motor fusion
what is Worth’s 3rd degree of fusion
stereopsis (highest degree)- ultimate sensory fusion
how do you test for the highest level of stereopsis (degree 3)
use Randot (VAC) stereo test
what is suspected if the patient has less than 40 sec of arc on the Randot stereo test
suspect suppression or a central scotoma
what test is used for flat fusion (degree 2)
the Worth 4 Dot test
what must the patient have in order to do the Worth 4 Dot test
flat fusion at 40cm
what does the Worth 4 Dot test for
binocular central suppression scotoma
when do you stop moving away from the patient with the Worth 4 Dot test
when there is a change in the number of dots seen or 3m
what happens if the patient covers one eye and the dots reappear
the patient has a scotoma under binocular conditions
what happens if the patient covers one eye and the dots do not reappear
the scotoma is under monocular conditions of the eye uncovered (check both eyes separately)
how many dots should the patient be able to see with only the OD
2 red
how many dots should the patient be able to see with only the OS
3 green
what does the patient have if they see 2 red dots binocularly
they are suppressing OS
what does the patient have if they see 3 green dots binocularly
suppressing OD
what does the patient have if they see 5 dots binocularly
not fusing images - diplopia
what does the patient have if they see 5 dots and the red dots are to their right
uncrossed diplopia (ESO deviation)
what does the patient have if they see 5 dots and the red dots are to their left
crossed diplopia (EXO deviation)
what does the patient have if they see 5 dots and the red dots are below the green dots
Right hyper-deviation
what does the patient have if they see 5 dots and the red dots are above the green dots
left hyper-deviation
what 3 things do you record for the Worth 4 Dot test
test distance, fusion or suppression, and Exo, Eso, R hyper or L hyper
what are 4 situations you would want to use the Worth 4 Dot test
determine suppressing eye (less than 40 sec arc), differential diagnosis of unilateral decreased VA (NIPH), detect small unilateral central scotomas, and preschool children
when would you use a 4BO prism test
to check for central scotomas (slightly reduced VA, mildly reduced stereo (30-80 sec arc), small angle strabismus, and macular diseases)
what type of target does the patient look at during the 4BO prism test
a single letter one line above better seeing eye
what is a normal response to the 4BO prism test
version and vergence on both eyes (separately)
what is an abnormal response to the 4BO prism test
neither eye moves in response to the prism (the eye that doesn’t move = suppressing eye because no diplopia occurred)
