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E Mezer, C Westall, G Mirabella, R Yagev, A Perron, JR Buncic; Is Sweep VEP Abnormal in Papilledema? . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1807.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To obtain initial observations of any changes in visual function in children with papilledema using a sweep visual evoked potentials (VEP) contrast sensitivity measure. Methods: Eleven children between 9 years and 16 years currently being treated for disorders associated with papilledema were tested at The Hospital for Sick Children. Four of these children were tested longitudinally with treatment. Patients were divided into 2 sub-groups of mild papilledema or moderate papilledema. Twelve controls, matched in age, were also recruited. Sweep VEPs were attained (Power Diva) with recording according to the International Society for Clinical Electrophysiology of Vision. Subjects viewed a contrast alternating (6 Hz) sinusoidal grating stimulus which was swept through a range of spatial frequency or contrast levels to determine thresholds. Two or three contrast sweeps and two spatial frequency sweeps provided data to determine the contrast sensitivity function. The contrast sensitivity function was plotted on a 2-dimensional graph denoting log contrast sensitivity versus log spatial frequency. The primary outcome measure was the y intercept of the contrast sensitivity functions, denoting peak sensitivity. Differences in y intercept between the mild papilledema group, the moderate papilledema group, and the control group, identified by one way ANOVA (p<0.05) were used to identify loss in contrast sensitivity or grating acuity. Results: In this study although the peak contrast sensitivity in the moderate and mild papilledema groups was found to be lower than in the control group (M=1.75 STD=0.28 and M=2.06 STD=0.24 vs. M=2.08 STD=0.35), it was not statistically significant (p=0.202). Three patients showed however dramatic recovery of their contrast sensitivity on short and long term follow-up post treatment of their intracranial hypertension. Conclusion: In a pediatric population the contrast sensitivity function in papilledema, as assessed with the sweep VEP, shows wide variation but may be useful to follow treatment for increased intracranial pressure (ICP) by shunting or medication as it seems to differentiate high from lower ICP without any clinical change in the appearance of the disc swelling. This technique may be especially useful in preverbal children with raised ICP.
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