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Transcript
Visual Fields
Definition
• Island of vision in sea of blindness.
The peak of the island represents the
point of highest acuity, the fovea
while the “bottom less pit”
represents the blind spot, the optic
disc.
Normal Monocular &
Binocular Field
Monocular:
• Nasal side
• Superior side
• Inferior side
• Temporal sideBinocular:
• Vertical field
• Horizontal field
50° to 60°
60° to 70°
70° to 80°
100°to110°
-
110°
200°
Visual Field Testing
1.Stimuli: Testing the island of vision at
various levels requires targets that vary in
(a) Size(b) Intensity(c) Colour
2. Field Test Methods:
Kinetic;
Mapping the contours of the
island at different levels, resulting
in one Isopter for each level
tested.
Static;
Vertical contours of the
island along a selected meridian.
Clinical testing methods
• Central fields - Below 30°
• Peripheral fields – Above 30° to 360°
Central Fields:
Confrontation method
Amsler’s grid
Bjerrum’s screen
Peripheral Fields:
Listen perimeter
Goldmann perimeter
Defects
• Retina
• Glaucoma
• Neuro
Retina
Field defect
• Central Scotoma:
* Central serious Retinopathy
* Macula Degeneration
* Macular Oedema ( any macular
disease)
*Centro-cecal scotoma
* Toxic Amblyopia
* Stargadits
Central Scotoma & Centro-cecal
Field Defect
• Contraction & Tubler field
* Retinitis pigmentosa
* High myopia
* CRAO with Sparing of
cilioretinal artery
Contraction
Field Defect
• Altitudinal defect:
* AION
• Depression:
* Retinal Detachment
• Ring Scotoma:
* High myopia
* Aphakic spectacle correction
* Retinitis pigmentosa
* Pan retinal photocoagulation
Altitudinal defect
Ring Scotoma
Glaucoma Fields
Glaucoma
Field defect
• Isopter contraction:
Peripheral Isopter
contraction may be significantly
smaller prior to any filed loss.
• Baring of the blind spot:
It is also considered to be an
early field defect in glaucoma.
Field defect
• Angio-scotomata:
Are long branching scotomata above
or below the blind spot which are
presumed to be resulted from shadow
created by large retinal vessels and are
felt to be an early change
• Para central scotoma:
One or more isolated Para central
scotomata develop in the Bjerrum or
arcute area.
Para central scotoma
Field defect
• Seidel’s scotoma:
A sickle shape defect arises from the blind
spot and tapers to a point in a curved course with
concavity towards the fixation point.
• Bjerrum’s or Arcute scotoma:
A relatively larger area of defect in the form of
arching scotoma, which eventually fills the entire
arcute area, from blind spot to the median raphe.
With further progression, a double arcuate (ring
or annular ) scotomata will develop.
Arcute Scotoma
Field defect
• Roenne’s nasal step:
The arcuate defects may not
proceed at the same rate in the upper and
lower portion of the eye. Consequently, a
step-like defect is frequently created
where the arcuate defects meet at the
median raphe. This is called Roenne’s
nasal step, and it is mostly superior nasal
step as, Superior field is involve
somewhat more frequently.
Field defect
• Contraction & Tubler field:
Generalized constriction of
the peripheral field along with double
arcuate scotoma- leads to Tubler
field of vision in which only central
vision remains clear.
Anatomy of the Visual
Pathway
• The Visual pathway
(i) The end-organ –It is the neural epithelium
of the rods & cones
(ii) The first order neurone – It is bipolar cell
with its axons in the inner layer of the retina.
(iii) The second order neurone – It is ganglion
cell of the retina its axons passes in to the nerve
fibre layer and along the optic nerve to the LGB
(iv) The third order nerurone – Originates in
the cells of LGB, then travels by way of the optic
radiations to the occipital cortex ( Visual centre)
The visual pathway thus consist of
•
•
•
•
•
•
Two Optic nerves
An Optic chiasma
Two Optic tracts
Two LGB
Two Optic radiation
Visual cortex on each side
Optic nerve
• It extents from the lamina crib Rosa up to
the optic chiasma
• The total length of optic nerve- 3.5cm
to5.5cm
it can be divided into four parts:
(i) Intra ocular part
- 1mm
(ii) Intra orbital part
- 2 to 3cm
(iii) Intracanalicular part - 4 to10mm
(iv) Intracranial part
- 1cm
Diseases of the Optic nerve
•
•
•
•
•
•
Congenital & Hereditary
Traumatic
Tumour
Inflammatory
Toxic
Vascular Lesion
Congenital
•
•
•
•
•
•
Mylinated nerve fiber defect
Coloboma
Hypoplasia
Drusen
Optic nerve pits
Tilted disc
Field defects
• Mylinated nerve fiber
*Blind spot enlargement
*Paracecal scotoma
*Ring scotoma
*Central scotoma
• Coloboma
*Superior nasal depression
*Contraction
*Superior altitudinal hemianopia
Field defect
• Hypoplasia:
* Central Scotoma
* Binasal&Bitemporal hemianopia
* Bilateral inferior extension of blind
spot
• Drusen:
* Blind spot enlargement
* Irregular nerve fiber bundle scotoma
Field defect
• Optic nerve pits:
* Blind spot enlargement with
or without macula involvement.
* Central scotoma
* Altitudinal hemianopia
* Upper temporal field defect
• Tilted disc:
* Upper temporal defect which may be
mistaken for chiasmal compression.
Hereditary
Field defect
• Optic atrophy (Lepers)
* Contraction
* Tubler Field
• Retinitis Pigmentosa
* Contraction
* Ring scotoma
* Tubler field
Traumatic
Field defect
• Traumatic optic neuropathy:
* Superior altitudinal defect
* Total Blind
Tumour
Field defect
• Glioma:
* Blind spot enlargement
* Contraction
* Tubler field
• Meningioma:
* Junctional scotoma
* Central scotoma
* Upper temporal field defect
Inflammatory
Field defect
• Papillitis:
* Central scotoma
* Centro-cecal scotoma
* Para central scotoma
* Blind spot enlargement
• Retro bulbar neuritis:
* Central scotoma
* Para central scotoma
* Sectoral scotoma
* Ring scotoma
• Neuro retinitis:
* Central Scotoma
* Centro- cecal scotoma
Toxic
Field defect
• Mild Toxic :
* Central scotoma
* Centro- cecal scotoma (BE)
• Severe Toxic :
* Peripheral contraction
* Total blind
Vascular lesion
Field defect
• Anterior Ischemic optic neuropathy:
* Altitudinal hemianopia
( mainly involving the inferior half)
Lesion due to pressure
• Papilloedema:
* Blind spot enlargement
* Peripheral contraction
* Total loss of visual field
Chiasma
Field defect
• Infra chiasmatic lesion:
* Bitemporal hemianopia
• Supra chiasmatic lesion:
* Central hemianopic scotoma
* Bitemporal hemianopia
* Junctional scotoma
* One eye is more field defect and
other is less field defect (inferior
temporal)
Bitemporal hamianopia
Field defect
• Posterior side:
* Infra Temporal field defect
* Bilateral inferior quadrant
scotoma ( near fixation point)
* Bitemporal hemianopia
Optic Tract
Field defect
• Part I:
* Homonymus hemianopia
• Part II:
* Incongruous hemianopia
RE Homonymous hemianopia
LGB
Field defect
• Congruous Homonymus lower
Quadrantropia
• Congruous Homonymus upper
Quadrantropia
Optic radiation
Field defect
• Bie in the Sky ( superior homonymus
quadrantropia )
• Bie in the floor ( Inferior homonymus
quadrantropia )
Visual Cortex
Field defect
• Congruous homonymus hemianopia
• Congruous quadrantropia
• Homonymus hemianopia with
macula sparring
• Homonymus hemianopia with
macula splitting
• Altitudinal hemianopia
• Tubler field