OPTIC-NERVE DECOMPRESSION IMPROVES HEMODYNAMIC PARAMETERS IN PAPILLEDEMA

Purpose: The purpose of this study is to examine changes in color Dopp ler imaging parameters before and after optic nerve sheath decompressi on (ONSD) for chronic papilledema caused by pseudotumor cerebri (PTC). Methods: Color Doppler imaging was performed within 48 hours before s urgery and within 48 hours after the procedure using a color Doppler u nit with a 7.5-MHz phased linear transducer. Pulsed Doppler spectrum a nalyses were recorded digitally on videotape from the ophthalmic, cent ral retinal, and short posterior ciliary arteries, using a 0.4 X 0.6-m m sample volume. Results: Blood flow velocities in the ophthalmic, sho rt posterior ciliary, and central retinal arteries of 24 eyes were sig nificantly decreased compared with a healthy age-matched group. Eyes w ith visual acuities worse than 20/30 before surgery had significantly decreased velocities in the ophthalmic, short posterior ciliary, and r etinal arteries, whereas in eyes with visual acuities better than 20/3 0, only the short posterior ciliary and central retinal arteries demon strated decreased velocities. In addition, Gosling's pulsatility index was increased for the central retinal artery but not the ophthalmic o r short posterior ciliary arteries. Thirteen eyes improving in visual acuity and field after ONSD demonstrated significant improvement in al l color Doppler imaging parameters for the short posterior ciliary art eries. The ophthalmic artery diastolic velocity also increased signifi cantly but the central retinal artery parameters did not change. The e yes that remained stable or worsened did not demonstrate significant p ostoperative changes. Conclusion: These results suggest that some of t he visual loss from chronic papilledema may be due to ischemia, and wo rsening visual acuity correlates with greater impairment of the retrob ulbar circulation. One of the mechanisms by which ONSD improves visual function may be reversal of this ischemic process.