Terminology Flashcards
Cornea
Transparent layer in front of the eye. Part of the outer protective layer of the eye. It’s bulging curvature provides the major refraction of the eye.
Layers of the cornea (superior to inferior)
Corneal epithelial Bowman's membrane Stroma of cornea (stroma damaged= corneal scar) also the largest layer Duas layer (recently discovered) Descemet's membrane corneal endothelium
Role of the corneal endothelium
Single layer of cells that bumps water OUT. too much water makes the cornea cloudy. If 1 cell is damaged, there is no fixing it and the neighbor cell will not pick up for it’s slack.
Pt wil have to take drops to remove water.
How many layers in the cornea
6 Corneal epithelial Bowman's membrane Stroma of cornea (stroma damaged= corneal scar) also the largest layer Duas layer (recently discovered) Descemet's membrane corneal endothelium
What layer of the cornea will cause a corneal scar if you damage it
Stroma
Does the cornea have nerve endings? What about blood vessels?
The cornea is highly sensitive and filled with many nerve endings. Although the epithelium regenerates quick, it is very painful.
There are no blood vessels or innervation on the cornea. It is a clear structure.
Plural of iris
Iridies
How do dilation drops work
Iris expands and contracts in order to alter the amount of light entering the eye.
Dilation freezes the constriction muscle and enhances the dilation muscle.
Alger brush
Drimmle tool that spins. Use when you have a wound that does not have clean edges. Ex: corneal abrasion. You want to alsow wound to heal in a nice clean order. Although the brush makes the wound bigger, epithelial cells can more orderly fall in the hole.
How far to drill with alger brush
Drill down to bowman’s layer- brush will stop because that layer is so thick. This will dramatically reduce healing time.
2 places in the eye that can generate pain
Cornea and ciliary body
Malingering
lying pt
trichitilamania
Compulsion to pull eyebrow/eyelash hairs. Anxiety.
Conjunctiva
The clear transparent membrane that lies over the sclera, and lines the inside of the eyelids. Mobile/movable. Most common site of “red eye”
Sub conjunctiva heme
Bruise on your conjunctiva. “think of it as a bruise, but you’re looking through glass instead of skin.”
If this is recurrent, there may be a blood disorder, pressure bowel moments or heaving lifting.
Why does your eye sting if you hold your eyes open for too long
Tears distributed across the eye protect. If tears evaporate, the nerves are exposed to air and is painful.
Eyelashes
The cilia or hair that prevents foreign structures from irritating the outer eye.
Eye brows
A pair of heavy areas above each eye that protects the eye. Wicking agent
What provides nutrition to the cornea
Aqueous humor, which is produced by the ciliary process and travels through the pupil to the anterior chamber. Absolutely clear.
What is the culprit of glaucoma
Aqueous humor. Causes the decrease in peripheral vision.
May be due to the increase of aqueous humor production (open angle glaucoma)
OR due to the aqueous getting clogged and not being able to exit. (closed angle glaucoma)
Your ___ does the seeing
brain. Your eyes just capture it. If optic nerve is damaged, you will not perceive anything although your photoreceptor cells are working fine.
What if a pt reports deep boring pain behind eye
Could be ciliary body. Causes eye fatigue
What if pt reports a sharp pain that makes you want to blink
Corneal damage
Crystalline lens
The resident, transparent structure in the eye that focuses light by changing its curvature. The reason why we can see so many distances. Controlled by the ciliary muscle and zonules.
How do cataracts and presbyopia occur
Cells create waste that is encapsulated inside the lens. This hardens the lens and makes it cloudy.
Ciliary muscles
The muscles that control the focusing of the eye by pulling/relaxing the grip on zoules, causing the lens to change shape.
Relax ciliary body (sitting)- contracted zonules- skinny lens for distance vision
Contract ciliary body (standing) - relaxed zonules- rounded lens for accommodation
Suspensory ligaments or zonules
The long, thin fibers that connect the lens to the ciliary muscle.
Vitreous humor
A clear, jelly like substance that fills the inside of the eye, behind the lens. As you age, the jelly becomes more liquified. This liquid can slosh around more, pulling away from the retina (retinal detachment). Also floaters are now easier seen since the jell is moving.
optic nerve
The bundle of nerve fibers that carry vision impulses from the retina to the brain, which is where vision happens.
Retina
The inner lining of the eye, composed of nerve cells, giving the eye its sensitivity to light. One of the most metabolically active tissues- very busy. Nourished by nerve fibers and blood vessels and the posterior choroid.
Choroid
The highly vascular layer between the sclera and retina, whose function is nourishment to the retina.
Macula
A small, thinned out layer of the retina, consisting of, almost exclusively, cone receptor cells which provide the eye with its clear, central vision. Exclusively provided nutrients by the choroid.
Macular degeneration disrupts central vision. Only place where you will not see superficial blood vessels. Avascular zone- better vision.
How does the macula get nutrients
Strictly from the chorioid. Does not have any overlying vasculature.
Cones
Retinal receptor cells that are responsible for clear and color vision. Concentrated in the fovea. Functions poorly in low levels of illumination.
Rods
Retinal receptor cells, responsible for movement and black/white vision. Functions in low levels of illumination.
When it is bright outside, rods are “bleached” and take time to turn back on once being in a dark room.
Optic nerve is always ____ to the macula
Nasal
