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Temporal Nasal |
Ring (Annular) scotoma Definition: Visual field defect that encircles fixation Visual acuity: Retained Retinal > Optic nerve lesions Mechanism: Corresponds to retinal region with greatest rod concentration Locations Mid-peripheral: 30° to 60° Retinitis pigmentosa Aphakic correction Peri-central: 5° to 30°; Ring incorporates blind spot Photoreceptor dystrophies Paraneoplastic/Autoimmune Central: Within central 10° Acute: High caffeine intake See: Martin |