Eyes Flashcards
(15 cards)
What is Sherrington’s Law?
When a muscle contracts, its direct antagonist relaxes to an equal extent, allowing smooth movement.
This law illustrates the coordinated action of muscle pairs in the body.
THINK SHARING
What does Hering’s Law state?
During any conjugate eye movement, equal and simultaneous innervation flows to the yoke muscles.
This law explains the synchronization of eye movements.
What is the term for deviation medially of the eye?
ESO
ESO stands for esotropia, a condition where one or both eyes turn inward.
Think oooooo looking at nose
What is the term for deviation laterally of the eye?
EXO
EXO stands for exotropia, a condition where one or both eyes turn outward.
EX BE LEAVING. BOY BYE
What is the term for deviation above the midline of the eye?
HYPER
HYPER refers to hypertropia, where one eye is higher than the other.
What is the term for deviation below the midline of the eye?
HYPO
HYPO refers to hypotropia, where one eye is lower than the other.
What does diplopia mean?
Double vision.
Diplopia can be monocular or binocular.
What is monocular diplopia?
Diplopia that affects only one eye.
It is less common and usually caused by refractive issues.
What are some causes of monocular diplopia?
- Light diffraction
- Metamorphopsia
- Cerebral polyopia
- Cataracts
- Astigmatism
- Extra-pupillary openings
- Tear-film disturbance
- Corneal and vitreous opacities
These conditions can distort vision and lead to monocular diplopia.
What is metamorphopsia?
A type of distorted vision where a grid of straight lines appear wavy or absent.
It is not true double vision and is usually caused by conditions like macular edema.
What is a common presentation of third nerve palsy?
Down and out eye, ptosis, large unreactive pupil, and vertical diplopia.
This condition can be caused by compression from an aneurysm or tumor.
What is the first sign of third nerve palsy due to compression?
Dilated pupil.
This occurs because parasympathetic fibers are compressed.
What are the two main considerations for third nerve palsy?
- Medical: vasculitic, infective, inflammatory causes
- Surgical: fixed non-reactive pupil or painful palsy
These considerations guide the approach to diagnosis and treatment.
What is a common characteristic of fourth cranial nerve palsy?
Patients will tend to have slight hypertropia and a head tilt to the contralateral side.
This can lead to difficulties in reading and double vision.
What is a common cause of sixth cranial nerve palsy?
Increased intracranial pressure.
It can lead to the appearance of cross eyes.
