Visual field Flashcards
Visual field
If the eye is considered to be at the centre of a sphere & is fixating a point on the sphere, then that part of the spherical surface that is visible is known as the visual field (or field of vision)
Scotoma
If an area of reduced sensitivity within the visual field. It may have complete or partial visual loss
Kinetic perimetry
A target of a certain size is moved from outside the visual field towards the fixation target & the px is required to state when the target is detected
Static perimetry
The stimulus is a fixed point. It is presented for a short time (0.20-0.25 seconds) and is increased in luminance (made brighter) until the px detects it
Full threshold test
Finds the actual threshold at a number of retinal locations
Supra threshold test
Presents targets that are of a slightly higher luminance than the expected threshold
Isopter
Boundary between the seeing and non-seeing areas with a specific target size and colour at a stated distance
Congruous visual field defect
They are identical field defects for the right & left eyes
Homonymous
The same side is affected for the right and left eyes
Hemianopia
Half a field defect
Right
Right side is affected
Right side homonymous hemianopia
Right side is affected in both eyes (half a defect each eye)
Field defect produced in early open angle glaucoma
*Enlarged blind spots
*Nasal step
Field defect produced in a pituitary tumour
A bitemporal hemianopia
Reasons for visual fields test as part of px examination
*Risk of glaucoma as high IOP
*Appearance of optic discs from ophthalmoscopy
- Family history of glaucoma
*Unexplained headaches
- Visual field loss
