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V.C. Greenstein, H. Eggers, S.R. Tari, D.C. Hood; The Extent and Depth of Visual Field Deficits in Strabismic Amblyopia: A Comparison Between Conventional Perimetry and the mFVEP . Invest. Ophthalmol. Vis. Sci. 2005;46(13):5711.
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Purpose: To compare the extent and depth of visual field deficits obtained with standard automated achromatic perimetry (AAP) to those obtained with the multifocal visual evoked potential technique (mfVEP) in patients with strabismic amblyopia. Methods:Nine patients (18–60 yrs) with strabismic amblyopia were tested. All patients had complete orthoptic examinations, ETDRS visual acuity, assessment of fixation, AAP (program 24–2) and mfVEP testing. Monocular mfVEPs were obtained from each eye using a pattern–reversal dartboard array, 44.5 deg in diameter containing 60 sectors. Recording electrodes were placed at the inion (I) and I+4 cm, and at two lateral locations up 1 cm and over 4 cm from I. Pupil position was monitored during recording. Monocular and inter–ocular analyses of amplitude and latency were performed and probability plots were derived [1–3]. Results:Eight patients had esotropia and one exotropia. Visual acuity in the amblyopic eye ranged from log MAR 0.2 to 1.3. Two patients with log MAR 1.0 and 0.7 had unsteady eccentric fixation 2 deg nasal to the fovea. Seven patients had foveal fixation which was either steady or unsteady. Eight patients showed mfVEP field defects in the amblyopic eye and one with log MAR 0.2 had normal mfVEP responses. For the eight patients with defects, mfVEP amplitudes were markedly decreased. They were decreased not only in the central 2.5 deg but also in the temporal and inferior field for patients with esotropia and in the nasal superior field for the patient with exotropia and hypotropia. There were no significant increases in latency. The same patients showed decreased foveal sensitivity and visual field defects on AAP. However defects were not as extensive in area, or as severe, as those found on mfVEP testing. Conclusions:The mfVEP which primarily reflects activity in V1 reveals visual field deficits in the amblyopic eye that are more extensive and deeper than those found with standard AAP. 1.Hood et al (2002) AO. 2. Hood and Greenstein (2003) Prog Ret Eye Res. 3. Hood et al. (2005) Doc Ophthalmol.
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