Flashcards in Opthamology lab Deck (47):
What is the cornea? What is its function?
the transparent anterior refracting surface of the eye. It accounts for 2/3 of the refracting power of the eye (the lens accounts for the remaining 1/3)
What are the three histological layers of the cornea? What happens if each is damaged?
an outer epithelium, a collagenous stroma, and an inner endothelium. If abraded or infected, the epithelium will regenerate without harming vision. But if the stroma is damaged, a scar forms to distort and opacify the cornea and reduce vision
What is in the endothelium that keeps water out of the cornea? What happens if this is damaged?
The endothelium has a metabolic pump that keeps water out of the cornea in order to maintain transparency
When it is damaged, the cornea becomes edematous and loses transparency.
What are the boundaries of the anterior chamber?
bounded by the cornea in front and the iris-lens in back
Where does the water-like fluid in the anterior chamber come from?
What happens to the anterior chamber when the iris becomes inflamed?
cells and protein leak into the aqueous to make it turbid ("flare")
What is a hypopyon?
A collection of white cells in the anterior chamber of the eye when there is an infection
What is a hyphema?
Trauma to the blood vessels of the iris will result in blood pooling in the anterior chamber
What are the two muscles that comprise the iris? What is each's innervation?
Circumferential = parasymp (M3)
Radial = sympathetically (alpha 1)
What are the boundaries of the posterior chamber?
Iris in front and the anterior vitreous face in back
What is the conjunctiva? What are its two parts?
the mucous membrane covering of the anterior eye. It has two parts: the bulbar conjunctiva that covers the sclera, and the palpebral conjunctiva that covers the inner eyelids
True or false: the canal of Schlemm is rarely implicated in disease
True---trabecular meshwork is the site of obstruction in glaucoma
What are the components of the vitreous humor? (3)
hyaluronic acid, collagen fibers, and a dilute salt water solution
What are "floaters"?
the vitreous detaches itself from the optic disc, leaving a floater.
What is the macula?
Retinal region containing a high density of cones and ganglion cells specialized in visual acuity and color vision.
What is the fovea?
Central depression within the macula in which the retina consists only of cones.
What are the only cells that the retinal arteries nourish? Where are these arteries in relation to the retinal layer?
These vessels travel in the innermost retinal layer, and are visible through the ophthalmoscope. The arteries nourish only the retinal ganglion cells and their axons. The deeper layers of the retina get their blood from the choroid.
What is the retina?
The neural inner layer of the posterior part of the eye. It has a nutrient retinal pigment epithelial outer portion and a sensory inner portion.
What is the choroid?
The vascular nutrient layer of the outer retina
What is the sclera?
the collagenous outer wall of the eyeball
Where does bilirubin accumulate to cause scleral icterus?
What are the two portions of the ciliary body?
a secretory epithelium and a muscle
What happens to the lens when the ciliary muscle contracts?
the zonules loosen, and the lens assumes a more rounded shape.
Rounding of the lens does what for vision?
Increases refracting power, and allows view at reading distances
What are the zonules?
Fibers that extend from the ciliary muscle to the lens
What are the cells that comprise the retina (from anterior to posterior)?
Where do the ganglion cells of the retina send signals to in the brain?
Lateral geniculate nucleus of the thalamus
What is the role of the retinal pigment epithelium?
Tight junctions keep fluid where it's supposed to be
What is the muscle that is sympathetically innervated, and raises the eyelid?
What is the orbital septum?
Collagenous curtain connecting frontal bone and upper eyelid tarsus
What are the glands in the upper eyelid that provide the oil base for the tear film?
What is trichiasis?
Inward movement of the eyelashes
What is the bulbar conjunctiva?
the mucous membrane covering of the sclera.
What is the palpebral conjunctiva?
The mucous membrane covering of the inner surface of the eyelids.
What is the muscles that raises the eyelid?
Levator palpebrae superioris
What are the upper and lower punctum? What happens if the upper one is blocked? Lower?
Oval openings at the upper and lower portions of the eyelids. The lower can accommodate all of the drainage from the top if necessary.
If the lower one is blocked, then the pt will develop a tearing problem
What is the gland, that produces tears? Where is it found?
Lacrimal gland, superior lateral to the eye
What is the plica semilunaris?
A crescentic fold in the medial conjunctiva lying lateral to the caruncle. It has no special function.
What are the upper and lower canaliculi?
ducts for drainage from the eye
What is the limbus?
The outer margin of the cornea.
What is the confluence of the upper and lower eyelid margins?
Medial and lateral canthi
What is the physiologic cup? What is the finding of this that would lead one to consider glaucoma?
Physiologic cup: the central depression within the optic disc
The physiologic cup diameter is variable, but should not exceed 50% of the total optic disc diameter. Otherwise, consider glaucoma a possible diagnosis.
What is the central depression within the macula?
What is the peripheral portion of the optic disc that carries the axons of the retinal ganglion cells called?
What is the superior/inferior orbital septums?
Collagenous curtain connecting frontal (maxillary) bone and upper lid tarsus
What are the tarsi of the eyelid?
A connective tissue plate that contains sebaceous glands providing an oily base for the tear film. The tarsus gives firmness to the distal portion of the upper lid.