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Basic optometry test 1
8/19/13 - 9/30/13
190
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Graduate
09/30/2013

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Cards

Term
What is exophthalmos/proptosis?
Definition
  • abnormal protrusion of globe 
  • may be caused by retrobulbar lesions or less frequently shallow orbit
  • direction can determine etiology
Term
Define pseudoproptosis:
Definition
facial asymmetry, lid retraction, enophthalmos
Term
What are possible causes of exophthalmos?
Definition
  • mass pushing eyeball (tumors)
  • systemic disease (thyroid disease)
  • trauma (can cause enophthalmos as well)
  • infections (esp. kids & young adults)
  • other (cavernous sinus syndrome)
Term
define ptosis:
Definition
abnormal position of upper lid
Term
define ectropion:
Definition
eyelid(s) turned out
Term
define entropion:
Definition
eyelid(s) turned in
Term
What can happen to a child diagnosed with congenital ptosis?
Definition
lose vision quickly & could develop amblyopia
Term
benign; goes away on its own; sneezing, coughing, weight lifting
Definition
subconjunctival hemorrhage
Term
[image]
Definition

Acute dacryocystitis

 

(inflammation of nasolacrimal sac)

Term
[image]
Definition
proptosis
Term
[image]
Definition
Ectropion
Term
[image]
Definition
subconjunctival hemorrhage
Term
[image]
Definition

severe bilateral epiphora

 

(overflow of tears; excessive tear production)

Term
[image]
Definition

(a) Left facial palsy and severe ectropion

(b) lagophthalmos

Term
Baseline pupil size is influenced by what factors?
Definition
  • Ambient light
  • Level of retinal adaptation
  • Level of arousal
  • Excitement/startle dilates pupil
  • Age of patient
  • Older patients = smaller pupils
  • Dilated pupils with high IOP / seizures
Term
For a consensual pupillary reflex, the other pupil will constrict equally due to the...?
Definition
pupillary pathways
Term
[image]
Definition
  1. superior colliculus
  2. pretectal nucleus
  3. lateral geniculate body
  4. edinger-westphal nucleus
  5. sphincter pupillae
  6. ciliary ganglioin
  7. 3rd nerve
Term
Afferent pupillary defect is also known as what? What is it diagnosed by?
Definition
Marcus Gunn pupil; diagnosed by swinging flashlight test
Term
What happens to the normal vs. diseased eye when stimulated by light in a RAPD patient?
Definition
  • normal eye stimulated: both pupils constrict
  • when light swung to diseased eye: both pupils dilate instead of constricting
Term
Define anisocoria:
Definition
unequal pupil diameters (not always abnormal)
Term
Characteristics of Physiologic anisocoria:
Definition
  • 0.4 mm difference or more
  • 20% of normal population
  • difference less than 1.0 mm
  • more apparent in dim light (than bright)
Term
Give all the effects/symptoms of Horner's syndrome:
Definition
  • ipsilateral ptosis, miosis, & anhydrosis
  • dilation lag when light turned off abruptly
  • light & near rxns intact
  • apparent enophthalmos
  • congenital Horner's patients demonstrate heterochromia
Term
The spacial resolving capacity of the visual system is the...?
Definition
visual function
Term
Measurement of what the patient is seeing is based on what three factors?
Definition
  1. image quality
  2. resolution
  3. focusing error
Term
Why is VA measurement an essential part of the eye & vision examination?
Definition
  • Most common & useful test for assessment of visual function
  • Measure of resolving pwr of foveal area (or surrounding retina)
  • Assessment of mpact of different conditions on visual function
Term
What is the cornerstone of the vision examination that is one of the first tests performed?
Definition

VA

  • normal VA ≠ normal vision
  • VA = smallest black letter on white background that can be read @ 20 ft
Term
The common aim is to compare repeated measurements made by more than one examiner. Elaborate on this concept with (a) the need for standards & (b) clinical practice.
Definition
  • need for standards/conditions = test, distance, optotype (letters used)
  • clinical practice = reliable & reproducible 
Term
In order of increasing resolution, list the four types of visual acuity:
Definition
  1. Minimum visible/detectable acuity (can you detect it?)
  2. Minimum misalignment (can you locate its position?)
  3. Minimum separable/resolvable (is there 1 or 2?)
  4. Recognition acuity (can you identify/recognize it?)*******
Term
Characteristics of Minimum Visible/Detectable Acuity:
Definition
  • smallest detectable object
  • ability to detect presence of objects w/o naming or resolving
  • i.e. star in sky, telephone wire in sky
  • as fine as 1 sec of arc (1/60 min; 1/3600 deg)
  • rarely used or measured clinically
Term
Characteristics of Minimum Misalignment Visual acuity:
Definition
  • smallest difference in position
  • abilitiy to discriminate/localize small displacement of one part of obj w/ respect to other parts
  • as fine as 3 sec of arc (1/20 min; 1/1200 deg)
  • rarely used/measured clinically; hyperacuity
Term
Characteristics of Minimum Misalignment visual acuity:
Definition
  • smallest difference in position 
  • Vernier acuity-discrimination of lateral misalignment in frontal plane that provides basis for measurements; keratometers & lensometers
  • also stereo acuity
Term
Characteristics of Minimum Separable/Resolvable Acuity:
Definition
  • smallest resolvable separation 
  • ability to resolve 2 or more spatially separated targets
  • threshold = 30 CPD; used clinically
  • gratings (eq. spaced b&w lines) or landolt C are examples
Term
Characteristics of Recognition Acuity:
Definition
  • smallest recognizable letter or object
  • aka minimum legible 
  • requires resolving obj, letter, #, form details
  • threshold = 30 sec to 1 minute arc
  • most common clinical test
Term
What are 3 examples of recognition acuity?
Definition
  • snellen chart
  • landolt C
  • tumbling E
Term
What are some considerations to take into account when measuring acuity?
Definition
  • Standard Optotypes
  • Scaling
  • Spacing
  • Same number of optotypes/row
  • Background luminance
  • Ambient luminance
  • Optotype contrast
Term
What are the optimal elements of a distance test chart?
Definition
  • Use of Sloan letters (C D K H N Z R S V O)
  • Specification of acuity: MAR/logMAR
  • Horizontal spacing: Eq. to optotype size
  • Vertical spacing: Eq. to size of preceding line & Steps of 0.1 log Units
  • # of optotypes: same number / row
  • Contrast: > 85% Background
  • Luminance: From 100 to 300 cd/m2
Term
What is the size of a Snellen Visual acuity letter?
Definition
  • letter height of 20/20 letter
  • tanθ = h/distance --> h = distance(tanθ)
Term
Ex: gap subtending 1 min arc at 6m (20ft)
Definition

h = (tan 1’) 6 m

= (tan 0.01667) 6

= 6 (0.000291)

= 0.001745 m

= 1.745 mm gap or stroke width

Letter height = 5 x 1.745 = 8.73 mm

Term
Snellen defined "standard vision" as the ability to recognize one of his optotypes when it subtended...? What is the Snellen fraction?
Definition
  • when it subtended 5 minutes of arc
  • test distance / distance @ which smallest letter read subtends 5 min arc
Term
An individual w/ normal recognition acuity can resolve an optotype w/ a visual angle of ___ and resolution angle (stroke) of ___ (minute of arc).
Definition
a individual with normal recognition acuity can resolve an optotype with a visual angle of 5’ and resolution angle (stroke) of 1’ (minute of arc)
Term
What is the minimum angle of resolution?
Definition

MAR = angular size of the gap of the smallest letters that pt can identify 

 

(the letter detail; 1/5 of letter height)

Term
What is the eqn for MAR?
Definition
MAR = 1/snellen fraction
Term
What are some disadvantages of the Snellen chart?
Definition
  • dif. # of optotypes per row
  • irregular progression in letter size
  • dif. in optotypes --> recognition difficulty
  • dif. in background luminance related to dif. chart manufacturers
Term
What are the characteristics of the Bailey-Lovie VA design?
Definition
  • constant # letters per row (5 letters/line)
  • constant logarithmic change in letter size
  • space b/n letters = letter width
  • scoring typically by letter
Term
Characteristics of SOSH VA chart:
Definition
  • low vision chart
  • #s @ bottom of pgs refer to letter size in ft
  • # represents distance @ which particular letter would subtend 5 min from top 2 bottom
  • testing distance (ft) / # of letter that patient can just make out
Term
Characteristics of Lighthouse Continuous Text card:
Definition
  • used for measurement of reading acuity, not single letter acuity
  • used for functional assessment w/ trial frame after subjective refraction
Term

What are other common optotypes to test VA?

 

Definition
  • early treatment of diabetic retinoscopy study
  • Allen pictures
  • LEA symbols
  • tumbling E
  • landolt C
Term
What is the eqn and minimum amount of luminance & illuminance for a VA chart?
Definition
  • luminance = [illuminance x reflection factor (usually 0.8)]
  • minimum luminance = 10 ft-lamberts
  • illuminance = (luminance flux incident on surface/unit area)
  • minimum luminance = 12-20 ft-candles
Term
What are the physical factors that affect VA?
Definition
  • luminance & illuminance
  • contrast of chart (letter contrast ≥ 0.85; little effect b/n 20-100%; not a clinical factor; most wall/projectors meet specifications)
  • optical properties of the eye (RE or state of Rx; optical aberrations; clarity of media)
Term
What are some physiological factors that affect VA?
Definition
  • eccentricity (retinal location)
  • pupil size
  • accommodation
  • age
  • Stiles-Crawford effect of the 1st kind
  • binocularity
  • fixation
  • tear film/anterior ocular health
Term
Characteristics of eccentricity in relation to VA:
Definition
  • VA is higest @ fovea - dec w/ increasing eccentricity
  • 10 deg. from fovea = 20/100
  • 20 deg. from fovea = 20/200
  • due to neural connectivity retinal summation areas & # of rods or cones/ganglion cells
Term
Characteristics of pupil size in relation to VA:
Definition
  • dec. pupil size --> dec. retinal illumination, inc. depth of focus, & dec. diameter of blur circles
  • as pupil size dec., VA increases (to a limit)
  • <2.5 mm = VA dec due to diffraction
  • >5 mm = VA dec due to spherical abberation
Term
Characteristics of accommodation & age in relation to VA:
Definition
  • poor/inappropriate accommodation --> defocus decreases VA
  • infants develop 20/20 by 6 months & dec w/ inc age
  • inc light scatter, dec ocular transmission, inc pupil rigidity & miosis, dec accommodation, dec # of cones
Term
Describe what the Stiles-Crawford effect is and how it affects VA:
Definition
  • Light rays striking the PR at oblique angles are not as efficient as those parallel to the PR axis (entering through pupil center > peripheral)
  • directional sensitivity of the receptors
Term
Describe how binocularity, fixation, & tear film/anterior ocular health affect VA:
Definition
  • binocular VA: 5-10% better than monocular (summation)
  • fixation: slow drifts, high-freq tremors, saccadic re-fixations
  • tear film/anterior ocular health: can dec VA
Term
What are the psychological factors that affect VA?
Definition
  • past experience/memory/learning effects (blur interpretation)
  • expectations (call letter for # @ end of line)
  • motivation (refuse to guess, embarrassed)
Term
What effects does a bright illumination have on distance VA?
Definition
  • inc. illumination --> dec pupil --> falsely high VA
  • decreases chart contrast w/ inc light
Term
What five steps must be taken if a pt CANNOT read the largest letter on a 20 ft chart?
Definition
  1. walk patient toward chart or bring chart to patient
  2. count fingers/hand motion
  3. light perception with projection (LP c proj)
  4. light perception w/o projection (LP s proj)
  5. No light perception (NLP)
Term
When is the only time you measure with a pinhole for VA? Where is PH tested conducted at?
Definition
  • when VA is 20/30 or worse at distance AND near
  • PH testing is conducted at distance only
Term
What does it mean if VA inc. w/ PH? VA inc. but still less than normal? VA stays the same or dec. w/ PH?
Definition
  • VA inc. w/ PH: uncorrected RE, corneal or lenticular abnormalities (dystrophies, irregular astigmatism)
  • VA inc. but < normal: high RE and/or amblyopia
  • VA stays same/dec w/ PH: not RE; organic or pathological problem
Term
How does PH work? (How does it nullify small amounts of RE?) What is the most effective PH diameter?
Definition
  • PH nullifies small amts of RE by inc. DOF by dec. diameter of blur circles on retina
  • dec. light scatter --> dec. aberrations
  • most effective PH diameter = 1.32 mm
Term
What are the variables in multiple PH acuity?
Definition
  • illumination (target, retinal, & room)
  • spectacle correction 
  • distance b/n PH & cornea (moving PH closer inc. retinal illumination & inc. FOV)
Term
What are five other uses for PH?
Definition
  • magnifier (presbyope hold target near)
  • optical irregularities (PH held @ anterior focal point, irregularities seen as shadows cast on retina)
  • gross refraction (ametropia; move PH away & dist obj smaller = myopic; move PH away & obj larger = hyperopic)
  • check for final correction (fully corrected if PH placed over final Rx & no change/reduction of VA)
  • therapeutic device (PH CLs)
Term

VA measurement pearls: What condition would you suspect for the following situations?

  1. pt missing several letters on each line
  2. pt trouble localizing; isolated line/full chart
  3. pt difficulty w/ first few letters
  4. pt difficulty advancing to next letter on next line (skips line)
Definition
  1. suspect uncorrected astigmastism or amblyopia
  2. suspect amblyopia
  3. suspect left hemianopia
  4. suspect right hemianopia
Term

What are other options besides Snellen letters to test VA in the following situations?

  1. pt doesn't read letters
  2. preschooler/illiterate pt
  3. additional options to obtain VA
Definition
  1. snellen numbers
  2. tumbling E, picture optotypes. HOTV
  3. FPL, OKN drum, Visual Evoked response
Term

Predicting RE from VA: For the following distance VAs, give the spherical myopic error:

  1. 20/15
  2. 20/20
  3. 20/25
  4. 20/30
  5. 20/40
  6. 20/50 ....
  7. 20/100
  8. 20/200
Definition
  1. 20/15 = plano sph
  2. 20/20 = -0.12 sph
  3. 20/25 = -0.25 sph
  4. 20/30 = -0.50 sph
  5. 20/40 = -0.75 sph
  6. 20/50  = -1.00 sph
  7. 20/100 = -2.00 sph
  8. 20/200 = -2.50 sph
Term
What is legal blindness defined as? (What is the best corrected VA and maximum diameter of their visual field?)
Definition
  • when patient's best corrected VA in their better eye is 20/200 or worse
  • maximum diameter of VF in the eye w/ larger field does not exceed 20 degrees
Term

Vs OD 20/20  V’s OD 20/20

     OS 20/20        OS 20/20

 

Refractive Error possibilities?

OD: ___________ OS: __________

 

If you know your patient has glasses that they wear for reading only, your best refractive error estimate would be?

Definition

Vs OD 20/20  V’s OD 20/20

     OS 20/20        OS 20/20

 

Refractive Error possibilities?

OD: E or mild H OS: E or mild H

(able to accommodate through low RE)

 

If you know your patient has glasses that they wear for reading only, your best refractive error estimate would be? hyperopia; need + lenses, esp. @ near

Term

Vs OD 20/40  V’s OD 20/20

     OS 20/25        OS 20/25

 

Refractive Error possibilities?

OD: ___________ OS: __________

 

 

Definition

Vs OD 20/40  V’s OD 20/20

     OS 20/25        OS 20/25

 

Refractive Error possibilities?

OD: -0.75 myope OS: astigmatism

Term

Vs OD 5/400 PH 20/25

OS 20/400 PH 20/25

 

V's OD 20/200 @ 20 cm

OS 20/200

 

Refractive Error possibilities?

OD: ___________ OS: __________

Definition

Refractive Error possibilities?

OD: > -2.50 M OS: > -2.50 M



high myopia --> still can't see 20/20 @ 40 cm so need to move closer; e.g. 5D myope

Term

Vs OD 20/40  V’s OD 20/30

 

     OS 20/25        OS 20/20


Refractive Error possibilities?

OD: ___________ OS: __________

Definition

Refractive Error possibilities?

OD: Astigmatism OS: -0.25 M



Astigmatism b/c VA improved but still not 20/20; probably some myopia too; 20/25 = -0.25

Term
If the eyes are not aligned (can be one eye or both), the patient has what condition?
Definition
Strabismus (eye turn); eyes can turn in/out/up/down/rotational
Term

manifest eye turn = ?

latent eye turn = ?

Definition

manifest eye turn = tropia

latent eye turn = phoria

Term

Name the tropias:

  1. eye turned in
  2. eye turned out
  3. eye turned down
  4. eye turned up
  5. eye turned rotational 
Definition
  1. ESOtropia
  2. EXOtropia
  3. HYPERtropia
  4. HYPOtropia
  5. CYCLOtropia
Term
What are the four recti & two oblique extra ocular muscles?
Definition
  • four rect: medial, lateral, superior, inferior
  • two obl: superior & inferior
Term

What cranial nerves supply the following EOMs?

  1. MR, SR, IR, & IO
  2. LR
  3. SO
Definition
  1. CN III
  2. CN VI
  3. CN IV
Term

What ocular movements are each EOM responsible for?

  1. MR
  2. LR
  3. SR
  4. IR
  5. SO
  6. IO
Definition
  1. MR = Adduction; move eye towards nose
  2. LR = Abduction; move eye away from nose
  3. SR = elevation
  4. IR = depression
  5. SO = intorsion; move top of eye towards nose
  6. IO = extorsion; move top of eye away from nose
Term
What is the name of movements of ONE eye? What EOM movements are examples of this?
Definition
  • Duction = movements of one eye
  • all EOM movements can be ductions (adduction, abduction, elevation, depression, intorsion, extorsion)
Term
What is the name of movements of BOTH eyes TOGETHER (same direction)? What are some characteristics of this?
Definition
  • Versions = movement of both eyes together
  • conjugate movements that can be corretional movements for head tilts (1 eye intorts, other extorts)
  • dextro, levo, dextro-elevation, dextro-depression, levo-elevation, levo-depression
Term
What is the name of disjugate movements of both eyes? What are its two types?
Definition
  • Vergence = both eyes; disjugate movements
  • convergence = both eyes move towards nose
  • divergence = both eyes move away from nose
Term
Eye movements can have one of what two functions?
Definition
  1. support high resolution of foveal vision 
  2. prevent neural blur of images due to retinal image motion
Term
What are the six movements that achieve either high resolution of foveal vision or reduced neural blue due to retinal image motion?
Definition
  1. Visual fixation (VF)
  2. Vestibulo-ocular reflec (VOR)
  3. optokinetic nystagmus (ON)
  4. saccades (S)
  5. pursuits (P)
  6. vergences (V)
Term
Center of rotation of the eye is about ______ behind the cornea (antr vitreous).
Definition

Center of rotation of the eye is about 13mm behind the cornea (antr vitreous)

 

slight inaccuracies in measuring eye movements due to center of rotation location

Term
Line of sight extends from ____________ to ___________________.
Definition
Line of sight extends from point of fixation to center of entrance pupil
Term
line from center of rotation to point of fixation = ?
Definition
Fixation axis
Term
The fixation axis is perpendicular to what? The eye is in what gaze? All other gazes are?
Definition
  • fixation axis perpendicular to plane of face
  • eye is in primary gaze
  • all other gazes are eccentric
Term
What is the fastest movement that supports foveal vision? How fast do they move and how do they move objects to the fovea?
Definition
  • fastest movement = saccades
  • 700 degrees per second
  • saccades move objects to fovea by sudden shift in direction of gaze
Term
Characteristics of saccades:
Definition
  • conjugate eye movement
  • rotate eyes equally & in same direction
  • can be reflexive
Term
What is another movement that supports foveal vision that is conjugate & relatively slow moving? What are its other characteristics?
Definition
  • smooth pursuit movements
  • conjugate; relatively slow moving targets are kept on retina (40 deg/sec)
  • smooth rotations of eye, rather than sudden movements
  • partly attentive; partly reflexive
Term
What is another movement that supports foveal vision that is disjugate and has a lower peak velocity compared to saccades? Other characteristics?
Definition
  • Vergence eye movements
  • disjugate; convergence or divergence
  • lower peak velocity (70 deg/sec) compared to saccades
  • shift off-foveal images to fovea by suddenly changing the distance of gaze
Term
What movements support stable retinal imagery by helping to minimize retinal image motion?
Definition
vestibulo-ocular & optokinetic eye movements
Term
Vestibular movements are stimulated by what? How long is its latency?
Definition
  • Vestibular movements stimulated by head motion & its effect on the inner ear vestibular apparatus
  • purely reflexive movements
  • has very short latency (16 milliseconds)
Term
A stationary observer viewing persistent unidirectional movements of large objects generates what kind of nystagmus?
Definition
optokinetic
Term
Characteristics of optokinetic nystagmus:
Definition
  • movement that supports stable retinal imagery
  • smooth & slow motion in direction of motion of target
  • fast saccade-like motion in the opposite side
Term
Describe Hering's Law of Equal Innervation:
Definition
  • equal innervation to yoke muscles
  • one motor command split & sent to both eyes
  • hering proposed that vergences are also yoked w/ respect to innervation
  • e.g. right lateral rectus & left medial rectus 
Term
What are the 4 types of vergence movements?
Definition
  1. tonic
  2. proximal
  3. accomodative
  4. fusional 
Term
Clinicians use what ratio to determine how many diopter you can converge for every diopter that you accommodate?
Definition

accommodative convergence to accomodation ratio

 

(how many prisms of convergence for every diopter of accommodation?)

Term
What is the built in convergence system that everyone has to keep the eyes straight & steady?
Definition
tonic vergence
Term
Tonic innervation provides what position of the eyes?  What does it vary with? What is it lost upon?
Definition
  • tonic innervation provides the physiological resting position of the eyes
  • varies with drugs, age, alcohol, stress, environment
  • lost upon death; eyes diverge at that time (also lost with anesthesia)
Term
Proximal vergence is a type of convergence induced by what? When does convergence innervation occur?
Definition
  • induced by awareness of near
  • convergence innervation when a near object is viewed
Term
The near triad involves more than just accommodative convergences. What else does it involve?
Definition
  • convergence, accommodation, & constriction of pupil 
  • very important measure in certain cases of strabismus 
  • must measure accommodative component of eye turns
Term
Define fusional vergence:
Definition
  • the flexible & powerful component of convergence that alters vergence of the eyes to achieve fusion
  • adds convergence when other 3 components do not provide enough
  • can also help diverge if other 3 overact
  • measure "break" with prisms
Term
What questions do you ask for NPC testing? Accommodation testing?
Definition
  • NPC - is target single?
  • accommodation - is target clear?
Term
Near point of convergence tests what? How is it tested?
Definition
  • tests ability to converge & keep images fused
  • move accommodative target close to pt until diplopia is reported or one eye loses fixation (eye turn)
  • record breakage & recovery
Term
Who gets eye turns? Eso is common in who? Exo is more common in who?
Definition
  • anyone can get eye turns (strabismus)
  • eso common in kids (newborn - 5yrs); kids w/ eye turn need referral to opt. bc chance for amblyopia (lazy eye)
  • exo more common in adults; sudden onset strabismus needs referral to neuro (in case of diabetic CN III palsy)
Term
What is a simple test to measure an eye turn?
Definition
hirschberg test
Term
How is the Hirschberg test performed and what results would be expected for normal pt? Pt w/ strabismus?
Definition
  • both eyes open; pt fixates penlight
  • compare the position of corneal reflex in both eyes
  • reflex should be @ same position OU
  • in strabismus: one eye will show a dif. position for corneal reflex
  • 1.0 mm = 22 prism diopter deviation (loose prisms used to compensate for deviation)
Term
What is the Krimsky method?
Definition
  • amount of loose prism required to bring both corneal reflexes @ same spot
  • both Hirschberg & Krimsky less accurate than cover test but useful in kids/adults who can't do cover test
Term
What is the most accurate way to measure eye turns?
Definition
cover test (use prisms to measure exact deviation of phoria/latent turn or tropia/manifest turn)
Term
What plays an important role in binocular vision status w/ regards to patient's lines of sight under monocular & binocular conditions?
Definition
pt's angle of deviation
Term
What are the two parts of covering testing?
Definition
  1. unilateral performed first - heterophoria/tropia
  2. alternating - magnitude & direction

both performed @ D & N using fixation targets

Term
Define heterophoria:
Definition
  • magnitude & direction that the visual axes of the eyes drift --> when fusion is disrupted (dissociated)
  • magnitude reveals amt of fusional vergence needed to secure single binocular vision
Term
What is the importance/significance of the angle of deviation?
Definition
  • potential for amblyopia
  • cosmesis
  • poor binocular fxn
  • asthenopia/HA
  • dec stereopsis (depth perception)
Term
Why do we test for phoria?
Definition
  1. to determine tendency of eyes to deviate from point of fixation & whether or not manifestation of possible muscle imbalance
  2. lenses/prisms prescribed to achieve visual comfort for pt w/ limited vergence compensation
Term
What are conditions/symptoms associated with tropia/strabismus?
Definition
  • diplopia
  • amblyopia: lazy eye
  • suppression: active cortical dampening of images from one eye
Term
symptoms associated w/ amblyopia:
Definition
  • reduction in best corrected VA (not organic etiology)
  • strabismus eye turn 
  • suppresion (refractive amblyopia)
Term
Subjective cover testing diagnosis:
Definition
  • not a true part of cover test
  • pt sees obj move in same direction as paddle = EXO
  • pt sees obj move opp direction as paddle = ESO
Term
apex of the prism should point in the direction of...?
Definition
the eye deviation
Term
Patients who are strabismic may experience double vision since their foveas are not aligned. What kind of diplopia are present for eso & exotropes?
Definition
  • esotropes have uncrossed diplopia (OD image on right, OS on left; diplopic image occurs on same side as deviating eye)
  • exotropes have crossed diplopia (OD image on left, OS on right; diplopic image occurs on side opp of deviating eye)
Term
In order to prevent diplopia, the pt may develop one of two compensating mechanisms:
Definition
  1. suppression
  2. anomalous retinal correspondence
Term
Define stereopsis:
Definition

perception of depth produced by binocular retinal disparity; fundamental test of binocularity

  • 1st deg: simultaneous perception
  • 2nd deg: flat fusion (2D)
  • 3rd deg: stereopsis (highest level)
Term
What monocular & binocular cues down depth perception consist of?
Definition

monocular

  • interposition/overlap
  • relative size
  • light & shade

binocular

  • stimulation of corresponding foveal points
  • retinal disparity
Term
Compare/contrast global vs. local stereopsis:
Definition

global

-requires bifoveation

-no monocular cues

-not present w/ constant strabismus

-ex: random dot shapes/forms

 

local

-includes monocular cues

-up to 70 sec arc even w/ constant strabismus

-ex: Wirt circles, lea symbols, & stereofly

Term
Define stereoacuity:
Definition
minimum amt of disparity that allows the pt to perceive depth; measured in sec of arc
Term
What are some factors that stereopsis:
Definition
  • blur
  • uncorrected RE
  • reduced contrast
  • strabismus
  • aniseikonia
  • suppression
Term
What is BP & why do we measure it?
Definition
  • force of blood against walls of vessel
  • saves lives, may be the only doctor pt sees
Term
What is hypertension/high blood pressure? It is the most common ________ _______ in America. Why is it dangerous?
Definition
  • HTN is elevated BP over time; most common primary diagnosis in U.S. (35 million off. visit)
  • risk to body: hrt dz, kidney dz, stroke, congestive hrt failure, atherosclerosis (hardening of arteries), coronary & carotid artery disease
  • risk to eye: hypertensive retinopathy, choroidopathy, optic neuropathy, blindness
Term

Systolic BP & Diastolic BP values for the following BP classifications:

  1. normal
  2. prehypertension
  3. stage 1 hypertension
  4. stage 2 hypertension
Definition
  1. SBP= <120; DBP = <80
  2. SBP = 120-139; DBP = 80-89
  3. SBP = 140-159; DBP = 90-99
  4. SBP= ≥160; DBP = ≥100
Term
What is the goal BP for hyoertensive & pts with DM/chronic kidney disease?
Definition
  • hypertension = <140/90
  • DM/kidney dz=<130/80
Term
formula to calculate BMI:
Definition
weight x (height)2 x 703
Term
The keratometer objectively measures the central curvature of the ____________. Since the cornea does most of the refracting of the eye, an indication of the _____________________________ and ______________ can be determined.
Definition
The keratometer objectively measures the central curvature of the cornea. Since the cornea does most of the refracting of the eye, an indication of the cylinder amount and location can be determined.
Term
The keratometer is used exclusively in contact lens patient care because the keratometer is calibrated for the index of ____________________.
Definition
The keratometer is used exclusively in contact lens patient care because the keratometer is calibrated for the index of tears = 1.3375.
Term
What is the most powerful refractive surface that is the first refractive surface & a reflective surface?
Definition
tear film
Term
What are the refractive properties that make measurement important? reflective?
Definition
  • refractive = keratometer uses reflective properties of cornea to measure its radius of curvature
  • reflexive = K acts as highly convex spherical mirror
Term
How does keratometry measure corneal curvature?
Definition
  • radius of curvature in each principal meridian found by measuring size of reflected mires
  • measures only 2 small areas on cornea surface
Term
history of keratometry:
Definition
  • Helmholtz invented modern keratometer (1854)
  • Javal & Schiotz developed clinical instrument (1881)
Term
Characteristics of regular astigmatism. Three types:
Definition
  • mires are not distorted & principal meridians are perpendicular
  • with the rule (more pwr in vertical; greatest curvature; vertical b/n 60-120); against the rule (more pwr in horizontal b/n 30-150); & oblique (prin. meridians lie b/n 30-60 or 120-150)
Term
Characteristics of irregular astigmatism.
Definition
  • distorted mires or principal meridians not perpendicular
Term
Objective refraction is comprised of what 2 parts?
Definition
  1. keratometry - corneal curvature/astigmatism
  2. retinoscopy - spherical ametropia/astigmatism
Term
What are the limitations of keratometry?
Definition
  • only samples central 3 mm
  • does not quantify irregular astigmatism
  • adjustment errors not uncommo 
  • error of about ± 0.25 to 0.92 D
Term
When doing the procedure what are your primary & secondary meridians?
Definition

horizontal = primary

vertical = secondary

Term
If the patient’s eye will not come into focus at either extreme of the focusing knob, adjust the...?
Definition
forehead rest
Term
If one of the minus mires is not visible superiorly, ask the patient to ______________ wider. The upper lid is cutting off the reflection.
Definition
open eyes
Term
If one of the plus mires is not visible laterally, adjust the _____________________________. It is cutting off the reflection.
Definition
keratometer (center)
Term
If the circular mires are broken or wiggly, the cornea is irregular or there is poor ____________.
Definition
tear quality
Term

Corneas flatter than 42.00generally indicate _________________.

Corneas steeper than 44.00 generally indicate _________________.

Definition

flatter than 42.00 = hyperopia

steeper than 44.00 = myopia

Term
___________ astigmatism: The most converging power on the cornea is in the vertical meridian. (Axis of minus cylinder approximately 180)
Definition
WTR
Term
________ astigmatism: The most converging power on the cornea is in the horizontal meridian (Axis of minus cylinder approximately 090)
Definition
ATR
Term
theoretical and academic formula for predicting a patient’s refractive cylinder (the cylinder amount in their spectacles).
Definition
Javal's Rule
Term
3 levels of visual field testing:
Definition
  1. screening 
  2. qualitative/diagnostic
  3. quantitative

screening can be automated or confrontation fields; performed on all pts w/o expectation of particular field defect

Term
In a problem-based screening, usually use a...?
Definition
  • suprathreshold automated perimeter
  • suspect "problem" & do quick test to rule out problem
Term
Qualitative or diagnostic perimetry:
Definition
  • suspect a defect in pt
  • determine characteristics of VF defect such as location, borders, shape, size, whether its homonymous
  • lesion can be localized/cause identified
  • often tests several points on VF & needs quantification 
  • screenings can be diagnostic
Term
Quantitative Perimetry:
Definition
  • quantify a known or suspected field defect in order to get baseline data as well as follow-up the defect over time
  • used to identify subtle defects
  • expensive for pt
  • GLC most commonly followed/diagnosed w/ quantitative perimetry
Term
Kinetic perimetry:
Definition
  • test stimulus placed in area where it is not seen (outside VF or inside blind spot) then move stimulus until just seen
  • stimulus moved in all directions
Term
Static Perimetry:
Definition
  • stimulus presented at chosen location; threshold or suprathreshold
  • determine sensitivity of one location
Term
What are three types of confrontation VF tests?
Definition
  1. finger count
  2. field-limits
  3. color confrontations (red-cap)

all done at 1 m distance

Term
What is the near triad made up of?
Definition
  1. accommodation
  2. convergence
  3. pupil constriction
Term
define accommodation:
Definition
Process where there is a change in the dioptric power of the crystalline lens so that an object at near can be focused clearly on the retina
Term
Define presbyopia:
Definition
Slow, normal, age-related, reduction in amplitude of accommodation
Term
Symptoms & traits of presbyopia:
Definition
  • Causes blur and eye strain with near work
  • Usually reported between ages 40-45
  • Onset from 38-48 years of age
Term
What is the current accepted mechanism of acccommodation?
Definition
helmholtz's theory
Term
What does the helmholtz's theory state?
Definition
  • Lens changes in shape, therefore changes in power
  • Objects at various distances can now be focused on the retina
  • Some animals have different mechanisms of accommodation
Term
What is the sensory input of accommodation?
Definition
blur (or awareness of proximity)
Term
What occurs during accommodation?
Definition
  1. blur sensory input
  2. inc freq. of firing of neurons that supply ciliary muscle
  3. ciliary muscle constricts
  4. lens zonule relaxes
  5. lens becomes more spherical
  6. overall lens pwr inc.
Term
What are the components of accommodation?
Definition
  • Reflex accommodation
  • Vergence accommodation
  • Proximal accommodation
  • Tonic accommodation
Term
Characteristics of reflex accommodation:
Definition
  • Automatic adjustment of refractive state to maintain a sharp focused image in response to blur or decrease in contrast
  • Usually occurs for small amounts of blur, up to TWO DIOPTERS
  • Largest component of accommodation in monocular and binocular viewing
Term
Characteristics of vergence accommodation:
Definition
  • Accommodation induced by neurological linking and action of fusional (disparity) vergence
  • Gives the CA/C ratio, which is 0.40D per meter angle in young adults
  • Second major component of accommodation
Term
Characteristics of proximal accommodation:
Definition
  • Accommodation due to the knowledge of perceived nearness of an object
  • Stimulated by targets closer than 3meters
Term
Characteristics of tonic accommodation:
Definition
  • Revealed in the absence of blur/ proximity/vergence cues
  • Represents baseline innervation from midbrain and is thus a stable input
Term
Accommodative facility (ranges by age):
Definition
  • Ranges between 3-5 Diopters in children around age 6 years
  • 4-7 diopters in age 12 years
  • Follows adult ranges after 12 years of age
Term
What test is used to assess accommodation? How is it measured?
Definition

Push-up method; Donder's Amplitude of accommodation

  • Measures diopters pt’s ability to change focus of lens in response to accommodative target
  • while wearing distant Rx pt must keep target clear & report 1st sustained blur
Term
what method is used for children to measure accommodation?
Definition
push AWAY method
Term
Hofstetter’s formula to measure accommodative amplitudes:
Definition

Expected Mean amplitude =

18.5 D – [0.30D x (age in years)]

Term
What are the benefits of binocular vision compared to monocular vision?
Definition
  • Enhance visual capability
  • Improved speed and accuracy (esp. in low contrast situations)
  • Binocular visual field is larger (2000); Monocular 60 up, 60 medial, 70 down, 100 temporal
Term
Poor binocular vision produces what?
Definition
fatigue, blur, headaches, & asthenopia
Term
distance perception = ?
Definition
absolute depth perception; determine (quantify) how far is a particular target compared to current position
Term
depth perception = ?
Definition
relative depth perception; determine the nearness of one target compared to the other
Term
Lateral separation of the eyes provide slightly different views of the world leading to what two factors?
Definition

binocular parallax & elicits convergence

 

also fine vs. coarse stereo (fine is foveal; coarse is off-foveal)

Term
Global stereopsis:
Definition
  • Random dot stereograms
  • Visual system performs significant interocular image fusion
Term
local stereopsis:
Definition
When visual system uses cues such as color, contrast to reveal one form to be distinct from another
Term
Ability to discriminate very fine differences of depth is a result of...?
Definition
geometric retinal disparity
Term
Foveal stereo threshold can be as low as? What is hyperacuity?
Definition
  • Foveal stereo threshold can be as low as 2 seconds of an arc
  • hyperacuity = when observer performs better than expected based on foveal cone diameter
Term
simple myopia:
Definition
  • refractive (strong eye)
  • axial (long eye)
  • parallel light focuses in front of retina
Term
Simple Hyperopia (or hypermetropia):
Definition
  • refractive (weak eye)
  • axial (short eye)
  • parallel light focuses behind retina
Term
Parallel light hitting an astigmatic eye forms...?
Definition
two separate foci
Term
Characteristics of myopia: symptoms, signs, & correction.
Definition
  • hereditary, environmental (near work), premature birth
  • distance blur, asthenopia/blur at near
  • squinting, push specs up nose
  • corrected w/ minus lens 
Term
Symptoms & signs of hyperopia:
Definition

symptoms

-asthenopia w/ near work

-child who is disinterested in school

-eye rubbing, red eyes

 

signs

-reduced amplitude accom, esp. for young ppl

-higher H > inc. need for accom., ET 

Term
When would you fully correct or partially correct for hyperopia?
Definition
  • fully correct: if pt is ET or vocational needs (near point demands)
  • partially correct: younger pts, vocational needs (mainly distnace work), pt is exo
Term
Formula to calculate spherical equivalent:
Definition
SE = sphere + (0.5)cylinder
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