Tuesday, January 29, 2008

Optic neuritis, symptoms and signs

(review in the Neurologist 2000; 6:205-13) author Jane Chan MD

1. In acute ON more than 90 % have loss of central vision. Occasionally patients get loss of peripheral vision to one side or superiorly or inferiorly.
2. Mild orbital pain above or behind the eye, preceding or concurrently with the visual loss, aggravated by upwards movement of the eye, and last up to several weeks. This may be due to triggering of trigeminal stimulation of the optic nerve sheath.
3. Less conmon symptoms are photophobia, dullness or loss of colors, perceptions of phosphenes (flashing lights with noise or eye movements) or decreased depth perception.

1. Visual loss worsens over hours, days or minutes and peaks within days to a week. Maximal return occurs within 3-6 months and does not correlate to initial visual loss.
2. Patterns of visual field loss was varied as central scotoma resolves to a small dim central or a paracentral deficit. Patterns include an arcuate scotoma, altitudinal scotoma (superior or inferior),peripheral constriction, central or cecocentral scotoma, bitemporal or hemianopic deficit. Patterns can vary day to day or hour to hour.
3. Color and contrast visionare reduced. The color defect is usually more severe than the acuity loss. The Farnsworth-Munsell 100 hue test is highly sensitive and specific. The short version with caps 22-42 has similar sensitivity for monitoring after ON. More blue yellow defects occur acutely, more red green defects occur after 6 months. Patients also have a decreased sensation of brightness.
4. RAPD is almost always present in acute ON; absence suggests optic neuropathy or other etiology.
5. Half of the patients in the ONTT had abnormal fellow eyes (contrateral) and many of these thought their vision contralaterally was normal.
6. PEARL-- RARELY an RAPD occurs in a retrochiasmal lesion due to pupillary fibers travelling together in optic tract

RED FLAGS or atypical features of optic neuritis
1. age greater than 50
2. Optic pallor at presentation
3. no pain
4. pain or vision loss that continues over weeks
5. poor visual recovery
6. associated systemic signs and symptoms

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