The document discusses the anatomy and function of the macula and various tests used to evaluate macular function. The macula is located at the center of the retina and contains the highest concentration of photoreceptors, enabling sharp, central vision and color perception. Several tests are described that can help diagnose and monitor macular diseases by assessing visual acuity, contrast sensitivity, retinal imaging, and potential remaining vision in the context of opaque ocular media.

1. Abubaker Ahmed
M.Sc Ophthalmolgy

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

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

7. Symptoms
• Central vision impairment
• Metamorphopsia
• Micropsia
• Macropsia

8.  MFT With clear media
 MFT With opaque media

9.  Visual acuity  Amsler grid
 Contrast sensitivity  Microperimetry
 Slitlamp  FFA
biomicroscopy
 OCT
 Photostress test
 Colour vision

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

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

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

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

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

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

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

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

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