Dr. Jensen - Intro to Phorometry

Question 1

What type of fusion process images on the retina and are combined into a single precept?

Answer 1

Sensory Fusion

Question 2

What is Binocular vision?

Answer 2

Occurs when retinal images of a fixated object for the 2 eyes are in good focus and on the fovea.

Question 3

What is the term called when points on the retina, when sperately stimulated produce perceptions that are of identical direction?

Answer 3

Corresponding Retinal Points

Question 4

What is Panum’s Fusional Area?

Answer 4

Fusion that is possible when 2 retinal images of an object are NOT formed on corresponding retinal points but one eye can produce sensory fusion.

Question 5

What is cyclovergence?

Answer 5

Eyes will rotate in the socket clockwise or counter-clockwise.

Question 6

What is motor fusion?

Answer 6

vergenence movements made in response to retinal disparity leading to the image on corresponding points so sensory fusion can occur.

Question 7

What is the formula you use for convergence demand?

Answer 7

Prism Diopters = pd x (1/distance)

Question 8

How is convergence maintained with Tonic Convergence?

Answer 8

By the EOM’s. The tonic measurement of the physiological position of rest to the known phoria position or tonic equilibrium.

Question 9

What is Accommodative convergence?

Answer 9

Convergence with the stimulus of accommodation

Question 10

What is the TRIAD response of Accommodative convergence?

Answer 10

Accommodation, convergence and miosis

Question 11

What is the AC/A ratio?

Answer 11

Accommodation convergence/accomodation. This measures the relationship between the two.

Question 12

What type of convergence is due to awarness or impression of nearness of an object?

Answer 12

Proximal.

Note: Influenced bye retinal image size, cue to nearness. The phoropter can generate this effect.

Question 13

What type of vergence has an autonomic response to retinal disparity, either at far extremeties of Panum’s area or away from it?

Answer 13

Fusional Vergence.

Note: Positive - converge

Question 14

True or False. Heterophoria is a latent deviation and manifests in both sensory and motor fusion are both broken?

Answer 14

False. Manifests only with Sensory fusion is broken

Question 15

What is Incyclophoria?

Answer 15

When the tops of the corneal vertical meridians incline towards each other.

Note: Excyclophoria - away from each other.

Question 16

What method do you use to measure distance phoria?

Answer 16

Von Graefe - alignment method.

Note: For near you use Von Graefe’s but you can use modified thorington

Question 17

What should be the setting on the Risley prism when measuring horizontal phorias?

Answer 17

OD: 12 BI
OS: 6 BO

Note: when moving the prism’s the rate should be 2PD/second

Question 18

When measuring lateral phoria, what would be the finding when the risley prism would be set to zero, BI and BO?

Answer 18

Zero = Ortho
BI = exophoria
BO = esophoria

Question 19

True or False. When measuring phoria’s, it is the image that moves not the eye.

Answer 19

True.

Question 20

True or False. When conducting vertical vergences, you always look for break and recovery only.

Answer 20

True.

Question 21

When measuring vertical vergences, what is another name when using BD?

Answer 21

Supravergence.

Note: RBD = LBU