HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Takayama, J. Articles by Araie, M. Search for Related Content PubMed PubMed Citation Articles by Takayama, J. Articles by Araie, M.

Time Course of the Change in Optic Nerve Head Circulation after an Acute Increase in Intraocular Pressure

¹From the Eye Clinic, Tokyo Metropolitan Geriatric Hospital, Tokyo, Japan; the ²Department of Ophthalmology, University of Tokyo School of Medicine, Tokyo, Japan; the ³Eye Clinic, Omiya Red Cross Hospital, Saitama, Japan; and the ⁴Institute of Medicinal Chemistry, Hoshi University, Tokyo, Japan.

PURPOSE. To investigate the time course of changes in optic nerve head (ONH) circulation after an acute increase in intraocular pressure (IOP), by using the laser speckle method, and to evaluate the effects of a calcium antagonist, the nitric oxide synthetase inhibitor, indomethacin, or sympathetic nerve amputation on the response in ONH circulation after an acute increase in IOP.

METHODS. In rabbits, the normalized blur (NB) level, a quantitative index of tissue blood velocity in the ONH, was monitored for 60 minutes after an increase in IOP from 20 mm Hg to 40, 50, or 60 mm Hg and for 25 seconds after increase in IOP from 20 mm Hg to 50 or 60 mm Hg with high time resolution. The effects of systemic administration of 1 µg/kg per hour nilvadipine (a calcium antagonist), 30 mg/kg N-nitro-L-arginine (L-NAME), or 5 mg/kg indomethacin, or those of sympathetic nerve amputation on the time course of the changes in NB were studied.

RESULTS. NB showed a quick recovery within several seconds after increase in IOP to 40 or 50 mm Hg, whereas no or little recovery occurred after an increase to 60 mm Hg. The nilvadipine treatment significantly increased NB at IOP of 20 mm Hg (baseline NB, P = 0.045) and apparently impaired the recovery of NB after the increase in IOP. After L-NAME administration, baseline NB significantly decreased (P = 0.028), and the NB recovery time was slightly but significantly prolonged (P = 0.012). Indomethacin showed no effects on baseline NB or NB recovery. Sympathetic nerve amputation increased baseline NB (P = 0.027), but did not influence NB recovery.

CONCLUSIONS. The current results showed a quick recovery response in the ONH circulation after an acute increase in IOP in rabbits. A calcium antagonist impaired the response. Production of nitric oxide or prostaglandins or the sympathetic nervous system is probably not mainly responsible for the reaction.

This article has been cited by other articles:

				Y. Liang, J. C. Downs, B. Fortune, G. Cull, G. A. Cioffi, and L. Wang Impact of Systemic Blood Pressure on the Relationship between Intraocular Pressure and Blood Flow in the Optic Nerve Head of Nonhuman Primates Invest. Ophthalmol. Vis. Sci., May 1, 2009; 50(5): 2154 - 2160. [Abstract] [Full Text] [PDF]

				I. K. Petropoulos, J.-A. C. Pournaras, A. N. Stangos, and C. J. Pournaras Effect of Systemic Nitric Oxide Synthase Inhibition on Optic Disc Oxygen Partial Pressure in Normoxia and in Hypercapnia Invest. Ophthalmol. Vis. Sci., January 1, 2009; 50(1): 378 - 384. [Abstract] [Full Text] [PDF]

				J. Takayama, A. Tomidokoro, Y. Tamaki, and M. Araie Time Course of Changes in Optic Nerve Head Circulation after Acute Reduction in Intraocular Pressure Invest. Ophthalmol. Vis. Sci., April 1, 2005; 46(4): 1409 - 1419. [Abstract] [Full Text] [PDF]