Internal Medicine

P1: SBT

0521779407-02 CUNY1086/Karliner 0 521 77940 7 June 7, 2007 19:18

Adult Optic Neuropathies 77

■Asymmetry of pupillary function – a Marcus-Gunn pupil (relative

afferent pupillary defect) indicates asymmetry between eyes of func-

tioning axons which subserve afferent limb of pupillary reflex; speaks

to unilateral involvement of one optic nerve, or asymmetric involve-

ment of both optic nerves; its presence is NEVER normal

tests

■Ophthalmologic consultation for determination of intraocular con-

tribution to process

■Snellen acuity measured with best refraction

■Bedside acuity determination done with pinhole viewing

■Measure color vision

■Measure intraocular pressure

■Formal automated perimetry to characterize visual field change and

narrow differential diagnosis

Laboratory

Work-up is driven by working diagnosis

■ESR and C – reactive protein to look for temporal arteritis

■Temporal artery biopsy if clinical suspicion for temporal arteritis

■Measurement of opening pressure on LP for raised ICP (after neuro-

imaging to rule out mass)

■CSF analysis to look for more widespread CNS process

■CSF immunoglobulins to look for markers of multiple sclerosis

■FTA-ABS and RPR to screen for syphilis

■B 12 and Folate levels to screen for hematologic etiology

■Toxicology screen to look for endogenous poisons

■Thyroid function tests to screen for dysthyroid contribution to optic

neuropathy

Imaging

■MR scan of head and orbits – MR better than CT for fine detail,

imaging myelin

■CT scan of head and orbits – CT better for imaging calcifications

■MR angiography – look for vascular cause and associated findings

Ancillary Ophthalmologic Testing

■Visual Evoked Response (VER)- may help in recognizing subtle optic

nerve dysfunction, and characterizing defect as demyelinative, if

major (P 100) waveform is delayed

■ERG, EOG, Dark adaptation – useful in defining retinal contribution

to process