Download Clinical Refraction Procedure

Clinical Refraction Procedure
Presented by
T.Muthuramalingam
Introduction
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It is a combination of adequate examination
and correction of vision .
According to eye care system clinical
refraction is used to described the process of
measuring a patients refractive error and
determining the optical correction needed to
provide patients with clear vision.
History taking
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Usually the optometry history should included
the following:
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Chief complaint
History of comfort ness with glass.
( if any)
Family history of ocular disorder
(myopic , blindness,squint)
Occupation
General Information
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Are essential facts that should be noted
Include patient Name,Address,Age and
occupation
Any allergy to drugs
Complaints related with vision
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Chief complaint should be noted first for which
patients has come to hospital.
Vision related complaints can be pain ,loss of vision,
eye fatigue and blurred vision.
For all these question ask the duration, date of
unset,sudden or gradual loss.
History of using glass
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Duration of glass used.
About of type of lens(glass or plastics)
Present problem with glass(if any)
Note the condition of glass like frame
alignment, scratches in lens etc.
Preliminary eye
examination
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It is done to record any gross abnormality by using
torch light
Position and size of eye balls and orbital socket.
Position and size of eye lids and its margins and
lashes.
Surface of cornea, its shape,size, opacities.
Position and color of Iris.
Ocular movement.
Pupillary action, size-dilated or not dilated.
Lens clear or opacity,aphakia or pseudophakia.
Preliminary
vision assessment
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It is done for finding out the existing vision .
Check vision monocularly unaided and aided.
Make sure whether patients is comfortable with
present glass or not.
Decide whether the refraction is needed or not
Objective refraction
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It is done by streak retinoscope
To determine objectively the actual refractive error
of patients.
It is done monocularly by trial lens method
It include following steps
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Positioning and alignment of patients.
Maintained the proper working distance
Observing the retinal reflex (with or against movement.
Finding the neutrality point using the appropriate lens.
Indication for
Auto refraction
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One who suspected to have high power in
retinoscopy
The uncooperative patients while doing
retinoscopy
One who comes for glass first time
particularly children
All astigmatic patients having above 1D
cylinder
Subjective
refraction
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Verification of findings obtained
from retinoscopy with patients.
Always proceed the subjective refraction monocularly and als
check the binocular comfortness.
Confirm the unaided vision first and proceed the lens
accordingly
Find out the spherical improvement first to avoid unwanted
cylinder
Add cylinder to correct the remaining.
Apply supplementary test to confirm the final prescription
Indication of Cycloplegic refraction
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All hypropes having the age group.
One who complains of Asthenopic symptoms.
Who come for glass for first time
Accommodation is abnormally active.
Near vision assessment
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The near vision test is preferably done at 40cm by
aging method
It is done with distance vision correction that is with
patients emmetropic level.
Determine the correction depend upon the
comfortness, working distance, visual need of
patients along with aging method.
Always check the unaided improvement first to find
better correction.
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E.g. if pt’s with good reading speed indicates the under
correction.
Prescription writing
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It should be clearly written regarding the sign
and cylinder axis.
Transpose the prescription with plus cylinder
to provide comfortness to patients.
Measure and write the IPD properly.
Mention the advice given to patients
regarding lens design.
Advice to patient
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Advice properly
Instruct the patients how to use the glass
(dist. Near,constantly)
Counsel the patients about the difficulties and
limitation of lenses.
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E.g: slow adaptation in PAL, jumping effect in
bifocal.
Instruction to optician
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Recommended only flat top bifocal for
constant uses.
Advice only the plastics lens for safety
reasons specially for children.