Cover-Uncover Test Quiz and Flashcards

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Questions and Answers

What is the term for the position of the eye when looking straight ahead with the visual axis parallel to the sagittal plane of the head?

Heterotropia

Orthophoria

Primary position of gaze (correct)

Heterophoria

What is the characteristic of heterophoria?

It is a manifest deviation

It is a condition in which the lines of sight meet at the object of regard, even when one eye is occluded

It is a latent deviation that can be observed only when one eye is covered (correct)

It is a type of tropia

What is the term for the ocular condition in which the two lines of sight meet at the object of regard, even when one eye is occluded?

Heterophoria

Heterotropia

Orthophoria (correct)

Primary position of gaze

What type of deviation is characterized by a manifest deviation that can be directly observed when looking at the patient's eyes?

Heterotropia Signup and view all the answers

What is the purpose of the cover test?

To observe the deviation when one eye is covered Signup and view all the answers

Which type of deviation can be intermittent?

Heterotropia Signup and view all the answers

What is the primary objective of the cover test in phoria and tropia testing?

To identify the presence and direction of ocular deviations Signup and view all the answers

What is the purpose of the fixation target in the cover test?

To keep the patient's attention to the target for active and stable accommodation Signup and view all the answers

What is the difference between the unilateral cover test and the alternate cover test?

The unilateral cover test measures the manifest deviation, while the alternate cover test measures the total deviation Signup and view all the answers

What is the purpose of the prism base cover test?

To measure the magnitude of total deviation Signup and view all the answers

What is the advantage of using room lights on during the cover test?

It helps to see ocular deviations better Signup and view all the answers

What is the purpose of the simultaneous cover test?

To measure the magnitude of manifest deviation Signup and view all the answers

What is the primary purpose of the cover-uncover test?

To distinguish between phoria and tropia Signup and view all the answers

In the alternating cover test, how long should one eye be covered?

2-3 seconds Signup and view all the answers

What does the unilateral cover test confirm?

Tropia Signup and view all the answers

How is left esotropia recorded?

LST Signup and view all the answers

What is the purpose of the prism bar cover test?

To measure the magnitude of deviation Signup and view all the answers

What is the direction of the base of the prism in a right exotropia?

Base in Signup and view all the answers

What happens when the fixating eye is covered in esotropia?

The deviating eye takes an outward deviation Signup and view all the answers

What is the purpose of prism neutralisation?

To shift the image position so that the light from the object of regard falls onto the fovea Signup and view all the answers

Study Notes

Ocular Deviations

Ocular condition in which the two lines of sight meet at the object of regard, even when one eye is occluded, is called Orthophoria.

Cover Tests

Cover Uncover Test: • Introduce cover in front of one eye first • Observe response of the other eye • Remove cover to allow viewing under habitual condition • Repeat 2-3 times • If eye movement seen in not covered eye - tropia • If eye movement seen in just uncovered eye - phoria • Only test to distinguish phoria from tropia
Alternating Cover Test: • Cover one eye for 2-3 seconds • Observe movement in the uncovered eye • Remove cover from one eye and transfer to fellow eye • Prevent binocular viewing • Total deviation = latent + manifest • Observe type of deviation - exo/eso/vertical • Estimate total angle of deviation using prisms

Prism Bar Cover Test

Measure magnitude of deviation
Total deviation = latent + manifest
Apex of prism toward deviation to neutralize it
Base of prism opposite to deviation

Prism Neutralization

Right exotropia → base in prism is used to neutralize
Prism shifts image position, so light from object of regard falls onto fovea

Phoria and Tropia Testing

Objective tests: • Cover Test • Hirschberg test using pen torch
Subjective tests: • Howell card • Maddox Rod • Modified Thorington • Maddox wing • Prism dissociation (von Graefe test)

Target for Cover Test

Requires patient cooperation to fixate
Fixation target - one line better than BCVA for distance
Keep patient's attention to target (20/30 target) for active and stable accommodation
Single letter
Room lights on for better view of ocular deviations
Do not block patient's view for distance viewing

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Description

This quiz covers the steps and observations of the Cover-Uncover Test and Alternating Cover Test, used to distinguish between phoria and tropia.

Cover-Uncover Test and Alternating Cover Test

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