Visual field defects and light reflex

1. VISUAL FIELD DEFECTS
OCULAR REFLEXES

2. Clinical correlation
• Loss of vision in one half
of the visual field (Rt or
Lt) is termed as
hemianopia.
• Homonymous
hemianopia: Loss of
vision in the same halves
of the visual field.
• Heteronymous
Hemianopia: Loss of
vision in the different
halves of the visual field.

3. 3

11. Pupillary Light Reflex
• When the amount of
light entering the eyes
increases, the pupils
constrict.
• Functions to help the
eye adapt extremely
rapidly to changing light
conditions.
• Direct light reflex:
same pupil constricts
• indirect (consensual)
light reflex: pupil of the
opposite eye constricts

12. Two type of light reflex
• Direct light reflex
• Constriction of pupil of the eye in which the light is
directed is called direct light reflex
• Consensual light reflex (In direct)
• Constriction of pupil of the other eye is called
consensual light reflex

14. Pathways of direct and indirect light
reflexes (v.imp.)
BY Muhammad Ramzan Ul
Rehman Nishtar Ken
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15. Pupillary light reflex
Direct
Consensual

16. Extrinsic Eye Muscles
Inferior rectus Inferior oblique
Medial
rectus
Superior
rectus
Superior
oblique
Lateral
rectus
(cut)
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• Superior rectus
• Rotates eye up and
medially
• Inferior rectus
• Rotates eye down
and medially
• Medial rectus
• Rotates eye
medially
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17. Extrinsic Eye Muscles
Inferior rectus Inferior oblique
Medial
rectus
Superior
rectus
Superior
oblique
Lateral
rectus
(cut)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• Lateral rectus
• Rotates eye
laterally
• Superior oblique
• Rotates eye down
and laterally
• Inferior oblique
• Rotates eye up and
laterally
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18. Medial and lateral
recti move eyes side
to side
Superior and inferior
recti move eyes up
and down
Superior and inferior
obliques rotate the
eyes
Extra ocular muscles
Nerve Supply
Figure 51-7; Guyton & Hall
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19. Accommodation
• It is the ability of the
eye to keep the image
focused on the retina
(as the distance
between the eyes & the
object varies)
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20. AccommodationAccommodation

21. NEAR RESPONSE or accomodation
for near vision
• The three components of near response
are:
1. accommodation,
2. convergence of the eyeballs &
3. Pupillary constriction

22. Pathway of Convergence
Reflex

23. ACCCOMODATION REFLEX
• When the eyes are
focussed from a distant to
near object, three
reactions take place
• 1. Constriction of pupils
• 2. thickening of lens due to
contraction of ciliary
muscles
• 3. Convergence of both eye
balls
These three reactions
together constitute
Accommodation or near
reflex

24. Accommodation
reflex

25. Visual Acuity
• Acuteness or clearness of vision
• It is the degree to which the details
and contours of objects are perceived
• It is defined in terms of the minimum
separable (shortest) distance by which
two lines can be separated and still be
perceived as two lines
• Thus the minimum separable in a
normal individual corresponds to a
visual angle of about 1 minute
• Clinically Snellen’s charts are used to
determine visual acuity

26. METHOD FOR STATING VISUAL
ACUITY
• Chart for testing eyes
consists of letters of
different sizes placed
20 feet ( 6 meters)
away from the person
being tested.
• Person is said to have
normal vision if he can
see the letters from the
distance of 20 feet or 6
meters. so he have
vision of 20/20 or 6/6
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27. CONFRONTATION METHOD TO TEST
THE FIELD OF VISION
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28. perimetry
Lister’s perimeter
• Perimetry maps and
quantifies the visual field,
especially at the extreme
periphery of the visual
field.
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29. GOLDMAN’S PERIMETRY
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30. Physiologic blind spot: In
all perimetry charts, a
blind spot caused by lack
of rods and cones in the
retina over the optic disc
is found about 15
degrees lateral to the
central point of vision, as
shown in the figure.
• Scotoma
A blind spot in any other
portion of the visual field
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