intro to eyeballs Flashcards
What is the macula
The pigmented part of the retina located in the very center.
what is the fovea
The fovea is the area of best visual acuity. It contains a large amount of cones—nerve cells that are photoreceptors with high acuity.
What is the order of the parts of the eye that light shines through when we see things
light reflects off of objects and goes through:
1. cornea
2. iris
3. pupil
4. lens
5. retina
6. optic nerve carries those light signals to brain.
what does hyperopia cause
farsightedness (nearby objects look blurry)
what part of the eye is where light actually enters the eye
the pupil
what is the job of the lense of the eye
to focus the light entering the eye by bending/flattening/changing shape to focus the light rays
What are the parts of the eye that are in charge of changing the shape of the lense
ciliary body/ciliary muscles
suspensory ligaments
How would the lense shape change in order to see an object that is near to you.
- ciliary muscles contract
- suspensory ligaments slacken
- lens becomes thicker
- light focuses on retina
How would the lense shape change in order to see an object that is far away from you.
- ciliary muscles relax
- suspensory ligaments become taut
- lens becomes thinner
- light focuses on retina
what happens to the focal length of the lens when looking at a close by object
focal length of the lens decreases
what happens to the focal length of the lens when looking at a far away object
focal length of the lens increases
What causes hyperopia
too little curvature of the cornea due to the eyeball being too short for the refractive power of the cornea and lens
What is the focal point
where light focuses precisely on the retina.
For good vision, the focal point must be on the retina
What is refraction
the process of bending light to produce a focused image on the retina.
why do most vision problems occur
because of an error in how our eyes REFRACT light
when do refraction errors occur
when the shape of your eye keeps light from focusing correctly on your retina
What are the types of errors of refraction
myopia
hyperopia
astigmatism
presbyopia
keratoconus
what causes myopia
too much curvature of the cornea due to the eyeball being too long for the refractive power of the cornea and lens.
What is the result of myopia
nearsightedness (trouble seeing distant objects)
where is the focal point in someone with myopia
in front of the retina
how is myopia corrected
with a concave lens
“Wide view lens, diverges light rays, makes objects look smaller than they are” idk what any of this means
where is the focal point in people who have hyperopia
light is focused behind the retina
how do you correct hyperopia
with a convex
“The rays meet at a single point on other side of lens
Magnify objects to make them look larger”
“Such lenses are used to focus a beam of light on making the object look clearer and larger.”
again, not sure what this means but im sure its important
describe the effect of a concave lens
- Spreads out light rays
diverging - Focal point in front of lens
- Parallel rays of light pass through the lens are spread out
- Image formed is smaller but clear
- Gives wider viewing angle
Describe the effects of a convex lense
- Focuses the light rays to a specific point
- Convergent
- Rays of light passing through it get bent in a inward direction towards a single point
- Brings light rays together to a focal point behind the lens
- Convex lenses hold magnifying abilities
what causes astigmatism
irregular shape of the cornea or lens (its not perfectly spherical, kinda like a football)
where is the focal point in someone with astigmatism
light reflected into multiple areas of the eye = multiple focal points
how does astigmatism affect vision, how is it corrected
retinal image to be blurred, corrected with cylindrical lenses that equalize the refraction of light
aka causes this picture
how is astigmatism corrected
with cylindrical lenses that equalize the refraction of light
what causes presbyopia
age related farsightedness that leads to loss of mobility and focusing power of the lense
how is presbyopia primarily initially noticed
usually by the inability to read small print around 44-46 years old, symptoms increase until about age 55 and then stabilize
how is presbyopia corrected
reading glasses.
What causes keratoconus
cornea becomes thin and conelike, etiology is unknown but it usually developes in puberty or early adulthood.
who is keratoconus most common in
people with a hx of corrective lenses, contact lenses, and cornea transplants.
what does keratoconus cause
blurred vision and sensitivity to light and glare
How is keratoconus corrected
it is chronic and progressive…… unsure of how its corrected tbh
What are the photoreceptors of the retina
rods and cones
what are rods specialized for
dim light (night vision)
what are cones specialized for
color perception (red, green and blue cones)
color blindness results from deficit of one type of cone.
what is the aqueous humor
the anterior cavity between cornea and lens
where is the aqueous humor produced
the ciliary body
what is the job of the aqueous humor
- supplies nutrients to cornea and lens because cornea and lens do NOT have blood vessels.
- maintains intraocular pressure!
What is the vitreous humor
the posterior cavity between lens and retina that is filled with a jelly like substance to maintain the shape of the eyeball and hold the retina in place
What is glaucoma
a group of eye diseases characterized by neuropathy of the optic nerve. this is caused by cupping of the optic disk on ophthalmologic examination
I think its technically caused by build up of aqueous humor fluid which leads to increased pressure and damage to the optic nerve. see pic.
what causes glaucoma
cupping of the optic disk on ophthalmologic examination
what is the FIRST leading cause of blindness
cataracts
what is the SECOND leading cause of blindness
glaucoma
what is the difference between narrow angle glaucoma and open angle glaucoma
narrow angle is acute angle closure, aka it happens suddenly
open angle is chronic glaucoma, aka it occurs slowly.
this was not on the slides, i googled this. it just helps me to remember that narrow angle is ACUTE and open angle is CHRONIC
draw out visual fields…. pic is on the other side of this card.
okie dokie
what controls pupillary contriction
the PNS
what controls pupillary dilation
the SNS
what muscles control pupillary constriction and dilation
the sphincter and dilator pupillae muscles (circular group of muscles surrounding iris)
How do you examine pupillary reaction
- have patient focus on far object, not your light
- observe pupillary reaction bilaterally
(when light is shone into eye and when light is moved away) - note direct and consensual reaction (magnitude, speed and symmetry)
what is RAPD
relative afferent pupillary defect - Marcus Gunn Pupil
normal consensual response but no direct response.
explanation: If an optic nerve lesion is present, the affected pupil will not constrict to light when light shone in that pupil. It will constrict, however, when light shone into other eye (consensual)
what test is needed when a relative afferent pupillary defect (RAPD) is suspected
the swinging eye flashlight test
what is anisocoria
asymmetric size of the pupils. The pupils have no or sluggish pupillary reaction to light.
what are the possible causes of amisocoria
may be a normal variant (20%) such as horners syndrome or adies syndrome.
could be pathologic (80% i assume) caused by lesion, tumor ect.
What is horner’s syndrome
categorized by a loss of sympathetic innervation which causes the PAM horner triad:
* ptosis
* anhidrosis
* miosis
what is the cause of horners syndrome
caused by a lesion along the sympathetic pathway.
When is horners syndrome typically found
infants and children.
suspect is increased if there is associated heterochromia.
what is adies pupil?
also known as tonic pupil
Categorized by pupillary reaction to light that is either absent or sluggish. This occurs with both direct and consensual.
what is commonly associated with Adies syndrome?
diminished DTR’s aka Holmes-Adie’s syndrome
what population is Adie’s syndrome most common in
common in women in 3rd/4th decade of life (30s-40s)
what ophthalmic disorder is a hallmark of tertiary syphilis
Argyll-Robertson Pupil
what is Argyll-Robertson Pupil
Pupils restrict to accommodation, but not light
Usually bilateral
so like they DO dilate/constrict to seeing things close up/far away but they do NOT dilate/constrict in response to light.
What are cataracts categorized by
loss of transparency of the lens, leading to blurred vision and the absence of the red reflex.
These are generally painless.
what is the fovea important for
Necessary for sharp, central vision
Reading, driving, any activity where visual details are needed
Provides greatest visual acuity of all
what is the macula important for
Functional center of the retina
Responsible for the central, high-resolution, color vision that is possible in good light
In your direct line of sight
what are some abnormalities that could be found on a fundoscopic exam
Retinal Detachment
Papilledema
Cotton Wool Spots
A-V Nicking
Boxcar Segmentation
Cherry Red Spot
Cupping
Flame Hemorrhages
Hard Exudates
Retinal Drusen
What do cotton wool spots aka soft exudates look like and what causes them
Small, yellow-white, slightly elevated lesions, which look like clouds on retinal surface
d/t interruption of blood flow with occlusion of precapillary blood flow, microischemia
what is the most common cause of cotton wool spots aka soft exudates
diabetic retinopathy and hypertensive retinopathy
what is retinal detachment
when the retina at the back of the eye pulls away from its normal position
definition from google cuz slide literally said nothing.
what is papilledema
swelling of the optic nerve
what is papilledema categorized by
- disc elevation
- venous distention and tortuosity
- obscuration of normal disc margin an overlying retinal vessels.
- absence of spontaneous venous pulsations.
what is retinal vein occlusion
widespread retinal hemorrhages that cause venous dilation and tortuosity.
what is central retinal artery occlusion
cherry red spot on the fovea with “boxcar segmentation” which is segmental blood flow
what is AV nicking
a small artery seen crossing a small vein which causes compression on the small vein.
this is due to indentation (nicking) of the retinal vein by a stiff (arteriosclerotic) retinal arteries
what is the most common cause of AV nicking
hypertensive retinopathy
what is copper and silver wiring
vascular hyperplasia caused by atherosclerotic vessel wall thickening and chronic hypertension
how does copper wiring present and what is it indicative of
indicative of moderate vascular wall changes that appear orange or yellow instead of red
how does silver wiring present and what is it indicative of
indicative of severe vascular wall hyperplasia and thickening that appears white instead of red.
where is copper and silver wiring seen
in hypertensive retinopathy
what is the cup
the center of the optic disc
what occurs when the optic nerve is damaged, such as in glaucoma? how does this affect the cup?
the nerve fibers fibers to the optic disc die off and blood flow is diminished. This causes the cup to become larger since the support structure is not there.
what do hard exudates look like in the eye
smallish, yellowish-whitish distinct spots with sharp borders
what causes hard exudates? what is the MC etiology that causes this.
MC etiology = diabetic retinopathy
Caused by breakdown of blood-retina border, allowing leakage from retinal vessels
This vascular permeability allows the leakage of fluid and lipoprotein into the retina
what is the MC etiology of flame hemorrhages
diabetic and hypertensive retinopathy
what occurs with flame hemorrhages.
When necrotic vessels bleed into the nerve fiber layer
More superficial layers of the retina
these are large
What are dot blot hemorrhages and how do they occur
Occur as microaneurysms rupture in the deeper layers of the retina
Blood accumulates in the inner nuclear layer
what occurs during neovascularization
Microvascular damage and ischemia cause release of vasoproliferative factors (Vascular Endothelial growth Factor)
This results in new vessel from the adjacent retinal vessels in an attempt to revascularize the diseased tissue
what is the MC etiology of neovascularization
diabetic retinopathy and macular degeneration
what is the appearance and cause of retinal drusen.
Yellow deposits under the retina
Made up of lipids and proteins
Scattered around macular region
“Tombstones” of dead retinal epithelium
where does retinal drusen occur
Appear in a layer of the retina called Bruch’s membrane
what is the MC etiology of retinal drusen
age related macular degeneration
what is a slit lamp examination used for
to look at structures in the anterior chamber of the eye including:
lids, lashes, conjunctiva, cornea, anterior chamber, iris, and lens
what is fluorescein staining used for
looks for corneal abrasions, ulcers, foreign bodies.
