Preliminary Testing

refraction & ambylopia

what are the most common causes of reduced VA in a pre-school child?

refraction & ambylopia

what are the most common causes of reduced VA in a school child?

refraction

what are the most common causes of reduced VA in a teenager-50 yo adult?

pathology

what is the most common cause of reduced VA in a 60-80 yo adult?

Sloan, LogMar, contrast

what are the alternate adult VA tests?

HOTV, number, tumbling E, tubling hand, LEA

what are the alternate pediatric VA tests?

sloan

chart that adheres to an international standard so it is thought to be more consistent than Snellan; alternate adult chart

LogMAR

similar chart to Sloan, has more consistent spacing

HOTV

alternate pediatric chart, only uses H, T, V, O letters

number chart

alternate pediatric chart, good for patients that do not know their letters but do know their numbers

tumbling E

alternate pediatric chart, E is rotated different orientations instead of different letters

tumbling hand

alternate pediatric chart, a hand is rotated different orientations and patient rotates their hand to match

landolt C

similar to tumbling e, but is a c; alternate pediatric chart

LEA

most common and reliable pediatric chart, different shapes are shown (ex: apple, house, square, circle)

VA is reduced for unknown reasons or patient is over 60

what are the reasons to use pinhole VA testing?

reduces blur circle on the retina

what does the pinhole do?

refractive error

if vision improves with pin holes, then the working dx is one of ______

pathology

if vision does not improve with pinholes, then the working dx is one of ________

NIPH

if vision does not improve with pinholes, what do you record?

shift to ocular health section first

if vision does not improve with pinholes, what would you do?

continue as normal flow

if vision does improve with pinholes, what would you do?

nystagmus

a rhythmic oscillation of one or both eyes due to visual deficit, intracranial lesions & drug toxicities, benign congenital idiopathies

manifest nystagmus

\-overtly seen in 1st year of life

\-both eyes oscillate

\-reduced VAs, greater than 20/70 with greater reduction when tested monocularly

\-usually have a null point

\-higher incidence of astigmatism

latent nystagmus

\-usually not seen until 1st eye exam, over 1 year

\-upon covering one eye, the other will oscillate

\-binocular VAs are normal

\-monocular VAs greater than 20/70

\-test with a translucent occluder

null point

point of minimum oscillation with abnormal head posture

allows some visual information to get to the eye but not the actual chart letters, reduced nystagmus

what is the point of using a translucent occluder or high plus lens with a pt with latent nystagmus?

amblyopia

non-pathological reduction of VA to 20/30 or less in one eye or a 2 line different VA b/t the eyes, not correctable with refraction alone; most common cause of vision loss in children (2-3%)

form deprivation

type of amblyopia due to a physical obstruction

isoametropic

type of amblyopia associated with a large corrective error

anisometropic

type of amblyopia associated with a large Rx difference between the eyes

strabismic

type of amblyopia associated with constant tropia (eye turn)

relative

type of amblyopia that occurs with pathology

not blurred, just unable to neurologically resolve the target below amblyopia

a corrected amblyopia eye is _____

letters are not blurry, just cannot see them

what do pt with amblyopia say in VAs?

no

do amblyopic pt have improvement with pin hole?

crowding effect

amblyopic pt can read some smaller letters if given one at a time due to what

following standard VA, ask pt to read smallest line of letters they can and note which letters they read (look for 1st and last)

how do you conduct VA testing on amblyopic pt?

20/70

when best corrected vision falls below _____ the patient is considered visually handicapped

1-meter LogMAR progression chart, reading fluency, contrast sensitivity charts

what are the options for low vision testing?

BAT testing

most commonly used glare tester, pt looks through 1/2 a white sphere for normal VAs, then a light source is turned on med/high with patient now having to look through surrounding glare; if VAs drop to greater than 20/50, pt has failed

jaeger test chart, point notation

what are the options for near low vision tests?

20/40 or better

what is the VA range for near normal vision

20/70-20/200 best corrected

what is the range for partial sight?

20/200 best corrected

what is the cutoff for being legally blind

VF less than 20 degrees at its widest

what is the cutoff for legally blind in terms of visual fields?

finger count, hand motion, projection of light, light perception, no light perception

what is the order for evaluating low vision that cannot be measured at any level on the chart?

finger count & distance

what is the first test for evaluating low vision off the chart?

hand motion & distance

used when pt cannot see fingers, test is they can even see your hand moving

projection of light & direction

used when pt cannot see hand motion, tests when (or if) they can see what direction a light is coming from

light perception

used when pt cannot see light being projected, test if they can even see if the light is on or off

no light perception

even w/ the brightest light shining right in the eye, no perception by the pt

to note any gross abnormalities

what is the goal of external observation?

when greeting the pt

when does external evaluation start?

posture, gait, head tilts, irregular speech or facial movements, symmetry, screen for pathology

what are things you should look for during health history (external observation)?

scan w/ transilluminator in H pattern tangentially to the face

how should the external evaluation be performed?

lesions, papillomas, scars, redness, crusting

what are you looking for when you do the external evaluation with your transilluminator?

clear, trace, 1+, 2+, 3+

what is the scale for evaluating the conjunctiva?

clear

this score corresponds to a white sclera

3+

this score corresponds to significant injection

iris color, shape of pupil, depth of anterior chamber

what do you look for when scanning conjunctiva, as well as the score for conjunctiva?

shadow test

estimates the depth of anterior chamber; light is held to the side of pt’s face 2-3cm from lateral canthus, with light at right angle to LOS, observe nasal half of the iris for a shadow

40 degrees

normal open chamber depth, shows no shadow

\-10 degrees

for every mm of shadow, the angle is affected ___

0-4+

scale for grading the anterior chamber angle

deep & open

if no shadow is observed on the iris, the anterior chamber angle is said to be _____ and the angle _____

bisect the pupil

how do you line the pd stick for measuring fissure and pupil size?

0\.5mm

if vertical fissure size differs by more than ______ then ptosis is said to be present

clock positions

how do you record conjunctival injections or other abnormality locations on the eyes?

2mm

what size difference is expected for the pupils in light vs dark settings?

direct response

looking at pupil constriction when light is shown directly into that eye

consensual response

looking at pupil constriction when light is shown into opposite eye

0-4

what is the scale for grading pupil reactions?

afferent pupillary defect

swinging flashlight test; defect occurs when there is a dilation more than the other eye with direct light stimulus

hippus

normal pulsating movement of the pupil

accomodative response

when an object is brought close to the eyes, the eyes will converge and pupil size will constrict in a yoked response

convergence

simultaneous inward movement of both eyes toward each other; only eye movement that is not conjugate

near point of convergence

point of intersection of lines of sight when maximum convergence is utilized; distance from point to the midpoint of the line connecting the center of rotation of the eyes (bridge of nose)

2x

how many time should you do NPC?

break/recovery

how is NPC recorded?

BON/x

how is NPC recorded when pt never sees double?

>4

when NPC is reported ____ times, symptomatic patients often show decay in convergence ability, asymptomatic pt do not have a change

8cm or less

what is the expected NPC?

accomodationg

mechanism by which the eye changes refractive power by altering the shape of the lens in order to focus objects at various distances

near point

nearest point seen with maximum accommodation

monocularly and binocularly

how is NPA measured?

amplitude of accommodation

reciprocal of NPA expressed in meters

25-0.4age

what is the maximum amplitude norm for NPA?

18\.5-0.3age

what is the probable amplitude norm for NPA?

15-0.25age

what is the minimum amplitude norm for NPA?

stereopsis

ability to perceive depth based on minimum retinal disparity that can be perceived

binocular

steropsis clues are _____

monocular

perspective clues are ______

innate

the ability to perceive depth through stereopsis is _____

learned

monocular clues of depth perception are _______

geometrical perspective, overlay, light & shadow, height relation to horizon

what are some learned monocular clues examples?

clarity of the image, eye alignment

a patient’s ability to detect small amounts of retinal disparity are affected by:

660m or 0.4mi

beyond this distance, stereopsis becomes useless and we rely on monocular clues

constant strabismics

these individuals have 0 random dot stereopsis but may have some contour line stereopsis

intermittent strabismics

these individuals often have some but reduced stereopsis but often none at distances of the tropia

amblyopia

______ reduces both types of stereopsis, but especially randot