REFRACTION: OBJECTIVE RETINOSCOPY AND SUBJECTIVE ACCEPTANCE

REFRACTION:
OBJECTIVE
RETINOSCOPY AND
SUBJECTIVE ACCEPTANCE
-ANAND PUROHIT

OBJECTIVE
REFRACTION
• The examiner determines the type
and degree of refractive error without
active participation of the patients.
• Very essential as well as useful for
determining the type and degree of
refractive error maily in young
patients and patients with poor
communication.

METHODS
The objective
refraction methods
include:
Retinoscopy
Conventional
refractometry
Autorefractometry

 The determination of the refractive state of the eye by
means of a retinoscope.
 It is invented by Ophthalmologist Dr. jack Copeland
 Its also known as “sciascopy” or “shadow test”
 Retinoscopy is an objective method of finding out the
refractive error by utilizing the technique of
neutralization.

PRINCIPLE OF RETINOSCOPY
 RETINOSCOPY IS BASED ON THE FOCAULTS’
PRINCIPLE
 IT SAYS THAT, WHEN 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 STATE OF THE
EYE

PURPOSE
■ Objective method of
measuring the optical
power of the eye
■ Retinoscope: to
illuminate retina
■ Reflected rays from
retina- passing through
optical components
■ Examining how the
emerging rays change

WHEN USEFUL?
1. Start point for subjective refraction
2. Communication difficult – objective
3. Children
4. Developmentally disabled persons
5. Deaf / Senile patients
6. Aberration of cornea/lens
7. Opacities of ocular media

PRE- REQUISITE
□ Streak Retinoscope
□ Lens Rack / Loose trial lenses
□ Trial Frame
□ Fixation Target : 20/400 or 20/200 E

CONTINUE….
• IF CYCLOPLEGIC IS NOT EMPLOYED:
LONG DARKENED ROOM
SLIGHTLY ECCENTRIC POSITION OF OPTOMETRIST
PATIENT ASKED TO LOOK PAST EXAMINER’S HEAD
 EXAMINER RIGHT EYE FOR PATIENTS RIGHT
• WHEN CYCLOPLEGIC IS USED,
THE PATIENT CAN DIRECTLY LOOK INTO THE
RETINOSCOPE

 ACCOMODATION IS PARALYSED, PUPIL DILATED AND MACULAR REFRACTION IS
ESTIMATED.
BUT
 DILATATION OF THE PUPIL ALTERS OPTICAL PROPERTIES OF THE EYE
 INTENSIFIES ABERRATIONS
 SMALLEST ERROR (ASTIGMATIC) THAT WE COME ACROSS AFTER CYCLOPLEGIA IS
FORCED UPON THE PATIENT WITH NO VISION IMPROVEMENT.
CYCLOPLEGIA:
WHEN TO USE CYCLOPLEGICS?
 CHILDREN UNDER 7 YEARS OF AGE WITH STRONG ACCOMMODATION
 CASES OF DISPUTABLE REFRACTION WITH SEVERAL CORRECTIONS

Streak Retinoscope
TRIAL FRAME
TRIAL SET
AUTO REFRACTOMETER

1
• Illumination stage :-
• Illumination of pt.’s retina
2
• Reflex stage :-
• Reflex imagery of illuminated area formed by pt.’s
dioptric apparatus situated @pt.’s far point
3
• Projection stage :-
• Projection of the image by the oberver

RetinoscopyTechniques
Static Retinoscopy includes…
Spot retinoscope(fig a): - Light source is spot of light
- Plane mirror effect
Streak Retinoscope(fig b):
 The bulb provides a beam in the form of a streak rather than a spot
 Plane mirror effect
 Concave mirror effect
(fig a)
(fig b)

CONTINUE….
 When using a “parallel” or “divergent” beam,
 “Against” movement – Myopic
- Neutralizes with minus lenses
 “With” movement – Hyperopic
- Neutralizes with plus lenses
When using a “convergent” beam = opposite

Streak retinoscope
o It incorporates both plane and concave mirror
o The orientation of the streak across the pt’s face is always
at right angles to the meridian of the eye being scoped
 When scoping the vertical meridian the examiner moves the instrument
vertically with streak oriented horizontally.
 In scoping the horizontal meridian the instrument is moved horizontally while
the streak is oriented vertically.

CLINICAL SET UP
◇ initial adjustments: height, trial frame PD.
◇ Examiner: working distance, keeps OU open, Right on right
◇ Room illumination: dim
◇ instructions to the patient

CLINICAL PROCEDURE –
》 Patient asked to look at the fixation target
》 Start with OD: Streak vertically Oriented –sweep horizontally
》 Reflex in the same direction: with movement-plus Lens
》 Opposite: against movement-minus lens

DEDUCTIONS…
FOR CALCULATION IN WET RETINOSCOPY:
 ATROPINE: 1 DS
 CYCLOPENTOLATE: 0.75 DS
 HOMATROPINE: 0.50 DS
 DRY/ TROPICAMIDE: NO DEDUCTION
 DISTANCE DEDUCTION:
 1METRE: 1 DS
 2/3RD METRE: 1.5 DS
 ½ METRE: 2 DS
( DIOPTRES = 1/ FOCAL LENGTH IN METRES)

POWER OF NEUTRALISING LENS
 WHAT IS NEUTRALISATION?
1. PUPIL FILLED WITH LIGHT
2. INCREASE IN SPEED OF MOVEMENT
3. INCREASE IN INTENSITY OF LIGHT

SPHERE TO SPHERE RETINOSCOPY
 A START IS MADE WITH HORIZONTAL AND VERTICAL
MOVEMENTS AND LENSES ARE PUT TO DETERMINE
NEUTRALIZATION POINT WITH OPTOMETRIST AT
ARMS LENGTH AWAY (2/3 METRE)

STEP-1
 IF ‘WITH THE MOVEMENT’ IS OBTAINED USING A
CONVERGENT BEAM
 CONVEX LENSES OF INCREASING STRENGTH ARE USED
UNTIL NEUTRALIZATION
 SIMILARLY IF AGAINST IS OBTAINED, CONCAVE LENSES
SHOULD BE USED

 INTERPRETATION…
 WITH THE MOVEMENT: HYPERMETROPIC
EMMETROPIC
MYOPIA<-1.5 D
 AGAINST THE MOVEMENT: MYOPIC >-1.5D
 NO MOVEMENT: MYOPIC= -1.5 D

 IF SAME LENSES NEUTRALIZE BOTH HORIZONTAL AND
VERTICAL MERIDIANS THEN ASTIGMATISM IS NOT PRESENT.
EG 1: +3.00
+3.00
STEP-2

EXAMPLE 1
 POWER CALCULATION FOR EG 1:
+3.00 DS – (+1.50D) FOR 2/3 METRE DISTANCE
RE: +1.50 DS/0.00DC/0

 IF 2 PRINCIPAL MERIDIANS ARE NEUTRALISED BY DIFFERENT POWERS
REGULAR ASTIGMATISM IS PRESENT
(what are types of astigmatism? Regular/ irregular and WTR/ATR)
SPH: HYPEROPIC POWER/ ANY MERIDIAN POWER WITH DEDUCTIONS
CYL: DIFFERENCE OF 2 MERIDIAN POWERS
AXIS: SPHERE
STEP-3

+1.00
-2.00
SPH: +1- (+1.50) = -0.50 DS
CYL: -3.00 DC ( POSITIVE TO NEGATIVE ON NUMBER LINE)
AXIS: 90 DEGREES
RE: -0.50 DS/ -3.00 DC/ 90
COMPOUND MYOPIC ASTIGMATISM ( ATR)
EXAMPLE 2

-2.00
-1.00
66CM W.D
SPH: -1.00 –(+1.50) = -2.50 DS
CYL: -1.00 DC
AXIS: 180
RE: -2.50 DS/ -1.00 DC @ 180
TYPE: COMPOUND MYOPIC ASTIGM ( WTR)
EXAMPLE 3

 IF, CLOSE TO THE NEUTRALIZATION POINT THE REFLEX ALTERS ITS
PLANE OF MOVEMENT INDICATING THAT ASTIGMATISM PRESENT IS NOT
WITH PRINCIPAL HORIZONTAL AND VERTICAL AXIS.
 NOW, THE EXAMINER MUST EXPLORE DIFFERENT PLANES OF EXTERNAL
MOVEMENT OF LIGHT UNTIL THEY CORRESPOND TO RETINOSCOPY
REFLEXES
OBLIQUE ASTIGMATISM

-2.00 45
+3.00
SPH: +3.00 –(+1.50) = +1.50 DS
CYL: -5.00 DC
AXIS: 45
RE: +1.50 DS/ - 5.00 DC/ 45
MIXED OBLIQUE ASTIGMATISM
CALCULATION OF OBLIQUE ASTIGMATISM
EXAMPLE 4

 IT IS MORE ACCURATE
 THE FIRST MERIDIAN IS CORRECTED WITH SPHERE AND 2ND WITH
CYLINDER
 CAN VERIFY THE POSITION OF THE AXIS
SPHERE TO CYLINDER RETINOSCOPY

 NEUTRALISING SPHEROCYLINDER ARE PLACED IN THE TRIAL FRAME BUT
THE CYLINDRICAL VALUE IS UNDERCORRECTED BY 0.5 D
 THIS MAKES IT UNDERCORRECTED HYPERMETROPE AND THE MIRROR
GIVES A SHADOW MOVING EXACTLY AT 90 DEGREES TO AXIS OF
CYLINDER
 BUT IF CYLINDER IS NOT IN PROPER AXIS, THE SHADOW WILL MOVE
OBLIQUELY.
 THE ANGLE THAT THE SHADOW MAKES WITH THE AXIS OF CYLINDER
CAN BE ASSESSED ROUGHLY AND THE CYLINDER MUST BE ROTATED AT
1/6TH ANGLE OF THIS.
STEP-1

 CORRECT: +3 DS, +4 DC @ 85
 SO, IF WE PUT +3 DS, +3.5 DC BUT WRONGLY AT 90
 SHADOW MOVES OBLIQUELY AT 150 ROUGHLY THAT IS 30 DEGREES
DIVERTED FROM 180
 AXIS MUST BE ROTATED 1/6TH OF THIS DIVERSION, THAT IS 5 DEGREES
 THEREFORE MOVED FROM 90 TO 85 DEGREES.
EXAMPLE

 REFLEX NOT VISIBLE
MEDIA HAZE
HIGH AMMETROPIA: START WITH +7D, +15D
SMALL PUPIL
 SPHERICAL ABERRATIONS: POSITIVE/ NEGATIVE
SPECIAL RETINOSCOPIES

 SCISSOR SHADOWS:
 2 BAND REFLEXES THAT MOVE TOWARDS AND AWAY IN
OPPOSITE DIRECTION
 CORNEAL SCARRING, CONING OF CORNEA, PTERYGIUM
 FIND A LENS THAT BRINGS THE 2 BLADES TO COME IN THE
CENTRE

SIMULATION OF RETINOSCOPY
WITH SCHEMATIC
Emmetrope
Hypermetrope
Low myope
Moderate - high myope

SUBJECTIVE REFRACTION:
 It is used to find out the most suitable lenses for the patient
with the active participation of the patient
 Should be done preferably after objective refraction
 Subjective refraction is not possible in - Very young children
- Non-comprehensive patients
 Post cycloplegic subjective refraction should be done after
 3-4 days ( Homatropine/ Cyclopentolate)
 14 days (Atropine)

 PREREQUISITES FOR SUBJECTIVE REFRACTION:
1. Darkroom- 6m or that can be converted into 6m with the help of a plane mirror
2. Trial set: 64 pairs of Spherical lenses (plus and minus)
20 pairs of Cylindrical lenses
10 prisms
Accessories – Pin hole Maddox rod
Plano lenses Occluder
Stenopic slit Red and green filters
3. JCC
4. Trial Frame
5. Vision charts- Distance: Snellens, Projector chart
 - Near : Jaegers chart

Steps of subjective refraction

MONOCULAR SUBJECTIVE REFRACTION
Aim
•To find out the best vision sphere and
•Cylindrical lens with exact power and
axis
Procedure
•Selection of baseline starting point
lenses
•Refinement of Sphere
•Refinement of cylinder axis
•Refinement of cylinder power
•Final refinement of Sphere

SELECTION OF BASELINE STARTING POINT LENSES
Retinoscopy
Autorefractometer
Old glasses
Level of visual acuity
Binary comparison for
sphere and cylinder
SNELLENS
V/A
REFRACTIVE ERROR
Spherical Cylindrical
6/6 0.12DS -0.25DS 0.25DC
6/9 0.50DS 0.50DC- 1.00DC
6/12 0.75DS 1.00DC-1.50DC
6/18 1.00DS 2.00DC
6/24 1.50DS 3.00DC
6/36 2.00DS 4.00DC
6/60 2.00DS –
3.00DS
>4.00DC

BINARY COMPARISON for sphere
ADD -0.25 DS and +0.25 DS alternatively
Ask the patient which one is better
Advance the sphere towards the preferred choice
Eg: If the patient prefers -0.25DS then the next preference should be between 0.00
and 0.50DS
Repeat until the two choices are same (Try to move from more plus to less
plus or less minus to more minus- this stimulates accommodation
minimally)

For cylinder
Dial in -0.50 cylinder
Reduce sphere power by -0.25DS
Rotate and ask if the patient perceives clear or is it the same
Clear at a particular axis No significant difference
Leave at the preferred orientation No significant astigmatism

Refining sphere
Maximum
(+)
(strongest
convex)
Minimum
(-)
(weakest
concave)

Fogging
Eye is made myopic by adding plus lens usually 1.5D
This is done to relax accommodation
Done monocularly
Retinoscopic value + (+1.5D) – V/A should decrease by atleast 2 lines
Reduced in steps of +0.25 D
Patient is asked to see 6/60 line
Keep defogging till maximum plus/ minimum minus

Duochrome test
 This is based on the principle of chromatic aberration
 Shorter wavelengths are focused in front of the retina and
longer wavelengths are focused behind the retina
 When the image is clearly focused in white light, the eye is
0.25D myopic- green light
0.25D hyperopic for red light
 This produces a chromatic interval of approximately 0.50 D
between red and green wavelengths

Continue…
 Can distinguish only small difference in sphere
power (<0.50D)
 Cannot be used in vision less than 6/12
 Should be performed both monocularly and
binocularly
 Can be used in colour-blind patients also

Pinhole testing
An improvement in visual acuity while looking
through a pinhole indicates that optical
correction in a trial frame is incorrect

REFINEMENTOF CYLINDER
In the presence of astigmatic error, it is
mandatory to refine and finalize the
cylindrical component before the spherical
component
TECHNIQUES
EMPLOYED:
ASTIGMATIC CLOCK
DIAL AND FOGGING
TECHNIQUE
JCC
ASTIGMATIC FAN
AND BLOCK
TECHNIQUE

STEPS USED IN ASTIGMATIC CLOCK DIAL
TECHNIQUE
1. Obtain the best V/A using spheres only
2. Fog the eye to approximately 20/50 by adding plus sphere
3. Ask the patient to identify the darkest and sharpest line of
astigmatic dial
4. Add minus cylinder with the axis perpendicular to the darkest and
sharpest line until all lines appear equal {rule of 30’s- eg blackest
line 3-9o’clock, 3*30= 90, therefore minus at 90. if the axis of the
dark line falls between hours on the clock i.e. between 1 and 2
o’clock multiply by (lowest no.+0.5)i.e. 1.5 X 30= 45}
5. Defogging-Reduce plus sphere (or add minus) until the best V/A is
obtained with the visual acuity chart

JCC
(JACKSON CROSS CYLINDER)
Cross cylinder is a
type of toric lens
used during
refraction
Also known as ‘flip
cylinder’.
Its use was
popularized by
Edward Jackson and
it is often referred to
as Jackson’s cross
cylinder.

• The cross-cylinder is a Combination of two cylinders of equal
strength but with an opposite sign placed with their axis at
the right angle to each other and mounted in a handle.
• The cross-cylinder is a sphero cylindrical lens in which the
power of the cylinder is twice the power of the sphere and
of the opposite sign
• The lens is mounted on a handle which is placed at 45 to the
axes of the cylinders.
Continue…

• The commonly used cross cylinders are of +/- 0.25D and
+/-0.50D.
Continue…
Colour code
plus axis–
green line
minus axis
red line

JCC TEST:
• Gives BVA done by fogging.
• The goal if astigmatism is present, is to place
the circle of least confusion of the sturms
conoid on the retina thus creating mixed
astigmatism.
Continue…

• If no cylinder correction is present initially, the cross-cylinder is placed
arbitrarily at 90 and180 degrees to check for astigmatism.
• If a preferred flip position is found, a cylinder is added with an axis
parallel to the respective plus or minus axis of the cross-cylinder until
the two flip choices are equal.
• If no preference is found with cross cylinder axes at 90 and 180, the 45
and 135 should always be checked before assuming that no astigmatism
is present.
1. Discovering the astigmatism

• Always done first.
• Because the correct axis can be found in the presence of an incorrect
power but the full cylinder power will not be found in the presence of an
incorrect axis.
• To check the axis, the cross-cylinder is held before the eye with its
handle parallel with the axis of the trial cylinder
• Pt is asked to tell about any change in the VA, pt notices no difference
b/w the two position- axis of the correcting cylinder in the trial frame is
correct.
• If VA is improved, cylinder correction is present
2. Refinement of the axis

The cross-cylinder is held in the preferred position and
the axis of the trial cylinder rotated slightly towards
the axis of the same sign on the crossed cylinder
The process is repeated until the trial cylinder is in the
correct axis for the eye.
Continue…

3. Refinement of cylinder power
• Cross cylinder is placed with its axis parallel to the axis of the cylinder
in the trial frame. First with the same sign and then the opposite sign.
• VA is not changing in either of the position the power of the cylinder in
the trial frame is correct.
• If VA is improved in any position corresponding correction should be
made and reverified till final correction is attained.

 Radially arranged lines are used to determine the axis of
astigmatism
 ASTIGMATIC FAN AND BLOCK TECHNIQUE

Astigmatic fan…
 On looking through an astigmatic fan if the vertical lines are more clear,
the diffusion ellipses on the retina must be vertical that is horizontal
meridian is more nearly emmetropic than vertical.
 a cylinder placed in front of the eye with its axis horizontal will therefore
correct the vertical meridian and when the correct glass is found all lines will
appear equally distinct.
 The cylinder which thus renders the outline of the whole fan equally clear is a
measure of the amount of astigmatism & Axis of the cylinder at right angles to
The line which was initially more clearly defined.

BINOCULAR BALANCING
 This allows both eyes to have retinal images simultaneously in focus, an
imbalanced correction can lead to asthenopia
 1.FOGGING WITH ALTERNATE OCCLUSION METHOD
 Both eyes are fogged with around 1D SPHERE then a rapid alternative
cover test is done, to tell which eye has a better clear image. If balanced
equals blur, if not add +0.25D SPHERE to better see eye until the balance
is achieved, now slowly defog till both eyes read 6/6
 2.DUOCHROME TEST WITH FOGGING

 3. PRISM DISSOCIATION METHOD
 Fog both eyes with 1 D sphere and then a vertical prism of 3 or 4 prism dioptre
is placed with base down 1 eye base up other, single line 6/12 is projected
 If the patient reports diff in clarity between upper and lower lines then a
+0.25 sphere is placed before the eye with better vision. this is done till two
eyes are equally distinct the prism is removed and defogged
 4. TURVILLE INFINITY BALANCE TECHNIQUE
 A set of letters is seen with a septum in the middle which masks some letters
from each eye. If all the letters can be seen clearly and equally this implies
binocular balance.
 5. POLAROID FILTERS
Continue…

NEAR VISIONCORRECTION
– USUALLY AFTER AGE 40
– NEAR VISION TESTING WITH JAEGERS CHART.
– In case near vision is defective further testing is as follows
1. Determine near the point of accommodation and amplitude
of accommodation
2. Determine the near point of convergence
3. Dynamic retinoscopy
4. Determination of near ADD

CORNEAL REFLECTION TEST
COVER TEST
ALTERNATE COVER TEST
OCULAR MOVEMENTS IN ALL POSITION OF GAZE and asked for any
diplopia
TEST FOR CONVERGENCE
DETERMINATION OF MUSCLE
BALANCE

 MODIFICATIONS IN THE PRESCRIPTION
• In children having refractive error
with associated manifest deviation
FULL CYCLOPLEGIC
CORRECTION
• To reduce the degree of
consecutive exotropia
AN UNDER CORRECTION
OF HPERMETROPIA
• Helps in controlling the
intermittent exotropia
SLIGHT OVER
CORRECTION OF MYOPIA
• In amblyopic eyes as penalization
treatment
OVERCORRECTION BY +1
TO +3D

• Useful in controlling deviation of patient having non-
refractive accommodative esotropia
BIFOCAL
GLASSESS
• Both eyes may be under corrected by by equal amount
of spherical power. This forces the patient to
accommodate constantly inducing convergence
IN EXOPHORIA
• Maximal spherical plus correction can be given
• Bifocals- in patients having esophoria of convergence
excess type
IN ESOPHORIA
• Lenses of optical correction can be decentred to
achieve prismatic effect, this relieving the stress on
patients vertical vergence control
IN
HYPERPHORIA
Continue…

• Best possible efforts should
be made to discover and
correct the associated
astigmatic refractive error
IN
CYCLOPHOPRIA
• Horizontal phorias
• Base in – Exophoria
• Base out - Esophoria
PRISM
Continue…

" Retinoscopy is an art which requires much pains taking
practice and can not be learned in a day ; and it is only after the
optometrist has done many Retinoscopies that he can justifiably relay
on his finding with any degree of safety "
THANK YOU FOR YOUR ATTENTION

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