6. Streak retinoscope
Light source is linear
Intensity &type of beam can be controlled.
Exact axis can be easily found.
It has two systems
projecting system
observation system
8. It is based Focault’s principle, it state that the
examiner should stimulate infinity at the
working distance to obtain refractive error.
9. The distance between pt’s eye & the observer
while performing retinoscopy is called WD.
Normally 66cm(+1.50D) or 50cm(+2.00D)
To compensate the WD we use working
distance lens.
Instant identification of refractive error (
myopia, hyperopia & astimatism)
10. The target given to the pt should be 20/200
or 6/60 in Snellen chart
It is given to the patient to relax
accommodation during retinoscopy.
12. Tell the patient about the test.
The pt should be instructed to fixate the distance
target.
The pt right eye should be examine with the
examiner’s right eye with the retinoscope in right
hand & vice versa.
WD should be maintained an arm length distance
(66 /50cm)
The examiner should keep both eyes open.
The examiner should stay as close to visual axis
as possible.
The examiner should not obstruct the view of
target.
13. Examine the four primary meridian
90,180,45&135 degree. Without any lenses
Three possible reflex may be observed
1) with motion = the pt is hyperopic,
emmetropic or myopic less than dioptric value
of the WD.
2) against motion= pt’s myopia is greater than
the dioptric value of WD.
3)neutrality=pt’s myopia is equivalent to the
dioptric value of WD.
14. Eg. Pt’s ref error is +3.00Dsph
we will get with movement without any lenses @66 cm.
There are two ways.
1.By placing WDL &
2.The other without WDL
step 1. try +1.00DS observe the movement in two
meridians still with.
2. +2.00DS still with
3. +3.00DS still with
4. +4.00DS still with
5. +5.00DS now against
6. +4.75DS against
7. +4.50DS No movement
Than deduct the WD( +1.50ds)
+4.50-(+1.50)=+3.00DS
16. Brightness Dim Far from
neutralization
Bright Close to neutralization
width narrow Far from ne…
wide close to ne..
speed slow Far from ne…
fast Close to ne…
Movement direction with need more plus
Against need more minus
18. If one meridian has against movement &
streaking 90deg away shows with movement
indicate the presence of astigmatism.
If both meridian are with movement & in case
of astigmatism you will observe different
speed, brightness & width from one meridian
to other.
Neutralise the slow movement first & vice
versa in against movement.
19. The thickness phenomenon
The intensity phenomenon
The break & skew phenomenon
Straddling the axis
BITS
20. Narrowest on the correct axis.
As we move from the correct axis the reflex
becomes wider.
21. Intensity
Reflex becomes brightest on the correct axis.
Dimmer on off axis.
Break
Reflex will stay on axis even if we rotated
streak off axis
This guide to come back on correct axis.
22. Skew phenomenon
if we steak off axis the reflex will tend to
travel along the correct axis.
this guide us to back on the correct axis.
Straddling the axis
if there is regular astigmatism, when one
meridian has been neutralized, the meridian
exactly 90deg away will have the strongest &
most defined reflex.
The streak turned to 45deg off axis both side
& if the axis correct with of refflex will samein
this 2 position.
23. There are three methods
1.Two sph eg. +2.00 (+2.50/-0.50*180)
+2.00
+2.50
+2.50
2.Sherical & cylinderical eg -2.50
+1.00/-3.00*180
+1.00
3. Two cylinder eg.
-2.00*90 -1.50
-1.50*180
-2.00
24. There are three ways
1. Changing the WD
2. Moving the sleeve up
3. Changing the lens
25. Wet retinoscopy
Cycloplegic drugs cause paralysis of accommodation & dilate the pupil.
Dry retinoscopy
Without cycloplegic drugs
Gross value
+5.00
-1.50 -1.00
+4.00 -1.50 -1.00
+ +
+2.50
Net value
+1.50
=
Rx +2.50/1.00*90
26. Atropine 1% =+1.25D
Cyclopentolate 1% =+0.75D
Homatropine 2%= +0.50D
So this value should be deducted from the
gross value as shown in the above slide.
27. Incorrect WD
Failure to locate principle meridian.
Scoping off the pt’s visual axis.
Corneal scar
Small pupil
Uncontrolled accommodation
Cataracts
Inexperienced
Defects in trail lenses
Lack pt’s coordination
28. Strabismus= occlude the eye which not being
tested
Aphakia= with +10.00D
Dull reflex= use high +/- lenses
Irregular reflex= neutralise central reflex
Post cataract Sx= mostly against rule
astigmatism (-cyl*90)
Small pupil=reduce the illumination of the
streak
29. You should do retinoscopy on every person
you examine.
It provide starting point of refraction.
It estimate ref error in person with difficult in
communication.
babies
mentally unstable
deaf & dumb
Detect some eye diseases like cataract,
corneal abnormalities etc.