Term
| what does fixing your eyes on a certain spot test? |
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Definition
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Term
| what does visual field testing evaluated? |
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Definition
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Term
| what is the normal visual field? |
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Definition
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Term
| what creates the physiological blind spot? |
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Definition
| this is due to the retinal ganglion cells which the brain usually fills in (located down and to the R - just lateral to midline). however this effect may also occur in other places of the retina which the pt will be unaware of = scotoma. |
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Term
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Definition
| loss of vision in one eye |
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Term
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Definition
| loss of vision in half of the visual field of each eye. |
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Term
| what is homonymous hemianopia? |
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Definition
| visual field loss of similar halves. |
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Term
| what is heteronymous hemianopia? |
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Definition
| visual field loss of dissimilar halves |
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Term
| what is homonymous quad anopia? |
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Definition
| visual field loss in similar halves but there is only a portion (a quadrant) that is affected. |
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Term
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Definition
| accurate discriminative vision in frontal vision is maintained, but the ability to discriminate shapes/movements in the peripheral parts is lost. (macular part of the retina is where there is the most clustering of the cone receptors of the retina) |
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Term
| what is the pathway of visual stimuli through the brain? |
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Definition
| retina -> optic nerve -> optic chiasm -> optic tracts -> geniculate nucleus -> optic radiations -> occipital cortex |
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Term
| what is light from the R halves of the visual fields going to hit? |
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Definition
| the nasal retina of the right eye and the temporal retina of the left eye |
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Term
| what is light from the L halves of the visual fields going to hit? |
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Definition
| the nasal retina of the left eye and the temporal retina of the right eye |
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Term
| where are the L aspects of both visual fields processed? |
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Definition
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Term
| where are the R aspects of both visual fields processed? |
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Definition
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Term
| what would a lesion at the optic nerve cause? |
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Definition
| anopia in the eye affected |
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Term
| what would a lesion (pituitary tumor/internal carotid aneurysm) at the optic chiasm cause? |
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Definition
| heteronomous hemianopia - L half of L visual field affected and R half of R visual field affected (outer portions of retinae are spared, which preserve immediately frontal vison) |
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Term
| what would a lesion at the optic tract (after chiasm, similar to lateral geniculate nucleus) cause? |
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Definition
| complete homonymous hemianopia (deficits will be homonymous from here back to the occipital cortex) |
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Term
| what would a lesion at the meyer's loop (optic radiations to temporal lobe) cause? |
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Definition
| homonymous quad anopia in the L upper quadrant (if R cortex affected) and the farther back in the temporal lobe, the greater portion of the visual field will be taken up, moving toward a more homonymous hemianopia |
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Term
| what would a lesion at the more anterior portion of the primary visual cortex cause? |
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Definition
| homonymous macular sparing |
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Term
| what would a lesion at the more posterior portion of the primary visual cortex cause? |
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Definition
| homonymous everything but macular sparing |
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Term
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Definition
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