Health Entrance Tests 1 Flashcards
Adnexa
Structures around eyes
Palpebral Aperture
Distance between open eyelids
Nystagmus
Involuntary rapid eye movement
Anisocoria
Unequal pupil size
Leukocoria
Abnormal white reflection from the retina of the eye
Ptosis
Drooping or falling of the upper or lower eyelid
Edema
An abnormal accumulation of fluid in the interstitium
Hyperemia
An excess of blood in the vessels supplying an organ or other part of the body
Hemorrhage
The loss of blood or blood escaping from the circulatory system (bleeding)
What is a PD test?
Pupillary Distance test. Determines distance between center of each eye.
What is a PD test used for?
Place optical center in phoropter / trial lenses and determine the optical center in prescribed glasses
How far away do you sit in front of a patient when performing a PD test?
40 cm
What the procedural order of a PD test?
Near PD (look at my left eye) then Distance PD (now look at my right eye)
When would you perform a Monocular PD test?
When the patient has asymmetrical facial features
How do you record a PD test?
Distance PD / Near PD (in mm)
What’s the average PD difference?
2 - 4 mm
What does a Visual Field Test measure?
The sensitivity of the central and peripheral visual fields
What may VF loss indicate?
Peripheral defects: Glaucoma, RP
Central defects: AMD
What is a limitation of the FCF test?
Subtle visual field defects will most likely not be found
How far away do you sit away from the patient when performing an FCF test?
60 - 80 cm
Where do you put your fingers during an FCF test?
Exactly mid-distance between doctor and patient
How do you record a FCF test?
Normal: Full
Defects: Restricted
What does a Facial Fields test measure?
Static screening test for gross central VF defects
How do you record a Facial Fields test?
Normal: Full
Defects: superior paracentral scotoma
How far away should you be from a patient when performing a Bruckner test?
80 - 100 cm
What instrument is used during a Bruckner test?
Opthalmoscope
What should you adjust for when using an Opthalmoscope during a Bruckner test?
Adjust the lens for distance (ex. +1.00D for 1m) and your refractive error if required
How do you record a Bruckner test?
Normal: OD = OS
Defects: OS brighter than OD
How do you interpret a Bruckner test?
Brighter / whiter pupil is the eye with problem
What is the visible spectrum of light?
about 380nm - 750nm
What is the Trichromacy Theory?
Young - 3 types of photoreceptors sensitive to red/yellow/blue in a ratio of 8:7:6
Von Helmhotz - only three wavelengths needed to create all colors
Rods
(scotopic): all rhodopsin. Peak at about 498nm
Cones
(photopic): 3 types of photopigments (opsins) with different wavelength at which highest light absorption is observed (lambda max)
What are the 3 types of photopigments and what are their peak wavelengths?
Short (Cyanolabe): peak at 430nm
Middle (Chlorolabe): Peak at 535nm
Long (Erytholabe): Peak at 565nm
The fovea lacks which photopigment?
S-cones (Cyanolabes)
What is the ratio of L- and M-cones to S-cones throughout the entire retina?
100:1
What is important to remember about cones and wavelength absorption?
Individual cones do NOT transmit information about wavelength of a light stimulus; what varies is the PROBABILITY that a photon will be aborbed
What dos the Trichromatic Theory NOT explain?
Color appearance or afterimages
What is the Opponent Process Theory of Color Vision?
There are four colors in two opposite pairs and three opposite channels:
Red versus Green
Blue versus Yellow
Black versus White
How can both theories of Color Vision be correct?
Trichromatic Theory: at the photoreceptor level
Opponent-Process: 3 colors are wired to produce the opposite color translation
Anomalous Trichromat
3 photopigments present, but one has “abnormal” spectral sensitivity function
Dichromacy
Only 2 types of photopigments are working correctly; third is either missing or defective
Monochromacy
Total color blindness. Two cone types are missing or defective
Protanomaly Trichromat
L-opsin altered (response towards green): poor red-green discrimination. About 1% of males.
Deutranomaly Trichromat
M-opsin altered (response towards red): mildly affects red-green hue discrimination. About 5% males.
Tritanomaly Trichromat
S-opsin altered. Affects blue-yellow discrimination. Rare.
Protanopia
Dichromacy. L-cones are missing
Deuteranopia
Dichromacy. M-cones are missing
Tritanopia
Dichromacy: S-cones are missing
Tetartanopia
Theoretical Dichromacy. No yellow.
Rod Monochromacy
Rod Monochromacy: Achromatopsia. No cones. Abnormal vision.
Cone Monochromacy
Color blindness. Cannot distinguish hues, but otherwise normal vision.
Percentage of boys vs girls with color blindness
Boys = 8%
Females = 0.4%
Due to X-Linked nature of disease
What makes blue-yellow congenital color anomalies special?
- Verrrrry Rare (0.005%)
- Autosomal Dominant
- In chromosome 7
Acquired Color Vision Defect Characteristics
- Asymmetric variance
- Due to pathological process
- Associated with medication
- Often blue/yellow defect, but can be red/green
- Usually non-selective results from tests
What is a limitation of the Ishihara test?
Can only detect red/green defects
What lighting is required by the Ishihara test?
“True Daylight” or Daylight Illuminator or incandescent bulb (60-100 watts) while patients wears C-Daylight glasses
How far away is the Ishihara test conducted from the plates?
75 cm
How many Ishihara plates does a patient need to get wrong in order to be considered color deficient?
If 7 or less correct, color deficient.
If 8-9 correct (rare): conduct another test
10 = pass
Ishihara plates #12 - #14 can be used to determine what?
MIGHT differentiate Deuteranopia from Protanopia
Are revisions accepted with HRR #4 plates?
Hell no!
What do plates HRR plates #5 - #10 measure?
Initial color test. If normal color vision, stop here
If a patient has a B/Y defect, what HRR plate(s) will he/she get wrong?
5 or #6. Then go to plates #21 - #24
If a patient has a R/G defect, what HRR plates(s) will he/she get wrong?
7 - #10. Then go to plates #11 - #20
How do you distinguish a proton vs deutan color defect with HRR #4 score sheets?
Column with greater number of checks is the defect. Ex. - if deutan column has more checks, the patient has a deutan defect
If same number of checks = unclassified
What do you do with a mydriatic eye drops bottle in a Red Desaturation Test?
Compare good eye recognition of the red bottle cap with the defective eye to determine what percentage that eye “desaturates” the color.
Anisometropia
The condition in which the two eyes have unequal refractive power
