Lecture Two Flashcards
Define Ataxia
loss of full control of bodily movements
If you observe a head tilt in patient what disease could be triggering this?
Strabismus, eye turn, head tilt could be compensating for this.
Define Adnexa
all structures surrounding what it is talking about i.e. all structures surrounding eye.
Define palpebral aperture
space between upper and lower eyelid
If the lower lid was protruding what could be happening? if it was intruding?
protruding could mean the tears are not being held in.
intruding could mean scratching of the cornea.
Define edema, hyperemia and hemorrhage.
edema: excess of fluid causing swelling
hyperemia: excess of blood in vessels
hemorrhage: bleeding
If external observation is all normal what do you record?
“eyes quiet, no asymmetries” indicate you did observe patient. do NOT write within normal limits. otherwise describe any abnormalties/asymmetries.
Pupilary distance measures what distance? how many measures of this do we do?
distance between pupil center of each eye.
two one for distance one for near.
What are average distance PD values in adults? average near values?
distance: 54-68mm
near: 2-4mm smaller than distance. both are smaller for children.
Central vision has what characteristics and involves what receptors? Peripheral vision?
involves cones, more detailed and colored.
involves rods, more gross and motion detection.
Visual field test measures what?
measure of sensitivity of central and peripheral visual fields.
Examples of peripheral vision defects?
glaucoma, retinitis pigmentosa
Examples of central vision defects?
AMD
Define hemianopia
half of visual field is gone i.e. all left side
Finger counting Visual Field test only tests for gross defects in which visual field?
peripheral visual field
Which visual field test can test for central vision?
Facial fields
Define Scotoma
gap in vision
another form of visual field testing besides static?
Kinetic. involves two people, one in back of patient brings object into peripheral field and front observer looks when patients eyes move.
Bruckners test looks for what three things?
- Eye health
- Binocular Vision (strabismus)
- Refractive error
Amblyopia caused by 1 of 3 reasons what are the three reasons?
- refractive
- strabismic
- deprivation
Light hits a surface of an object and then does what?
absorbed or reflected. more absorption object appears darker.
Newton found what with color?
White light going into the prism gave all colors. therefore white light has all wavelengths.
Trichromatic theory of color vision thought what?
3 types of photoreceptors sensitive to red/yellow/blue. only three wavelengths needed to create all colors. the three different types thought to be S (more sensitive to short wavelengths), M (more sensitive to medium wavelengths) and L (more sensitive to larger wavelengths)
What is the difference between S, M and L cones? Do rods differ?
Different opsins.
No. they all have rhodopsin (peak around 498nm)
What is the peak for S cones? Opsin type?
peak 430 nm, cyanolabe
What is the peak for M cones? opsin type?
peak 535nm, chlorolabe
What is the peak for L cones? opsin type?
peak 565nm, Erytholabe
Which type of cones are there the most of?
very few S cones, more M/L cones.
What varies with wavelength?
the probability that a photon will be absorbed
Trichromatic theory does not explain what?
after images or color appearance
Opponent process theory of color vision describes what?
what happens beyond photoreceptors
Normal color vision is called? how many photopigments?
Trichromatic: 3 types of photopigments
What is Anomalous Trichromat?
3 types of photopigment but one has abnormal sensitivity function (most common)
What is Dichromacy?
only two types of photopigments, third one is absent or defective
What is Monochromacy?
total color blindness, two cone types missing. only one pigment.
Anomalous Trichromat has one opsin not normal, what are the three different types?
- Protanomaly/protanomalous trichromat: L-opsin altered (response toward green): poor red/green discrimination.
- Deuteranomaly/deuteranomalous trichromat: M opsin altered (response toward red) mildy affects red/green hue discrimination (most common in males)
- Tritanomaly/Tritanomalous Trichromat: S opsin altered. very rare. affects blue/yellow discrimination.
Dichromacy has 2 pigments, what are the three different types?
- Protanope: absence of L cones
- Deutenarope: absence of M cones
- Tritanope: absence of S cones, rare.
- tetartanopia: no yellow
Monochromacy total color blindness only one type of photoreceptor, what are the two types?
- Rod monochromacy: no cones, abnormal vision, achromatopsia
- Cone monochromacy: color blindness, cant distinguish hues otherwise normal vision.
Signs that color vision defects are congenital?
- both eyes are equally affected
- stable over time
- nearly always red green defects
- usually VA and VF not affected
- higher incidence in males
Males much more commonly have color defects what is the percent?
8% in males (likely congenital), 0.4% in females (likely acquired)
Signs that color vision defects are acquired?
- asymmetry
- pathological process
- changes overtime
- decreased VA
- often blue/yellow defect but can be red/green
- random mix of results in testing
- equal prevalence in male/female.
Blue/yellow acquired color vision defects could be due to what diseases? Red green?
B/Y: outer retina/media changes (i.e. in lens, cataract)
R/G: inner retina diseases i.e. optic nerve, visual pathway or visual cortex, MS.
Other diseases that can cause color vision defects?
- diabetes mellitus (DM)
- Alcoholism
- MS
- Medications
three major groups of color vision tests are?
- Color Matching
- Pseudoisochromatic Plate tests (Ishihara, HRR, most common one)
- Color arrangement tests
Disadvantage of Ishihara?
only tests for congenital red/green defects
What VA must the patient have in order to do the Ishihara test?
20/400 or better.
HRR advantages?
can detect both R/G and B/Y defects. For R/G can determine is its protan or deuteran and whether it is mild, moderate or severe.
Scattered results in HRR could indicate?
malingering, acquired color vision defects or monochromatism.
Are acquired color defects common or rare in children?
RARE. if they do have one its almost always R/G.
Define persistant pupilary membrane
remaining embryonic tissue in the pupil
Define epicapsular stars
persistent pigment on anterior surface of lens, usually benign
Define Mittendorf dot
remaining embryonic tissue on posterior surface of lens
Define Mydriasis, Miosis and Anisocoria
dilated pupil
constricted pupil
pupils are different sizes
Four functions of the pupil
- control retinal illumination
- facilitate light/dark adaptation
- reduce optical aberrations
- increase depth of focus i.e. PH effect
Average pupil diameter? is hippus normal? do pupils normally differ in size?
1.1-8.5 mm
pupilary unrest: very normal however may be abnormal in disease or cease of hippus may be abnormal.
In most individuals the pupils are the same size and shape.
Pupil size depends on?
age (older patients 60-70 have generally smaller pupils), light intensity, emotional state
Define amplitude of pupils? As we have increasing stimulus intensity, latency (onset) does what? rate (speed) does what?
extent of pupils response to light
Latency decreases, rate increases
Parasympathetic causes what to pupils? sympathetic?
Constriction (causes circular muscles to contract around pupil), also involved in accommodation.
Dilation (causes radial muscles to contract)
Afferent pathways go from what to what?
Efferent?
Afferent: eyes to CNS
Efferent: CNS to eyes
Sphincter muscle is what? What does it cause when it constricts? innervated by what?
Dilator?
annular band of smooth muscle around pupil, constriction causes miosis. parasymp.
Myoepithelial cells running radially, constrction causes mydriasis. symp.
One of the main reasons pupil testing is so important?
neuro-opthalmologic test! evaluation of visual pathways and ANS (para/symp).
At the optic chiasm, do all the fibres cross paths to the opposite side?
NO not 50/50. some go to the same side. 54% cross paths (nasal fibres) and 47% stay on the same side (temporal fibres).
Damage of optic tract may cause what?
afferent pupillary defect (RAPD)
When ganglion axons are entering optic nerve is this a 50/50 split?
YES.
If a patient has ptosis what would you look for?
pupils, EOM and accommodation because they are all grouped with CN3.
Synkinetic Triad (or Near response) when changing view from distant to near your eyes do what three things?
- Converge
- Accommodate (ciliary muscles)
- Pupils constrict (sphincter of iris)
(all are independent of one another, one can be affected and others not).
In order for dilation to occur, what must the parasymp and symp systems do?
Parasymp must be inhibited: sphincter relaxes
Symp must be excitied: dilator (radial muscle contracts).
is the sphincter or dilator more strong in response?
Sphincter
Drugs that can dilate?
Parasymp antagonists: (relax parasymp sys, affects accommodation): Tropicamide and Cyclopentolate (causes blurriness for a while) Sympathetic Agonists (does not affect accommodation): phenylephrine
Darker iris’s need stronger or weaker drops? those with diabetes?
stronger.
weaker.
What is a direct response?
light shown in one eye, watch for response in that same eye.
What is a consensual response?
light shown in one eye, watch for response in other eye.
If patient is healthy the direct and consensual responses in both eyes should be?
same magnitude, briskness and latency.
You can evaluate integrity of afferent pupillary reflex pathway by doing what? afferent input in each eye should be what?
swinging a light between the eyes.
symmetrical.
With the swinging flashlight test, the one sec test is good for what? 3 sec?
1: for large RAPDs
3: smaller RAPD but harder to see responses
Is it normal for the eye to dilate a little and then constrict when doing the swinging flashlight test?
yes, due to hippus.
Define amaurotic
Blind eye
Muscles Paresis is? Paralysis?
Paresis: mild/moderate muscle weakness
Paralysis: severe or complete loss of motor function
CN 3 innervates which muscles?
IR, IO, MR, SR, LPS and sphincter or iris.
Hirschberg reflex is what? What is the normal result? if corneal relfexes differ between the two eyes what is most likely happening?
Reflection of cornea. White reflection seen in the middle of pupil or slightly nasal.
Strabismus.
If hirschberg reflex is observed further out what is happening? if it is observed further in?
Eye is turned in therefore esotropia
Eye is turned out therefore exotropia
If children experience discomfort or pain in the EOM testing most likely due to?
orbit disease (tumor).
