A scotoma (Greek for darkness) is an area of diminished or absent retinal sensitivity. It is most commonly referred to in visual field test interpretations. A defect in which no light is seen in the affected area is referred to as an absolute scotoma. If the test shows that the patient cannot view the dimmest light presented during testing, but does respond to brighter lights, the defect is referred to as a relative scotoma. Following are descriptions of common scotoma types based on their location:
- Central- vision decrease in the center vision
- Cecocentral-horizontal oval defect that includes both the fixation point and the physiologic blind spot
- Paracentral-defect in the periphery of the visual field
Test Time. Looking at the picture of the swans and crows, imagine the crows to be absolute scotomas. What type of scotoma is the flying crow? How about the perched crow?
Answer: The flying crow represents a central scotoma while the perched crow represents a paracentral scotoma.
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