Scotoma

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Related to ring scotoma: paracentral scotoma, scotomata

scotoma

[skə′tō·mə]
(medicine)
A blind spot or area of depressed vision in the visual field.

Scotoma

 

a blind area within the visual field, not affecting the surrounding area of the eye. Physiologic scotoma is that area of a healthy eye’s visual field corresponding with the optic disk, which does not have photoreceptors. Pathologic scotoma is a diagnostic symptom of many diseases, including retinitis and atrophy of the optic nerve. It is perceived as a dark spot (positive scotoma) or as a blank spot (negative scotoma) that can be detected only through special testing. During teichopsia (scintillating scotoma), which lasts 20–30 minutes, flickering is perceived along the eye’s periphery; the condition is usually accompanied by persistent headaches, nausea, and vomiting. Treatment of scotoma is directed toward the underlying disease.

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In all cases, both eyes were open, while a visual stimulus or target (a small checkerboard square), presented to the second eye only, appeared randomly in different parts of the ring scotoma area.
Techniques that are used for patients with discrete central scotomas, such as magnification and training for steady fixation with a peripheral PRL, are used for patients who will read with the retina outside the ring scotoma.
However, these strategies seldom suffice in the case of ring scotomas (see Figure 1), which border three or four sides of fixation and have been present in 20%-47.
Of interest is that 8 of the 9 eyes with the macular ring scotoma remained in that configuration throughout the follow-up period.
Figure 4 shows a patient with a macular ring scotoma from Stargardt disease whose reading rate was measured for larger letter sizes.
In this report, we describe the case of a patient with macular disease whose relatively good visual acuity was maintained but whose fixation was surrounded by a ring scotoma.
Foveal fixation was present in his good left eye surrounded by a complete ring scotoma.
Ring scotomas completely surrounding the functioning fovea or a PRL were present in 17.
When correcting refractive error, full aperture lenses must be used since reduced aperture lenses can simulate tunnel vision and induce peripheral ring scotomas.