The Amsler chart is used to evaluate the central 20 degrees of visual field to screen for and monitor macular diseases. It consists of a 10cm square grid with 400 smaller 5mm squares that the patient focuses on from 16 inches away while reporting any distortions, blurriness, or missing areas. There are 7 chart types including the standard high contrast grid, ones with diagonal lines, red squares, random dots, and varying line patterns to detect different visual field defects that may indicate conditions like macular edema, tumors, metamorphopsia, scotomas, or glaucoma.
2. Amsler Grid
• The grid chart evaluate the central 20 degree of the visual field.
• It is a diagnostic tool that is used mainly in screening, detection and monitoring
macular diseases.
(e.g. Macular degenerations)
as well as the optic nerve and the visual pathway.
3.
4. Procedure
• The patient is made to wear his reading glasses if any, holds
the chart at 16 inches(40cm) away infront of the eye.
• Patient looks with each eye separately by covering one eye.
• He is asked to focus at the small dot in the centre of the grid.
• While he is looking at the dot, ask him to report if any line on
the grid is(distorted, broken, blurred area, missing area, dark
area, corners, sides).
• Mark the area of abnormality, if any on the chart and refer to
the ophthalmologist.
5. There are seven charts, each consisting of a 10cm square.
CHART I
It is most commonly used.
It comprises a high contrast
white grid on a black
background. The outer grid
encloses 400 smaller 5mm
squares. When viewed
about one-third of a meter,
each small square subtends
an angle of a 1 degree.
6. CHART 2
Is a similar to chart
1 but has diagonal
lines that aid
fixation in patients
unable to see the
central spot as a
result of a central
scotoma
7. CHART 3
Is to identical to chart 1
but has red squares.The
red on black design aim
to stimulate long
wavelength foveal
cones. It is used to
detect colour scotomas
and desaturation that
may occur in toxic
maculopathies, optic
neuropathies and
chiasmal lesions.
8. Chart 4
Consisting only of
random dots is used
mainly to distinguish
scotoma from
metamorphosia, as
there is no form to
be distorted.
9. Chart 5
Consisting of
horizontal lines and is
designed to detect
metamorphosia along
specific meridian. It is
of particular value in
the evaluation of
patients with reading
difficulties.
10. CHART 6
It a similar to chart
5 but has a white
background and
the central lines are
closer together
enabling more
detailed evaluation.
11. CHART 7
Exhibits a fine
central grid, each
square subtending
an angle of a
degree and is
therefore more
sensitive.
