dynamic retinoscopy types ,procedure and interpretation

1. DYNAMIC
RETINOSCOPY
Srijana lamichhane
B.optom,IOM (MMC)

2. What is retinoscope ?
 Is an instrument used to determine the refractive error
 Is an objective method
What is retinoscopy ?
 The purpose of retinoscopy is to obtain an objective
measurement of patient’s refractive state
 it is based on the fact that when the light is reflected from a
mirror into the eye, the direction in which the light will travel
across the pupil will depend upon the refractive state of the
eye

3. Types of retinoscopy
 static retinoscopy: the patient is looking at a
distance object, with accommodation relaxed
 Dynamic retinoscopy: the patient is looking at a
near object ,with accommodation active
 near retinoscopy: the patients is looking at a near
object, with accommodation relaxed

4. Dynamic retinoscopy
 Objectively determines the point that is conjugate to
the retina when the pt. is viewing a particular target
 NO WORKING DISTANCE POWER IS ADDED OR
SUBSTRACTED FROM THE FINDING

5. Movements
same as that of static retinoscopy
 With movement : eye conjugate to a point either
behind the eye or behind the retinoscope.
 Against movement : eye conjugate to a point
between the eye (patient’s) and retinoscope.
 Neutrality : eye conjugate with retinoscope

6. History
 early 1900s, various investigators began utilizing the
retinoscope to determine the amplitude or status of
accommodation in non-verbal patients - term dynamic
retinoscope emerged
 A.J. Cross is credited with introducing the basic theory
and method for dynamic retinoscopy
 Sheard, Nott, and Skeffington - elaborated on the
theory and procedure

7. Goals
 to determine accommodative Response
 also helped to determine the most appropriate near
prescription with testing conditions
 Reveals the degree to which accommodation is
fluctuating when attending to a near target & if the
eyes are balanced equally at near
 provide the information and insights regarding the
patient’s abilities and level of visual processing at the
chosen distance

8. Accomodation
 Accomodative stimulus is defined by the near target
stimulus
 Because of depth of focus and depth of field the
accommodative response is generally less than the
stimulus
 Near point is usually located around 10-17cm
beyond near target at 40cm

9. Accommodation
 Accomodative demand is provided by the target
distance as well as the refractive error
 Over minus or under plussed: has extra accommodative
demand required to see target clearly
 Under minused :does not have to accommodate as
much

10. Accommodation
 Accommodative response is a measure of the actual
accommodation that is present
If your accommodative system likes to “hang out”
Right on the target accommodative
response = stimulus
In front of the target accommodative
response >stimulus (i.e. accommodative lead)

Behind the target accommodative
response< stimulus ( i.e.accommodative lag)


11. Types of dynamic retinoscopy
Monocular Estimation Method (MEM)
Nott retinoscopy
Bell retinoscopy

12. MEM (monocular estimated method)
 Founder Dr. Harold Haynes
 Clinician neutralize the reflex of the eye while patient
accommodates to fixate a target placed at the
patient’s customary reading distance (usually at 40cm)

13. Materials
 series of cards with a central aperture mounted on
a retinoscope
 cards can have printed letters, or words, or pictures
that range in size from 20/160 (6/120) to 20/30 (6/9)
 Arranged around the aperture

15. Procedures
 instructed to keep the targets clear
 sweeps the retinoscope beam
 observes the motion of the retinoscopic reflex
 quickly interposes a trial lens at the spectacle plane

16. Interpretation
 “lag of accommodation” is the amount of plus lens
that neutralizes the reflex
 has been found to accurately measure the lag of
accommodation in an objective manner
Example
If the retinoscopic reflex is neutralized by +1.75D then
lag is
ADD = +1.75 – (+0.75)
= +1.00

17. Limitation
 Plus lenses – relaxation of accommodation –
accommodative response measured by this value
found to be 10% less
 No longer than one fifth of a second

18. Bell retinoscopy
 Developed by Drs. W.R. Henry and R.J. Appel
 Evaluate the performance of the accommodative
system under moving & real life conditions in free space
 cognitive demand is low
 term “Bell” is used because the procedure was done
originally using a cat-bell suspended on a string.

19. Materials
 Three dimensional viewing target
 a small, highly reflective bell dangling from String –
replaced with a Wolff Wand(½ inch diameter, metal
ball mounted on the end of a rod)

20. Procedures
 wand is held by the examiner
 moved closer to and farther from the patient -
slower than 2 inches/sec
 retinoscope is positioned at a fixed distance of 50
cm (20 inches)
 patient fixates the target and the examiner notes the
direction of the reflex

21. Contd
 target is moved closer to the patient there will be a
point where the motion changes from “with”
to“against’’
 Target is again moved away from patient until with
motion is observed

22. Interpretation
 The two measurements are recorded as a fraction e.g.
30/40 (meaning that the inward change from “with”
to “against” occurred at 30cm and the outward
change from “against” to “with” occurred at 40cm.
 The expected values for Bell retinoscopy are: Inward
shift at 42.5 to 35cm and outward shift at 37.5 to
45cm.
 If the lag of accommodation does not fall within
these ranges, the procedure is repeated with plus
lenses. Lenses which normalize these ranges are
considered an acceptable nearpoint prescription.

23. Contd
 eye movement control can be assessed by judging
the extent to which the ball can be fixated
 eye-hand coordination can be evaluated by asking
the patient to touch the Wolff Ball during the
procedure
 NPC can be determined by the normal means
limitation
 patient converges - scoping more off axis

24. Nott’s retinoscopy
 developed by I. S. Nott in the 1920s
 main purpose is identical to the MEM method
 cognitive demand is moderate

25. materials
 reduced block of 20/20 (6/6) letters is
placed at 16 inches (40 cm) from the patient

26. Procedures
 Patient wearing their best correction is instructed to
view a detailed and high contrast target placed on
the retinoscope
 Retinoscopic reflex is examined from the plane of
target and retinoscope is moved closer or farther
away from the target until neutrality is achieved

27. Interpretation
 Dioptric difference between these two distances
equals the lag of accommodation
Example
Distance from the target to spectacle plane = 40cm
Distance from retinoscope to spectacle plane = 50cm
Lag of accommodation = +2.50D – 2.00D
= +0.50D

28. Book retinoscopy
 Also known as getman retinoscopy.
 Developed at gesell institute of child
development at yale university.
 Develop to obtain information about
the visual processing of nonverbal
infants .
 Cognitive demand is high.

29.  Getman and kephart described the following
response levels with this technique.
A. free reading level : Desirable , reflex varies from
neutral to with
B. Instructional level : more demanding than the free
reading level , reflex is a varying fast against motion. •
C. Frustration level : Even though the subject is
“focused” on the page he is not interpreting the
information properly slow against motion
 Reflex color is bright and white when the words are
understood.

30. Contd
 Reflex color is more pink and dims slightly if the
patient is struggling to comprehend a word or
passage.
 Reflex color is dull and brick colored when the patient
has given up on comprehending a word or reading
passage.

31. Cross retinoscopy
 Andrew J. Cross (1911) •
 Start with static retinoscopy finding .
 Patient made to view target at 40cm .
 Examiner performs retinoscopy adding plus lens till
neutrality.
 A alternative to cycloplegic refraction
 Method of adding plus lens power to obtain a
reversal

32.  Determining the correction in cases of
Astigmatism
Presbyopia
Subnormal accommodation in young patients

33. Limitation
 A measurement of negative relative accommodation
 Plus power recommended – patient would not persist

34. Sheard’s method
 Charles Sheard (1920)
 Introduced the concept of “ Lag of accommodation”
 add plus lens power until neutrality occurred

35. Tait’s method
 Tait(1953)
 Working distance = 33cm
 Fogging with a considerable amount of plus lens
power and then approaches neutral by reducing the
plus lens power
 Found an average of approximately +1.50 D more
than sheard system , thus total lag of accommodation
= +2.25 D
 Close to +2.50D i.e Negative relative accommodation.

36. low neutral and high neutral methods
Sheard ( low neutral method)
 The end point is the least plus power required for a
neutral reflex to be observed.
Cross ( high neutral method)
 Addition of plus power beyond neutrality until a
reversal occurs.

37. Stress point retinoscopy
 developed by Harmon and Kraskin
 evaluate the response of the entire organism to stress
 in stress-point retnoscopy - looking at the change in
reflex quality
 Cognitive demand is moderate to high

38.  reasoning behind stress-point retinoscopy is that
vision is intimately related to the whole body and
that a physiological change in stress occurring in the
body can be perceived through a change in the
retinal reflex
 Three things occur when near-point stress is
experienced
 Firstly - there is a change in the individual's pulse
 Secondly - there is an inner canthal twitch and
 lastly - change in the colour of the retinal reflex is
observed

39. Procedures
 Wolff ball is moved closer to the patient - looks at
which distance the reflex "pops"
 initially brightened and then became dull and finally
brightened again - termed "popping" of the reflex -
about 4 inches in front of the patient
 distance is noted and then different lenses are placed
binocularly and the procedure is repeated

40.  ideal lens is the one which makes the stress point as
close to the subject as possible
 more desirable to have the stress-point closer to the
patient - they are not working under physiological
stress
 For example; if the stress-point of a subject is 40cm
and they habitually read at 30cm they would be under
constant near-point stress

41.  plus lenses move the stress-point
closer to the subject and minus lenses
move it away
 in children the stress-point should be
10cm closer to the subject than the
Harmon distance.
 In adults, the stress point is 20 to
22.5cms from face.

42. Near retinoscopy by mohindra
 Near retinoscopy by mohindra in 1977.
 For use in determining the refractive state of infants
and children
 The stimulus or fixation is the dimmed light source
of the retinoscope in a darkened room.
 The retinoscope is held at a distance of 50 cm with
hand-held trial lenses.

43.  Near retinoscopy differs from other forms of dynamic
retinoscopy in the following ways:
1. it is performed in complete darkness , the only
illumination in the room is supplied by retinoscope
with child fixating at retinoscope light .
2. It is monocular procedure that is eye not being
examined is occluded.
3. The adjustment factor of -1.25 D is algebrically
combined with the spherical component of the gross
sphero - cylindrical lens powers.

44. Contd

45. Lag of accommodation
 Time lapse between the presentation of an
accommodative stimulus and occurrence of the
accommodative response
 Average time
 - Far to near accommodation is 0.64 seconds
 - Near to far accommodation is 0.56 seconds

46. Lag of accommodation
 Accommodative lag = accommodative demand (
+2.50D at 40 cm) – accommodative response
 Lags are greater when closer test distances are used
 Lag of accommodation exhibits a slow but
progressive increase to adult levels
 Binocular accommodative system normally respond
with only +1.75D to +2.00D of increased plus power

47.  Normal Lag: +0.50 or +0.75 diopters
 High Lag: +1.00 diopters or higher
 Lead : +0.25 diopters or less

48. Lag > +0.75D/ High Lag
 Inadequate accommodative response:-
 as a result of :- near esophoria
poor negative vergences
accommodative insufficiency
uncorrected hyperopia
Patient is Overminused

49. Low Lag /lead of accommodation <
+0.50
 Overaccommodating
 As a result of :- near exophoria
spasm of accommodation
Over Plus Correction
inadequate positive vergences

51. Source of error
Same as those with static: scissors, small pupils,
dim media (cataracts, etc.), angle
More sensitive to physical arrangement for the
measurement (distance, lens adaptation),
instructions given and patient’s cooperation
 Changes in patient’s fixation or accommodative level
(often related to failure to understand task or to
cooperate)

52. Patient looking at a target at a different distance
than requested
A +0.50 to +0.75 lag is not normal if not testing
at 40cm
Lag increases as fixation distance is reduced
Adaptation to lenses with MEM: relaxes with plus
lenses, stimulates with minus lenses

53. Refrences
o Clinical Procedures in Optometry by J.D. Bartlett, J.B.
Eskridge, J.F. Amos
o Theory and Practice of Squint and Orthoptics by
A.K.Khurana
o Borish’s Clinical Refraction by W.J. Benjamin
o Internet