The document outlines the process of subjective refraction to determine refractive errors, emphasizing the importance of various testing factors and techniques used to assess vision clarity, including the use of fogging and cycloplegic refraction. It provides detailed methods for establishing best vision spheres, assessing astigmatism, and balancing binocular vision, as well as the application of tools such as jcc and duo-chrome charts. Various methods for determining near additions based on accommodation and age are also discussed, along with techniques for achieving visual acuity maximization in both distance and near vision settings.

2. • THE PURPOSE OF SUBJECTIVE REFRACTION IS
TO DETERMINE THE REFRACTIVE ERROR BY
SUBJECTIVE MEANS.
• THE COMBINATION OF SPHERICAL AND
CYLINDERICAL LENS NECESSARY TO
ARTIFICIALLY PLACE THE FAR POINT OF EACH
EYE AT INFINITY.
• THE DIOPTRIC COMBINATION OF CORRECTIVE
LENS RESULTING IN MAXIMUM V/A, WHICH
ULTIMATELY PLACES THE FINEST CIRCLE OF
LEAST CONFUSION AT THE OUTER LIMITING

3. TESTING FACTOR’S SUCH AS:-
• TARGET
• ROOM ILLUMINATION
• PUPIL SIZE
• RETINAL ADAPTATION
• TARGET DISTANCE AND COMPOSITION AND TIME ALLOWED FOR
DISCRIMINATION BETWEEN LENS CHOICE
• AND ESSENTIALS ELEMENTS OF THE SUBJECTIVE REFRACTION THAT
INFLUENCE THE PATIENTS SUBJECTIVE PERFORMANCE.

5. ENTERING VISION.
DECIDING THE STARTING POINT.
ESTIMATING REFRACTIVE STATE FROM VISION AT THE
STARTING POINT.
FINDING THE BEST VISION SPHERE.
ASTIGMATIC ANALYSIS.
MONOCULAR ENDPOINT.
BINOCULAR BALANCE.
BINOCULAR ENDPOINT.
DETERMINING THE NEAR ADDITION.
WRITING THE FINAL PRESCRIPTION.

6. • ONE SHOULD KNOW BEFORE STARTING
SUBJECTIVE REFRACTION THE UN-AIDED V/A
FOR BOTH DISTANCE AND NEAR SHOULD BE
DONE.
• AIDED V/A OF CURRENT SPECTACLE OR
CONTACT LENS CAN BE KNOWN AS ENTERING
VISION.
• IF THE BEST V/A IS LESS THEN 6/6,PIN -HOLE
ACUITY SHOULD BE TESTED.

7. • THE REFRACTIVE ERRORS DETERMINED BY OBJECTIVE
TECHNIQUES (RETINOSCOPY OR AUTOREFRACTION) ARE
ENTERED.
(OR)
• CURRENT SPECTACLES.
• PREVIOUS EXAMINATION RESULTS (P.G.P).

8. SnellenV/A Uncorrected SphereError Uncorrected Cylinderical Error
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 More than4.00DC
Ref:- Borish Clinical Refraction pg.no -
637

9. • BVS IS THE MAXIMUM PLUS OR MINIMUM MINUS
ONE REQUIRES TO VIEW CLEARLY THOUGHT
SPHERICAL LENS.

10. Step
s
Lens Result Comments
1 0.00D 6/24 Error > +/-
1.50DS
2 Compare +1.50DS & -
1.50DS
-1.50D
Better
Myopic or
pseudo myope
3 -1.50DS 6/9 Within 0.25DS
4 Compare -1.25DS & -
1.75DS
-1.75D
better
BVS…?
5 -1.75DS 6/6 BVS…?
6 Compare -1.75DS & -
2.00DS
-2.00D
Better
V/A better than
before
7 -2.00DS 6/5 -2.00 Indicated
8 Compare -2.00DS & - Equal Patient is ???
9 0.25D on top of -2.00DS&-
2.25D
6/6 -2.00DS is B.V.S

11. FINDING OF B.V.S IN
HYPERMETROPIA AND PRESBYOPIA …?

12. The Best sphere places the cirlce of least confusion on
the retina.
Examiner must differentiate between Clearer and More
legible.
View of sharp focused is known as Clearer
If the circle of least confusion is on the retina then the
letters will appear More legiable.

13. • WHAT IS ACCOMMODATION BASICALLY ?
• DOES THE ACCOMMODATION SHOULD BE
ACTIVE OR RELAXED WHILE DOING
SUBJECTIVE REFRACTION ?
• WHAT HAPPENS IF WE DO NOT RELAX THE
ACCOMMODATION ?

14. • PART OF THE EMPHASIS ON CONTROL OF
ACCOMMODATIVE ACTIVITY MAY HAVE
RESULTED FROM THE TRADITIONAL CONCEPT
THAT OPHTHALMIC ASTHENOPIA WAS CAUSED BY
OVERACTIVE CILIARY MUSCLE CONTRACTION.
• REFRACTIVE STATUS IS REPRESENTED BY THE
FOCAL POSITION OF THE EYE RELATIVE TO THE
OUTER LIMITING MEMBRANE OF THE RETINA,
WITH ACCOMMODATION AT REST IN A NORMAL
TONIC STATE.

15. HOW TO KEEP ACCOMMODATION
RELAXED ?
• TWO CLASSIC MEANS OF DOING SO COMMONLY:-
 CYCLOPLEGIC REFRACTION.
 FOGGING (NON-CYCLOPLEGIC REFRACTION)

16. CYCLOPLEGIC REFRACTION ?

17. • IN NON-CYCLOPLEGIC TESTING,
ACCOMMODATIVE ACTIVITY IS BEST
CONTROLLED BY PLACING THE FOCUS OF A
DISTANT FIXATION TARGET IN FRONT OF THE
RETINA, A TECHNIQUE KNOWN AS THE
FOGGING TECHNIQUE.

18. • THE ACCOMMODATIVE SYSTEM CANNOT
SIGNIFICANTLY IMPROVE VISION OF THE TARGET.
IN FACT, ACTIVATION OF ACCOMMODATION CAN
ONLY SUCCEED IN MOVING THE FOCUS FORWARD
AND FARTHER FROM THE RETINA.
• FOR THE HYPEROPIC EYE OR THE EYE HAVING
COMPOUND HYPEROPIC ASTIGMATISM, THE
FOGGED STATUS IS ATTAINED BY PLACING
SUFFICIENT PLUS REFRACTIVE POWER BEFORE
THE EYE TO ENSURE THAT BOTH PRIMARY
MERIDIANS ARE FOCUSED IN FRONT OF THE
RETINA

19. PROCEDURE
• IN MODERN PRACTICE, THE EXAMINER BEGINS
WITH THE OBJECTIVE REFRACTIVE FINDINGS AND
ADDS SPHERICAL PLUS POWER IN FRONT OF THE
EYES, SEPARATELY TO EACH, UNTIL THE PATIENT
REPORTS THAT DISTANCE VISION WITH EACH EYE
BECOMES PROGRESSIVELY WORSE.
• WHEN OPTIMAL FOGGING IS ACHIEVED, DISTANCE
VISUALACUITIES IN EACH EYE SHOULD BE IN THE
RANGE OF 20/100 (6/30) AND 20/120 (6/36)

20. • THEN THE PLUS POWER IS REDUCED BEFORE
THE EYE, OR MINUS POWER IS ADDED, IN STEPS
OF 0.25DS UNTIL THE VISUAL ACUITY IS
IMPROVED TO THE POINT THAT THE PATIENT CAN
DISTINGUISH A CHART PRESENTED AT DISTANCE
FOR ASTIGMATIC DISCRIMINATION. THIS
PROCESS IS CALLED UNFOGGING.

22. • CLOCK DIAL CHARTS ARE IN 30° STEPS AND ARE
MARKED AS THE HOUR MARKING OF AN CLOCK.
• IF THE CLEAREST LINES ARE SPECIFIED AS AN HOUR
BETWEEN 1 & 6 THEN MULTIPLY THE HOUR BY 30°{EX:-
4×30°= 120°} WHICH GIVES THE NEGATIVE CORRECTING
CYLINDER.
• THE DISADVANTAGE IS THAT THE CLEAREST MERIDIAN
CAN BE ESTIMATED ONLY TO WITHIN 15°

24. • IF THE PATIENT IS CORRECTLY FOGGED THE AXIS OF
CORRECTING NEGATIVE CYL IS AT RIGHT ANGLES TO THE
LINES WHICH APPEARS CLEAREST.
• THE RADIAL LINES MAY BE SPACED AS 10°,15°.30°
INTERVALS.
• THE 10° SPACING GIVES BETTER ACCURACY BUT MAY BE
CONFUSION.
• WHEN CHART IS VIEWED DIRECTLY THE NUMBERS ON
THIS CHART CORRESPOND TO STD AXIS NOTATION ON
THE PATIENTS EYE.

26. • SOME CHARTS HAVE PARTS WHICH CAN BE ROTATED SUCH AS
ARROW-HEAD {V SHAPED}.
• IF THE ARROWHED IS NOT POINTED ALONG ONE OF THE
PRINCIPLE MERIDIAN THEN ONE OF ARMS WILL APPEAR
CLEARER THAN THE OTHER ARM.
• THE CLEARER ARM IS SIMPLY THE ARM WHOSE ORIENTATION
IS MORE SIMILAR TO THE CLEAREST FAN LINE.
• ROTATE THE ARROWHEAD IN THE DIRECTION AWAY FROM THE
CLEARER ARM UNTIL BOTH ARMS APPEAR EQUALLY CLEAR.
• EX:- CLEAREST LINE IS 130°MERIDIAN,SO THE CORRECTING
CYL AXIS IS 40° MERIDIAN.

27. • THE ROTATING CHART HAS TWO ARROWHEAD.
• THE ONE WITH THE LESS ACUTE ANGLE WOULD
BE USED FOR FINDING THE AXIS IN LOW
DEGRESS ASTIGMATISM.
• THIS CHARTS HAVE BLOCKS.
• IF THE BLOCKS ARE ALLIGNED SO THEY ARE
PARALLEL TO PRINCIPAL MERIDIANS OF THE
FOGGED EYE,THEN ONE SET OF LINES WILL
APPEAR CLEARER.
• CYLINDERICAL POWER IS ADDED UNTIL BOTH

30. • JCC USED TO FIND USED TO DETERMINE THE CYLINDRICAL
AXIS AND THE CYLINDRICAL POWER FOR THE PATIENT.
• SPHERICAL EQUIVALENT IS ZERO

31. • PATIENT DIRECTED TO OBSERVE A ROUND TARGET
ALIGN HANDLE WITH TRIAL LENS AXIS IE: 180

32. DETERMINING CYLINDER AXIS
• JCC IS FLIPPED SUCH THAT TWO VIEWS ARE SHOWN.
• PATIENT ASKED TO :“IS VIEW ONE IS
ROUNDER,SHARPER,CLEARER OR VIEW TWO?

33. REFINING THE AXIS
•IF VIEW ONE IS CLEARER ,TURN TRIAL LENS’ AXIS TOWARDS RED
LINES (~5-10 DEGREES).
Turn 10
Degree’s

34. Power of Correcting Cyl Estimated lnitial Rotation
Required
0.25DC 30°
0.50DC 15°
0.75DC 10°
1.00DC - 1.75DC 5°
2.00DC - 2.75DC 3°
3.00DC - 4.75DC 2°
Above 5.00DC 1°

35. • JCC IS FLIPPED AGAIN SUCH THAT TWO VIEWS ARE SHOWN.
• PATIENT ASKED: “IS VIEW ONE ROUNDER, SHARPER, CLEARER
OR VIEW TWO?”
• ALIGN DOTS WITH TRIAL LENS AXIS IE: 170

36. •IF VIEW TWO IS CLEARER TURN TRIAL LENS’ AXIS TOWARDS
RED LINES (~5 DEGREES).

37. DETERMINING CYLINDER POWER
• PATIENT DIRECTED TO OBSERVE A ROUND TARGET.
• ALIGN RED LINES OR WHITE LINES ALLIGNED TO TRIAL LENS
AXIS .

38. • JCC IS FLIPPED SUCH THAT TWO VIEWS ARE
SHOWN.
• PATIENT ASKED: “IS VIEW ONE ROUNDER,
SHARPER, CLEARER OR VIEW TWO?”

39. • IF VIEW ONE IS CLEARER, ADD -0.25
DC

40. • IF VIEW ONE IS CLEARER, ADD +0.25
DC

42. CHROMATIC ABERRATIONS
• THE DUO-CHROME CHART WAS A DISTANCE VISUAL-ACUITY
CHART WITH BLACK LETTERS, AND THE CHART WAS SPLIT
EQUALLY INTO TWO IDENTICAL HALVES.
• LETTERS ON THE RIGHT HALF OF THE CHART HAD A GREEN
BACKGROUND AND THE IDENTICAL LEFT HALF OF THE CHART
HAD A RED BACKGROUND.
• GREEN LIGHT OF 535 NM TENDS TO FOCUS 0.20D IN FRONT OF
THE RETINA.
ON WHAT PRINCIPLE THE DUOCHROME TEST IS
BASED ?

43. • AN EYE THAT IS RESIDUALLY MYOPIC BY A SMALL DEGREE OF
SPHERE POWER SEES THE LETTERS HAVING A RED
BACKGROUND TO BE CLEARER AND DARKER, WITH MORE
DEFINED BORDERS.
• LETTERS ON THE GREEN BACKGROUND APPEAR SLIGHTLY
FUZZY AND LESS DARK, WITH LESS DEFINED BORDERS.
• AN EYE THAT IS RESIDUALLY HYPEROPIC BY A SMALL DEGREE
OF SPHERE POWER SEES THE LETTERS ON THE GREEN
BACKGROUND TO BE CLEARER, DARKER, AND MORE DEFINED.
• THE RESIDUALLY EMMETROPIC EYE SEES THE LETTERS ON
BOTH SIDES OF THE DUO-CHROME CHART TO BE OF EQUAL
CLARITY, DARKNESS, AND DEFINITION.

45. PROCEDURE
• THE ROOM ILLUMINATION SHOULD BE DARKER BECAUSE DARKER
THE ROOM ILLUMINATION,PUPIL GETS DILATED AND THERE WILL BE
SLIGHLTY INCREASE IN CHROMATIC ABERRATION OF EYE.
• THE CONTRALATERAL EYE IS OCCLUDED, AND THE SUBJECT IS
REQUESTED TO NOTE WHETHER THE LETTERS ARE EQUALLY
VISIBLE OR PROMINENT ON BOTH BACKGROUNDS OR MORE VISIBLE
OR PROMINENT AGAINST ONE OF THE BACKGROUNDS.
• VISION IS SLIGHTLY FOGGED BY ADDING PLUS SPHERE
MONOCULARLY IN +0.25 OS STEPS UNTIL THE LETTERS ON THE RED
BACKGROUND APPEAR TO STAND OUT BETTER.
• THE PLUS POWERED SPHERE BEFORE THE EYE IS THEN REDUCED
UNTIL LETTERS ON THE TWO CHARTS APPEAR EQUALLY DISTINCT, AS
IN RESIDUAL EMMETROPIA OR UNTIL THE NEXT REDUCTION OF ONLY
-0.25 DS MAKES LETTERS ON THE GREEN BACKGROUND APPEAR
MORE DISTINCT, AS IN A SLIGHT RESIDUAL HYPEROPIA

46. PROCEDURE
• IN SIMPLE :-
RED CLEARER – REDUCE PLUS OR {INCREASE
MINUS} R.A.M
GREEN CLEARER– GIVE PLUS OR {DECREASE
MINUS} G.A.P

49. • THE TRADITIONAL FORM OF SPHERICAL EQUALIZATION
ORIGINATED EARLY IN THE LAST CENTURY. IT CONSISTS, FIRST,
OF FOGGING THE VISION IN BOTH EYES TO THE 6/12 ACUITY LINE
BY ADDITION OF PLUS POWER OVER THE SPHERO-CYLINDRICAL
CORRECTIONS DETERMINED MONOCULARLY.
• THIS ASSUMES THAT THE EYES ARE BOTH CAPABLE OF 6/6 OR
BETTER VISION.
• IF ONE EYE HAS REDUCED ACUITY COMPARED WITH THE OTHER
EYE, A ROW OF LETTERS AT LEAST TWO ROWS LARGER THAN
THAT OF THE POWER EYE'S BEST ACUITY SHOULD BE USED.

50. • THE EYES ARE BOTH OCCLUDED, AND THE CHOSEN ACUITY LINE
(OR) CHART IS THEN DISSOCIATED BY EQUAL AMOUNTS OF VERTICAL
PRISM: USUALLY 3 OR 4 P.D.B.U IS PLACED BEFORE ONE EYE AND 3
OR 4 P.D.B.D IS PLACED BEFORE THE OTHER EYE.
• UPON REMOVAL OF THE OCCLUSION, THE BINOCULAR PATIENT
SHOULD BE ABLE TO RECOGNIZE TWO IDENTICAL TARGETS, AS IN
DIPLOPIA, WITH EACH EYE OBSERVING ITS RESPECTIVE IDENTICAL
ACUITY LINE OR CHART

51. • IF THE PATIENT CANNOT PERCEIVE TWO TARGETS SIMULTANEOUSLY,
THE CLINICIAN SHOULD ALTERNATELY COVER THE TWO EYES WHILE
DIRECTING THE PATIENT TO REGARD THE TARGET ALLOWED FOR
THE UNCOVERED EYE.
• THIS ENSURES THAT EACH EYE SEES ITS RESPECTIVE TARGET,
MONOCULARLY, AND ENABLES THE PATIENT TO REALIZE THE
LOCATIONS OF THE TWO TARGETS SUPPOSED TO HAVE BEEN
OBSERVED BI-OCULARLY.
• UPON REMOVAL OF THE OCCLUSION, AGAIN, THE PATIENT SHOULD
BE ABLE TO VISUALIZE BOTH TARGETS AT THE SAME TIME.

52. • IF THE PATIENT IS YET UNABLE TO PERCEIVE DIPLOPIA, THE VISION
OF ONE EYE MAY BE SUPPRESSED.
• IN THE ABSENCE OF SUFFICIENT BINOCULARITY, A DISSOCIATED
METHOD OF EQUALIZATION MUST BE ABANDONED, AND THE FINAL
SUBJECTIVE DISTANCE REFRACTION IS ACHIEVED AT THE
MONOCULAR SPHERICAL ENDPOINTS.

53. GOODWIN DISSOCIATED
BALANCE
• THUS, GOODWIN PERFORMED THE DISSOCIATED BALANCE AT THE
POINT OF MAXIMUM ACUITY.
• BRIEFLY, THE TARGET IS DISSOCIATED WITH EQUAL VERTICAL PRISM
BEFORE EACH EYE, AND THE EYES ARE EACH SLIGHTLY FOGGED
AND UNFOGGED IN INCREMENTS OF -0.25 DS.
• UNFOGGING IS DISCONTINUED WHEN THE DISTANCE VISION IN EACH
EYE DOES NOT IMPROVE BY ADDITION OF THE LAST -0.25 DS. THE
EXAMINER THEN PLACES THE SPHERICAL POWERS BEFORE THE
EYES THAT ARE THE MOST PLUS/LEAST MINUS POWERS THAT
ACHIEVED THE MAXIMUM ACUITY.

54. • IF VISUAL ACUITY IS EQUAL BETWEEN THE TWO EYES, THE
ACCOMMODATIVE BALANCE HAS BEEN ACHIEVED.
• AROUND THE ENDPOINT, AN INCREMENT OF +0.25 DS IS ADDED
TO EACH EYE, ONE EYE AT A TIME, AND THE PATIENT IS ASKED
TO COMPARE THE SLIGHT BLUR BETWEEN THE TWO TARGETS
PERCEIVED. WITH THE ADDITIONAL +0.25 DS BEFORE EITHER
EYE, THE AFFECTED EYE SHOULD BE SLIGHTLY BLURRED
WHEN COMPARED WITH THE EYE WITHOUT THE +0.25 DS.
• SHOULD THE PATIENT INITIALLY REPORT THAT THE ACUITY OF
ONE EYE IS BETTER, +0.25 DS IS ADDED BEFORE THE EYE
WITH THE CLEARER VISION.
• IF THIS DOES NOT EQUALIZE THE VISION, -0.25 DS IS ADDED
BEFORE THE EYE WITH THE REDUCED VISION.
• YET ANOTHER +0.25 DS IS ADDED BEFORE THE CLEARER EYE

55. TROUBLE SHOOTING
• IF THESE ALTERATIONS DO NOT PRODUCE
EQUALITY OF VISION, EQUALIZATION IS
DISCONTINUED AND THE MONOCULAR
SUBJECTIVE FINDINGS ARE RECHECKED.

57. DISSOCIATED DUOCHROME
(BICHROME) BALANCE
{BIN OC U LAR EN D POIN T}
• THE PATIENT VIEWS A CHART WITH LETTERS AS SMALL AS (6/6).
• THE CHART IS SPLIT INTO HALF GREEN AND HALF RED
BACKGROUNDS, AND IS VIEWED BY THE PATIENT IN A DARK
EXAMINATION ROOM THROUGH THE SPH-CYL CORRECTION AS
DETERMINED MONOCULARLY.
• BOTH EYES ARE OCCLUDED AND THE CHART IS DISSOCIATED
BY VERTICAL PRISM, 3-4 P.D. IN FRONT OF EACH EYE,
ENSURING EQUAL PRISMATIC DISTORTION OF THE IMAGES
PRESENTED TO THE TWO EYES.
• THE PATIENT MUST BE CAPABLE OF PERCEIVING DIPLOPIA.

58. • SUFFICIENT PLUS POWER OF IDENTICAL AMOUNTS, USUALLY IN
+0.25 DS STEPS, IS PLACED BEFORE BOTH EYES UNTIL THE
BLACK OPTOTYPES OF BOTH CHARTS RESOLVED BY THE
PATIENT ARE MORE PROMINENT (CLEARER, DARKER) WITH THE
RED BACKGROUND. THUS, BOTH EYES ARE SLIGHTLY FOGGED
INTO THE PLUS.
• ONE EYE IS UNFOGGED IN INCREMENTS OF-0.25 DS, WHILE THE
PATIENT IS INSTRUCTED TO OBSERVE THE CORRESPONDING
TARGET AND TO REPORT WHEN
THE LAST POWER INCREMENT HAS BEEN REACHED AT WHICH
LETTERS ON THE RED BACKGROUND REMAIN MORE PROMINENT.
THE FIRST POINT IS ATTAINED AT WHICH LETTERS ON THE RED
AND GREEN BACKGROUNDS APPEAR EQUAL IN PROMINENCE
("EQUALITY")
 THE FIRST POINT IS ATTAINED AT WHICH LETTERS ON THE

59. • THE OTHER EYE IS THEN SIMILARLY UNFOGGED
AS THE PATIENT REGARDS THE
CORRESPONDING TARGET
• WHEN THE BALANCE ENDPOINTS FOR BOTH
EYES HAVE BEEN REACHED,THE RED/GREEN
BALANCE HAS BEEN COMPLETED.
• THE DISSOCIATION IS REMOVED, AND THE
EXAMINER PROCEEDS TO THE DETERMINATION
OF THE BINOCULAR SPHERICAL ENDPOINTS.

60. METHODS OF DETERMINING NEAR
ADD
• ADDITION BASED ON AMPLITUDE OF ACCOMMODATION
• TENTATIVE ADDITION BASED ON AGE
• PLUS BUILD-UP METHOD
• CROSS-CYLINDER METHOD
• RELATIVE ACCOMMODATION METHOD
• NEAR BICHROME METHOD.
• DYNAMIC RETINOSCOPY

61. ADDITION BASED ON AMPLITUDE
OF ACCOMMODATION
ROYAL AIR FORCE RULER:-
•TO DETERMINE NPA WITH RAF RULER A SLIDING
TARGET WITH 6/9 LETTERS OR NUMBERS OR A
FINE LINE IS MOVED FROM OR TOWARDS THE
EYE UNTIL THE CLEAREST POINT IS FOUND AT
WHICH PATIENT CAN SEE CLEARLY.
•DURING THIS TEST THE PATIENT HAS TO WEAR
HIS FULL OPTICAL CORRECTION.

62. EXAMPLE
CUSTOMARY WORKING DISTANCE OF PATIENT(WD)=
40CM
RAF (AOA) = 2.00D
WHAT SHOULD BE THE NEAR ADDITION?
ACCOMMODATION REQUIRED FOR WD = 2.50 D
ACCOMMODATION IN RESERVE = 1.00D
AMOUNT OF ACCOMMODATION LEFT = 1.00D
AMOUNT OF NEAR ADDITION = (2.50 –1.00)
= +1.50D

63. TENTATIVE ADDITION BASED ON
AGE
• AMPLITUDE OF ACCOMMODATION TO AGE
(HOFSTETTER)
• MAXIMUM = 25.0 — 0.40 (AGE)
• AVERAGE = 18.50 — 0.30 (AGE)
• MINIMUM = 15.0 — 0.25 (AGE)

65. PLUS BUILD-UP METHOD
• WORKS BEST WHEN V/A AT DISTANCE IS CORRECTED
ACCURATELY.
• CAN BE DONE BINOCULARLY OR MONOCULARLY
• PLUS LENSES ARE INCREASED IN STEPS OF 0.25DSPH TO
THE AMOUNT NECESSARY TO FIRST READ THE DESIRED
LETTERS(USUALLY N6) AT A CUSTOMARY WORKING
DISTANCE.
• THE POWER OF ADD IS THEN INCREASED IN 0.25DSPH
STEPS TO THE AMOUNT PREFERRED BY THE PATIENT.

66. CROSS-CYLINDER METHOD
• USED TO ESTABLISH THE POINT OF ACCOMMODATION FOR A
CUSTOMARY NEAR WORKING DISTANCE (SAY 40 CM)
• ADDING PLUS LENSES UNTIL THE HORIZONTAL AND VERTICAL
LINES ON THE CROSS CYLINDER GRID GET EQUALLY DARKER
SUBJECTIVELY (BY THE PATIENT)
• THE TARGET CONSISTS OF 3 TO 4 VERTICAL AND HORIZONTAL
LINES PRESENTED TO PATIENT AT 40 CM
• ILLUMINATION IS DIFFUSE, SUFFICIENT TO ALLOW PATIENT TO
SEE TARGET SATISFACTORILY.

67. • THIS IS PERFORMED AT 40 CM WITH ± 0.50 D CROSS-CYLINDERS
(MINUS AXIS VERTICAL) PLACED IN FRONT OF EACH EYE.
(THIS LENS IS EQUIVALENT TO +0.50X180/-0.50X090.)
• THE PATENT IS LOOKING THROUGH THEIR DISTANCE SUBJECTIVE
PRESCRIPTION.
• IF THE ADD IS EXPECTED TO BE APPROXIMATELY +2.00 D OR
GREATER DUE TO THE PATIENT'S AGE OR HISTORY, THEN A +1.00
D LENS IS USED AT THE START TO ALLOW SOME VISION AT NEAR.
• A ± 0.50 D CROSS CYLINDER LENS IS PLACED IN FRONT OF THE
EYES.
• THE EXAMINER IS SEATED IN FRONT AND TO THE SIDE OF THE
PATIENT WITH EASY ACCESS TO TRIAL FRAME.
• THE ROOM LIGHTING IS ON FULL AND AN ADJUSTABLE LAMP IS
DIRECTED SUCH THAT THE NEAR TARGET IS ILLUMINATED

68. • THE PATIENT VIEWS A CROSSED GRID PATTERN WITH BOTH EYES
WHICH IS A BLACK GRID ON A WHITE BACKGROUND.
• THE TARGET IS HELD BY THE PATIENT PLACED AT 40 CM.
• ASK THE PATIENT WHICH IS CLEARER AND DARKER, THE
HORIZONTAL OR VERTICAL LINES?
• NORMALLY THE PATIENT SEES THE HORIZONTAL LINES AS BEING
DARKER THAN THE VERTICAL LINES.
• PLUS LENSES ARE ADDED IN 0.25D STEPS UNTIL THE PATIENT
REPORTS THAT THE VERTICAL AND HORIZONTAL SETS OF LINES
ARE EQUALLY DARK.

69. RELATIVE ACCOMMODATION
METHOD
 NEGATIVE RELATIVE ACCOMMODATION –
• MEASURE OF MAXIMUM ABILITY TO RELAX
ACCOMMODATION WHILE MAINTAINING CLEAR, SINGLE
BINOCULAR VISION OF A TEST OBJECT AT A SPECIFIED
DISTANCE
POSITIVE RELATIVE ACCOMMODATION –
• MEASURE OF THE MAXIMUM ABILITY TO ACCOMMODATE
WHILE MAINTAINING CLEAR, SINGLE BINOCULAR VISION
OF A TARGET AT A SPECIFIED DISTANCE
• THE DIFFERENCE BETWEEN THE NRA AND THE PRA IS
CALLED THE RELATIVE ACCOMMODATIVE AMPLITUDE.

70. • BASED ON THE CONCEPT OF PLACING THE ACCOMMODATIVE
DEMAND IN THE MIDDLE OF THE RANGE OF RELATIVE
ACCOMMODATION
• TO MEASURE NRA AND PRA
• PATIENT'S DISTANCE REFRACTION AND A TENTATIVE ADD IS
PLACED IN THE TRIAL FRAME.
• THE NEAR POINT TEST CARD (N6 TARGET) IS PLACED AT THE
READING DISTANCE (USUALLY 40 CM).

71. PROCEDURE
• THE PROCEDURE IS CONVENIENTLY PERFORMED WITH THE PATIENT
WEARING TRIAL FRAME
• WITH THE OVERHEAD LIGHTS ON, A READING LAMP BEHIND THE
PATIENT'S SHOULDER ILLUMINATES A READING CARD WITHOUT
SHADOWS.
• THE PATIENT IS DIRECTED TOWARDS FINE DETAIL (SAY N6 @ 40CM)
• PLUS LENSES ARE ADDED UNTIL THE PATENT REPORTS BLUR, THEN
MINUS LENSES ARE ADDED UNTIL BLUR IS REPORTED.
• IF LETTERS DO NOT REMAIN BLURRED BUT BECOME CLEAR AFTER THE
INITIAL BLUR, THE ENDPOINT HAS NOT BEEN REACHED AND FURTHER
PLUS (OR MINUS) POWER MUST BE ADDED.
• THE PRA IS THE HIGHEST MINUS LENS POWER ADDED BEFORE THE
PATIENT REPORTS BLURRING OF THE TARGET LETTERS, AND SIMILARLY
THE NRA IS THE HIGHEST POSITIVE LENS POWER ADDED.
• THE NEAR ADD IS TAKEN AS THE DIOPTRIC MID-POINT OF THE PRA AND
NRA.

72. NEAR BICHROME METHOD
• BASED ON NATURAL CHROMATIC ABERRATION OF EYE
• WIDELY USED FOR DETERMINING SPHERICAL
COMPONENT OF DISTANT CORRECTION
• WHEN AN AMETROPIC EYE IS OUT OF FOCUS FOR
DISTANCE,
- RED TARGET IS CLEARER IN MYOPIA
- GREEN TARGET IN HYPEROPIA
• THE SAME PRINCIPLES APPLY AT NEAR DISTANCE

73. • FOR PRESBYOPIC PATIENT RED & GREEN ARE FOCUSED BEHIND THE
RETINA WITH RED FARTHER AWAY
• FOR UNCORRECTED OR UNDERCORRECTED PRESBYOPIC PATIENT
- LETTERS ON GREEN BACKGROUND CLEARER
• AN OVERCORRECTION FOR A NEAR TARGET
- THE LETTERS ON RED BACKGROUND CLEARER
• PATIENT’S DISTANCE CORRECTION IS PLACED ON A TRIAL FRAME
• BI-CHROME TARGET IS PLACED AT HABITUAL NEAR DISTANCE (SAY
40CM)
• TELL THE PATIENT TO LOOK AT LETTERS ON BOTH GREEN AND RED
BACKGROUND CAREFULLY
• ASK THE PATIENT WHICH SIDE HAS THE SHARPER AND CLEARER
LETTERS
- GREEN CLEAR : ADD PLUS
- RED CLEAR : REMOVE PLUS

74. DYNAMIC RETINOSCOPY
• DYNAMIC RETINOSCOPY IS THE METHOD OF OBJECTIVELY
DETERMINING THE PATIENTS REFRACTIVE ERROR AT NEAR
POINT.IN ORDER TO DETERMINE HOW MUCH PLUS OR LESS MINUS
LENS POWER IS REQUIRED AS COMPARE TO STATIC RETINOSCOPY.
• IN DYNAMIC RETINOSCOPY THE EXPECTATION IS THAT
ADDITIONAL PLUS POWER AS COMPARE TO SUBJECTIVE
REFRACTION AT DISTANCE WILL BE REQUIRED. THIS ADDITIONAL
PLUS POWER IS A MEASUREMENT OF LAG OF ACCOMMODATION.
SOME COMMONLY USED METHODS ARE:-
 NOTT DYNAMIC RETINOSCOPY
 MONOCULAR ESTIMATION METHOD

75. NOTT DYNAMIC RETINOSCOPY
• THE PATIENT SHOULD WEAR THEIR OPTIMAL DISTANCE
REFRACTIVE CORRECTION IN THE TRIAL FRAME, THE
PHOROPTER SHOULD NOT BE USED FOR THIS TEST
BECAUSE OF THE RISK OF INDUCING PROXIMAL
ACCOMMODATION.
• PLACE A NEAR-POINT CHART OR BLOCK OF SIMILAR (6/6 TO
6/9) SMALL LETTERS ON THE NEAR-POINT ROD AT THE
READING DISTANCE, USUALLY 40 CM.
• A NEAR-POINT CARD WITH A HOLE IN THE MIDDLE CAN BE
USED.

76. • DIRECT THE PATIENT TO BEGIN READING THE LETTERS. PLACE
THE RETINOSCOPE JUST TO THE SIDE OF THE LETTERS, AND
ADJUST IT TO PROJECT A VERTICAL STREAK.
• NOTE THE DIRECTION OF THE REFLEX IN ONE EYE, AND MOVE
THE RETINOSCOPE EITHER TOWARD OR AWAY FROM THE
PATIENT (IF OBSERVING "WITH" MOTION, MOVE AWAY; IF
OBSERVING "AGAINST" MOTION, MOVE TOWARD) UNTIL
NEUTRALITY IS FOUND.
• NOTE THE POSITION OF THE RETINOSCOPE ON THE NEAR-POINT
ROD.
• THE DIOPTRIC DIFFERENCE BETWEEN THE POSITION OF THE
TARGET AND THE POSITION OF THE RETINOSCOPE WHEN
NEUTRALITY IS FOUND IS THE LAG OF ACCOMMODATION FOR
THAT EYE.
• IF THE NEUTRALITY POINT IS ON THE SIDE OF THE TARGET AWAY

77. MONOCULAR ESTIMATION
METHOD
THE MONOCULAR ESTIMATION METHOD (MEM) OF
PERFORMING DYNAMIC RETINOSCOPY IS AN
OBJECTIVE METHOD OF MEASURING
ACCOMMODATIVE LAG AND CHECKING FOR
ACCOMMODATIVE OR REFRACTIVE IMBALANCE AT
NEAR.
• USE MODERATE ROOM ILLUMINATION, AND DIRECT
MODERATE ILLUMINATION FROM THE OVERHEAD
LAMP ONTO THE NEAR-POINT PLANE.
• THE PATIENT'S DISTANCE SPECTACLE REFRACTION
SHOULD BE PLACE IN A TRIAL FRAME.

78. • SET THE RETINOSCOPIC MIRROR AT PLANO, AND OBSERVE THE
DIRECTION OF THE REFLEX IN ONE EYE.
• IF YOU DO NOT OBSERVE NEUTRALITY, QUICKLY INSERT AN
APPROPRIATE SPHERICAL LENS (USUALLY FROM A TRIAL LENS SET) IN
FRONT OF THAT EYE, AND TRY TO OBTAIN NEUTRALITY.
• "WITH“ MOTION, WHICH INDICATES A POSITIVE ACCOMMODATIVE LAG,
REQUIRES THAT A PLUS SPHERICAL LENS BE PLACED BEFORE THE EYE.
• "AGAINST" MOTION, WHICH INDICATES A NEGATIVE ACCOMMODATIVE
LAG, REQUIRES THAT A MINUS SPHERICAL LENS BE PLACED BEFORE
THE EYE.
• REPEAT THE PROCEDURE WITH STRONGER LENS POWERS UNTIL YOU
OBSERVE NEUTRALITY, BRACKETING IF NECESSARY. DO NOT HOLD THE
RETINOSCOPE LIGHT OR THE LENS IN FRONT OF THE PATIENT FOR
MORE THAN 2 SECONDS; THE LESS TIME, THE BETTER.
• YOU WANT THE PATIENT TO MAINTAIN BINOCULARITY, AND YOU DO NOT
WANT THE ACCOMMODATIVE SYSTEM TO RESPOND TO THE CHANGE IN

79. DATE
AG
E

80. BORISH’S CLINICAL REFRACTION –IRVIN
M.BORISH
CLINICAL VISUAL OPTICS –RONALD B RABBETTS