FACTS & HINTS
High-Yield Facts
Clinical Points
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General Testing of Extraocular Muscles
Extraocular muscles act as synergists and antagonists and are responsible for multiple movements of the eye.
It can be difficult to test each eye muscle individually.
A generalist, however, can gain a general idea of extraocular muscle (or nerve) impairment by checking the ability of individual muscles to
elevate or depress the globe with the eye abducted or adducted, thereby aligning the globe with the pull (line of contraction) of the muscle
Ask patient to "Follow my finger with just your eyes" and move your finger in the form of the letter H.
Superior rectus is tested by moving your finger superiorly and medially to the eye (to counteract the interaction of the inferior oblique)
a. Inferior rectus is tested by moving your finger inferiorly and medially to the eye (to counteract the interaction of the superior oblique)
b. The medial and lateral rectus muscles are tested by moving your finder medially and laterally to the eye.
c. The inferior oblique is tested by moving your finger superiorly and laterally to the eye
d. The inferior oblique is tested by moving your finger inferiorly and laterally to the eye.
Remember that because all the muscles are involved in the continuous movement of the eye, it is difficult to isolate the action of just one
with absolute clinical certainty via this test.Clinical Points
Cataract
Most common clinical condition of the eye worldwide
Involves opacification or cloudiness of the lens
Risk factors include: smoking, age, alcohol, diabetes, steroid use, and exposure to ultraviolet (UV) rays
Treatment involves surgical removal of the lens
Eyesight is corrected with an implant, glasses, and/or contact lensClinical Points
Glaucoma
One of most common cause of blindness world wide
Build-up of pressure in anterior and posterior chambers of the eye
Usually a result of resistance to outflow of aqueous humor via angle of eye and through canal of Schlemm
Results in compression of neural layer of retina
Leads to visual field defects and ultimately blindness
Increased intraocular pressure classified as open or closed angle
a. Open angle-develops gradually with blocking of canal of Schlemm or obstruction of angle
b. Closed angle-occurs rapidly when iris and lens block passage of aqueous humor through pupilClinical Points
Orbital "blow-out" Fractures
Medial and inferior walls of orbit are very thin, so a blow to the eye can fracture the orbit
Indirect trauma that displaces walls is called a "blow-out" fracture
Fractures of medial wall may involve ethmoid and sphenoid sinuses
Fracture of the floor may involved the maxillary sinus
Fractures can result in intraorbital bleeding
Blood puts pressure on eyeball, causing exophthalmos
Blood and orbital structures can herniate into maxillary sinusClinical Points
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Conjunctivitis
Common condition often referred to as "pink eye"
An inflammation of the conjunctiva
Symptoms include redness, irritation, and watering of the eyes and sometimes discharge and itching
Can be triggered by infection
a. Highly contagious
b. Caused by bacteria or viruses
c. Sexually transmitted diseases (STDs), such as gonorrhoea and chlamydia, can cause it
d. Viral conjunctivitis is common with several viral infections and can arise as a result of or during a common cold or flu
Can be triggered by allergies
a. More freqently occurs in children with other allergic conditions, e.g., hay fever, animal fur
b. Typically affects both eyes at the same time
Can be triggered by an external irritant
a. Can be caused by pollutants such as traffic fumes, smoke
b. Can be caused by chemicals such as soap, chlorine