Assessing the Deviation

Question 1

3 categories of Ocular Deviation or misalignment?

Answer 1

1. Heterophoria
2. Heterotropia
3. Fixation Disparity

Question 2

Eye movement must be ___________ to be a phoria

Answer 2

latent

Question 3

Is heterophoria measured under associated or dissociated conditions?

Answer 3

dissociated

Question 4

Von Graefe, Prism and alternate cover test, Maddox rod and modified thorington card are all techniques to measure what type of misalignment?

Answer 4

Heterophoria

Question 5

Is Heterotropia manifest or latent?

Answer 5

manifest

Question 6

Is heterotropia measured under associated or disocciated conditions?

Answer 6

associated

Question 7

What are the techniques used to measure heterotropia?

Answer 7

Unilateral cover test, simultaneous prism cover test, Hirschberg

Question 8

What do we call a small misalignment that occurs even while fusion is present?

Answer 8

fixation disparity

Question 9

Is fixation disparity measured under associated or disociated conditions?

Answer 9

associated

Unit: minutes of arc

Question 10

Disparometer, Saladin or Wesson cards and the Bernell Box are used to measure which type of ocular misalignment?

Answer 10

Fixation disparity

Question 11

prismatic effects of high Rx

Does high plus increase or decrease the devation?

Answer 11

decrease

BO induced for ET; BI induced for XT

High minus will increase the devation

Question 12

What is the typical value for Angle Kappa?

Angle Kappa: anatomical; angle between pupillary and visual axis

Answer 12

+0.50 mm

(+)= nasal

Question 13

Hirschberg is performed monocular/binocular while Kappa is performed monocular/binocular

Answer 13

binocular, monocular

We compare the measurements from both, if there is a difference, then strabismus is suggested

Question 14

When do we use Hirschberg/Kappa to determine the presence of strabismus?

Answer 14

Very young patients or patients with very poor monocular VA

Question 15

What are the corneal reflex locations for the following deviations?
1. Esotropes
2. Exotropes
3. Hypertrope
4. Hypotrope

Answer 15

1. Temporal
2. Nasal
3. Inferior
4. Superior

Question 16

What type of deviations are the following atypical head positions associated with?
1. Tilt
2. Tip
3. Turn

Answer 16

1. possible cyclo/ vertical
2. possible A/V pattern
3. Possible horizontal muscle/ nerve, null point

Question 17

Do the following factors magnify ET or XT?
* negative angle kappa
* wide nose bridge
* prominent epicanthal folds
* small PD
* Wide Face

Answer 17

ET

XT is magnified by opposite factors: large PD; absence of epicanthal folds; narrow nose bridge and positive angle kappa

Question 18

what important quality about a deviation is NOT identified by performing PACT?

Answer 18

laterality

can ONLY report amount and direction of prism used to neutralize

Question 19

When is a vertical deviation considered primary?

Answer 19

When it is present with horizontal neutralization

Secondary: vertical no longer present after horizontal neutralization

Question 20

During Simultaneous Prism Cover Test, which eye gets the prism and which gets the occluder placed in front of it?

Answer 20

deviated eye: prism; non-deviated eye: occluder

Question 21

What type of deviation MUST be present to perform simultaneous prism cover test?

Answer 21

manifest- either constant or high frequency intermittent (90+%)

Question 22

Why can’t we stack prisms in the same plane?

Answer 22

Resultant power is stronger than simple addition

CAN stack in opposite planes (ie BI with BD)

Question 24

Which test determines small angle strabismus?

Answer 24

4 BO prism test

Question 25

How is the magnitude of cyclo determined when performing double Maddox Rod?

Answer 25

rotate Maddox rod lenses until lines are parallel, then read straight off of trial frame (if rotated 5 degrees outward, then 5 degrees excyclo)