Suppression Tests: worth 4 dot and 4BO test

Question 1

what is Worth’s 0 degree of fusion

Answer 1

no sensory fusion- suppression/monocular vision (may also have diplopia)

Question 2

What two tests can be used when central suppression scotoma is suspected

Answer 2

Worth a-Dot and 4-Prism Base Out tests

Question 3

what is Worth’s 1st degree of fusion

Answer 3

simultaneous fusion- diplopia/confusion

Question 4

what is Worth’s 2nd degree of fusion

Answer 4

flat fusion/superimposition- no diplopia, no stereo, has motor fusion

Question 5

what is Worth’s 3rd degree of fusion

Answer 5

stereopsis (highest degree)- ultimate sensory fusion

Question 6

how do you test for the highest level of stereopsis (degree 3)

Answer 6

use Randot (VAC) stereo test

Question 7

what is suspected if the patient has less than 40 sec of arc on the Randot stereo test

Answer 7

suspect suppression or a central scotoma

Question 8

what test is used for flat fusion (degree 2)

Answer 8

the Worth 4 Dot test

Question 9

what must the patient have in order to do the Worth 4 Dot test

Answer 9

flat fusion at 40cm

Question 10

what does the Worth 4 Dot test for

Answer 10

binocular central suppression scotoma

Question 11

when do you stop moving away from the patient with the Worth 4 Dot test

Answer 11

when there is a change in the number of dots seen or 3m

Question 12

what happens if the patient covers one eye and the dots reappear

Answer 12

the patient has a scotoma under binocular conditions

Question 13

what happens if the patient covers one eye and the dots do not reappear

Answer 13

the scotoma is under monocular conditions of the eye uncovered (check both eyes separately)

Question 14

how many dots should the patient be able to see with only the OD

Answer 14

2 red

Question 15

how many dots should the patient be able to see with only the OS

Answer 15

3 green

Question 16

what does the patient have if they see 2 red dots binocularly

Answer 16

they are suppressing OS

Question 17

what does the patient have if they see 3 green dots binocularly

Answer 17

suppressing OD

Question 18

what does the patient have if they see 5 dots binocularly

Answer 18

not fusing images - diplopia

Question 19

what does the patient have if they see 5 dots and the red dots are to their right

Answer 19

uncrossed diplopia (ESO deviation)

Question 20

what does the patient have if they see 5 dots and the red dots are to their left

Answer 20

crossed diplopia (EXO deviation)

Question 21

what does the patient have if they see 5 dots and the red dots are below the green dots

Answer 21

Right hyper-deviation

Question 22

what does the patient have if they see 5 dots and the red dots are above the green dots

Answer 22

left hyper-deviation

Question 23

what 3 things do you record for the Worth 4 Dot test

Answer 23

test distance, fusion or suppression, and Exo, Eso, R hyper or L hyper

Question 24

what are 4 situations you would want to use the Worth 4 Dot test

Answer 24

determine suppressing eye (less than 40 sec arc), differential diagnosis of unilateral decreased VA (NIPH), detect small unilateral central scotomas, and preschool children

Question 25

when would you use a 4BO prism test

Answer 25

to check for central scotomas (slightly reduced VA, mildly reduced stereo (30-80 sec arc), small angle strabismus, and macular diseases)

Question 26

what type of target does the patient look at during the 4BO prism test

Answer 26

a single letter one line above better seeing eye

Question 27

what is a normal response to the 4BO prism test

Answer 27

version and vergence on both eyes (separately)

Question 28

what is an abnormal response to the 4BO prism test

Answer 28

neither eye moves in response to the prism (the eye that doesn’t move = suppressing eye because no diplopia occurred)