RETINOSCOPY
FARHANA ADNIN
B.OPTOM~2ND YEAR
ICO,CU.
WHAT ISOBJECTIVE REFRACTION ???
Where the result depends purely
on the examiners judgement to
determine the optimum optical
correction.
Methods for objective
refraction Keratometry
Ophthalmoscopy
Optometers
Auto refraction
Photorefraction
&
Retinoscopy [Most important & common
method ]
What is
Retinoscopy & Retinoscope?
Retinoscopy or skiascopy is the primary method for objective determination of the total refractive status of the eye.
Retinoscopy is done with the help of an instrument called Retinoscope.
It illuminates the inside of the eye,to observe the light that is reflected from retina.By examining how emerging rays change,refractive power of eye can be determined.
History~
Sir William Bowman in 1859,reported the movement of light and shadow effect.
Used since 1873 – reflecting mirror spot
retinoscopes, externally illuminated.
Modern streak design that brought
significant change in 1927, by Jack C.
Copeland.
INSTRUMENTATION
Head-light bulb
-peephole
-mirror
Neck
Sleeve-for rotating
Handle-electrical
supply
Techniques
2 main techniques of retinoscopy are :
1)Static Retinoscopy: It is the refractive state
determined when patient fixates an object at a
distance of 6m with accomodation relaxed.
2) Dynamic Retinoscopy: The refractive state
is determined while the subject fixates an
object at some closer distance, usually at or
near the plane of retinoscope itself with
accomodation under action.
Cont…
Static Retinoscopy include
Spot retinoscope: Light source is spot
of light.
Streak retinoscope: The bulb is
constructed so that is provides a beam
in the form of a streak rather than a
spot.
Spot retinoscope Streak retinoscope
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
-Accomodative lag
can be determined
Significance ofspot & streak
Round filament Scoped in any
meridian Assessment of
the contact lensfitting
Dealing with pediatric patients
Vision screeningprograms
-Linear filament
-Quickly change
from plano mirror
to concave mirror
-Narrowing the
width makes it
easy to pin down
the principal
meridians
Principle of retinoscopy
To locate the far point of the eye/ plane
conjugate to the retina
Bring far point to the infinity by using
appropriate lenses
Accommodation at a minimum.
Continue......
Mirror with central hole
SubjectObserver
Incoming light
Outgoing light
Variable condensing lens
Origin of Retinoscopic Reflex
Interface between the vitreous and
retina.
Pigment epithelium of retina or
Bruch’s membrane
Stages of Retinocopy
Illumination stage
Projection stage
Reflection stage
Neutralization stage
Illumination Stage
Depends on ~
concept of the immediate source of light
the movement of the illuminated area of the fundus ,with the movement of reflecting mirror.
Plane mirror : immediate source of light moves with the movement of the mirror.
Concave mirror : immediate source of light moves against the movement of the mirror.
PROJECTION STAGE
1.Light source
2.Condensing lens
3.Mirror
4.Focusing sleeve
5.Current source
Reflex Stage
Depending upon the refractive status
of
the eye:~
Characteristics of reflex
1.Speed: large refractive errors have a
slow-moving reflex, small errors have a fast
reflex.
2.Brilliance: large errors have dull reflex,
small errors have a bright reflex. Becomes
brighter when neutrality approaches.
3)Width: Narrow in high degree error &
widen in low degree error.
Mirror effect… Plane mirror effect:
◦ Effective source lies behind the plane of mirror (most commonly used)
◦ The rays of light form the source goes parallel or slightly diverging
◦ Does not cross between the source and the patient’s eye- with movement – hyperopia
Against movement - myopia
Concave mirror effect:
◦ Generally not used
• keep the effective source in front of the plane
of the mirror, so that the rays emitted from
source are more converging and cross at a
certain distance between patient and the
source
with movement – myopia
Against movement - hyperopia
Concave mirror
effectPlane mirror effect
Working distance & lens
selectionBeginning retinoscopy, the examiner must
choose a WD.
Depends upon the length of the examiner’s
arm. If arm permits-
1. 66cm-WD=+1.50D
2. 50cm -WD=+2.00D
Prerequisite for
objective retinoscopyDark room
Retinoscope
A trial set
A trial frame
Distance fixation target
PROCEDURE~Patient sits at a distance of
66cm/50cm from the examiner.
~Patient is asked to fix at a distance
target to relax accommodation.
~Light is thrown on the patient’s
eye from retinoscope.
~By rocking the light slowly the
characteristics of the reflex
are observed.
~Then neutralizing the reflex.
~Examiner must be examined the
patient’s Rt eye by his/her Rt eye
& vice versa.
Nature of reflexes in ametropia
(plane mirror) Myopic far point of accommodation
located at a finite distance
infront of the eye
Hyperopes far point of
accommodation is located at
some point behind the
primary focal plane of the eye
• Emmetropic eyes far point
of accommodation is located
at infinity
Observation System• When we view the reflex in patient’s eye, it seems to
move in the direction
• If the retinoscope is tilted upward, reflex will move to the opposite direction ;in case of myope;
• same direction of retinoscopic light & reflex ; in case of hyperope and emmetrope;
• no movement (with working lens) at all in case of emmetrope.
Streak motion
Hyperopic patients
◦ Light focuses behind the retina
◦ Streak movement in
same direction as the
retinoscope . i.e.,
displays with motion
◦ Add plus lenses to bring
the focusing point up to the retina
Cont….
• Myopic patients–Light focuses at the point
before the retina
–Streak movement in
opposite direction as the
retinoscope
i.e., against movement
–Add minus lenses to move
the focal point back onto the retina.
Emmetropic patients
◦ No motion of the reflex observed in the
pupil
◦ Also known as neutral motion or complete
flashing
Spherical or Cylindrical ???
Streak both the
horizontal and vertical
meridian to determine
the astigmatism
Finding cylinder axis
1.Break: seen when the streak
is not parallel to the principal
meridian and disappears when
the streak is rotated to
the correct axis.
2. Width: reflex appears
narrowest when the streak
aligns with the axis.
3.Intensity: Line is brighter when the streak
is on the correct axis.
4. Skew: When the streak
is off-axis,it will move in a
slightly different dirrection
from the pupillary reflex
and move in the same
dirrection when the streak
is aligned with the principal
meridian.
Straddling:
Finding axis can be confirmed by this technique.
Performed with the estimated correcting cylinder in place.
Streak is turned 45⁰ off-axis in both dirrections.
If the axis is :Correct – widths should be equal in
both position.Incorrect – widths will be unequal.
Cont….
Finding the cylinder power
With 2 sphere : After the 2 principal meridians are
identified, spherical techniques are applied to each
axis.
With a sphere and a cylinder :
1st neutralize one axis by a spherical lens
↓
Over the lens,neutralize the other axis 90⁰
away by a cyliderical lens
Scissors reflex
When 2 band reflexes appear which move
towards & away from each other like the
blades of scissors….
Most of the time occurs in only one meridian
Seen in Keratoconus & irregular astigmatism
pt’s
.
◦ Neutralization~ ?
Neutralization point
Point at which the peephole becomes
conjugate with the patient’s retina.
Point at which the reversal of the
reflex is observed.
Neutralization . . .
With motion – Plus lenses are
added until neutrality occur.
Against motion – Minus lenses
are added…
The width of reflex widens progressively as
the neutralization is approached & at the
end point ~streak disappears~pupil completely
illuminated
End point of neutrality
1.Over correction of ±0.25D
2.On altering the WD.
3.Changing the mirror.
Clinical use…
Objective determination of refractive error
Starting point of subjective refraction
To find out regular & irregular astigmatism
Helpful for non-communicative or non-verbal pt’s
Screening for ocular disorders [keratoconus,
media opacities]
Some special assessments can be determined [Accommodation stability,Accommodative lag]
Errors of retinoscopy
1. Incorrect WD.
2. Failure of the patient to fixate the
distant target.
3. Scoping of the patient’s visual axis.
4. Failure to obtain a reversal.
5. Failure to locate the principal
meridians.
6. Failure to recognize scissors motion.
References…
Primary Care Optometry~ TheodoreGrosvenor
Clinical Procedures in Optometry~
Theory & Practice of Optics & Refraction~A.K.Khurana
Internet
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