2. Macula is a round area at the posterior pole
temporal to the optic disc 5.5mm in diameter
It is yellowish color derived from the presence
of xanthophyll pigment
3.
4. Densest concentration of cones
a one to one photoreceptor-
ganglion cell relationship
Cones more elongated and slender
Absence of rods at the foveola
RPE cells are taller, thinner and
deeply pigmented
Presence of xanthophyll pigment
5. This special anatomy enable the
fovea for:
highest discriminative ability(VA)
colour perception
6. Uses of macular function tests
Diagnosis and Follow up of macular diseases
For evaluating the potential macular function
in eyes with opaque media such as cataract
and dense vitreous hemorrhage
10. Maddox rod test
Focal ERG
VEP
Laser interferometry
Potential visual acuity meter test
Entoptic phenomena
B scan
11. V/A is measured by the visual resolution of a
letter, symbol or a pattern under conditions
of maximal contrast
In pts with macular disease VA is frequently
worse when the pt looks through a pin-hole
12.
13. Contrast sensitivity is a measure of the minimum
amount of contrast needed to distinguish a test
object
indirectly assesses the quality of vision
Can detect early/subtle visual loss when VA is
normal
14.
15. To detect retinal conditions like DR, ARMD and
other retinal, macular and optic nerve diseases
Optical conditions like refractive error, refractive
surgery, cataract and intraocular lens
implantation and normal aging of the eye
16.
17. Is an effective test
for monitoring
potential decreases
in contrast
sensitivity function
over time.
18. With a strong convex lens
affords excellent visualization
of the macula
19. PRINCIPLE :
The test involves exposing the macula to a light
source bright enough to bleach a significant
proportion of the visual pigments.
Return of normal retinal function and
sensitivity depends on the regeneration of
the visual pigments
20. pathological states that affect the
photoreceptors,Bruchs membrane, chorio-
capillaries or choroid can prolong visual
recovery time.
no such prolongation is observed in diseases
affecting the neural conducting pathways
21. Evaluates the 10 ̊ of visual
field centered on fixation
Used in screening and
monitoring macular diseases
square 10*10 cm divided
into 400 5*5 mm squares to
be held at 30 cm
22. reading glasses, cover 1 eye
Pt asked to see the central spot
Presence of abnormalities like blurred areas,
holes, distortions, or blank spots
Pt with maculopathy reports that the lines are
wavy whereas pt with optic neuropathy
remarks some lines are missing or faint
23.
24.
25. Colour vision is the function of three
populations of retinal cones
Blue ( tritan) 414-424 nm
Green ( deuteran) 522-539nm
Red (protan) 549-570nm
Normal person possess all these three cones
and called trichromat
26. Acquired macular diseases tends to produce
blue yellow defects and optic nerve lesions
red green defects
Deutran anomaly is the most common and
those subjects can not differentiate between
red and green colours
27.
28. Farnsworth-Munsell
100 Hue test is the
most sensitive but
seldom used
29. The principle of microperimetry rests on the
possibility to see —in real time— the retina
under examination (by infrared light) and to
project a defined light stimulus over an
individual, selected location
30. SLO microperimetry was the first technique
which allowed to obtain a fundus-related
sensitivity map
SLO uses a near infrared diode laser
(675nm)beam that rapidly scan the posterior
pole.
The reflected light is detected by a confocal
photodiode and the digitized image is stored in
a computer
31.
32. SLO fundus perimeter did not allow to
perform fully automatic examination.
Moreover, automatic follow-up examination
to evaluate exactly the same retinal points
tested during baseline microperimetry was
not available with this instrument.
33. The limitations of SLO have been
overcome by MP1 microperimetr a
recently developed automatic
fundus perimeter
MP1 microperimeter automatically
compensates for eye movements
during the examination via a
software module that tracks the
eye movements
34. Dark appearance of the fovea on FFA is
caused by FAZ and blockage of the choroidal
background by xanthophyll and dense RPE
FFA is a very useful tool in diagnosing
macular disorders e.g. diabetic maculopathy,
CSR , CNVM and can reveals the functionality
of the lesion e.g. ischemic maculopathy
35.
36. OCT it is non invasive noncontact imaging
that produce high resolution cross sectional
image
Useful in diagnosing macular disorders and
to delineate retinal layers and detect subtle
anatomical changes
37.
38. Maddox rod
Focal ERG
VEP
Laser interferometry
Potential visual acuity meter test
Entoptic phenomena
Preferential hyperacuity perimeter (PHP)
B scan
39. Simple and reliable test and can
be used in semi opaque media
Pt is asked to fixate light at a
distance of 1/3m through M.R.
with opposite eye occluded
Any breaks/holes;
discoloration/distortion
indicates a macular lesion
40. ERG is only abnormal when a large area of
retina is functionally impaired
Focal ERG needs a stimulus localized to one
area without scattering of light to stimulate
the rest of the retina
41. It is a hand held foveal ERG
It employs a 3-4 degrees
whit flickering light focused
on the fovea with a 10
degrees annulus of constant
white light to desensitize
surrounding retina
42. VEP Measure of the electrical potential
generated in response to a visual stimulus
it represents integrity of entire visual pathway
from retina to occipital lobe so can not
differentiate between macula ,ON and cortical
pathology
43. Two types of stimulus either
by flash of light or by
patterned stimuli
If the issue is the V/A then
the amplitude is measured
If the issue is the lesion in
the visual pathway then the
latency is measured
44. Utilizes coherent white light or helium-neon laser
generated interference stripes or fringes that are
projected onto the retina through the ocular
media
Brightness increased in pts with dense cataracts
The laser interferometer resolving power
converted to standard V.A
45. 1. subjective
2. Laser fringe vision>vision of letter acuity.
3. over predicts visual potential in amblyopes
46. PAM introduced in1983
This is attached to a slit lamp and
projects a reduced Snellen’s chart
via narrow beam of light through a
pinhole clear area in the cataract
towards the macular region
The resulting potential acuity is the
smallest line where the patient was
able to read three characters
47. Subjective
methods that require an alert and cooperative
patient and skilled compassionate examiner
But it is easier than laser interferometry
48. It is refer to visual perceptions that have their
origin in the structure of an observer's eye
Three types are used for testing the macula in
opaque media
1/ PURKINJE VASCULAR E.P
2/ Flying spot( blue field entoptic phenomenon)
3/Haidinger’s Brushes
49. The Purkinje’s vascular entoptic
test is a simple method which
elicits the response by placing a
penlight against a closed eyelid
or the globe and moving it back
and forth, creating images of the
patient’s retinal vascular tree
50. Blue field entoptoscopy relies on
the observation of leucocytes
flowing in the macular retinal
capillaries. The leucocytes appear
as ‘Flying Corpuscles’ when the
retina is diffusely illuminated with
a bright blue light.
51. Subject looks at a surface
illuminated with blue light
through a polarizer
hourglass shaped yellowish
brushes seen radiating from the
point of fixation. On rotating
polarizer, brushes rotate
52. Phenomenon caused by variations in
absorption of plane polarized light by
oriented molecules of xanthophyll
pigment in foveal retina
Used to sensitize the fovea in
amblyopic child with eccentric fixation
53. limited by the patient’s subjective
interpretation
May yield false negatives if the retina cannot
be sufficiently illuminated through a dense
cataract
54. PHP relies on the concept of hyperacuity
which is the ability to discern a subtle
misalignment of an object.
This can be explained by the fact that an
extended edge will stimulate an array of
cones and when there is a break in this line
the fovea can perceive it.
55. if the patient’s
photoreceptors are slightly
misaligned due to macular
lesion (e.g. drusen) then
this misalignment can be
perceived by the patient
and recorded by the PHP.
56. This gives a gross idea about the anatomic
normalcy of the eye, and rules out
pathologies like vitreous hemorrhage, retinal
detachment, optic nerve anomalies, etc
Scanning does not offer any information on
macular function
57. Evaluation of the macular function of a
patient with opaque media is a challenging
problem commonly faced by us
No single test is infallible