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PRESENTER; DR. LEENA VADHEL
MODERATOR: DR. MRUDULA BHAVE
Contrast:- defined as the degree of blackness to
whiteness of target.
Contrast threshold:-is the smallest amount of
contrast required to be able to see the target.
Contrast sensitivity:- is the reciprocal of the
WHAT IS CONTRAST SENSITIVITY
the ability to perceive slight changes in
luminance between regions which are not
separated by definite borders and is just as
important as the ability to perceive sharp
outlines of relatively small objects.
SNELLENS VISUAL ACUITY VERSUS
Snellen’s charts test VA at a very high contrast
thus many patients have a good snellens VA but
they may be visually handicapped in real life
The VA drops in the situations with low contrast
and the quality of vision is not good.
It provides the information that cannot be
obtained from visual acuity, and it is often a
better predictor of visual performance then VA.
CONTRAST SENSITIVITY CURVE
C .S is presented
as curve which
plots the lowest
contrast level a
patient can detect
for specific size
The x-axis curve is
is for contrast
CONTRAST SENSITIVITY FUNCTION
The contrast sensitivity function proposed
by Manos and Sakrison.
A plot of CS over a range of spatial
frequencies gives the contrast sensitivity
Contrast sensitivity depends on spatial
Spatial frequency of visual stimuli is given in
cycles per degree.
CONTRAST SENSITIVITY FUNCTION
Contrast sensitivity function (CSF) is a
subjective measurement of a person's ability
to detect a low contrast pattern stimuli,
usually vertical stripes of decreasing shades
of black to grey. The resulting measurement
is said to give a more accurate
representation of the eyes' visual
CONTRAST SENSITIVITY FUNCTION
CSF has a peak value
of approximately 1 to 8
Distinction of high
possible because of
limited number of
CONTRAST SENSITIVITY FUNCTION
Neural and optical
the high spatial
Point where the
CSF cuts the x axis
is called cut off
L max- Lmin/Lmax+Lmin
Lmax = Luminance on the lighter surface
Lmin = Luminance on the darker surface
Defined as ( Lb – Lt ) / Lb
Lb & Lt are the luminance of the background and
Weber contrast used in calculating the contrast of
low medium high
• The modulation transfer function (MTF) indicates the ability of an
optical system to reproduce (transfer) various levels of detail (spatial
frequencies) from the object to the image.
• Its units are the ratio of image contrast over the object contrast as a
function of spatial frequency.
• It is the optical contribution to the contrast sensitivity function (CSF).
MTF: Cutoff FrequencyMTF: Cutoff Frequency
0 50 100 150 200 250 300
spatial frequency (c/deg)
Rule of thumb: cutoff
frequency increases by
~30 c/d for each mm
increase in pupil size
One adjacent pair of light and dark bars
makes up one cycle.
The thickness of the grating is described by
their spatial frequency in cycles per degree
of the visual angle at the eye..
Large number of grating can fit with in a
degree of visual angle
Gratings are broader and are of low spatial
Spatial phase defines its position.
Change in spatial phase by 180 degrees
indicates that the grating is displaced by half
Sine wave gratings
These gratings are
lacking in sharp
are used because
they are not subject to
Only the contrast and
spatial position are
Square wave gratings
a square such as
SPATIAL CONTRAST SENSITIVITY
Detection of striped pattern at various levels of
contrast and spatial frequency.
Sine wave gratings of parallel light and dark
Measured with stationary gratings
width of the bar is defined as spatial frequency
High spatial frequency- narrow bars.
low spatial frequency- wide bars.
The spatial frequency
exponentially from left
to right. The contrast
100% at the bottom to
about 0.5% at the top
TEMPORAL CONTRAST SENSITIVITY
Temporal contrast sensitivity is measured with
gratings that reverse contrast at various rates over
here contrast sensitivity function is generated
for the time related processing in the visual
system by presenting a uniform target field
modulated sinusoidal in time.
Both the system provides more complete and
systemic data on the status of visual
The shape of the contrast sensitivity function
varies with factors:
Neural mechanism of contrast
Campbell and Green gave the concepts of
different visual channels for handling
information about bands of spatial frequencies.
This concept indicates that the retina is not
Fovea is specialized for high acuity and is
responsible for high spatial frequencies.
In the retinal periphery, only low frequency
channels are represented.
M and P------- pathways
Ganglion cells divded into
p- Cells :- small,slow
conducting axons that input
into parvocellular layers of
the lateral geniculate body.
P-Cells have higher spatial
m-Cells :- large ,fast
conducting axons that input
into the magnocellular layers.
M- Cells have higher contrast
sensitivity and temporal
resolution and lower spatial
CSF is a function of several independent parallel
Each channel is highly sensitive to some particular
Visual world is broken into its separate spatial
frequency components and this information is then
passed in separate channels to the cortex,where it
Visual system consists of 4 to 6 spatial frequency
CSF channel could be due to a series of ganglion
cells that have receptive fields of different sizes so
that they are maximally sensitive to different spatial
Stimuli smaller than the center receptive field only
produce a partial response from the ganglion cell.
Stimuli larger than the center receptive field also
stimulate the surrounding area so that the overall
response from ganglion cell is reduced.
SYMPTOMS OF CONTRAST SENSITIVITY
Have problems with night
driving, including inability to
see traffic lights
May require extra light to read
Their eyes may become tired
when they read or watch
Not being able to see spots on
clothes, counters, or dishes
Missing facial gestures
MEASUREMENT OF CONTRAST SENSITIVITY:
There are three variables in measurement of
1. Average amount of light reflected depends on
illumination of paper and darkness of ink.
2.Degree of blackness in relation to white
background that is contrast.
3. The distance between the grating periods of
cycles per degree of visual angle.
The various methods available to measure CS
Pelli Robson test
Bailey Lovie chart
Vision contrast test system (VCTS) by Vistech
Cambridge low contrast grating
PELLI ROBSON CONTRAST SENSITIVITY
letters of the same
size but with
two charts and two
Each chart has 6
letters in each row
organized into two
triplets of varying
illumination of the
chart is 85 cd/mm2
1 meter distance
The score of the
test is recorded by
the faintest triplet
out of which at
least 2 letters are
The log CS value
for this triplet is
given by the
number on the
CAMBRIDGE LOW CONTRAST GRATING
It is a rapid and simple screening test for
Performed at a distance of 6m.
It comprises of 12 pair of plates consisting of
stripes of varying contrast.
First one is for demonstration and rest are for
the proper testing and are numbered from 1-10.
The plates are changed sequentially starting
from plate 1 till the patient fails to respond.
Then a new series is begun starting 4 plates
prior to where the patient failed to respond.
Four such series are completed and the score
of each series is noted (numbered as per the
number of plate read) and added.
The final total value is converted into contrast
sensitivity from the provided table.
BAILEY LOVIE CHART
Low contrast acuity testing & acuity testing in
presence of glare.
Each row has same no. of symbols & constant
spacing is used between rows & letters.
Chart is logarithmic based & visual acuity is based
on log of minimum angle of resolution or logMAR.
Berkely Glare Test provides 10% of contrast & is
provided with glare source
FUNCTIONAL ACUITY CONTRAST
FACT charts were developed by Dr. Arthur
FACT comprises of a chart with sine-wave gratings
of varying frequencies.
The chart tests five spatial frequencies (sizes) and
nine levels of contrast
The Contrast varies in a row, decrease from left to
And the spatial frequencies increase as one
move down the various columns from top to
This test is performed at a distance of 10 feet.
The patient determines the last grating seen for
each row (A, B, C, D and E) and reports the
orientation of the grating: right, up or left.
The last correct grating seen for each spatial
frequency is plotted on a contrast sensitivity
THE ARDEN PLATE TEST
Introduced in 1978.
Consists of a booklet
containing several sine
wave gratings patterns
Each grating is oriented
The contrast varies from the
top to the bottom of the
grating, lowest at the top
and highest at the bottom.
VISTECH CONTRAST SENSITIVITY TEST
These charts consist of sine wave gratings.
Each chart contains five rows and nine columns
of circular photographic plates (disc) on gray
Each row has different spatial frequency (1.5 to
18 c.p.d. at three meters) and contrast within
the row reduces from left to right.
The gratings are presented in three
orientations: vertical 90 degrees, 15 degrees
clockwise or anticlockwise.
Two separate Vistech charts are available: the
VCTS-6500 for distance testing and the VCTS-
6000 for near testing.
A projector slide the VCTS-500S is also
A luminance of between 103 and 240cd/m2 is
It can be used to document the performance of
low vision patients.
REGAN LOW CONTRAST LETTER CHARTS
Consists of three letter charts, printed on white
cardboard having contrast of 97%, 7% and 4%
3 meter with eight letters in each line
Patients are instructed to start at the top and to
continue reading until they can correctly identify
no letters on a line.
For one chart letter size goes on reducing and
contrast remains constant
Regan in 1988 suggested there chief role in
detecting early visual loss in diabetes and
It is widely used in the world
This test provides four rows
of sine-wave gratings
The test distant 2.5 meters,
these gratings test the
spatial frequencies of
3,7,12,and 18 cycles/degree
Good for evaluation eye
Use for screening refractive surgery patients
Used for in or out of office screening and for
Used to evaluate both contrast sensitivity and
low contrast acuity
Contain 3 contrast levels
Provided the same tests as standard CSV-
1000-S expect that acuity is presented in
landolt c format
Useful when patient cant read English
It is special test designed specifically for food
and drug administration clinical trials
Uncorrected refractive disorders manifest
themselves as a decline in contrast sensitivity
first at smaller grating sizes or higher spatial
frequencies for mild refractive disorders.
As the degree of refractive disorder increases,
contrast sensitivity declines at the middle and
then larger grating sizes (middle to lower spatial
Measurements were made at distance (with
Vistech charts), at near (with Arden gratings),
and with a pinhole to control pupil size.
Under all conditions, when visual acuity was
reduced by spherical lenses, there was a loss of
contrast sensitivity over a broad range of spatial
Ophthalmology 1988 Jan;95(1):139-43.
Eeffectof visual blur on contrast sensitivity. Clinical
Marmor MF, Gawande A
There occurs a definite decrease in contrast
sensitivity with increasing age.
The pathogenesis of this decline in vision is
likely involves changes in the spherical
aberration of the crystalline lens
As the aperture of lens increases the average
focal point move towards the lens so that a
larger pupil produces greater spherical
Spherical aberration of cornea changes little
with the age of the people.
Total wavefront aberration of the eye increases
more than threefold, between 20 to 70 years of
the aging lens loses its balance with the
cornea, because both the magnitude and sign of
its spherical aberration change significantly.
A loss of balance between corneal and
lenticular spherical aberration causes the
degradation of optical quality in the aging eye.
Monocular and binocular contrast sensitivity
function for a range of spatial frequencies was
measured in two groups of subjects with normal
In the age range 50-87 years there was a linear
decline in contrast sensitivity with age for
medium and high spatial frequencies, but
sensitivity for low spatial frequencies was
independent of age.
Effect of age on contrast sensitivity function: uniocular and
J E Ross D D Clarke and A J Bron.
Early cataracts generally cause contrast
sensitivity losses similar to refractive disorders
at higher spatial frequencies.
The addition of glare source will exacerbate the
results for patients with cataract, producing
lower contrast sensitivity at some or all grating
significant loss of contrast sensitivity at all
spatial frequencies with increasing cataract
severity. Contrast sensitivity was significantly
reduced at high spatial frequency (18 cpd) in
cortical cataracts in the presence of glare in day
light and at low spatial frequency (3 cpd) in night
Contrast sensitivity scores may offer additional
information over standard VA tests in patients
with early age-related cataracts.
Ophthalmic Vis Res. 2011 January; 6(1): 26–31.
Effect of Cataract Type and Severity on Visual Acuity and Contrast
Javad Heravian Shandiz MSc, PhD,1
Akbar Derakhshan MD,2
to ensure proper contact lens fit as well as
determining when replacement is necessary.
Uncorrected residual astigmatism from soft
contact lens can result in decrease contrast
sensitivity at the middle and higher spatial
frequencies when compared to hard contact
study concluded that those female professional
and collegiate tennis players wearing no
corrective lenses were significantly higher in CS
at intermittent and high spatial frequencies than
those who wore daily-wear soft contact lenses
Kluka, D.A. and Love, P.A. “Effects of Daily – Wear Contact Lenses Upon
Contrast Sensitivity in Selected Professional and Collegiate Female Tennis
Players,” UBA at Birmingham
Glaucoma: Glaucoma can reduce contrast
sensitivity for all grating sizes, a number of studies
shown reduce contrast sensitivity mostly at the
middle spatial frequencies.
study was carried out to explore the effects of
glaucoma on low-spatial-frequency contrast
sensitivity by using tests designed to assess
performance of either the magnocellular (M) or
parvocellular (P) visual pathways. Sensitivity was
reduced foveally and in the midperiphery across the
spatial frequency range. In the area of early visual
field loss, the glaucoma group demonstrated further
sensitivity reduction across the spatial frequency
The low-spatial-frequency-sensitive channels of
both pathways, which are presumably mediated
by cells with larger receptive fields, are
approximately equivalently impaired in
Contrast sensitivity changes due to glaucoma and normal aging: low-spatial-
frequency losses in both magnocellular and parvocellular pathways.
McKendrick AM Sampson GP, Walland MJ, Badcock DR
Invest Ophthalmol Vis Sci.2007 May;48(5):2115-22
A study was carried out to evaluate the contrast
sensitivity at near and distance after MFIOL
implantation in 21 patients. A control group with
monofocal iol was also studied. CS measured
after 1,3,6,12,and 18 months after IOL.
(6, 12 AND 18)
SENSITIVITY AT NEAR
L Cataract refractive surgery.2003apr;29(4):703-11
Montes mico R
- - BETTER -
DIST. CS HIGH HIGH - LOW
multifocal In patients with unilateral cataract,
monofocal, accommodating and partially diffractive
multifocal IOL provided higher CS scores when
compared with refractive IOL.
Clinical and experimental ophthalmology
Differences in contrast sensitivity between monofocal,
accommodatingintraocular lenses: long-term results
Cem Mesci MD, Hasan H Erbil MD, Ali Olgun MD, Nihat Aydin MD,
Article first published online: 3 NOV 2010 DOI: 10.1111/j.1442-
In diabetic retinopathy patients, contrast
sensitivity loss may occur for all grating sizes.
a study was carried out to evaluate contrast
sensitivity (CS) and visual acuity (VA) in
detecting functional losses in participants with
type 2 diabetes.
LogMAR VA and letter CS were measured on 20
type 2 diabetic and 24 age-matched control
participants. The diabetic participants were
sub-grouped according to the level of
Letter CS was able to distinguish those
participants with and without macular oedema
and those with no or minimal diabetic
retinopathy from the control group, whereas VA
Clinical optom 2003 May;86(3):152-6
Letter contrast sensitivity changes in early diabetic retinopathy
Stavrou EP, Wood JM
A variety of optic neuropathies including
afferent pupillary defect, optic neuritis, and
multiple sclerosis will affect contrast sensitivity
losses over some or all grating sizes.
Multiple sclerosis can sometimes affect only
Pituitary adenoma has been shown to cause
contrast sensitivity loss at the middle grating
Cases report was made by
neuroophthalmological examination in two
patients with parasellar pituitary adenoma
before and after surgery.
The twelve months follow-up of visual
dysfunction includes standard Snellen visual
acuity and low contrast number visual acuity.
The presented cases indicate that the low
contrast acuity tests in patients with parasellar
pituitary adenoma are sensitive indicators.
The loss of low contrast visual acuity improved
after surgery as did other visual measures,
except in cases with significant low contrast
deficit at 1.5% contrast.
Kruzer, A.R. (1986) “ Contrast Sensitivity Signals Pitutary Adenoma,” Rev. Of.Opt.
Several occupational studies have indicated
that chronic, airborne exposure adversely
affects neurobehavioral functions in workers,
particularly visual color discrimination and
tasks dependent on rapid visual-information
Frenette, B.,Mergler, D. And Bowler, R.(1991) “Contrast Sensitivity Loss in Group of
Microelectronics Workers with Normal Visual Acuity,” Opt. and Sci.,68(7),.
CONTRAST SENSTIVITY AND LASIK
Why refractive surgery can affect the quality of
there are other factors in the eye, which affect
vision quality, that are unrelated to eye focus.
These factors can cause the quality of vision to
vary greatly, even when a patient has 20/20 or
better acuity. Contrast sensitivity is the best
method for quantifying the quality of vision
Examples of the change in contrast sensitivity
with lasik refractive surgery:
The graphs show the pretreatment level of
contrast sensitivity (with the patient wearing his
or her glasses) and the contrast sensitivity after
1 day, 1 week and 1 month of surgery (with the
patient wearing the best correction).
the patient contrast sensitivity does not recover to the
presurgery levels. The following graph shows an
example of this response in vision quality
Several surgeons have noted that some patients with high levels
of myopia (> - 9 diopters) actually improve contrast sensitivity
after LASIK surgery. The graph below shows an example. The
reason for this improvement in the quality of vision is not
completely understood, but it is thought to be due to the poor
quality of vision that some patients have through their glasses or
contact lenses before LASIK.
glare testing, which shines a bright light in the
patient's eye, reduces pupil size and typically causes
vision to improve. The graph below shows the results
of a patient tested for contrast sensitivity in darkness
and then again with glare. the glare condition
dramatically improves the contrast sensitivity
With glare, the yellow filter also improved
contrast sensitivity in LASIK patients, but not
J Refract surgery2005 Mar-Apr;21(2):158-65.
Effect of a yellow filter on contrast sensitivity and disability glare after laser in
situ keratomileusis under mesopic and photopic conditions.
Pérez-Carrasco MJ, Puell MC, Sánchez-Ramos C, López-Castro A, Langa A.