Download Preliminary Testing

Preliminary Testing
 Visual Acuity
o Purposes:
 To establish a baseline
 Legal reasons (driver’s licenses, insurance claim, pension, and disability
based on legal blindness)
 Legal blindness: 20/200 or worse in better eye OR less than 30 of
visual field in the widest meridian of the better eye
 Monitor progression or improvement of eye disease
 Guide for the rest of the exam (prediction of refractive error, correlation of
data, determines additional testing)
o Always the first test performed after history
 Exception: chemical burn/spill; irrigate first, then check VA
o Definition: the resolving power of the eye, or the ability to see two objects as
separate
 “Normal” resolving power is defined as the ability to detect a gap with a
width of 1 min of arc
o VA is highest at the fovea and decreases with increasing retinal eccentricity
o VA best if pupil is 2-5 mm
o Types
 Minimum Detectable Resolution (minimum visible): the ability to distinguish
an object from its background
 Minimum Separable Resolution (minimum resolvable): the ability to resolve
two or more spatially separated targets
 Gratings, bars, Vernier acuity, preferential looking
 Recognition Resolution (minimum legible): the ability to recognize letters,
numbers, and geometric forms
 Snellen, Landolt C, Tumbling E
o Snellen acuity chart is the universal method of measuring VA
 Snellen optotypes: width of each stroke is equal to the width of a gap on
that line
 “Best” letter is E (3 strokes and 2 gaps)
 “Not as good” letters are T and L ( no gaps)
 At 20 feet, a 20 foot optotype subtends 5 min of arc
 Its details each subtend 1 min of arc
 20/20 letter is defined as a letter that has a height (x) such that it subtends
5’ arc at 20 ft
 Letter height can be altered with test distance
 Details (gaps and strokes) each subtend 1’ arc at 20 ft
 Utilizes a “folded” room/operatory system
 Projector with letters, 2 mirrors and a screen
 Test distance= patient to mirror + mirror to screen
o MAR (minimum angle of resolution) in minutes of arc is equal to the reciprocal of
the decimal acuity value or the Snellen fraction
 Snellen fraction = 1/MAR
20 ft (6m) is considered optical infinity, which is defined as the distance at
which no accommodation is being used
 Snellen fraction =
testing distance
distance at which the smallest letter read subtends an
angle of 5’ of arc
 Also described as the distance at which a “normal” eye can see the
smallest letter read by this patient
Snellen equivalent is used when VA is taken at a distance other than 20 ft or when
other nomenclature is used
 It is better to report the actual acuity, not the equivalent
Limitations:
 Number of letters tested per line changes as you move down
 Letter sizes between lines do not change by a constant ratio
 Between row and between letter spacing is not proportional to the letter size
 Legibility for optotypes often varies
Standard Chart Specifications
 Chart luminance: at least 10 foot lamberts
 Chart contrast: at least 90%
 Subdued room illumination to enhance chart contrast
 Uncorrected refractive error is more likely to impact VA when pupils
are slightly dilated
Distance VA should be performed during ALL patient encounters
 Procedure
 Seat patient comfortably and dim lighting
 VAs taken without correction(sc) and then with correction(cc)
o Minimizes chance of patient memorizing
 Clean occluder with alcohol swab
 Begin with full chart open and ask “Which of these is the smallest line
of letters that you can read?”
 Isolate smallest LOL that the patient can read; continue to scroll
down to the next LOL and have patient read it; stop when the patient
is unable to read the entire LOL
o Find the patient’s threshold
 OBSERVE the patient (no squinting, cheating, leaning forward, etc)
o Observe the speed and degree of difficulty
 Record VA as the smallest line in which not more than 2 letters were
missed for OD, OS, OU
o The number at the end of each line signifies the level of acuity
o Some use several 20/20 lines to minimize memorization
o “normal” best-corrected VA is 20/20
 Corrected visual acuity (best corrected VA) is measured with the best
refractive correction in place
 Habitual visual acuity is measured with patient’s own spectacles/CLs
Near VA performed during full/comprehensive exam and if they have a near vision
complaint
 Procedure

o
o
o
o
o



Use full illumination: stand lamp on recording card
Done without, then with near correction
Measure the distance from the patient’s spectacle plane to the
reading card in cm
 Cover OS and instruct to “Read the smallest paragraph that you are
able to”, switch to cover OD, and then remove to read with both eyes
open
 Re-measure the working distance with their correction
 Record working distance (in meters!) over the smallest print read for
OD, OS, OU
 M system: a 1M letter subtends 5’ of arc at 1 meter
 Allows patient to hold card at their desired reading distance
 Reduced Snellen system: gives the appearance of expressing the distance
VA that is equivalent to the near VA
 Should NOT be used for near VA (not appropriate to use a term that
suggests a test at 20 ft when that distance is not relevant to near
vision)
 Jaeger system: indicates the size of the print by the letter J followed by a
number
 Poor system because there is no standardization of the Jaeger sizes
and there is no intrinsic meaning to the “J” number
o Pinhole testing: a measure of potential visual acuity
 Nullifies small amounts of refractive error by 1) increasing the depth of focus
and 2) decreasing the size of the blur circles
 Most effective diameter is 1.32 mm
 If VA improves with pinhole, suggests that refractive error is probably the
cause of the reduced VA
 Done when entering acuities are 20/40 or worse (based on better VA)
 Record PH followed by VA obtained
 If no improvement, record PHNI
 Super Pinhole, PAM (potential acuity measure) and laser interferometer are
commonly used to determine potential VA before cataract surgery
o Brightness Acuity Test (BAT): used when you suspect acuity would be worse in a
glare situation
 VA with BAT is worse than without BAT for patients who have glare
problems
o Alternative distance VA charts
 OKN drum: cortical function only; objective test
 Teller acuity cards: infants, non-responsive patients
 Tumbling E: preschool, illiterate or non-verbal patients
 LEA chart: children
 Allen figures: children
 Landolt C:
 HOTV chart: amblyopes
 Each letter is surrounded by crowding bars

Amblyopia: decreased VA (not correctable to 20/20) NOT due to
pathology
o Snellen chart produces contour interactions (slow responses,
some correct responses over a wide range of letter sizes,
correct end-letter responses, out of order responses, perform
better with isolated lines or letters)
 Feinbloom chart: patients unable to see the 20/400 E on Snellen
 Full illumination and test distance of 5 or 7 ft
 Record test distance over smallest number size seen
o Alternative near VA charts (used during low vision)
 Bailey-Love Chart: patients unable to see large print on other cards
 Space between the letters is equal to the letter width (prevents
crowding effect)
 5 letters on each line
 Between row spacing is equal to the height of the letters in the
smaller row
 Lighthouse cards
o Other measures of VA
 Light perception (performed at ~ 1 ft)
 LPP: light perception with projection
 LPO: light perception only
 NLP: no light perception
 Hand motion (used as last ditch effort when Feinbloom efforts exhausted)
 Count Fingers
 “Fix and follow”: unresponsive patients
 MUST ALWAYS ATTEMPT TAKING VISUAL ACUITIES
o Correlation of VA and refractive error
 General rule: each 0.25DS of uncorrected refractive error accounts for ~ 1
line of Snellen VA
 For cylinder, take spherical equivalent (sphere + ½ cyl)
 For oblique axis, add a line for the axis
 Patient must have NO accommodation or be cyclopleged
 Pupil Testing
o Pupil performs 3 primary functions
 Controls entering light
 Modifies depth of focus (inverse relationship)
 Smaller pupil increases depth of focus
 Varies optical aberrations (smaller has less aberrations)
o Should be performed during ANY patient encounter regarding eye health
 Important because it is a neurological test that can detect optic nerve
disease, brain mass and aneurysm
 Gross examination can detect iris abnormalities, media opacities, and
leukocoria
o Shape
 Pupils should round and centered within the iris on optic axis
 Irides should be of the same color

o Size



Abnormalities
o Corectopia: displaced or misshapen pupil
o Ectopic pupil: significantly decentered
o Polycoria: more than one pupil
o Heterochromia: iris color different between eyes or between
different areas in one eye
o Aniridia: absence of iris, therefore non-existent pupil
Average of 3.5 mm in adults under normal illumination
Become smaller after adolescence due to senile miosis
Should equal one another within 1 mm
 Anisocoria: unequal pupil size
 20 % have physiologic anisocoria
 Controlled by the autonomic nervous system
 Iris dilator muscle dilates; sympathetic innervation
 Iris sphincter muscle constricts; parasympathetic innervation
o Pupillary pathways
 Afferent
 Light enters pupil impulse in retina (PR and ganglion cells) optic
nerve optic chiasm: ½ cross, ½ ipsilateral optic tracts to superior
colliculi pretectal nuclei of hypothalamus crossed and uncrossed
fibers to EW synapse with efferent fibers
 Parasympathetic efferent
 From EW nucleus travels with CN III (inferior division) cavernous
sinus pierces globe deviates from CN III and synapses at ciliary
ganglion postganglionic fibers reach iris sphincter via short ciliary
nerves
o 97 % of the fibers control accommodation (ciliary body)
o Only 3 % innervate the sphincter
 Sympathetic efferent
 Hypothalamus synapses at ciliospinal center of Budge (C8-T4)
2nd order neurons leave spinal cord ascending close to the apex of
lung synapses at superior cervical ganglion 3rd order neurons
follow the ICA’s to the globe iris dilator via the long ciliary nerves
 Sympathetic innervation reaches Muller’s muscle in upper lids
o Response to light
 Miosis (=constriction) occurs via parasympathetic innervation
 Some latency in initial constriction is normal (depends on brightness
and age)
 Direct response: response that occurs in one eye while the light is shone in
that eye
 Consensual response: response that occurs in one eye while the light is
shone in the other eye
 Pupillary escape: gradual and partial re-dilation without change in light
intensity
Pupillary unrest or hippus: small oscillations in pupillary diameter that occur
during maintained stimulation
 Due to normal fluctuation in sym/parasym equilibrium
o Response to near
 Independent of retinal illumination
 Near reflex is ALWAYS present when direct light reflex is intact
 Near triad: pupil constriction, convergence, accommodation
o Swinging flashlight test
 Compares the strength of the direct pupillary response with that of the
consensual response
 Detects afferent pupillary defect due to retinal abnormalities or optic nerve
pathway anterior to LGN (APD or RAPD)
o Procedure
 Remove spectacles and examiner positioned off to one side
 Use a distant, non-accommodative target (2-3 lines above VA)
 Measure pupil size under normal lighting conditions
 Expected findings: should equal one another
o Size in bright: 2-4mm
Size in dark: 4-8mm
 If pupils are unequal, measure size in both dark and bright light
 To visualize dark irides, use:
o Burton lamp: hold ~25 cm (10in) from the patients and below
the patient’s line of sight
o Ophthalmoscope: use as a dim flashlight to illuminate both
eyes simultaneously (“light from below”)
 Judge the roundness of each pupil and describe any abnormalities
 Observe pupil’s response to light in dim illumination
 Note the magnitude of change (quantity) using scale 0-3
 Note the rapidity of reaction (quality) using slow (-) or fast (+)
 Expected findings
o Direct response of OD should equal direct response of OS
o Consensual response of OD should equal consensual
response of OS
o Direct response of OD should equal consensual response of
OD
 Perform the swinging flashlight test
 Expected findings
o Rate and amount of constriction should be the same for both
pupils
o Direct should equal consensual for both eyes
 If it is not the case for either eye: afferent pupillary defect in the eye
with less constriction
 Record using PERRLA (-) APD if all reflexes are normal
 PE: pupils equal
 R: round
 RL: reactive to light (direct and consensual)
 A: responsive to accommodation

 (-) APD: no APD
o Afferent pupil anomalies result in an APD
 Severe retinal disease, optic nerve diseases or compromise, mass/lesion
behind eye compressing optic nerve or chiasm
 NOT with disorders of ocular media
 Afferent pupillary defect (RAPD) indicates unilateral or asymmetric damage
to the anterior visual pathways
 When the consensual response is greater than the direct response of
one eye
 If present, pupils of both eyes will constrict less when the light is
directed into the affected eye
o Both eyes will constrict when light beam directed into
unaffected eye
 When light beam is directed in affected eye, causes less constriction
in
o Affected eye: reduced direct reflex
o Unaffected eye: reduced consensual reflex
 Graded from trace to 4+
o 3-4+APD: immediate dilation of the pupil, instead of
initial/equal constriction
o 1-2+APD: no change in pupil size immediately, followed by
dilation
o Trace APD: initial constriction, but greater escape to a larger
intermediate size than when light is swung back to normal eye
 Amaurotic Pupil: severe or 4+APD
 Patients have an eye with “NLP”
 Light beam directed into affected eye no direct response in
affected eye and no consensual response in unaffected
 Light beam directed into unaffected eye direct response in
unaffected eye and consensual response in affected eye
 Near reflexes will be intact
 Reverse (indirect) APD
 Performed when one pupil is fixed, dilated, or constricted
o ONLY observe the reactive pupil
 If APD in eye with reactive pupil, that pupil will constrict more with
consensual stimulation than with direct
 If APD in eye with fixed pupil, the reactive pupil will constrict more
with direct stimulation than with consensual
 Note reverse APD (implies you used a reverse technique)
o Efferent pupil anomalies: unilateral defects/lesions will often generate anisocoria
 Anisocoria: usually 2-4 mm difference in dark and light
 If same degree of anisocoria in light and dark: physiologic
 Big pupil problems: anisocoria greater under bright conditions due to a
defect/lesion of the parasympathetic
 Adie’s tonic pupil
o Relatively common; primarily in females 20-40

o Presentation
 Unilateral semi-dilated pupil
 Pupil with minimal and slow reaction to light
 Pupil with reduced direct, consensual (poor constriction
of sphincter) and near responses to light
 May present with a reduced near vision complaint
 Vermiform motion of iris: quivering motion of iris at
pupillary border due to segmental palsy of sphincter
 10-20% eventually affecting other eye
 Reduced direct response to light bilaterally
 Decreased near VA
 Prolonged pupil cycle time
o Etiology
 Lesion of the parasympathetic pathway (ciliary
ganglion) on the side of the pupil problem
 Viral
o Diagnosis
 0.125% pilocarpine (wait 10-15 min)
 Constriction: Adie’s confirmed
 No constriction: either pharmacologic or 3rd
nerve
o Management
 Rule other orbital and ocular conditions
 Cosmesis
 Accommodation
 Near add, sometimes unequal adds
 Equalize accommodation during refraction and
other near or binocular testing
 Accommodation generally returns within 2 yrs
Cranial Nerve Palsy
o Presentation
 EOM paresis—exotropia and hypertropia (“down and
out”) of eye affected
 Ptosis
 Fixed and dilated pupil, or non-reactive pupil
o Etiology
 Pupil fibers are on the outside of CN III; they are
involved early in a compressive lesion and are rarely
involved in an ischemic infarction
 Lesions that involve the pupil: tumor and aneurysm
 Lesions that spare the pupil: vascular disease causing
ischemia (diabetes, hypertension)
o Diagnosis
 0.125% pilocarpine—will NOT constrict

1% pilocarpine—WILL constrict
o Management
Presentation of acute 3rd nerve palsy with pupil
involvement considered a medical emergency!
 Manage diplopia and systemic cause of palsy
 Pharmacologic anisocoria: dilation of one eye
o Presentation
 Usually unilateral, fixed and dilated pupil
 Anticholinergic substances block the action of
acetylcholine on the ciliary muscle and cause mydriasis
o Etiology
 Scopolamine
 Jimsonweed
 Antihistamine drops
 Atropine, homatropine, cyclopentalate
o Diagnosis
 0.125% pilocarpine—Will NOT constrict
 1% pilocarpine—Will NOT constrict
o Management
 Reassurance and patient education
Little pupil problems: anisocoria is greater in dim conditions due to a
defect/lesion to the sympathetic nervous system
 Horner’s syndrome
o Presentation
 Miosis (can be mild: less than 1 mm of anisocoria)
 Ptosis
 Anhydrosis
***All on the same side as the lesion***
o Etiology
 Interruption of the sympathetic system anywhere in its
path
 Congenital Horner’s: idiopathic or trauma at birth
 Heterochromia and anhydrosis
 Central lesions: stroke, MS, spinal cord cancer, neck
trauma
 Preganglionic lesions: pancoast tumor, trauma, thyroid
enlargement or lesion
 Postganglionic lesions: extracranial or intracranial
cause (Raeder’s, ICA dissection, complicated otitis
media)
o Diagnosis
 Look at old photographs
 History of trauma, endardectomy, thyroidectomy?
 Dilation lag test
 Take picture immediately after turning off lights
and take another picture 15 seconds
 Horner’s pupil has a dilation lag in the dark of
~15 sec
 0.5% Apraclonidine (Iopidine) (wait 15-30 min)


 Dilates: confirms diagnosis of Horner’s
10% Cocaine drop in affected pupil (wait 15 min)
 Does NOT dilate: confirms diagnosis of Horner’s
o Management
 Important to determine before or after the bifurcation of
the carotid artery
 Differentiate by testing for anhydrosis (prism bar test
and corn starch under heat lamp)
 Postganglionic lesions generally do not cause
anhydrosis
 1 % hydroxyamphetamine (done 48 hrs after
cocaine test)
o Dilation: central or preganglionic lesion
o No dilation: postganglionic (“fail safe”
affected pupil fails to dilate)
 Argyll-Robertson pupil
o Presentation
 Bilaterally miotic, irregular pupils
 Difficult to dilate
 Direct and consensual responses absent or sluggish in
affected eye(s)
 DOES react to near (there is light-near dissociation)
o Etiology
 Midbrain lesion
 Neurosyphilis or neuropathy from diabetes,
alcoholism
 Pharmacologic anisocoria: constriction of one eye
o Cholinergic agents: pilocarpine (glaucoma drop) and
physostigmine
o Near-Light Dissociation: pupils fail to respond to light, but near response intact
 Afferent pathways interrupted, efferent pathways intact
 Examples of conditions that manifest near-light dissociation
 Neurosyphilis: Argyll-Robertson pupil
 APD or amaurotic pupil
 Aberrant regenerations
o Pupil Irregularities
 Aniridia: congenital absence of the iris (usually bilateral)
 Iris coloboma (“keyhole” pupil)
 Usually involves the inferior nasal portion of the iris
 Wider at the pupillary margin than at the iris root
 Corectopia: displaced pupil (frequently bilateral)
 May be displaced in any direction
 Iridectomy: surgically created sector cut of the iris
 Iris atrophy
 From age, inflammation, ischemia, trauma
 Iris holes may form creating polycoria

 May be sectoral (herpes zoster) or widespread
Iris cysts/tumors
 If extensive enough, may distort pupillary margins
 Laser iridotomy: hole created in iris usually located superiorly at 10:00 or
12:00
 Shape of the pupil usually not affected
 Persistent pupillary membrane (PPM): persistent embryolic structure
 Rarely affects pupillary movement
 Trauma
 Tears of pupillary margin and sphincter
o Traumatic mydriasis and abnormal pupil light reflexes
permanent
 Iridodialysis
o Tear at the iris root; D-shaped pupil
o Monocular diplopia may occur
 Posterior synechia: attachment of iris to anterior lens surface from active or
history of anterior uveitis or intraocular inflammation
 Iridonesis: quivering of the iris
 Pupillary margins are irregular and reactivity will be reduced
 Seen in aphakic patients
o Pharmacologic dilation (bilateral)
 Anticholinergics
 Antihistamines
 CNS depressants
 Sympathomimetis and CNS stimulants (bind with alpha receptors on dilator
muscle to cause mydriasis)
 Epinephrine, Cocaine, amphetamines
o Pharmacologic constriction (bilateral)
 Barbituates
 Opioids
 Levodopa
 Marijuana
 Vitamin A
 EOM Testing
o Saccades
 Rapid abrupt conjugate movement; stimulated by alternately fixating objects
 Can be voluntary or reflex
o Pursuits (Versions)
 Slower smooth conjugate movements; stimulated by target movements
 Used to test binocular, conjugate movements of the eyes allowing the lines
of sight (LOS) to move in a parallel direction (or fixed angle)
o EOM
 Innervation
 CN VI (abducens): LR
 CN IV (trochlear): SO
 CN III (oculomotor): MR, SR, IR, IO

Planes of action
 LR and MR: horizontal plane
 SR and IR: vertical plane, 23-25° temporal
 SO and IO: vertical plane, 51-53° nasal
 Muscle paresis is most obvious when the LOS is directed to move
the eye in the direction of its primary action within its plane of action
 Synergistic muscles: muscles in same eye that assist in an action
 Antagonistic muscles: muscles in same eye that have opposite actions
 Yoked muscles: neurologically paired in opposite eyes
 Hering’s Law of Equal Innervation
o Procedure
 Remove spectacles and use high illumination
 Fixation target held ~40 cm from patient’s eyes
 Instruct patient to follow light as its moved in “H” pattern
 Make sure you test to the extreme field of gaze (limit of the EOM)
 Note any overactions (+) or underactions (-); perform ductions
 Ductions are monocular eye movements into the 6 cardinal positions of
gaze
 Identifies the faulty muscle(s)
 Can test each muscle in its field/plane of action
 Parks 3-step used for hyper deviations to determine faulty muscle
 Record EOM: full and smooth (F and S)
 FROM: full range of motion
 SAFE: smooth accurate full extent
** Also record if ductions=versions, etc**
 Stereopsis
o Stereopsis: the perception of 3-D visual space due to binocular disparity cues
(disparities of the two retinal images)
o Stereoacuity: ability to discriminate very fine differences of objects in space by
using binocular vision
 Stereo acuity is not the same as depth perception
 Must have some level of binocular vision to appreciate stereo acuity
 Requires changes in both vergence and accommodation
o Monocular cues to depth perception must be learned
 Retinal image size, linear perspective, texture density, luminance variations,
aerial perspective, overlay, motion parallax, kinetic depth, myosensory cues
from muscles controlling accommodation and convergence
o Each point on the retina has a local sign or directional value
 Fovea: principal visual sign (straight ahead)
 Corresponding retinal points: pairs of points in each eye that have the same
local sign (point in one eye corresponds to an area in the other eye)
 Objects that stimulate a pair of corresponding points appear to be single
and located at the same position in space
o Stereo Tests Designs
 Local stereopsis (line or contour)


Targets have edges that are separated on background to produce
disparity
 Smaller separation defines better stereopsis
 Howard Dolman Peg Test
o Thresholds stereopsis
o Most accurate
o Two types of testing: null threshold and JND
 Titmus Stereofly
o Linear polarized test
o 3 parts: “fly” for gross stereo (3,000’’), “animal” test (400’’100’’), Wirt circles (800’’-40’’)
 Stereo Reindeer
 Global stereopsis
 Matrix of black dots on gray background
 Lateral shift in central pattern
 NO monocular cues
 Random Dot
o Uses 3-D cross polarized spectacles
o Right side: 8 random dot figures-- 500 sec of arc on top and
250 sec of arc on bottom-----must identify which cell is empty
o Left side: modified circles (400’’ – 20’’), animals (400’’ – 100’’)
o Procedure
 Present test perpendicular to LOS at a distance of 40 cm (16 in)**
 Spectacles are placed over habitual
 Score last number correct after 2 errors
 Record sec of arc @ test distance, test used and note cc or sc
 Color Vision
o Three types of cones responsible for color vision
 Each contain photopigments that maximally absorb different wavelengths
 Red (long), green (middle), blue (short)
o Defects
 Protan: red wavelength (L cones)
 Deutan: green wavelength (M cones)
 Tritan: blue wavelength (S cones)
o Inherited color deficiencies
 Anomalous trichromat (3 cone pigments)
 Protananolmalous: red weak
 Deutananolmalous: green weak
 Tritananolmalous: blue weak
 Dichromat ( 2 cone pigments)
 Protanopia
 Deutanopia
 Tritanopia
 Monochromat
 Rod
o True color blindness (may have few cones but abnormal in
shape) and poor vision
 Cone
o Variation of color blindness (only one cone type present)
Inherited
Acquired
Permanent (not correctable)
Changes with progression or
regression of primary cause
Test result relatively stable
Test results strongly influenced with
changes in test conditions
Defect same in each eye in both type Severity may be greater in one eye, or
and severity
one eye could be normal and the other
not
More prevalent in males
Equally prevalent in males and
females
Always binocular
Can affect only one eye
Almost always red/green
Most are blue/yellow
Transmitted via X chromosome
Caused by medications (plaquinel),
disease, toxic effects of chemicals,
aging
o Prevalence
 Overall 4%
 Males 8%
o Protanomaly 1%
Protanopia 1%
o Deuteranolamly 5% Deutranopia 1.1%
o Tritanopia 0.002%
 Females 0.5%
o Patient selection
 Children at an early age
 Patients at initial office visit
 Unexplained decreased in VA
 Report changes in color vision
 Abnormal fundus findings
o Types of color vision tests
 Color Naming
 Color Mixing
 Anomaloscope
o Assess ability to make metameric matches
o Change mixture of monochromatic red and green
 Color Confusion
 Pseudoisochromatic plates (PIC)
o Diagnostic plates: figure is isochromatic for one defect but not
for another so it identifies type of deficiency
o Vanishing figure: normal sees, defective does not see
o Transformation: normal and defective see different figures
o Hidden digit/symbol: defective sees, normal does not see
o Screening mostly for inherited defects

HRR
o Detects inherited and acquired defects
o Can be used on illiterate patients (symbols used)
 Ishihara
o Screen for inherited red/green anomalies
 Color Matching (arrangement)
 Detects inherited or acquired
 Farnsworth D-15
o Quantifies depth of defect (mild/severe)
o Used only as diagnostic (not screener)
 Farnsworth-Munsell 100-Hue
o Good for detecting/classifying early acquired color
deficiencies caused by ocular disease
o Detects subtle color discrimination
 Occupational
 PIC, D-15, Farnsworth Lantern test (FALANT), ISCC Color Matching
Aptitude test
o Procedure
 Use “standard” illumination “C”
 MacBeth Easel Lamp
 Incandescent lighting inadequate
 HRR
 Plates perpendicular to LOS at 75 cm
 Use correction unless tinted and test monocular!
 Ask patient how many symbols, what are they, and have trace where
they are with brush
 Time limit: 20 sec/page
 Record check marks when correct for screening plates 5-10
o If ALL 6 correct: normal CV
o Only plate 5 or 6 missed test plates 21-24: B/Y defect
o Only 1 or more plates 7-10 missed test plates 11-20: R/G
defect
 Ishihara
 Plates perpendicular to LOS at 75 cm
 Use correction unless tinted and test monocular!
 Ask patient what do they see
 Time limit: 3 sec/plate
 Record number plates correct over number tested with pass/fail
noted and the numbers said if missed
o Normal if 10/1l
o If </= 7 correct, test plates 12,13,14 to classify whether protan
or deutan
 Farnsworth D-15
 Caps should be 45 deg to patient’s LOS at 50 cm
 Use correction unless tinted and test monocular
 Instruct patient to place caps in chromatic order
 No time limit
**When recording, note the test used and if cc or sc**
o Management
 Rod chromatism (poor VA and photophobia)
 Tinted lenses (red and amber) to obtain low scotopic luminance
transmittance but decreased visibility in short wavelengths
 Acquired defects should be directed to cause
 Inherited defects: counseling, career limitations
 Cover Test
o Fusion: both eyes are looking at the same target at the same time
o Alignment
 Orthophoria (ortho): “normal”, both eyes fixate on the same spot even after
you break fusion
o Misalignment
 Tropia (strabismus): manifest deviation of the line of sight of one eye
 The LOS of one eye is directed toward the object and the LOS of the
other eye is directed elsewhere
 If the eye is misaligned outward it is called exotropia
o Will move in when the other eye is covered
 If the eye is misaligned inward it is called esotropia
o Will move out when the other eye is covered
 If the eye is misaligned upward it is called hypertropia
o Will move down when the other eye is covered
 If the eye is misaligned downward it is called hypotropia
o Will move up when the other eye is covered
 Patient may have symptoms such as double vision, eye strain, headaches,
fatigue, and reduced stereo
 Phoria: latent deviation of the LOS
 Eye aligned except when fusion is disrupted
o Bruchner: observe the red reflex from the retina with the ophthalmoscope to detect
leukocoria, strabismus, or anisometropia
o Hirschburg: use the transilluminator to find the corneal light reflex
 To see 1 mm, patient must have 22 diopters
o Krimsky: perform Hirschburg and line up the corneal light reflex with prism
o Cover Test: objective test to determine the presence, amount, and direction of
misalignment
 Unilateral cover test (cover-uncover): detects tropia
 Alternating cover test: to detect phoria and measure amount of tropia
o Procedure
 Unilateral
 Distance: patient fixates on a letter that is one line larger than the
best VA of the worst eye
 Near: patient uses a fixation stick with a small accommodative target
o Done at 40 cm or working distance
 Important to come from the nose

Clinician covers OD and watches OS for movement; then covers OS
and watches OD for movement
o Presence of movement indicates strabismus or tropia
 Alternating
 Patient still fixates a target
 Clinician covers OD for 2 sec, then swings cover paddle from one
eye to next
 Do NOT allow patient to view with both eyes at the same time
o Presence of movement on alternating but not on unilateral
indicates phoria
o If there is movement on both unilateral and alternating, it is a
tropia (tropia trumps a phoria)
o If there is no movement on both unilateral and alternating,
check with 4 BI and 4 BO and there should be equal and
opposite movements
o Measuring magnitude
 Prisms deviate the image towards the apex
 ‘Exos’ need the image sent OUT---- use base IN
 ‘Esos’ need the image sent IN---- use base OUT
 ‘Hypers’ need the image sent UP---- use base DOWN
 ‘Hypos’ need the image sent DOWN---- use base UP
 Procedure
 Put the prism behind the cover paddle and place in front of the eye at
the same time
o For eso and exo, put prism in front of either eye
o For hyper and hypo, put prism in front of deviated eye
 Move occluder to other eye without allowing binocular fixation
 Increase prism amount without allowing binocular fixation until
movement stops=neutrality
 Continue to increase amount until the direction of the movement
reverses
 Record amount of prism that resulted in neutrality before reversal
o Recording
 Orthophoria (lack of manifest or latent deviation)
 Horizontally ortho
 Vertically ortho
 Ortho both horizontally and vertically
 Magnitude: prism diopters
 Direction: exo (X), eso (E), hyper, hypo*
 Only name the hypo eye if it also has a horizontal constant tropia
 Laterality: right (R), left (L), alternating (A)
 Note the fixation preference
 Frequency: constant (C) or intermittent (I)
 If intermittent, write down percentage
 Nature: comitant or incomitant
 Use 9-gaze test or Park’s 3-step test
 Also note: Testing distance, cc or sc
 Normal: Distance 1 XP + 2
Near 3 XP + 3

o Duane’s Classifications
 Basic: <8 Δ difference between distance and near
 Distance vs. Near Deviations
 Convergence Insufficiency
o Exo at near > distance
 Convergence Excess
o Eso at near > distance
 Divergence Insufficiency
o Eso at distance > near
 Divergence Excess
o Exo at distance > near
 Blood Pressure
o Important to do routine BP measurements:
 Elevated blood pressure increase the risk of coronary heart disease, stroke,
and kidney failure
 “Silent killer” since you cannot tell by the way you feel
 Patients will often seek eye care before other health care
 HTN can result in significant visual morbidity
o Risk Factors for HTN
 Smoking, high cholesterol, obesity, diabetes, age (elderly), family history,
race (African-Americans), gender (male) and stress
o Systolic pressure: ventricular contraction
o Diastolic pressure: ventricular relaxation
o Korotkoff Sounds
 Phase 1: appearance of clear taping sounds (systolic)
 Phase 2: swishing of sounds
 Phase 3: increase clear sounds, increase intensity
 Phase 4: abrupt muffling of sounds (diastolic I)
 Phase 5: complete disappearance of sound (diastolic II)
 Auscultatory gap: early, temporary disappearance of sound between phase
1 and 2 that can cause serious underestimation of systolic (or
overestimation of diastolic pressure)
o Procedure
 Patient should be seated and relaxed with legs uncrossed
 Patient’s arm should be slightly bent, resting on the arm rest with palm up
and unrestricted baring of arm
 Palpate for systolic pressure
 Place cuff ~1’’ above antecubital crease
 Palpate the radial artery at wrist using fore finger and middle finger
 Inflate cuff to ~30mmHg above level at which the pulse disappears
 Note reading and deflate cuff
 Place diaphragm over brachial artery between the crease and the lower
edge of the cuff
 Inflate cuff to 30 mmHg above systolic (determined by palpation)
Deflate at a rate of 2-3 mmHg/sec
Listen for phase 1 sound (regular tapping sound)
 Note reading: systolic pressure
 Continue deflation and listen for phase 5 (complete disappearance of
sound)
 Note reading: diastolic pressure
 If sounds are too weak, ask patient to open and clench fist ~10x or inflate
cuff quickly
 Repeated inflation will cause venous engorgement and decrease
sounds
 Deflate cuff and remove
 Record: systolic/ diastolic, arm used, posture, time of day, and cuff size if
other than regular
o Sources of Error
 Falsely High
 Brachial artery below heart level
 Asucultatory gap (diastolic)
 Cuff too small
 Anxiety or fear
 Isolated sources: anxiety, stress, recent exertion, pain, caffeine
 Falsely Low
 Brachial artery above heart level
 Asucultatory gap (systolic)
 Cuff too large
 Deflating too rapidly
Hypertension Classification
Pressure
Normal BP
PreStage I
Stage II
hypertension
Systolic
< 120
120-139
140-159
> 160


Diastolic
< 80
80-89
Referral Guidelines
Initial Screening Blood Pressure
(mmHg)
Systolic
Diastolic
<130
130-139
140-159
160-179
180-209
> 210
<85
85-89
90-99
100-109
110-119
> 120
90-99
> 100
Follow-Up Recommended
Recheck in 2 yrs
Recheck in 1 yr
Confirm within 2 months
Evaluate or refer to source of care within 1mo
Evaluate or refer to source of care within 1 wk
Evaluate or refer to source of care immediately
 Confrontation Visual Fields
o Visual field: the perceptual space available to the fixating eye
o Purpose: to provide a gross check for any defects in the peripheral visual field
o Extinction phenomenon
 Patients with right parietal lesions can exhibit a form of visual extinction.
When shown two objects, one contralateral (left) and one ipsilateral (right)
to the lesioned hemisphere, subject will report seeing only the one in the
ipsilateral (right) field
o Riddoch’s phenomenon
 Some patients with neurological defects suffer from stato-kinetic
dissociation
 Moving objects are perceived better than static ones
 Defects present on automated perimetry (static) tend to be more
extensive compared to those measured by manual perimetry (kinetic)
o Finger counting
 Tests the patient’s ability to correctly identify gross targets in each of the 4
major quadrants
 Procedure
 Examiner and patient remove spectacles
 Sit at eye level and 1m away
 Have patient occlude OS with palm of their hand and fixates
clinician’s OS with their OD (clinician’s visual field corresponds to the
patient’s)
 Place one hand in the mid-plane (50 cm) at about 45° from fixation
o Important to be exactly between you and the patient so the
patient’s field can be compared to yours
 Fingers more than 50 cm from patient patient’s field
will be underestimated/constricted
 Fingers are less than 50 cm from patient field will
appear to be normal but you may be more likely to miss
a defect/constriction
 Present one, two, or four fingers in one of the four quadrants
 Repeat for other 3 quadrants
 Present both hands simultaneously in both superior quadrants
 Present the fingers of both hands and ask patient to add together
o Do NOT use the same numbers in each hand
 Repeat for OS
 Record normal fields as FTFC (full to finger counting) OD, OS
o If not full, then document/draw constricted quadrant
 Advantages
 Sensitive to homonymous (neurologic) quadrantic and hemianopic
VF defects
 Fast and can be performed in any location
 Can test for extinction phenomenon
 Disadvantages
 Results are not meaningful to the DMV
 Sensitivity is not very high
 Limits of the VF are not tested
o Field Limits
 Compares known peripheral field limits to the patient’s peripheral field limits
 Procedure
 Patient removes spectacles and occludes OS; have patient fixate
your nose
 Move target (wand) from behind patient (non-seeing to seeing)
toward the horizontal limit of the field
o Test slightly above and below the temporal midline
 Have patient tell you when it comes into view
 Do the same for the superior and inferior visual field
o Test on both sides of the superior and inferior midline
 Test nasal side
o Test on either side of the nasal midline
 Repeat for OS
 Record limits (ALWAYS record from the patient’s perspective)
o Normal
Advantages
 Provides a means to quantify confrontation fields
 Easier for patient to understand and/or respond
 Disadvantages
 Testing the limits of the VF produces variable sensitivity , therefore
difficult to detect true visual field loss in the far peripheral field
 Does not screen for extinction phenomenon
 Interpupillary Distance
o Distance between centers of the entrance pupils
 Important for:
 Alignment of optical instruments (avoids prismatic effects induced)
 Spectacle design considerations
o Optical centers match PD’s (if not, induces prism)
 Documentation of craniofacial abnormalities
 Measure monocular PD’s for high powered spectacle prescriptions, PALs
o Procedure for binocular PD
 Sit at eye level with patient ~40 cm away
 Close your right eye and have patient look into your open left eye
 Place zero at the temporal limbus of the right eye (DO NOT MOVE)
 Note position that is aligned with the nasal limbus of the left eye: NEAR PD
 Close left eye and have patient look into your open right eye
 Note position that is aligned with the nasal limbus of the right eye:
DISTANCE PD

 Record distance/near
o Procedure for monocular PD
 Place ruler on the patient’s bridge
 Close your right eye and have patient look into your left eye
 Align zero mark with the center of the pupil (CANNOT use pupil margin or
limbus)
 Note the mark centered on the bridge: OD MONOCULAR PD
 Move ruler and place an easily recognized mark on the center of the bridge
(use this as the zero mark)
 Open your right eye, close your left, and have patient look into your right
eye
 Note mark centered in the patient’s left pupil; subtract the ‘zero’ reading
from the last reading: OS MONOCULAR PD
o Use Prentice’s rule to calculate the induced prism from decentration
 P= dF
o Errors: unsteady positioning, error in parallax, patient’s with fixation disparities and
doctor’s PD significantly wide (will overestimate)
 Ocular Dominance
o The preferential sighting of a target with one eye
o In monovision CLs fitting, the dominant eye is generally fit with the distance
o Useful when the subjective match in the clarity of the lines of letters cannot be
achieved during binocular balance
 Leave dominant with slightly clearer vision
o Do not leave the VA of the dominant eye worse than the non-dominant eye
o Place prism before the non-dominant eye
o Procedure
 Instruct patient to fully extend arms and create a triangle with both hands
 Patient looks through aperture at the doctor’s right eye
 Eye aligned with the doctor’s is the dominant eye
 Record ocular dominance