3. Introduction
An accurate objective measurement of the refractive
state of an eye can be made using the retinoscope
The technique is called retinoscopy
Pupilloscopy, shadowscopy, skiascopy,
umbrascopy, scotoscopy
4. History
• 1873,F.Cuigent the father of retinoscopy- first
described a retinoscope
1878, M. Mengin
1880, H. Parent - retinoscopie
• 1927, Copeland -streak retinoscope
6. Reflecting mirror retinoscope
• A perforated mirror by which the beam is reflected in to
the patients eye and through a central hole the emergent
rays enter the observer’s eye
• Movements of the illuminated retinal area are produced
by tilting a mirror, either a plane or concave
9. Self illuminated retinoscope
• The light source and the mirror are
incorporated in one
• STREAK RETINOSCOPE- Light source is
a linear (uncoiled) filament
19. Optical Principle
• Retinoscope works on Focault's principle
• Retinoscopy is based on the fact that when 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
22. Reflex Stage
An image of the
illuminated retina is
formed at the
patient's far-point
Exercises in Refractometry.
Thorofare, NJ: SLACK Incorporated; 1990
23. Projection Stage
The image at the far-point is located by
moving the illumination across the fundus
and noting the behaviour of the luminous
reflex seen by the observer in the patient's
pupil
30. Working Distance
• The distance from the retinoscope to the patient’s eye
• D = 1 ÷ F
• The length of the average person’s arm is 66 cm.
The power of a lens that focuses parallel light rays
at 66 cm is +1.50 D
31. Should I use a “working lens” to
compensate for the working distance?
Advantages-
Instant identification of myope or hyperope.
Working lens might help relax accommodation.
No need for mental arithmetic to allow for working
distance
Disadvantages-
Too much blur does not necessarily relax
accommodation.
Working lens adds extra reflections to the view.
32. Formation of the Secondary Fundus
Source or "Fundus Reflex"
• Light reflected from the fundus has two components:
• A diffuse component, which is also called backscatter
• A directed component
33. Fundal reflex
Properties of the fundal reflex indicate the refractive status
of the eye
• Brightness
• direction of motion
• speed of motion
• Width
34. Brightness of the Retinoscopic
Fundus Reflex
The brightness of the
fundus reflex is greatest
when the retinoscope
aperture coincides with
the far point of the eye
In highly myopic and
highly hyperopic eye the
pupillary reflex appears
dim
35. Direction of Motion of the Retinoscopic
Fundus Reflex
No movement of red reflex indicates myopia
of 1D
36. Contd..
• Red reflex moves along with the movement of the
retinoscope, it indicate emmetropia or hypermetropia or
myopia of less than 1D.
37. Contd..
• A movement of red reflex against the movement
of the retinoscope, indicates myopia of more than
1D.
38. Speed and width of the Retinoscopic
Fundus Reflex
• Indicates that how far we are from neutrality
• A slow moving streak reflex - long way from neutrality.
39. Finding the cylinder axis
• In the presence of astigmatism, one axis
is neutralized with the spherical lens &
the second axis still shows the
movement of reflex in the direction of
axis of astigmatism
40. Finding the cylinder axis
Break
Break in the alignment
between the reflex in the
pupil and the band outside it
is observed when the streak
is not parallel to one of the
meridian
41. Finding the cylinder axis
Skew
if the streak is not
aligned with the true
axis oblique motion of
streak reflex will be
observed on
movement of the
steak.
43. Finding the cylinder power
3 Methods-
With two spheres
With a sphere and cylinder
With two cylinders
44. With two spheres
First neutralize one axis with appropriate sphere
Then keep on changing the sphere till the second axis
is neutralized
Astigmatism is measured by the difference between
the 2 spheres
+2.00D
+3.00D
+ 2.00Ds / + 1.00 Dc X 900
45. With a sphere and cylinder
First neutralize one axis with an appropriate spherical
lens.
Neutralize the other axis with a cylindrical lens at the
appropriate orientation
The spherical cylindrical gross retinoscopy may be
read directly from the trial lens apparatus
46. Enhancement
This technique is to approximately estimate the amount
of refractive error with minimal use of trial lenses.
If the reflex inside pupil gets more thinner by changing
the sleeve width,it suggests a significant refractive error
Thinnest retinal reflex is called Enhanced band
49. Types of retinoscopy
• Static Retinoscopy: the patient is looking at a distant
object, with accommodation relaxed.
• Dynamic retinoscopy: the patient is looking at a
near object, with accommodation active.
• Near retinoscopy: the patient is looking at a near
object, with accomodation relaxed
51. MEM Retinoscopy
Help to calculate patients lag or lead
of accomodation
Lettered targets are applied to the head of a
retinoscope
Fixation target is placed at harmon distance/50 cm
with patients corrected refractive error
the refractive power of the trial lens that brings
neutrality is the accommodative lag/lead
52. Nott’s method
It determines lag/lead of accomodation by moving
retinoscopic apperture towards or away from the eye
Target is the letters around the aperture of a near point card
At a distance of 40 cm
The accommodative response, in diopters, is subtracted from
the accommodative demand,to determine the accommodative
lag/lead
53. Bell Retinoscopy
The retinoscope remains in
a fixed position and the target is moved
The retinoscopy is performed from a fixed
distance of 50 cm
The distance between the retinoscope and the
target when the change in motion occurs is a
physical measure of the lag/lead of
accommodation
54. Near retinoscopy /Mohindra
retinoscopy
Also known as near monocular retinoscopy
Estimate the refractive status of the eye
The stimulus or fixation is the dimmed light source
of the retinoscope in a darkened room
The retinoscope is held at a distance of 50cm with
hand-held trial lenses
Borish's Clinical Refraction. 1998. WJ Benjamin. WB Saunders Company.
Philadelphia, London, Toronto.
55. Radical retinoscopy
Done in patients with small pupils, cataract, or any
other opacity
Working distance here is 20cm or even less upto 10cm
56. Chromoretinoscopy
Helps in a clinical measurement of the chromatic
aberration of an eye
Transmittance filters with selected dominant
wavelengths, are placed in the light path between the
light source of a retinoscope and the retinoscopist's
eye
57. Types of retinoscopy
• Wet retinoscopy- with cycloplegic retinoscopy is
performed
• Dry retinoscopy-without cycloplegic
58. Indications for wet retinoscopy
Accommodative fluctuations indicated by a
fluctuating pupil size and/or reflex during retinoscopy
Patients with esotropia or convergence excess
esophoria
A retinoscopy result significantly more positive or
minus (>1.00 DS) than the subjective result
59. cycloplegic drugs used in wet
retinoscopy
Atropine sulphate 1%
Cyclopentolate 1%
Homatropin 2%
60. Disadvantages of cycloplegic
retinoscopy
Temporary symptoms of blurred vision and
photophobia
The degradation of vision is caused by the abolition of
the accommodation response
Increase in ocular aberrations as a result of dilated
pupils.
Adverse effects and allergic reactions to
cyclopentolate are rare
61. Problems in retinoscopy
• Red reflex may not be visible -small pupil, hazy
media & high degree of refractive error
• Scissoring shadow-may be seen in healthy cornea
but with unusual difference in curvature in the
centre & the corneal opacities
62. contd
Patient with strabismus-it is easier to change the
fixation of good eye so that retinoscopy can be
performed along the visual axis of the strabismic eye
Retinoscopy in nuclear cataract shows index myopia
in early stages
63. contd
• Spherical aberrations -lead to variation of refraction in the
centre & periphery of pupil. It may be seen in normal eyes
but more marked in lenticular sclerosis.
• Conflicting shadows- moving in various directions in
different parts of the pupillary area with irregular
astigmatism
• Triangular shadow- may be observed in patients with
conical cornea
64. Non-refractive uses of
retinoscopy
Opacities in the lens and iris -dark areas against the
red background
Extensive transillumination defects in uveitis or
pigment dispersion syndrome -bright radial streaks
on the iris
Keratoconus distorts the reflex and produces a
swirling motion
65. contd
Retinal detachment involving the central area will
distort the reflecting surface and a grey reflex is seen
A tight soft contact lens will have apical clearance in
the central area which will cause distortion of the
reflex
66. Reason for false reading
Inexperience
Not aligning with Visual axis of the patient
Definite working distance is not maintained
Lack of subject’s accommodation
Defect in trial lenses
Lack of patient’s co-ordination
The term "objective refraction" is used when the refractive error of an eye is determined without input by the patient
Retinoscopy is a form of objective refraction in which the judgment of a human operator is required to determine the refractive error
Retinoscopy can be performed on
infants, the mentally infirm, low-vision patients, and
uncooperative or malingering patients.
1902 Jack C. Copeland was studying astigmatic reflexes with Wolff’s spot retinoscope, when he dropped the instrument on floor, damaging the bulb filament
SPOT RETINOSCOPE- Light source is a small coiled filament
The hole should be pierced and not to be formed by a defect in silvering of an in perforated mirror as the glass reflects an appreciable fraction of light,which should enter the eye. If it is pierced ,annoying reflexes may be formed at edges but these are avoided if the sides of the hole are blackened ,& are made widen out posteriorly so that it is narrowest at the mirror end.
SPOT RETINOSCOPE- Light source is a small coiled filament
Plano mirror effect:
The light rays emanating from the retinoscope are slightly divergent and movement of the retinoscope downwards makes the image of the filament move upwards.
Concave mirror effect:
By using a concave mirror of focal length less than the distance between the patient and the observer and close to the patients eye, a real image of the light source is formed between the patient and the observer close to the patients eye. This image acts as a bright light source for illuminating the patients retina and there fore the illumination moves in the opposite direction to the plan mirror.
Usual method of vergence control (lens is fixed). Copeland type
Mechanism that controls the width of the streak also allows to switch between plane mirror and concave mirror.
Copeland streak retinoscope:
All the way up, plane mirror is in position with a wide streak.As it is lowered gradually , the streak decreases in width.
And widens again.At the lowest adjustment the streak is again at its maximum width but with concave mirror effect.
Alternative method ergence control (bulb is fixed). We.lch Allyn type
American Optical and Welch Allyn: These instruments are in plane mirror mode when the mechanism is all the down rather than all the way up
Enhancement of hyperopia by raising the sleeve. Enhancement is one technique that combines changing in the illuminating system with properties of the viewing system. In hyperopic eyes, it is possible to narrow the beam on the retina sufficiently so that its borders can be seen despite the magnification (cross-hatched) of the viewing system. The amount that the sleeve is moved and the width of the facial intercept permit estimation of the amount of hyperopia. Moreover, meridional comparison is the basis for detection of hyperopic astigmatism.
What the Patient Needs to Know-
The retinoscope helps determine your glasses prescription
Just keep both eyes open and look at the letters on the chart, even if they are blur
Do not look at the light
You can blink whenever you need to
Let me know if I block your view of the letters
PRE-REQUISITES-
Semi-dark Room
Trial set
Lens Rack
Trial Frame
Phoropter or Refractor
Fixating targets [distance & near charts, illuminating source etc.]
A light source was located beside the patient's head, and light
reflected into the patient's eye from a plane or concave mirror held by the observer. The observer
viewed the patient's eye through a small hole in the mirror. The electric retinoscope has largely replaced
this system. However, the principles and nomenclature have remained unchanged.
When a plane mirror is used, light is moved across the patient's fundus from A to B by rotating the
plane mirror from M1 to M2. Note that the illuminating rays move in the same direction as the mirror.
A concave mirror of focal length less than the distance between patient and observer is occasionally
used for retinoscopy. A real image of the light source is formed
A ray from point A of the retina R on the principal axis of the eye, which leaves the eye along the
principal axis.
(2) A ray from a retinal point B, off the principal axis, which travels parallel to the principal axis as far
as the principal plane, P, of the eye, where it is refracted to pass onward through the anterior principal
focus, Fa, of the eye.
A ray from retinal point B which passes undeviated through the nodal point, N.
The observer views the image A1B1 of the illuminated retina AB from a convenient distance, usually m.
Figure 14.22 depicts this and is constructed by drawing Fig. 14.21 and adding a hypothetical ray from
point B1 passing through the observer's nodal point, No, to the observer's retina, Ro. This ray locates the
point Bo, the image of B1 on the observer's retina, and allows completion of the diagram. The observer
does not see the actual image A1B1, but rays from A1B1 are seen as an illuminated area or reflex in the
patient's pupil.
In hypermetropia the luminous reflex seen in the patient's pupil moves in the same direction as the
illuminating light – a 'with' movement, indicated by the arrows in Fig. 14.22. Once again a 'with'
movement is observed.
When the patient's myopia is less than the dioptric value of the observer's working distance a 'with'
movement is still obtained.
This is the distance at which
the eye is focused when the reflex has been neutralized
(you remember that D = 1 ÷ F, right?). In other words, the eye on which
you just performed retinoscopy has 1.50 D of plus-powered sphere more than it needs (unless you
want to measure visual acuity at 66 cm”
If the distance is between 54 and 61 cm,
use 1.75 D as your working lens. Those with a working distance between 62 and 72 cm should
use 1.50 D
To allow the eye to focus at 20 feet (6 m), this power must be taken away from the gross retinoscopy result.
This is done by dialing 1.50 D toward the minus, also known as “removing the working lens’’
“Retinoscopy lens” built into most refractors; the lens is inserted prior to performing retinoscopy and simply removed at the completion
a diffuse component, which is also called backscatter,
the result of light scattered because of reflection from
microscopic and macroscopic particles or structures
within the volume of the retina, the pigment epithelium,
the choroid, or even the sclera
A directed component, the result of light that
has been reflected from the neighborhood of the
retina/pigmented epithelium interface and is waveguided
by the retinal cones
The streak reflex is a diffuse reflection of light from the
illuminated fundus: an elongated patch of fundus that
becomes the illuminated object for refraction out of the
eye.
the reflected light that exits the pupil
has a focal point that lies in front of the eye, as in a
myopic primary meridian, or a virtual focal point that
lies in back of the eye, as in a hyperopic primary meridian
At neutrality, the retinoscopic refractive endpoint is
reached when the focal point-or far point-has been
moved to coincide with the aperture of the retinoscope
The brightness of the fundus reflex is greatest when the retinoscope aperture coincides with the far point of
the eye. Nearly all of the light making up the fundus image enters the pupil of the retinoscopist's eye. According
to the inverse-square law, when the retinoscope aperture and the far point do not coincide, only a portion
of the wavefronts will enter the retinoscope aperture to be collected by the retinoscopist's eye
With movement-it indicated that the far point was behind
the retinoscope aperture, in the continuum between the
operator and infinity (slightly myopic and emmetropic
eyes) or behind the eye (hyperopic eyes). In the case of
"with" motion, lenses of progressively more plus refractive
power must be inserted at the spectacle plane for
neutrality to be achieved
"Against" motion of the streak
indicated that the far point was between the retinoscope
aperture and the patient's eye (moderately to highly
myopic eyes). In the case of "against" motion, lenses of
progressively more minus refractive power must be
inserted at the spectacle plane for neutrality to be
achieved
-When add plus spherical power, the streak tends to narrow & speed in its apparent motion.In high degrees of refractive error, it is narrow.
-In low degree, it is wide.
-At the neutralization point, the entire pupil is filled with light.
Speed & prilliance-
- In low degree of refractive error the shadow (red reflex) seen in the pupillary area is faint & moves rapidly with the movement of the mirror.
- In high degrees of refractive error, it is very dark & moves slowly
B=DxY/X
where B= blur-circle diameter on the retina; D = diameter
of the entrance pupil; X = distance from pupil to
focus within schematic eye; and Y = distance from focus
to blur circle at retina
Break in the alignment between the reflex in the pupil and the band outside it is observed when the streak is not parallel to one of the meridian. The band of light in pupillary area lies in a position intermediate between the band outside the pupil and that from axis of the cylinder.
The axis even in the case of low astigmatic error can thus be determined by rotating the streak until the break disappear. The correcting cylinder should placed at this axis.
The oblique axis can be determined by rotating the streak until the break disappears.
skew ( oblique motion of the steak reflex ) may be used to refine the axis in small cylinders. The steak and reflex will move in the same direction only when steak is aligned with one of the principal meridian. Therefore if the streak is not aligned with the true axis skewing will be observed on movement of the steak.
The streak is turned 450 off axis in both directions
If the axis is correct the width of the reflex should be equal in of the two positions.
If the axis is not correct the widths will be unequal in the two position. In such a situation the narrower reflex serves as the guide towards which the cylinder axis should be turned
Example : - if the 1800 is neutralized with + 2.00 sph. & the 900 with + 3.00D sph, the gross retinoscopy will be + 2.00Ds / + 1.00 Dc X 900
The Least positive power becomes the sphere power (+2.00DS)
The amount of astigmatism is recorded as cylinder, and is the difference between the power of the two primary meridians
The axis is the position of the beam in the most negative/least positive meridian
Then with this spherical lens in place,
the
accommodative system in a young adult lags 0.50 to
0.75 behind a near target at 40 cm
such that the
target and retinoscopic aperture are located at the same
distance from the eye
MEM is unique in that lenses are primarily used to verify the observation of the doctor
The amount of the “lag of accommodation” is the amount of plus lens corresponding to the movement seen
the amount of lens is estimated based on the amount of movement observed
Named so because small shiny bell dangling from a string that was used as a fixation target
Measures the lag of accommodation as a linear measurement rather than with lenses.
Typically we expect to see a change from “with” to “against” on the way in at 35 - 42
cm. (14 - 17inches) and a change from “against” to with at 37.5 - 45 cm. (15 -18 inches)
In this case,
The darkness of the room will facilitate the child to keep their attention on the retinoscope’s light
The accommodation activity during the examination is small
and the same in both eyes. It is important during the examination to keep the light
of the retinoscope on the child’s pupil for only a short period of time so as not to stimulate
accommodation;
child-friendly and requiring less co-operation from the child
The retinoscope is held at a distance of 50cm with hand-held trial lenses used to find the neutral point
the result achieved by the Mohindra procedure in children between six months and four years of age is similar to wet retinoscopy (using cyclopentolate 1%), with a difference of only 0.50DS
Retinoscopy may be done undercycloplegic or mydriatic drugs or without any drug
Cycloplegics are the drugs
which cause paralysis of accommodation & dilate the pupil
These are used for retinoscopy