Endothelin-1 has been implicated as contributor to a variety of different diseases. Plasma concentrations of the peptide have been found to be increased up to 10-fold in cardiovascular diseases, primary pulmonary hypertension, vasospastic disorders, but also in patients with renal failure or solid tumors (for reviews, see Jain et al.
2 and Shah
3). To ensure that the observed increases in ET-1 in glaucoma patients in previous studies were not confounded by increased ET-1 concentrations in blood plasma we excluded patients with any other condition that might be related to an increase in ET-1 plasma concentration.
These include the following: cardiovascular diseases > Grade II (as classified by the New York Heart Association), previous stroke or myocardial infarction, vasospastic disorders (e.g., migraine, Prinzmetal's Angina, Raynaud's Syndrome), autoimmune diseases, malignant tumors, pulmonary diseases (including asthma, chronic obstructive pulmonary disease, chronic bronchitis, primary pulmonary hypertension), insulin-dependent diabetes mellitus, and all kidney disorders.
Patients with a history of ocular disease other than those specified in the inclusion criteria, as well as patients with ocular manifestations of other diseases, such as diabetic or hypertensive retinopathy, were excluded from the study. Patients who had undergone previous ocular surgery (including refractive and cataract surgery) were also excluded.
Based on these inclusion and exclusion criteria, we screened approximately 2300 patients scheduled for either cataract surgery or trabeculectomy in our clinic over the course of 2 years. In all, 110 patients were included in the study.