To know all subjective refraction technique

1. Subjective Refraction
Md.Azizul Islam
Junior Optometrist(Oculoplasty)
Ispahani Islamia Eye Institute & Hospital
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e-mail: ajijulislam513@yah00.com
twiter: @ajijulislam513 , Cell:01724-310486

2. Aims of Today,s Class…
To know……
Basic idea about refraction.
 Able to done subjective refraction
confidently.
To know Subjective refraction techniques.
The sequence of the subjective refraction.
Binocular Refraction:-
1.Binocular balancing
2.Binocular best Vision sphere
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3. What is Refraction?
Determination of the refractive
status(prescription) of the eye.
OBJECTIVE
Retinoscopy
SUBJECTIVE
Subjective Refraction
Subjective Refraction
To determine by subjective means the
combination of spherical and cylindrical
lenses necessary to to provide best visual
acuity. (with accommodation relaxed)
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4.  Subjective determination of the
combination of sphere and cylindrical
lenses that artificially places the far
point of Each Eye of patient at infinity.
 Maximum PLUS, minimum minus.
 Take into account vertex distance
 Especially for high prescription
 This is the combination of lenses that
provides best VA with accommodation
relaxed
Principle of subjective refraction
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5.  Jackson Cross Cylinder
Fogging Method
Duochrome Test
WFDT(Worth Four Dot Test)
Stenopic Slit
Ast:fun
Sun brust Dial/clock dial
Red Green filter
Maddox Rod
Binocular Balancing
Binocular Best Vision Sphere
Subjective refraction techniques.
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6. Jackson Cross Cylinder
JCC used to find used to determine the
cylindrical axis and the cylindrical power for
the patient.
In a cross-cylinder the axes are 45 and 135
deggre.
 Patient directed to observe a round target.
Patient asked: “Is view one rounder,
sharper, clearer or view two?”
We turn the axis 5 degrees towards it and
the opposite if the patient wears a negative
one instead.
We repeat the process until the patient
doesn’t refer any difference in his vision.
This is the correct axis.
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7. Fogging Method
Used only when VA is EQUAL in both eyes
1. Fog both eyes with + 0.75DS
2. Direct patient to view 3 lines above best VA
3. Alternately occlude each eye for ~0.5 secs each
while
asking patient: “ Which eye sees clearer/sharper?”
4. Add +0.25DS to the better eye
5. Repeat step 3 and 4 until both eye’s vision is
equalised
6. Slowly reduce fog until best VA is reached
7.A plus (a mild plus) is used to relax eye focusing
muscle completely in distant viewing. The eye is
no longer accommodated with such a lens for
distant vision. Tightened focusing muscle must
be completely relaxed in order to see clearly.
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8. Example:
Suppose you are performing
retinoscopy on a +3.00 D
hyperopic OU for the first
time, and he does not have an
old Rx that would give you a
clue. Using even +1.50 or the
"R" lens would not get you
close to fogging the fellow eye.
Conversely, if the eyes where -
3.00 D OU, the "R" lens over
the fellow eye would be
serious overkill.
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9. Duochrome Test
Ask the patient: "Are the
rings/letters/dots clearer and backer on
the red or on the green, or are they the
same?”
 If the rings on the green are
clearer, add plus power needed to
obtain balance.
 If the rings on the red look
clearer, add minus power obtain
balance.
 If more than +/- 0.50 DS is required to
balance, this usually indicated the
duochrome test is not reliable for this
patient and should be ignored.
N.B:A Duochrome test is a test commonly used to refine the final
sphere in refraction, which makes use of the chromatic aberration
of the eye.
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10. WFDT(Worth Four Dot Test)
THE PATIENT SEES ALL FOUR DOTS :
-Normal binocular response with no
manifest deviation.
THE PATIENT SEES FIVE DOTS:
- uncrossed diplopia with esotropia, red
dots appear to the right.
- crossed diplopia with exotropia, red
dots appear to the left of the green dots.
IF THE PATIENTS SEES THREE GREEN
DOTS, SUPPRESSION OF THE RIGHT
EYE
IF THE PATIENT SEES TWO RED DOTS,
SUPPRESION OF THE LEFT EYE
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11. Stenopic Slit
The stenopic slit found in all
the trial sets is 1-2 mm by 15-35
mm in size. It splits an opaque
disc into two halves. It is
useful in finding out the axis
of the cylinder . Black opaque
disc with vertical / horizontal
straight slit at centre To
differentiate causes of haloes
Fincham’s test
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12. Astigmatism fan
The Fan and Block test is
used to determine the
axis and magnitude of
astigmatism. The fan is
used to determine the
presence of any
astigmatism and its
principal axes.
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13. Sun Brust Dial/Clock dial
Clock dial
Sun Brust Dial
The sun brust dial
and clock dial
test is also used to
determine the
axis and
magnitude of
astigmatism.
Those are used to
determine the
presence of any
astigmatism and
its principal axes.
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14. Red-Green filters
Red placed in front of
right eye
Green glass in front of
left eye
Used for diplopia
charting
To test binocular vision
in Worth’s four dot test
For malingering test.
Red-Green filters also
used to cheek colour
sense of the retina
before cat Sx. IIEI&H

15. Maddox Rod
4-5 cylinders of red glass
prisms.
Fused side by side in a
round disc frame.
May give the effect given
by….
Deeply grooved red
glasses(mad groove).
To detect heterophoria.
As it dissociates two
retinal images.
As macular function test.
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16.  The Amsler Grid looks like graph
paper, with dark lines forming a
square grid.
 Some versions have white lines on
a dark background.
 One of the first signs of macular
degeneration can be wavy, broken or
distorted lines OR a blurred or
missing area of vision.
 The Amsler Grid can help you spot
these early. Early detection of wet
AMD is critical because laser
treatment, when indicated, is most
successful when performed before
damage occurs. Since dry AMD can
lead to development of wet AMD.
Amsler Grid
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17. Binocular Balancing
The binocular balance test occurs after a monocular
subjective refraction to ensure that accomodation is
balanced in the two eyes. There is no need to perform this
test if the patient is monocular, or if they have no
accomodation (i.e. patients over the age of 60 or
pseudophakic). There are several techniques that have
been described previous. which effectively uses the
plus/minus technique of best vision sphere
determination under binocular conditions after first
fogging rather than occluding the non-tested eye.
Methods for binocular balancing
Prism Dissociated Blur Balance
Alternate Occlusion
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18. Under binocular conditions, the
amblyopic eyes accept more of the
indicated correction and obtains better
acuity
 VA in RE 6/6 VA in LE 5/60
On retinoscopy: RE +1.00 DS LE +4.00
DS
VA in LE with +4.00 DS = 6/60
on monocular subjective refraction
LE: 6/24 with +2.50 DS
on binocular condition
LE: 6/18 with +3.50 DS
Example:
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19. Prism dissociated blur balance
 RE – 3 ∆ Base Down
 LE – 3 ∆ Base UpTwo
charts will be seen
separated vertically
If vision in both eyes to 6/12, on to sphero/cylinder lenses
found monocularly;
- assuming eyes capable of 6/6 acuity
If one eye has reduced VA;
-A row of letters at least two rows larger than that of the
power eye of best acuity
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20. Alternate occlusion technique
Target: Smallest acuity letters patient can read
through the spherocylindrical correction
Alternately occlude the patient’s eye with cover
paddle .
If the images equally clear- balance is correct.
If not, two options:-
1.add plus sphere in +0.25 DS steps before the eye
with better image till both the images are equally
blurred
2.add minus sphere in 0.25 DS steps before the eye
with poorer image till both images are equally clear
Finally to confirm, add +0.25 DS before each eye. If
the balance is correct BE will be equally blurred
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21. Binocular Best Sphere
The eyes are simultaneously fogged and then
unfogged until maximum binocular acuity is
attained
The spherical endpoints are the maximum plus
or minimum minus power providing maximum
binocular visual acuity
These endpoints are usually about +0.50 DS more
plus or less minus than those found monocularly
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22. Subjective refraction at near
 Near refraction refers to the measurement of the refractive state
when the patient is fixating at near point.
 Useful in conditions that significantly alter the refFinding the
Near Addition.Age (in Years) Estimated Add (in D) refractive error
when patient fixates at near..
 Age add
 38 -40 + 0.75 to + 1.00DSP
 40 -43 + 1.00 to + 1.25 DSP
 43 -45 + 1.25 to + 1.50 DSP
 45 - 47 + 1.50 to + 1.75 DSP
 47 – 50 + 1.75 to + 2.00 DSP
 50 – 52 +2.00 to + 2.25 DSP
 52-55 +2.25 to +2.50 DSP
 55-Above +2.50 to +3.00DSP
N.B: Needs +3.00 DSP Near Add
for Aphakia patient.
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23. History
Working distance
Fixation target
Patient instructions
Record Visual acuity (VA)
distance Unaided, Added, Pinhole
test.
Starting point
Locating principal meridian
Procedure for astigmatism
Record Near vision + Near
correction
Messurement IPD
Prescription and Advice
PROCEDURE of SUBJECTIVE
REFRACTION
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24. References
 Examination Protocol(Ophthalmology)
 Clinical Procedures in Optometry
 A Hand Book of Basic Optometry & Refraction
 Essentials of Ophthalmology , Basak 5th Edition.
 Internet (Google)
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25. IIEI&H
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26. Question
Please……
.
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