Anatomy
What bones make up the floor of the orbit?
Maxilla, Palatine, Zygomatic
What are the sections of the brain, usually taken by an MRI?
Axial = Horizontal Section, Coronal = Frontal Section, Sagittal = Medial Section
What are normal retinal correspondence?
Retinal elements in each eye that share a common visual direction
What is the vestibulo-ocular reflex?
Key Features of eye movements
Latency, Velocity, and Accuracy
What muscle surrounds the eye that closes the lid and what CN innervates it?
Obicularis oculi
What is the LGN and what is it's purpose?
Lateral Geniculate Nucleus; a crucial structure in the thalamus that acts as a relay station for visual information from the retina to the visual cortex
Compare Visual confusion to Diplopia.
Visual confusion is two dissimilar objects superimposed in the same location while Diplopia is the same image perceived in two different locations.
What is the Optokinetic Reflex and what tool is used in clinic to test it?
An involuntary movement that keeps a moving target on the fovea, by completing a smooth pursuit followed by a fast saccade. An OKN drum is used in clinic to test this reflex.
What is the purpose of vestibulo-ocular reflex?
To hold images steady on the retina during brief head rotations
What is the main artery that supplies blood to the eye?
The Ophthalmic Artery
What are the elements of the near triad components and what is it used for?
Accommodation, Convergence, Pupil constriction
Brings image into focus on corresponding retinal points
Which form of suppression is present only under binocular conditions w/o a scotoma when monocular?
Facultative
What are the central vestibular pathways and what are the vestibular nuclei that is signals?
To process information from the peripheral vestibular organs to maintain balance and eye stability. Nuclei that are signaled: Cerebellum, Spinal Cord, Cerebral cortex, and Oculomotor nerve nuclei via the MLF
What is the difference between a pursuit and a saccade? What brain structure signals them?
A smooth pursuit is to hold the image of a moving target on the fovea while a saccade is used to bring an image onto the fovea.
They are signaled by the occipital lobe
What is Lockwood's Ligament?
Fascial band under eye formed by blending of sheaths of the IO and IR rectus muscles
Where is the mostly likely location of a lesion causing a third order Horner syndrome?
Ciliary ganglion
What are the monocular cues to depth?
Object overlap, Relative object size, Highlights and shadows, Motion parallax, Perspective and Aerial haze
What are the complex eye movements?
Saccades, pursuits, vergences and Vestibular mediated eye movements
What are the different types of vergences and what is their stimulus?
Fusional: Stimulus is retinal disparity
Accommodative: Stimulus is retinal blur
Proximal: Stimulus is awareness of nearness of a target
Tonic: Resting state when no stimulus present
Which EOM inserts inferiorly, posteriorly and laterally onto the globe?
Inferior oblique
What is the ocular differences between 3rd, 4th and 6th CN palsies?
4th: Ocular torsion and hypertropia
6th: Limitation to abduction
What is Abnormal Retinal Correspondence and what are the different type?
When one fovea loses monitor value zero and a pseudo-fovea assumes monitor value zero.
Two Types: Harmonious ARC and Unharmonious ARC
What is an inhibitional palsy and what causes it?
When the patient fixates with the paretic eye the yoke muscle receives less innervation due to Sherrington's law then the yoke muscle appears weak even though it is not actually paretic
Convergence- D: 15-20 PD, N: 30-40 PD
Divergence- D: 6-10 PD, N: 12-15 PD
Vertical vergence- 2-3 PD
Cyclovergence- Range from 0 to 10 degrees