COLOR DOPPLER IMAGING AND PLASMA-LEVELS OF ENDOTHELIN-1 IN LOW-TENSION GLAUCOMA

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide produced by va scular endothelin cells There are reports in the literature that ET-1 plasma levels are raised in low tension glaucoma (LTG). ET-1 plasma co ncentration and Color Doppler Imaging (CDI) evaluation in ophthalmic a nd posterior ciliary arteries were measured in 15 LTG patients and in 15 healthy subjects. The blood flow index recorded for the ophthalmic artery in normal subjects was a PSV of 36.646+/-6.611 cm/sec with RI o f 0.717+/-0.019 while in the LTG patients it was 32.961+/-3.045 cm/sec (p<0.003) with RI of 0.789+/-0.018 (p<0.001). For the posterior cilia ry arteries in the same two groups, we obtained a PSV of 13.878+/-4.14 9 cm/sec vs 8.720+/-1.645 cm/sec (p<0.001) and an RI of 0.679+/-0.039 vs 0.722+/-0.024 (p<0.001). The plasma ET-1 level in normal subjects w as 1.720+/-0.174 pg while in LTG patients it was 2.947+/-0.217 pg (p<0 .001). On the basis of our experience, we thing that GON and the visua l field damage found in LTG can be attributed to an alteration in the endothelial self-regulating sections and consequent vascular insuffici ency, particularly pronounced in the posterior ciliary arteries which, since it is these that provide the blood supply to the optic nerve he ad, leads to irreversible functional damage.