3RD LECTURE Flashcards
(24 cards)
What is the primary aim of clinical eye movement testing?
To introduce the student to clinical eye movement testing techniques.
This is part of the learning outcomes for undergraduate orthoptists.
What are the learning outcomes for an undergraduate orthoptist after clinical placement 1c?
Assess ocular movements, discuss management for strabismus, appreciate refractive error’s role.
These outcomes focus on both clinical skills and theoretical understanding.
What are the four ocular motor systems?
- Saccades
- Smooth Pursuit
- Vergence
- Optokinetic / Vestibular
Define saccades.
Rapid movements of the eyes that abruptly change the point of fixation.
What is the purpose of saccades?
To shift the fovea to objects of visual interest.
What is the normal latency for generating saccades?
About 200 ms.
What is the typical range of peak velocities for saccades?
60 °/s to 600 °/s for movements of 1 to 30 ° in amplitude.
What does the saccadic system use to initiate and maintain eye position?
A pulse and step firing pattern.
What does a pulse-step firing pattern consist of?
- Pulse initiates the saccade
- Step maintains the new eye position
What can impaired saccades significantly impact?
- Reading
- Writing
- Following sport
- General day-to-day viewing
What is the function of the pursuit system?
To maintain stable eye tracking of a moving object on the fovea.
What is the normal latency for smooth pursuit?
About 100 ms.
What is ‘gain’ in the context of the pursuit system?
The ratio of eye velocity to target velocity.
Fill in the blank: The vergence system functions to maintain _______ alignment.
binocular
What are the two types of eye movements associated with vergence?
- Convergence
- Divergence
What is the purpose of the vestibular system?
To maintain stable retinal images during head movement.
What sensory signals contribute to the vestibular system?
- Labyrinthine semicircular canals
- Otoliths
- Visual system
What is the normal response during caloric testing with cold water?
Nystagmus with fast phase to the opposite side.
What does a positive response in the spinning baby test indicate?
An intact brainstem.
What is the primary purpose of the OKN system?
To maintain stable retinal image during head movement.
What is the typical testing method for OKN?
Using a black & white striped drum rotated at a constant velocity.
What is recorded when assessing smooth pursuit?
- Smoothness of movement
- Accuracy of tracking
What conditions can be assessed through abnormal saccades?
Some supra/internuclear conditions.
What is the maximum velocity of pure vergence movements?
About 20 °/sec.
