Dilation of large retinal vessels caused by rise in intraocular pressure

Purpose. To measure dilation of large retinal branch vessels. Methods. Diameters of a vessel section of a branch artery and vein were exa mined by the retinal vessel analyzer. Intraocular pressure (IOP) was increa sed briefly by an oculo-oscillo-dynamograph. The examination was repeated a fter 2 weeks. Results. A vessel reaction was found in all volunteers. The mean venous dia meter decreased 9.9+/-9.4% during the suprasystolic phase of intraocular pr essure. A maximal dilation was found in arteries (7.0+/-6.2%) and veins (9. 3+/-5.2%) 1 min after lowering of IOP. The results were reproduced in the s econd examination for veins in all phases of the examination and for arteri es in the middle phase after lowering IOP (4 min). Various changes in mean systolic blood pressure did not significantly affect reproducibility of the vessel reaction. Conclusion. The vessel reaction caused by rise in IOP can be measured for s ingle vessel sections. The venous reaction is well reproducible in healthy volunteers. Further research should examine the benefit of this method in t he diagnosis and follow-up of glaucoma.