This presentation discusses retinoscopy, which is an objective method of determining refractive error by neutralizing the movement of light reflected from the retina. The history, theory, procedure, and types of retinoscopy are explained. Static retinoscopy finds the far point, while dynamic retinoscopy assesses accommodation. Observations of the retinoscopic reflex indicate refractive errors, and neutralization with lenses determines the prescription. Potential sources of error and techniques to confirm astigmatism are also reviewed.

1. Presenter: Hira Nath Dahal
B. Optometry
MMC, IOM

2. Presentation Layout
 Introduction
 History
 Theory
 Procedure
 Types of retinoscopy
o Static and dynamic
 Problems
 Uses

3. Introduction
 Objective method of finding out the error of
refraction by utilizing the technique of
neutralization
 Based on the fact that when the light is
reflected from the mirror into the eye, the
direction in which the light will travel across
the pupil will depend upon the refractive
states of the eye

4. History
 Sir William Bowman (1859)
noticed a peculiar reflex in
the pupil of astigmatic eyes
that occurred during
ophthalmoscopy
• Cuignet (1873) developed the technique to use
the reflex to determine and correct for
refractive errors

5.  Explanation of optical concept was first
attempted by Landolt in 1878
 Parent in 1880 began to quantitatively assess
the refractive error through the use of lenses
inserted in front of the eye

6.  Retinoscopy ( “vision of the retina”) :
misnomer; was initiated by Parent in 1881
 Retinoscopy is actually modification of a
Focault knife-edge method for determining
the refractive power of the lens applied to the
eye

7. Focault knife edge test

8.  When the knife edge is in front of the focus,
the shadow direction moves the same
direction at the knife edge

9.  When the knife edge is behind the focus , the
shadow moves in the direction opposite to
the knife edge

10.  When the knife edge is at focus, the light
appears and disappears spontaneously

11.  Retinoscope
 small, handheld device that emits
visible light toward the pupil of eye
being analyzed and allows the
operator to view the red reflex of light
reflected back through the pupil from
the ocular fundus

12. Contd..
 Has a reflecting surface, which allows light
originating from below to be reflected
towards the patients eye
 The reflecting surface is either perforated or
half silvered, which allows the operator to
view the patient’s eye through the central
aperture

13. Optics of retinoscope
 The detail optics of retinoscopy can be
considered into three stages:
1. Illumination stage
2. Reflex stage
3. Projection stage

14.  A divergent beam of light from the filament
source is refracted by the plus condensing lens
below the reflecting surface, before it is reflected
by the perforated or half silvered mirror
 The reflected rays is usually divergent & is
directed towards the patient’s pupil
 Most retinoscopes now have a control for
changing the vergence of emitted light beam
such that the vergence of emitted beam can be
made significant divergent or convergent

16. Contd..
 Divergent beam emitted by retinoscope is
considered the incident beam of the optical
system underlying retinoscopy
 The incident beam can be moved back and
forth tilting the retinoscope and its reflecting
surface

18. Contd..
 As the reflecting surface is tilted the apparent
source moves in the opposite direction across
the line connecting retinoscopic aperture and
the eye
 The divergent incident beam sweeps from
one side of the pupil to the other, in the
direction of the tilt of the reflecting surface &
the beam that enters the pupil sweeps across
the retina in that direction as well

19. Blur patch in the retina moves in the same direction as the
mirror (plane mirror position)

20. Plane mirror VS concave
mirror

21. Clinician
So
S1
S2
Patient
Optical principles
The light in the pupil is called the “ret
reflex”

22. Origin of retinoscopic reflex
• Still in controversy;
 Junction between the retina and vitreous (most
acceptable)
 From the Bruch’s membrane – not accepted as
RPE absorbs the light
• For subjective refraction: Layer of photoreceptors
is considered
• Retinoscope indicates higher hyperopia or less
myopia
• Called as plus bias in retinoscopy

23. Charcterstics of retinoscopic
reflex
Brightness
 Light focused at aperture in emmetrope or at
neutrality –bright reflex.
 Focused sufficiently in front or behind the aperture
in ammetrope – relatively dull reflex.
• large errors have dull reflex, small errors have a bright reflex.
• Dimmer reflex- smaller pupil (hyperopes and elderly)
darkly pigmented RPE
media opacities.

24. Speed of reflex
 WhenWD constant, relative speed of reflex depends
on eye’s residual ammetropia.
 Speed less than half – ammetropia more than
3.00DS from neutrality.
 Speed 3 times – 0.50DS from neutrality.
 Speed 6 times – 0.25DS from neutrality.
 Speed infinity at neutrality, so pupil seems covered
with reflex.

25.  Width
Streak narrow when you are far from far
point
Broadens as you approach far point

26. Ret reflex can tell us a lot
Reflex Observation Meaning
Brightness Dim Far from Rx
Bright Close to Rx
Streak size Narrow Far from Rx
Wide Close to Rx
Movement direction With Need more plus
Against Need more minus
Movement speed Slow Far from Rx
Fast Close to Rx

27.  There are mainly two kinds of retinoscopy:
1. Static retinoscopy and
2. Dynamic retinoscopy

28. Static retinoscopy
 Objective of static retinoscopy is to find the
position of the far point (punctum remotum)
of the eye
 Far point is the point that is optically
conjugate to the fovea when accommodation
is relaxed

29. Contd..
 Far point of the emmetropic eye is located at
the peephole of the retinoscope
 Far point of the myopic eye is located in front
of, or anterior to the eye along the line of
sight

30. Contd..
 In case of a hyperopic eye far point is located
behind or posterior to the eye
o Paraxial light that converges towards a
focus in the plane of the far point focuses at
the retina & light diverging from a hyperopic
retina exits the eye as if it is diverging from a
plane containing far point
 In case of astigmatism, retinoscopy finds two far
points one for each of the two primary power
meridians

31.  In case of emmetropic eye all the rays from
the light source from the retina will enter the
clinician’s pupil and the entire pupil of the
patient will appear to be illuminated .
 It signifies that the clinician’s pupil is
conjugate to the patient’s retina

33. Reflex stage: neutral
Clinician
Patient
No effect on reflex
Reflex disappears
Mirror tilts forwards
Mirror tilts further forwards
S2
S2
No S2
S1
Neutral position:
Far point conjugate with
observers nodal point.
No movement of reflex,
sudden change from red
reflex to no reflex.

34.  As in low myopia, the
light rays emerging
from the illuminated
spot of the fundus are
convergent and meet
behind the observer,
sitting at 50cm from
the patient

35. Observer Subject
Reflex disappears
Reflex moves down,
i.e. with direction
of movement of light
Mirror tilts further forwards
Mirror tilts forwards
S2
S2
Far point behind
observers pupil
Within pupil
Outside pupil
No S2
S1
With movement Far point behind observers pupil.
With movement of reflex, gradual
change from red reflex to no reflex

36.  In high myopia, light
emerging out of the
patient’s eyes from the
illuminated spot on the
fundus are convergent
and meet at the space
between the patient
and the observer

37. Observer Subject
Far point in front of
observers pupil
Reflex disappears
Reflex moves up,
i.e. against direction
of movement of light
Mirror tilts forwards
Mirror tilts further forwards
S2
S2
Within pupil
Outside pupil
No S2
S1
Against movement Far point in front of observers pupil.
Against movement of reflex,
gradual change from red reflex to no reflex

38.  In hypermetropia the
light rays emerging out
of the eye from the
illuminated spot of the
fundus are divergent

39. Degree of ametropia and the
reflex
As subject becomes more myopic, the cone of light becomes
wider
Greater portion of light falls outside of practitioner’s pupil, so
dimmer reflex
1
2

40.  "with" motion of the pupillary streak reflex-as
compared with movement of the incident
divergent beam indicates a far point location
behind the retinoscope aperture, in the
continuum between the operator and infinity
(slightly myopic and emmetropic eyes) or behind
the eye (hyperopic eyes).
 "Against" motion of the streak indicates a far
point location between the retinoscope aperture
and the patient's eye (moderately to highly
myopic eyes).

41.  If the retinoscopic reflex is at neutrality-
showing neither "with" nor "against" motion-
the far point is located at the aperture of the
retinoscope.

42. Types of retinoscope
1. Reflecting (mirror
retinoscope):
A source of light is required
when using mirror retinoscope,
which is kept above and behind
the head of the patient
 May consists of a single
plane mirror or the
combination of plane and
concave mirrors (Priestley-
Smith’s mirror)

43. 2. Self illuminated retinoscope:
more popular now a days
two types are available:
a. Spot retinoscope
b. Streak retinoscope

44. Spot Vs Streak
 The “spot retinoscope” reflects a beam of light
from a circular source, whereas the “streak
retinoscope” emits a beam from a line source
 Of these two major forms of retinoscope, the
streak retinoscope is more useful clinically
because it can be more readily applied to the
determination of astigmatic corrections by
assessment of the axis of cylinder and refractive
powers in the two primary ametropic meridians

46. Procedure

47. Observations
Depending upon the movement of the red reflex
(when a plane mirror retinoscope is used at the
distance of 50cm), the result are interpreted as
follows:
a. No movement of red reflex indicates myopia of
2.00D
b. The movement of red reflex along with the
movement of the retinoscope indicates either
emmetropia of hypermetropia or myopia less
than 2.00D
c. The movement of red reflex against the
movement of the retinoscope implies myopia
more than 2.00D

48. With movement

49. Against movement

50. Neutralization point

51. Neutralization
 To estimate the degree of refractive error, the
movement of red reflex is neutralized by
addition of increasingly convex (+) spherical
lenses (when the red reflex was moving with
the movement of plane mirror)
Or
concave (-) spherical lenses (when the red reflex
was moving against the movement of plane
mirror)

52.  When simple spherical error alone is present,
the movement of red reflex will be
neutralized in both vertical and horizontal
meridian
 In the presence of astigmatism, with its
principal axis horizontal and vertical, one axis
is neutralized with the appropriate spherical
lens and the second axis (vertical or
horizontal) still shows the movement of reflex
in the direction of the axis of the astigmatism

53.  End point:
When streak retinoscopy is performed, the
width of the reflex widens progressively as
the neutralization is approached, and at the
end point, streak disappears and the pupil
appears completely illuminated or
completely dark

54. Confirm/identifytheaxisofthe
astigmatism
 TheThickness Phenomenon
 The Intensity Phenomenon
 The Break and Skew Phenomena
 Straddling the Axis

55. The thickness phenomena
 The streak reflex appears to be narrowest when
we are streaking the meridian of the correct
axis.
 As we move away from the correct axis, the
streak reflex becomes wider.

56. The Intensity Phenomenon
 The streak reflex appears brightest when you
are streaking the meridian of the correct axis.
 As you move away from the correct axis, the
streak reflex becomes more dim.

57. •In higher amounts of astigmatism, the streak
reflex will tend to stay on-axis even if the
streak is rotated off-axis, this guides you back
to the correct axis .
Break phenomenon

58. Straddling the cylinder axis
o Introduced by Copeland – finding and bracketing
astigmatic axis
o Rotate the retinoscopy streak such that it
becomes align 45 degrees oblique to the axis of
correcting cylinder, to either side
o Compare the speed of rotation and alignment of
fundus reflex streak with correcting cylinder axis
o If not align fundus reflex streak would be
misaligned in one of the 45 degree position

59. Clinician
S2
Patient
Working distance
neutrality
negative vergence is
introduced due to our
working distance (WD)
= 1/d (m)
Where d = distance in m,
measured between your
ret and patient’s eye
added lenses
To get the right prescription
we need to compensate
Rx = lens power – 1/d
So to get neutral, we needed:
lens power = Rx + 1/d

60. Working distance
compensation
Calculation
 For example, if neutrality is achieved with a +3.00DS
lens and your working distance is 50cm
 Rx = +3.00DS – (1/0.50)
 = +3.00 – 2.00
 =+1.00DS
Rx = lens power - 1/d

61. Potential errors
 Variations inWD.
False neutrality
 When the beam is made convergent by
collar sometimes the focus lies apparently
at the aperture before the reversal of the
streak.
 Full fundus glow is achieved regardless of
the residual ammetropia.

62. Scissors (fish mouth) reflex
 Due to
 large pupil diameter (aberrations)
 Irregular astigmatism
 Irregular retina
 Tilted lens
 Corneal scar
 Neutralized by lens that provides more or less
equal thickness and brightness to the opposing
reflex

63. Scissors movement

64. Contd..
Obliquity of observation
 As observer is slightly temporal there’s residual
oblique astigmatism induced
 Error is 0.12DC@ 90 if 5 degree 0.37DC@ 90 if
10 deg; 0.75DC@ 90 if 15 deg; & 1.37DC @ 90 if
20 deg oblique

65.  Accommodative status
 Plus bias: hyperopia of +0.25 to +0.50 in youthful
eyes is seen.
Is due to effective reflecting surface being behind
the outer limiting membrane.
also due to spectral composition of fundus reflex.
Contd..

66. 66
 When retinoscopy is used to test accommodation
for near objects, it is called dynamic retinoscopy
 The patient views a nearpoint test card at a typical
nearpoint working distance, e.g., 40 cm.
 This establishes a known accommodative stimulus
Dynamic Retinoscopy

67. 67
 Lag of accommodation can be assessed clinically
using various retinoscopic procedures.
 Lag of accommodation=
 Accm response < Accm stimulus
 Normal Lag: +0.50 or +0.75 diopters
 High Lag: +1.00 diopters or higher
 Lead : +0.25 diopters or less

68. 68
 To investigate the accommodative state of the eye
in near vision.
 There are two different techniques:
 The patient observes a separate fixation object
with the retinoscope behind it. The distance
between the object and retinoscope at reversal
indicates the accuracy of accommodation.
Types of Dynamic Retinoscopy

69.  The fixation object is on the retinoscope, the
level of accommodation being measured by
trial lenses placed before the eyes.
 In both techniques the patient wears the distance
correction as found by the subjective.

70. Cross-Nott’s technique
 Doesn’t require the use of supplementary lenses
 Pt wears first the distance refractive correction,
and is directed to view the near target
 If the with movement is seen (reflecting the
typical lag of accommodation), then the
retinoscopist adjusts the working distance away
from the patient, while the fixation target
remains stationary
 The reciprocal of the retinoscopy WD (in metres)
at which the neutral reflex is observed indicates
the magnitude of accommodative response

71. Sheard’s technique
 He indicated that lag of accomodation could
measured by placing a target which is
attached to the retinoscope mirror at the
patient's usual reading distance, an
performing retinoscopy at that distance
 Appropriate spherical lenses are added until
the neutral reflex is observed
 Stated that the lag of accomodation is given
by the lens power which provides “the first
indication of neutral shadow”

72. 72
 dynamic retinoscopy method using lenses, the
stimulus to accommodation is altered by the
presence of the trial lenses.
 the patient also binocularly fixates a stimulus
mounted on the retinoscope.
 The target is a set of letters on the retinoscope
or a card attached to the retinoscope
MEM Retinoscopy

73.  a single lens is briefly held in front of one eye
and the beam passed across.
 The method is applied to one eye at a time.
 The lens giving reversal gives the value of the low
neutral.

74. RADICAL RETINOSCOPY
 Due to small pupils/cataract/other media
opacities/faint retinoscopic reflex
 The practitioner find easy as moving closer to
the patient.
 Involve aWD as close as 20 cm/or even 10cm.
 Eg: if possible at 20 cm WD then +5.00D is
subtracted from lens power in the refractor.

75. STATIC Vs DYNAMIC
 Accomodation fully
relaxed.
 Working distance lens
added or subtracted
from the objective
finding.
 Fixates letters at 6m.
 Only ametropia or
emmetropia can be
determined.
 Accomodation fully in
play.
 No influence of working
distance.
 Fixates at the bulb of
retinoscope or letters
clinged on it.
 Accommodative lag can
be determined.

76. Uses
 Objective measurement of refractive error
 Evaluation of refractive state in nonverbal
patients and also in low vision patients
 Regularly used in laboratory for
measurement of refractive status in animals
 Starting point for subjective refraction

77.  Used to prescribe where subjective refraction
can’t be performed
 Screening for ocular disease
 Keratoconus, media opacities
 Also useful in determining accomodative
stability and accomodative lag

78. THANKYOU!!