HEENT 1

What is the function of the eyebrow?

provide shade, prevent sweat from running into eyes, Visual cues

What is the conjunctiva?

transparent membrane covering sclera, and inside of eyelids

What are eyelashes?

highly innervated with nerves, triggers blink response

What are tarsal glands?

modified sebaceous gland, produces oily substance, prevents adherence of eyelids

What are tears composed of?

Lipid layer – provides hydrophobic barrier that help hold the tear together

Aqueous layer – Spreads the tear, osmotic regulation, and antimicrobial controls (Lysozyme)

Mucous layer – coats the cornea helping to prevent dehydration and spreads tear evenly

What are the three types of tears?

Basal – keeps cornea hydrated and lubricated

Reflex – Response to wash noxious stimulus out

Psychic – Emotional driven tears “crying”

What is a blockage of the tarsal gland – causing large firm typically non-tender swelling?

Chalazion

What is an infection of smaller sebaceous eyelash gland (Glands of Zeis), small acutely tender swelling?

Hordeolum

What is an obstruction or infection of the nasolacrimal apparatus that can be caused by stone formation, or infection (*S. Aureus)?*

Dacryocystitis

What are the most common infective agents of conjunctivitis?

Adenoviruses,  Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae

What is the first and second most common orbital fracture?

Inferior blowout and medial wall blowout

What type of imaging do you have to get for an orbital fracture?

CT scan

Where does the anterior segment of the eye run from?

corneal endothelium to the lens

The anterior segment is divided into

Anterior and posterior chamber

What is the substances that the anterior segment is filled with?

Aqueous humor

Where does aqueous humor flow out of?

Canal of Schlemm

What is the transparent front part of the eye?

Cornea

the cornea is responsible for __ of the eye's total optical ability

2/3

What type of pumps does the corneal epithelium have?

active sodium pumps that maintain clarity by keeping H2O low 

what is special about the cornea?

demonstrates immunologic privilege (Ability to tolerate the introduction of antigens without eliciting an inflammatory response), allows for corneal transplantation

Which glaucoma is painless, peripheral vision goes first,   drainage problems

Open angle

Which glaucoma is the sudden rise in pressure, red/painful, sudden vision issues?

Closed angle

What is a wedge of conjunctival tissue growth onto the cornea and what is it caused by?

Pterygium; UV radiation

What gene does UV radiation causes a mutation in to get pterygium?

p53 tumor suppressor gene

What occurs when your cornea or lens is curved more steeply in one direction than in another?

Astigmatism

What are the two types of astigmatisms?

Corneal astigmatism- Mismatched Corneal curves

Lenticular astigmatism- Mismatched lens curves

What is considered the eyes “diaphragm”, regulating the amount of light entering the posterior chamber of the eye?

Pupil

Iris is composed of two layers of smooth muscle: 

Sphincter pupillae: Constricts the pupil, decreasing the amount of light entering the posterior chamber of the eye; Innervated by **Parasympathetic Nervous System**

Dilator pupillae: Dilates the pupil, increasing the amount of light entering the posterior chamber of the eye; Innervated by **Sympathetic Nervous System**

What happens in blue eyes?

No melanin in Iris, Tyndall scattering of light

What happens in brown eyes?

High melanin, dominate eye color

What happens in green eyes?

Light brown pigmentation, Rayleigh scattering, and presence of lipochrome

What is the absence of an iris which can be either congenital or caused by trauma?

Aniridia

What gene mutation causes anirdia?

PAX6

What is missing pieces of structures in the eye; can occur in iris, retina, choroid or optic nerve if the retinal/choroid fissure does not close?

Coloboma

What is coloboma a mutation of?

PAX2 gene or real coloboma syndrome

What is the condition where blood accumulates in the anterior segment?

Hyphema

What is the lens and what is it composed of?

Biconvex lens; composed of crystallin proteins

How is the lens suspended in place?

by the suspensory ligaments of the lens, which attaches the lens to the ciliary body

When looking at something in the distance, the ciliary muscles are ___ and the lens is ______

relaxed; flattened

When looking at something up close, the ciliary muscles are ___ and the lens is ______

contracted; bulging

In a myopic eye, a person is considered ________

nearsighted

A myopic eye is too __ and the focal point is_____ the retina

long; front

What types of lens are needed to fix myopic eyes?

Concave lens

In a hyperopic eye, a person is considered ________

farsighted

A hyperopic eye is too __ and the focal point is_____ the retina

short; behind

What types of lens are needed to fix hyperopic eyes?

Convex lens

What is clouding of the lens of the eye?

Cataracts

What are the causes of cataracts?

Age, trauma, pathology (river blindness)

What do cataracts account for blindness?

5 % blindness in US, 60% blindness in African and South America

What are the three layers of the posterior segment?

Retina – Photosensitive layer of eye 

Choroid – Highly vascular and pigmentated layer firmly attached to retina

Sclera – White of the eyes, tough opaque layer of tissue 

What is the substance in the posterior segment of the eye?

Vitreous humor

Where is the vitreous humor adhered to?

Optic disc and ora serrata via collagen fibers

What is the composition of vitreous humor?

98-99% water, no blood vessels, Müller Cells transport water into vitreous body via Aquaporin-4 channels

What is the perception of floaters?

Myodesopsia

What are the two cells of the retina?

Rod and cones

Which cells account for dim light (night vision)?

Rods

What light sensitive protein do rods use?

Rhodopsin

What cells account for bright light vision?

Cones

What light sensitive protein do cones use?

Photopsin

What structure has no rods, high density of cones, area of very highly visual acuity?

Optic fovea

What is the surface of the optic nerve, no rods of cones so it is the blind spot?

Optic disc

What is the structure that is an oval-shaped pigmented area in the center of the retina, responsible for the central, high-resolution, color vision?

Macula luteaOpsin a

What are the photosensitive proteins that are found on the deepest layer of the retina?

opsin and rhodopsin

What are the wavelengths of color?

Blue 420 nm

Rods 500 nm

Green 530 nm

Red 560 nm

What mutation causes color blindness and which is the most common?

Mutation of X chromosome; Red-green colorblindness

Upon a fundoycopic exam, what can be visualized?

Optic Disc, Optic Cup, Arteries, Veins, Fovea and Macula

What may be given to a patient to perform a fundoycopic exam due to pupillary relfex?

A mydriatic agent, tropicamide (anti muscarinic agent)

What can be visualized in a patients eye with hypertensive retinopathy?

Copper wiring – light reflex occupies central aspect of arteriole, blood vessel appears like a strand of copper wire

Silver wiring – Light reflex occupies entire arteriole, blood vessel appears like a strand of silver wire, occlusion of arteriole

AV nicking

What are symptoms of a retinal detachment?

“curtain” effect across the field of vision, flashes of light, floaters

What are the two forms of Macular Degeneration?

Wet: blood vessels grow under the macula, causing blood and fluid to leak into the retina

Dry: presence of drusen, tiny yellow or white accumulations of extracellular material that build up between Bruch's membrane and the retinal pigment epithelium

What are areas of white blotches on the retina caused by micro infarcts typically in patients with diabetes or hypertension?

Cotton wool spots

What is bulging of the optic disc?

Papilledema

What is the modality of the optic nerve (CN II)

Special sensory nerve: sense of vision

Where does CN II originate?

Axons of the ganglion cell layer of the retina

Where does CN II exit?

Optic canal

What is the pathway of the optic nerve?

Optic nerve

Optic chiasm

Optic tract

Lateral Geniculate Nucleus

Optic radiations

Primary visual cortex of the occipital lobe

What occurs when there is a lesion to CN II?

Marcus Gunn pupil (If light is shone into unaffected eye, both pupils constrict, when light is shone into effected eye, both eyes appear to dilate)

Where are temporal fields of view perceived?

Nasal aspect of the retina

Where are the nasal fields of view perceived?

temporal aspect of the retina

Where does temporal retinal information go?

sent to the brain on the same side and do not cross at the chiasm

where does nasal retinal information go?

The information is crossed at the chiasm

Visual Field Deficits

What are the modalities of oculomotor nerve (CN III)

Somatic efferent and visceral efferent

What is the somatic component of CN III?

Innervation of superior rectus, inferior rectus, medial rectus, inferior oblique, and lavatory palpebrae

What is the visceral efferent component of CN III?

Constriction of pupil and light response and accommodation

Where does the somatic efferent component of CN III arise and exit?

arises from nerve nuclei in midbrain and exits through superior orbital fissure

Where does the visceral efferent component of CN III arise and exit?

arises from the Nucleus of Edinger Westphal to the ciliary ganglion behind the eye

How does a CN III palsy present?

Dilated pupil and downward abducted eye

What is the modality of the trochlear nerve (CN IV)?

Somatic efferent

What does trochlear nerve innervate?

Superior oblique

What is the presentation of a patient with CN IV Palsy?

Extortion of affected eye and a weakened downward gaze; patient experiences diplopia

Patients tilt head towards unaffected side

What is the modality of the abducens nerve (CN VI)?

Somatic efferent

What does the abducens nerve innervate?

Lateral rectus

What does a CN VI Palsy present as?

Strabismus/Esotropia of one eye, result is diplopia; head turned to side of lesion restores binocular vision

What is the midline structure in which CN III and CN VI communicate?

Medial longitudinal fasciculus

What are the four types of strabismus?

Esotropia – Eyes converge inward

Exotropia – Eyes diverge outward

Hypertropic – Eyes diverges superiorly

Hypotropia – Eyes diverge inferiorly 

When clinically testing the superior rectus, the patient must move their eye

Laterally and **upward**

When clinically testing the inferior rectus, the patient must move their eye

Laterally and **downward**

When clinically testing the lateral rectus, the patient must move their eye

Laterally

When clinically testing the medial rectus, the patient must move their eye

Medially