Topical proparacaine and episcleral venous pressure in the rabbit.
OBJECTIVE
To determine the effect of proparacaine-induced topical anesthesia on episcleral venous pressure (EVP).


METHODS
In anesthetized rabbits (n = 11), EVP was measured with a servonull micropressure system, with glass pipettes with 2- to 3-microm tips used to cannulate episcleral veins. Additional measurements included arterial, intraocular, and orbital venous pressures obtained by direct cannulation, to assess the ocular pressure gradients, and carotid blood flow and heart rate, to verify preparation stability. The protocol entailed 5 to 10 minutes of stable baseline recording followed by topical application of proparacaine (0.5%, 10 microL) with continued measurements for another 5 to 15 minutes.


RESULTS
Baseline EVP without topical anesthesia was 12.3 +/- 1.1 mm Hg. EVP decreased significantly to 8.7 +/- 0.9 mm Hg within minutes after application of proparacaine. A small decrease also occurred in intraocular pressure. All other measured variables were unchanged.


CONCLUSIONS
These results suggest that the episcleral circulation is under tonic neural control and that either an upstream resistance site is under tonic vasodilatory control or a downstream site is under vasoconstrictor control.
Zamora
David O
DO
Department of Ophthalmology, University of Texas Health Science Center, San Antonio, Texas 78229, USA. zamorado@uthscsa.edu
Kiel
Jeffrey W
JW
D000287:Administration, Topical; D000772:Anesthesia, Local / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage*; D000818:Animals; D005260:Female; D006339:Heart Rate / Q000502:physiology; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D011430:Propoxycaine / Q000008:administration & dosage*; D011817:Rabbits; D012039:Regional Blood Flow; D012590:Sclera / Q000098:blood supply*; D014160:Transducers, Pressure; D014690:Venous Pressure / Q000502:physiology*
D000779:Anesthetics, Local; C005717:proxymetacaine; D011430:Propoxycaine