Effect of acute intraocular pressure changes on short posterior ciliary artery haemodynamics
- Karen M Joosa,b,
- Matthew D Kayb,
- L E Pillunatb,c,
- Alon Harrisd,
- E Kym Gendronb,
- W J Feuerb,
- Brett E Steinwanda
- aDepartment of Ophthalmology and Visual Science, Vanderbilt University, Nashville, TN, USA, bBascom Palmer Eye Institute, University of Miami, Miami, FL, USA, cUniversitats-Augenklinik, Hamburg, Germany, dDepartment of Ophthalmology and Physiology, Indiana University, Indianapolis, IN, USA
- Dr K M Joos, Department of Ophthalmology and Visual Science, Vanderbilt University, 8017 MCE, Nashville, TN 37232-8808, USA.
- Accepted 30 July 1998
Abstract
BACKGROUND/AIMS Vascular insufficiency due to abnormal autoregulation has been proposed as a major factor in the development of glaucoma. The anterior optic nerve is primarily perfused by the short posterior ciliary arteries. The autoregulatory capacity of these vessels in response to acutely elevated intraocular pressure (IOP) was examined in normal human subjects.
METHODS Colour Doppler imaging was performed on the short posterior ciliary arteries of 10 normal subjects at baseline and during four incremental IOP elevations. Using a scleral suction cup placed temporally, IOP was elevated to approximately 25, 30, 40, and 50 mm Hg. Additional measurements were performed immediately after pressure release. Systolic and diastolic flow velocities were measured and Pourcelot’s resistivity index was calculated.
RESULTS Systolic and diastolic flow velocities decreased linearly with each incremental increase in IOP (p<0.001). Pourcelot’s resistivity index increased linearly with each incremental increase in IOP (p<0.001). Changes in end diastolic velocity, peak systolic velocity, and Pourcelot’s resistivity index were linearly related to changes in IOP.
CONCLUSION The normal healthy eye is not able to autoregulate to maintain PCA blood flow velocities in response to acute large elevations in IOP.
