Download Advanced Pre-testing - Heart of America Contact Lens Society

Advanced Pre-Testing
Lynn E. Konkel, MS, CPOT
Heart of American – February 2013
Introduction
Will discuss the procedures and common results of the
following pre-testing skills:
o
o
o
o
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pupillary reflexes
eye movements
cover test & maddox rod
near point of accommodation
confrontation visual fields
Overview
• Patient pre-testing is used to gather information
regarding the patient’s visual system. Pre-testing is not
used to diagnose conditions of the eye or visual system.
• This course is for the technician who is performing basic
pre-testing skills.
• This is an advanced course and may be useful for
technician level certification examination prep.
Overview
• Prior to performing pre-testing the technician should
o Wash hands
o clean equipment with specialized antiseptic agent
o Briefly explain test to patient prior or as starting to perform
Pupillary Responses
• Pupil Facts
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o
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Normal size varies 3-7mm
Smaller than normal as we age, infant
Myopes have larger pupil size
Pupils dilated when surprised
Some medications cause miosis or mydriasis
• Why test pupil responses?
o Important test of neurological integrity
o Objective evaluation of 2nd cranial nerve
o Pupils important sign of ocular disease
When to evaluate pupil
reflexes?
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All primary eye examinations
All cases of vision loss/reduced vision
Prior to dilation
Prior to contact lens fits, vision training, low vision
evaluations
Five steps in pupil
evaluation
• Step 1
o Explain test
o Evaluate for anisocoria
• Step 2
o Evaluate lid position
Steps to Pupil Testing
• Step 3
o Evaluate light responses
• Direct
• Consensual
• Step 4
o Evaluate for afferent pupil defect
• Swinging flashlight test
• Step 5
o Evaluate near response
o Record findings
Video of Pupil Testing
Abnormalities
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Marcus Gunn
Argyll Robertson
Adie’s Pupil
Horner’s Syndrome
Eye Movements
• Ductions - movement of a single eye
• Versions - conjugate movements of both eyes together
• Rotations/Pursuits - following movements
• Saccades/Fixations - jumping movements
Eye Movements
• Explanation - test your eye movements
• Instructions - follow my light with your eyes, do not
move your head
• Evaluate muscles in primary position, up/down, 6
cardinal positions of gaze - see handout
Eye Movement Procedure
• Testing is performed at 30-40 centimeters
• Move target in an exaggerated H pattern
• Observe both eyes together & separately
• Record lag, limits, paralysis, smooth, accurate versus jerky
movements.
• If eye movements are normal may record SAFE (smooth,
accurate, full, extensive)
Cover Test
• Equipment - occluder and small letter
• Heterophorias - tendency for the eye to deviate
• Heterotropias - fixed deviation of the eye the patient
cannot overcome.
• Specified as to the position of the eye: eso = inward, exo
= outward, hyper = upward, hypo = downward.
• The movement the eye will make when performing the
cover test is the opposite motion to the above listed
direction of deviation
Cover Test
• Explanation - test to determine the position of your eyes
• Instructions - I will be simply swinging the occluder in
front of your eyes, look at the letter at all times, ignoring
the occluder. Feel free to blink your eyes.
Cover Test
• Cover/Uncover
Cover Test
• Alternating Cover
Maddox Rod
• Equipment - maddox rod and light
source
• Will detect position of eye; eso,
exo, hyper or hypo will not
differentiate from a phoria or
tropia
• Rods of maddox rod placed
vertically will detect hyper/hypo
• Rods of maddox rod placed
horizontally will detect eso/exo
Maddox Rod
• Explanation - test to determine the position of
your eyes
• Instructions - hold the red lens in front of your
right eye (technician positions the rods
correctly). Keeping both eyes open look at
the light. Do you see a red line and white dot
of light? Where is the red line in relationship
to the light?
o record position of eyes; eso, exo hyper or ortho
• Procedure
Maddox Rod
o place maddox rod in front of one eye, shine
light at midline of patient
o instruct patient to keep both eyes open
o verify that patient sees the red line and white
light
• Ask patient to give position
of red line
o rod placed vertically red line will be above,
below or directly on the red line
o rod placed horizontally red line will be in
towards nose, out towards ear or directly on
red line
Near Point of
Accommodation (NPA)
• Equipment - occluder, small letters and PD stick
• NPA is the measurement of the ability of the
crystalline lens to add plus power for near focus.
• Explanation - test to measure the eyes ability to
change focus
• Instructions - look at the smallest line of letters
you can see. I will move the chart in towards
your nose, tell me when the line blurs.
NPA – Cont.
• Procedure
o Perform monocularly and with full distance Rx
o Move small letter target smoothly in towards eye and have patient report when
the letter blurs.
o Measure in centimeters and convert to diopters.
• Convert centimeters to meters
• D = 1/ f (meters)
• Example you measure NPA of 40 cm (40/100 = 0.4 meters). Diopters of
accommodation = 1/0.4 = +2.50 D
• Expected outcome
o Donder’s amplitude of accommodation — 10 yr. old = 14.00 D, 40 yr. old = 4.50
D
o Hofstetter’s average = 18.5 – (0.3 x age)
Near Point of
Convergence (NPC)
• Equipment - small letter target and PD stick
• NPC is the measurement of the ability of the
eyes to converge (move in toward midline) while
maintaining single binocular vision.
NPC
• Explanation - test to measure how well your
eyes move in together.
• Instructions - look at the smallest line of
letters you can see. I will be moving the
letters in toward your nose. Tell me if the line
of letters doubles, if it does, keep looking at
the letters, I will move the target away and tell
me when the line is single again.
Procedure
• Perform with near
Rx
• Move the target
smoothly toward the
nose and stop when
the patient reports
double or you see
one of their eyes
move out
NPC - Measurement
• Measure the distance, in centimeters, the patient
reported double or their eye turned out. Also note
which eye turned out.
• If the patient reported double, smoothly pull the target
away and stop when the patient reports single
• Measure the distance, in centimeters the distance at
which the patient reported single.
NPC - Expected Results
• NPC of 5.5 cm or less except in presbyopia where
normal is 8 or 9 cm or less
• Recovery should be no more than 8 cm in people less
than 40 yr. of age
Confrontation Visual Field
• Gross Screening
• Equipment - fingers, white target, or penlight
• Explanation - this is a test to evaluate your peripheral
vision
• Instructions - cover your left eye and look at the
bridge of my nose. Keep looking at my nose at all
time.
Confrontation Procedure
• Face patient at eye level - 60 - 80 centimeters apart
• Illuminate area between patient and technician. Dark
background behind technician if possible
• Ask patient if they can see all your face as they look
at the bridge of your nose. Is there any part of your
face missing? Any part of your face blurry or
distorted
Confrontation Part 2
• Have patient remain looking at your nose, tell them you are
going to hold up fingers in their side vision. They are to tell
you how many fingers you are holding up.
• Hold up 1,2, or 5 fingers in the four quadrants of their
peripheral vision. If patient incorrectly identifies number of
fingers, redo area at least once. If it is a true visual field
defect it will be repeatable
• Record any deficiencies, note eye and which areas
Summary
• We have covered a number of advanced
pretesting techniques.
• Recommend you take this information back to
the office, discuss the techniques with your
doctor, adjust procedures to fit your particular
office situation.
• Please complete the course evaluation form.
Note your comments regarding this course as
well as topics you would like to see
addressed in the future.
• Thank you for coming.
Where to get more
information
• For additional reading:
o AOA Paraoptometric Section, Self-Study Course for Paraoptometric Assistants
and Technicians, Revised 3rd Edition. Butterworth-Heinemann. 1997
o Stein, Stein, Freeman, The ophthalmic assistant 8th edition Mosby 2006
o Cassin, Rubin, Dictionary of eye terminology 6th edition Traid 2011
• Websites:
o http://www.richmondeye.com/apd.asp - has interactive pupil responses
o http://cim.ucdavis.edu/eyes/version15/eyesim.html - interactive muscle testing
simulator.
o http://cim.ucdavis.edu/EyeRelease/Interface/TopFrame.htm - pupil reflex testing
simulator.
o http://www.kellogg.umich.edu/theeyeshaveit/index.html - the University of
Michigan, Kellog Eye Center