History taking , Visual acuity , refraction , visual field , contrast sensitivity of low vision patient

1. Examination of Low Vision
Patient : Visual Acuity
Refraction & Visual Field
Moderator Presenters
Dr. Sanjeev Bhattarai Aayush Chandan
Kamal Luitel

2. Low Vision
WHO Definition
• Defined as the impairment of visual functioning
even after treatment and /or standard refractive
correction and has a visual acuity of less than 6/18
( 20/60) to light perception or a visual field of less
than 10 deg from the point of fixation , but who
uses or is potentially able to use vision for the
planning and /or execution of a task

3. Visual acuity
• Visual acuity is the assessment of the finest spatial
detail that the visual system can resolve
• measures minimum angular size of detail that can
be just resolved

4. Objectives of VA in Low Vision
Evaluation
• Provides the examiner with baseline
information from which the course of
pathology may be monitored
• Essential for calculating a patient’s
magnification
• Provides the patient with an appreciation for
residual vision
• Documents a level of VA that may establish
eligibility for services , benefits and even driving
privileges

5. Visual Acuity Charts

6. contd
• Multitude of VA charts are available to the low
vision practioner
• VA may actually vary from chart to chart
• Number of optotypes presented per line of acuity
• Spacing between optotypes & between rows of
optotypes
• Configuration of optotypes
• Contrast of charts
It is therefore important to use the same chart for
each visit to monitor visual acuity status .

7. Distance VA charts
1. Projector Charts
• Snellen’s Chart
2. Printed Visual acuity Charts
• Feinbloom distance test chart
• Ferris-Bailey ETDRS chart
• Chronister pocket acuity chart
• Keeler A series charts
• Sloan distance acuity charts
• Bailey–Lovie charts
• Waterloo charts
• Symbol charts

8. Snellen’s projector Chart
• Most commonly used chart in assessement
of distance visual acuity
• Not recommended for low vision patients
• Luminance level of the chart is generally fixed
and not easily varied during examination
• Large gradation of acuity
• Poor contrast levels
• Unequal spacing between the letters and lines
• No geometric progression of letter size
• Unequal number of letters in each line
• Difficult to measure acuity at various distance

9. Feinbloom distance test chart
• Consists of numeric optotypes
• Calibrated for 20ft but may be
used at any distance
• As the size of optotypes decreases
, more numbers are added to each
row
• Because of the reduced number of
optotypes , numerals are easier to
guess than letters

10. Ferris-Bailey ETDRS chart
• Consistent number of letters i.e 5 in each row
• Separation between optotypes and between rows of
optotypes are proportional to the size of the optotype
• Results in smaller spacing in the higher visual acuity
levels , giving the chart its characteristics triangular
configuration
• Geometric (logMAR) progression of size difference
between lines
• Optotypes on each line are 0.1 log unit or 25% larger
than the preceding line

12. • Logarithmic progression and proportional spacing
of optotypes allows for consistent and accurate
evaluation of visual acuity levels
• May be used at any distance , but testing distance
are typically 4m or 2m
• Available in Landolt C configuration , LEA symbol
test system , HOTV chart for pediatric low vision
patient

13. Chronister pocket Acuity Chart
• Uniquely designed for use with patients during “out
of office” examinations in hospitals and nursing
homes , and during home visits and screening
• Calibrated for 20ft but may be used at any distance
• Also contains a near acuity test in log-MAR format
• Can be recorded in reduced snellen at 40cm or in
the meter system

15. Keeler A series charts
• Designed by Charles Keeler
• based on a logarithmic (constant ratio) scaling
system
• 20 different series of letters, ranging from A1 (6/6
[LogMAR 0.0 ] equivalent) to A20 (1/60 [LogMAR
1.9] equivalent)
• Each line differed from its nearest neighbour, in
size, by a factor of ×1.25
• Near equivalents, also calibrated in A series format

16. Sloan distance acuity charts
• American equivalent to the Keeler chart
• Uses the ‘M’ or metric series notation
• Never achieved worldwide usage
• Best known for its use in the assessment of near
acuity
• System is linear so that 3M letters are exactly three
times larger than the 1M letters

18. Bailey-Lovie Charts
• Based on logarithmic basis
• Same no. of letters in each row
• Separation between optotypes and between rows
of optotypes are proportional to the size of the
optotype
• Equal legibility for optotypes at each level
• Clinical scoring is reliable as each letter is given a
score

20. How Are Bailey-Lovie Charts and
ETDRS different?
• Bailey-Lovie charts incorporate the European
design of LogMAR, where letter sizes are
rectangular instead of square
• For example, a 20/20 ETDRS letter is square, 5
minutes of arc by 5 minutes of arc. For the Bailey-
Lovie Chart Design, a 20/20 letter is rectangle, 4
minutes of arc by 5 minutes of arc

21. Waterloo charts
• Canadian charts
• Similar in design and concept to the Bailey–Lovie
charts
• letters are oriented such that letters of equal size
are placed in columns rather than rows.
• An additional feature of the Waterloo chart is the
inclusion of interactive surround bars, which ensure
that letters at the start and finish of each line are as
difficult tread as those within the lines.

22. Symbol charts
• Have been developed for paediatric use but
equally useful when assessing the visual status of
those with learning disability

23. Prospective evaluation of visual acuity assessment : A
comparison of snellen versus ETDRS charts in clinical practice (AN
AOS THESIS)
Peter K Kaiser MD Trans Am Ophthalmol Soc 2009;107:311-324
Purpose:
The purpose of this study was two fold: first, to prospectively compare visual
acuity (VA) scores obtained with Snellen charts versus Early Treatment
Diabetic Retinopathy Study (ETDRS) charts and second, to see if there was a
difference in visual acuity measurements obtained with ETDRS charts starting
at 4 or 2 meters
Methods:
Prospective, consecutive evaluation of patients who underwent best-
corrected visual acuity testing of their right eye performed at a single seating
by the same experienced, certified vision examiner in the same room with
standardized low light conditions using a projected Snellen chart at 20 feet,
and two different back-illuminated ETDRS charts placed 4 and 2 meters from
the patient.

24. Results:
• One hundred sixty-three eyes were included in the study
• The mean Snellen VA was 0.67 logMAR (20/94), ETDRS VA at 4 meters was
0.54 logMAR (~20/69), and ETDRS VA at 2 meters was 0.51 logMAR
(~20/65).
• The mean difference was 6.5 letters better on the ETDRS chart
(P=.000000001).
• As the VA worsened, there was increased variability between the charts
and the mean discrepancy between charts also increased.
• Subgroup analysis revealed the greatest difference between charts was in
the poor vision subgroup (<20/200) with a difference of 0.2 logMAR (10
letters; P=.0000002).
• Patients with exudative age-related macular degeneration (AMD) had the
greatest disparity on vision testing, but patients with dry AMD and
diabetic retinopathy also exhibited significant differences.

25. Conclusions:
• Visual acuity scores were significantly better on ETDRS charts compared
to Snellen charts.
• The difference was greatest with poor visual acuity (<20/200) and in
patients with exudative AMD. Thus, caution should be exercised when
comparing data using the different charts

26. Distance acuity specifications
Snellen Acuity
• most universally accepted
•
𝑇𝑒𝑠𝑡𝑖𝑛𝑔 𝐷𝑖𝑠𝑡𝑛𝑎𝑐𝑒
𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑎𝑡 𝑤ℎ𝑖𝑐ℎ 𝑠𝑚𝑎𝑙𝑙𝑒𝑠𝑡 𝑙𝑒𝑡𝑡𝑒𝑟 𝑟𝑒𝑎𝑑 𝑠𝑢𝑏𝑡𝑒𝑛𝑑𝑠 5 min 𝑜𝑓 𝑎𝑟𝑐
• Metric units = 6/3 6/6 6/9 6/12 6/60
• English units = 20/10 20/20 20/30 20/40 20/200

27. Decimal Acuity
• Calculated by dividing the numerator of snellen
fraction by its denominator.
• 6/12 = 0.5
• 6/4 = 1.5
• Specification of acuity in this way is, however,
regrettable as results can easily be confused with
LogMAR results, which are unrelated.

28. Percentage Acuity
• Decimal acuity multiplied by 100

29. Minimum Angle of Resolution
(MAR)
• Reciprocal of Snellen fraction
e.g. 6/24 MAR = 4
i.e. a patient is unable to resolve a gap or stroke of
less than 4’ of arc
• LogMAR is simply the logarithim to the base of 10
of the ‘MAR’
• (6/6 = MAR 1 = LogMAR 0).

30. Visual Acuity Rating (VAR)
• VAR = 100 – (50 * logMAR)
• 6/6 → 100
• 6/60 → 50

31. Near Acuity Charts
• Single letter charts
Reduced snellen’s chart
Sloan M series charts
N system chart
Reduced Ferris Bailey
ETDRS chart
• Word and continuous
text charts
Jaeger chart
Lighthouse game card
Lighthouse continuous
Text card
MNREAD card

32. Reduced snellen’s Chart
• designed such that a 20/20 letter subtend a 5’
angle at a given distance (typically 40cm)
• As in standard snellen distance charts , the levels
of acuities are limited

34. Sloan M series charts
• A 1M optotype will subtend 5’ of arc at 1m .
• A 1M letter viewed at 1m may be equated to
snellen acuity in the following manner
• 1.00/1M = 20/20 snellen equivalent
• Because near acuity is frequently measured at
40cm , 1M is equivalent to 20/50 at 40cm
• Testing may occur at any distance
• Recorded as
𝑇𝑒𝑠𝑡𝑖𝑛𝑔 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒(𝑚𝑒𝑡𝑒𝑟𝑠)
𝑀 𝑛𝑜𝑡𝑎𝑡𝑖𝑜𝑛
• E.g 3M at 25cm would be recorded as 0.25/3 M

36. N system chart
• An 8-point optotype (N8) suntends 5 minutes of arc
at 1m viewing distance
• N notation may be converted to M notation by
dividing by 8
• E.g N4 is equivalent of 0.5M print

37. Reduced Ferris Bailey ETDRS chart
• Maintains a constant number of letters in each row
• As in the distance ETDRS chart , there is a
geometric progression of size differences between
lines
• Consistent and accurate evaluation of visual acuity
levels
• May be used at any distance .
• Provides snellen equivalent acuities for 40cm and
20cm

38. Jaeger chart
• Paragraphs are numbered from J1 TO J20 with J1
representing the smallest print size
• The character and form of the type varies from
edition to edition
• Rows of letters were of unequal height and
diameter when compared from edition to edition
• No predictable relationship between the rows of
jaeger letter e.g J4 is not necessarily twice as large
as J2

40. Lighthouse Game Card
• Uses the same geometric progression as the
single letter chart with each three row
progression representing a halving or doubling
of VA levels at any viewing distance
• VA obtained with this chart may be poorer
than that obtained from a single letter ETDRS
chart due to the presence of increased
contour interaction between letters of each
word
• May be used at any distance , but the snellen
equivalent provided are calculated at 40cm

41. Lighthouse Continuous Text Card
• Follows same geometric progression as the
lighthouse Game card
• Recorded VA may be poorer than single-letter VA ,
especially in cases in which central scotomas are
present
• Snellen equivalent noted on the testing card are
calculated for 40cm

43. MN Read Card
• Combines a quick reading performance
assessement with a reading acuity assessement
• Reading passages are printed in decreasing M sizes
in logarithmic progression from 8.0 M to below
0.2M
• Each three-line sentence has an identical no. of
characters ( letters & spaces)
• Enables the examiner to determine optimal print
size for fluent reading tasks

45. Distance Visual Acuity Testing
Procedure
• Acuity should be tested until threshold is reached
• Progression of testing distance for the ETDRS chart is
typically 4m , 2m ,1m . When testing at closer distance
the patient should be corrected for the accommodative
demand induced by the viewing distance
• It is not acceptable to record acuities as finger
counting.It is frequently demoralizing to a patient to be
asked to count fingers as opposed to identify optotypes
on a chart

46. • It is far more effective to bring an appropriate chart
to the equivalent viewing distance and obtain a
standardized and reproducible visual acuity
• The examiner should isolate the optotype to
determine if resolution is enhanced .This may
provide higher level of acuity ,as counter
interaction is eliminated
• Measurement of acuities with pinhole may reveal
the presence of uncorrected refractive errors or
significant media abnormalities

47. • The examiner should record whether a patient
consistently loses his or her place or omits sections
of the chart . Such information is helpful in
establishing strategies for instruction in the use of
optical devices and for overall enhancement of
visual skills

48. Near Visual Acuity Testing
Procedure
• Single letter acuities should be evaluated until
threshold is reached
• Eccentric fixation positions should be explored and
recorded if present
• Isolation of letters and words through the use of a
typoscope
• VA should be recorded with any near magnification
devices that the patient brings to the office

49. Refraction
in
Low Vision

50. What is Refraction in Low Vision
means ?
• Refracting the low vision patient is not simply a
matter of asking the patient to discriminate clarity
between two lenses, but the integration of the
following measurements and information which
direct the examiner towards the refractive error
and finally the lens prescription.
• A careful refraction is the single most important
test in the sequence of the low vision evaluation

51. Refraction In Low vision Patient
Is it necessary?
• They tend to have high prevalence of uncorrected error.
• certain ocular pathologies have characteristic refractive
findings that may be undetected or change more rapidly
compared to healthy eyes. For example , ‘cataract there may
be 10D myopic shift and in diabetic 2D or more myopic shift
• some individuals may overlook their own visual needs,
perhaps accepting their blurred vision as a result of their
ocular pathology or as a natural consequence of aging.(they
think its common)
• many patients referred for this service have come from
settings where refractive care is simply not emphasized, or
is performed by unqualified personnel.

52. • The basic techniques of refraction of low vision persons are not too
different
• Although specialized techniques like bracketing and over- refraction
are commonly used.
• The refraction is performed both objectively and subjectively.
• In both procedures it is important to adjust procedures according to
the eye condition if each individual client.

53. Bracketing
• Types of Subjective refraction
• Mostly used in low vision patient
• In which large and equal steps of dioptric changes
are made above and below the presumed correct
answer and then reducing the size for the dioptric
changes and shifting the center of the range , until
the finest and Just detectable blur is induced by
equal steps above and below the refractive error

54. Just Noticeable difference
• The amount of spherical lens power needed to
elicit an appreciable change in clarity or blur is
called the Just noticeable difference
• The lower the acuity , the larger the JND(means
patient having low VA needs more spherical lens )
• The denominator of the 20 foot Snellen acuity is a
good rule-of-thumb estimator of the JND for a
given eye.
• For example, a 20/150 eye will be sensitive to a
lens change of approximately 1.50 dioptres using
this rule.

55. Significant refractiive findings. In
certain disorders?
• Pseudophakia- (3-4) of ARA due to surgery
• Cataract – up to 10D of myopia shift
• Diabetes – fluctuation mostly myopic shift depends
on blood glucose level
• Degenerative myopia – progressive higher degree
of up to -35D
• PK – higher corneal astigmatism up to 12D seen at
any axis
• Albinism – (3-4) of CA(WRA) and usually
symmetrical in BE

56. Predictable pattern?
• ROP- myopia & Keratoconus
• Coloboma & Microcornea- hyperopia
• Lenticular Subluxation- Aphakia & myopia

57. Basic for Low vision Refraction
• Hand held trial lenses are more comfortable than
phoroptor
• Large jump in lens power for JND ‘
• Vertex distances play the major role
• Use hand held cross- cyl of +/- 1.00D
• Try concave and plano-mirror illumination
• Refraction over spectacles- Haldberg or Janelli clips

58. Should make the following six adjustments
of the trial frame in LV:
1. temple length
2. bridge height
3. pupillary distance
4. pantoscopic tilt
5. horizontal tilt(level)
6. vertex distance

59. Vertex Distance
• Take note of the vertex distance in prescriptions
over +,-10.00D. Small errors in the estimation of
vertex distance create clinically significant
differences in refractive corrections.

60. • Pantoscopic tilt is defined as a lens tilt about the
horizontal axis, with respect to primary gaze of a
subject. In a simple way, it can be explained as “The
rotation of lens bottom towards the cheeks”.
Typically these tilts range from 0-12 degrees, and
tilt up to 3-7 degrees are considered normal.

61. Subjective refraction
• Find the best sphere
• Test for astigmatism
• Retest for the best sphere

62. Find the Best Sphere
• The first step in subjective testing is to find the best
sphere.
• The starting lens in the trial frame(spheres in the
back barrel, cylinders in the front) should be the
retinoscopy finding,
• or if unobtainable, the patient's past spectacle
prescription.
• If this is also unavailable, use your best judgment
based on their eye history and entering acuities.

63. • Direct the patient's attention to a line large enough to
maintain fixation but small enough to detect
differences in blur.
• Present the patient with the JND interval using a plus
and minus lens of equal absolute value and ask to
compare the clarity.
• For example, a 20/200 eye with a JND of 2.00D should
be shown a +1.00 sphere and a -1.00 sphere
sequentially(total lens change = 2.00D).
• If they have a preference for either lens, change the
sphere in the back barrel of the trial frame in the
appropriate direction. A reasonable amount of change
would be the JND.

64. • Example: Patient A
Entering acuity, OD=20/200, OS=NLP
retinoscopy unobtainable
old glasses unavailable
JND= 2.00D
Trial frame has no lenses in it

65. • Find the best sphere:
• 1. Ask the patient to compare +1.00sph. To -
1.00sph. Patient states that +1.00 sph. is clearer.
Place +2.00sph. in the trial frame.
• 2. Again ask the patient to compare +1.00sph. to -
1.00sph, this time through the +2.00 sph. in the
trial frame. If the patient still prefers the plus lens
to the minus, replace the +2.00 in the trial frame
with a +4.00sph.

66. • Again ask the patient to compare +1.00sph. to -1.00sph this
time through +4.00 sph. in the trial frame. If they now
prefer the -1.00 to the +1.00, this is called a reversal and you
now know the "best sphere" is more than +2.00 and less
than +4.00.
• You can enter a +3.00 in the trial frame and continue
refining the best sphere by letting the patient compare the
JND lenses in front of the +3.00 sphere in the trial
frame. Notice that you are determining the best sphere by
bracketing around it with stronger and weaker lenses. In this
way, the refractive error can be arrived quite accurately and
reliably in patients with significant loss of sensitivity to blur.
•

67. Test for astigmatism
• After finding the best sphere, test for astigmatism.
If the K reading or retinoscopy indicate
astigmatism, refine axis first, then power using a
hand held Jackson cross cylinder, its strength
chosen using the same JND rule of
thumb. Use a +,-1.00 JCC to test the patient.

68. Retest for the Best sphere
• After the test for astigmatism, the final step in the
subjective is to retest for best sphere with the JND
lenses.
• using the bracketing method

69. • Be sensitive to the patient's heightened anxiety for the
subjective test; test slowly and carefully, giving the
patient enough time to discriminate blur. Repeated
presentations to certain patients are necessary to yield
valid results.
• The effective prescription and ultimate use of low
vision devices is usually dependent on the accuracy of
the refraction. Careful and logical technique will
improve the validity of this challenging and important
test, with improved visual function for your patient as
the great reward.
•

70. Decision to change Rx
• Discuss with clients to change the glasses
• VA may not improve signigicantly give Rx on the
basis of visiability of everyday objects.
• Face of acompaiined person is the best object to
make patient compare about the vision by new Rx
• If feels not much of diggerece not to change
• If feels a bit better than that could be of great help

71. Ancillary refraction techniques
• Radial retinoscopy – if the media is unclear
• Keratometry - find high cylinder
• Five diopters step to cover broad range of powers
quickly
• Placido disc
• Stenopaic slit Is use for high astigmatism
• Pinhole useful but decrease illumination
• Current glasses – starting point
• Ophthalmoscopy
• Autorefractors may not be reliable in opacities and
irregularities reveal high cylinder

72. Visual Field In Low Vision

73. Assessment of visual field
• Normal extend
Superior field = 60°-70°
Inferior field = 70°-75°
Temporal field = 90°-110°
Nasal field = 60°-65°
• Low vision
< 20° or 10° in either side of fixation

74. Uses of Visual Field in Low Vision
• To document visual field parameter for legal
Blindness
• To fulfill the eligibility criteria for those states which
require a minimum visual field
• To provide objective information about scotoma in
visual field which may explain unexpectedly poor
performance
• Orientation & Mobility : learn skills and influence
plan for rehabilitation
• To follow disease progression

75. Various Diseases related to Visual
field Defect
• Glaucoma: it includes paracentral scomata ,arcuate scotomas nasal
steps and temporal wedges.
• ARMD : a central or paracentral scotoma with normal peripheral
findings
• RP: visual field loss begins in the midperiphery , extending inward and
outward creating a donut- shaped field defect
• Diabetic retinopathy: in PDR , retinal ischemia , laser scars and RD can
causes corresponding field loss
• RD: VF defects develop corresponding to the site of RD
• ROP: VF defects are variable , most common nasally
• Macular hole: result in dense central scotomas
• Optic Atrophy: Central vision affected , paracentral cecocentral or
central scotomas may present
•

76. • Cataract : central and peripheral field defect
• Multiple sclerosis: several patterns of field loss
occur in patients . Central and cecocentral
scotomas may be present although altitudinal
defects occur most commonly
• Myopic Degeneration : high degree of myopia can
result in central ring shaped scotoma as well as
hemianopia and quadratic defect .

77. Glaucoma
ARMD
Types of visual field loss

78. How Visual field defects affects in
Low vision Patient
• Patient report running into objects
• Tripping, falling
• Being startled by objects or people that suddenly
appear in front of them
• Difficult to detect objects, movements orientation
• Patient often loose their place while reading

79. • Central visual field loss is the main cause of Low
vision

80. Central field testing
1. Amsler’s grid
2. Tangent perimeter (E.g
Bjerrum’s screen)
3. Arc perimeter
4. Automated perimeters
5. Goldmann perimeters
1. Goldmann perimeter
2. Automated perimeter
3. Confrontation method
Peripheral field testing
Various Devices for measuring VF in low vision
patient
PLPR

81. 1. Amsler Chart
Measures central 20
degrees (Macula)
Only one eye at a time
Look for distortion
 Uses reading glasses

82. It consists of seven grid like charts each
with slightly different patterns
It is mounted on stiff cardboard in a ring
binder.
When held at 30 cm from eye, allow
assessment of central 20 degree
This corelates anatomically with area just
inside the temporal vascular arcades not
including optic disc
Cont..

83. Amsler chart design
∙All charts in the shape of square covering an area of 100
cm square
∙Each square measures 5 mm and when the grids are held
at 30 cm from the patient each square subtends 1 degree
on the retina

84. • Designed by Marc Amsler
• These charts consists of a series of seven grid like
charts designed for evaluating the central visual
field, mounted on stiff cardbord in a ring binder
• 20 degree visual field
• Performed at 30cm
• First uniocular then binocular

85. Types of distortions that patients would report:
1. Chorioretinal scar
2. Central scotoma
3. Arcuate scotoma
4. Macropsia
5. Micropsia
6. Metamorphopsia
metamorphopsia

86. indication
• Unexplained visual acuity loss
• Report of a visual disturbance in or near the
fixation area
• A questionable appearance of macular area in
ophthalmoscopy

87. 2. Tangent screen
• Only measures central 30
degrees
• Testing distance in30 cm
• Varying size of target
(increased sensitivity)

88. 3. Confrontation
• Illuminated targets
• Non illuminated
target

89. Confrontation visual field exam:
a simple and preliminary test
extent of visual field tested by this method is
120̊
examiner separated with the patient by a
distance of about 60cm and asked to cover
one eye and stare at the examiner

90. when the patient covers their right eye, the
examiner covers their left eye, and vice versa.
The examiner will then move his hand ( or some
other test object)from a position as far as
possible from the line of sight inward until
patient reports seeing it
Cont..
this process should be repeated in each of the
four quadrants
the target should be moved in a plane
equidistant from the examiner so that the
examiner may compare the patient's visual field
with his.

91. Arc perimeter
• It provides a quick estimation of the
extent of peripheral field constriction
• With this test the practitioner can
evaluate all mericians but typically only
45, 90,135, 180
• Degree meridians are evaluated

92. 4. Goldmann Perimetry
Evaluate both the central and
peripheral visual field
the standard test performed by
most perimetrists
Test Targets: dots of Varying size
and illumination

93. Goldmann Perimetry : target size
Sizes of Stimuli [0...V scale]
Each size increment equals
• a two fold increase in
diameter and a fourfold
increase in area
Diameter (mm) Area (mm2)
0 0.28 1/16
I 0.56 ¼
II 1.13 1
III 2.26 4
IV 4.51 16
V 9.03 64

94. 5. Automated visual fields
Static perimetry
Measurement of threshold values
Statpac(HFA)- comparison to normative data
Inbuilt program for analysis- diagnosis and
progression

95. Advantages of AVF…
1. Removal of examiner variability
2. More sensitive to subtle field defects
3. Reproducibility
4. Restests abnormal points automatically
5. Has relaiablity parameters

96. PLPR
• When none of the test show result and the visual
field is very low , we can do PLPR test just to get a
gross idea of whether the light perception is
present in any of the four quadrants