Secondary vascular glaucoma is increased intraocular pressure due to venous obstruction in or outside the eye. Its main aetiological features are lesions of the vortex veins and the anterior ciliary veins and orbital and cavernous sinus obstruction; increase in orbital volume, tenonitis/scleritis posterior and idiopathically elevated episcleral venous pressure are described. In 8 out of 148 patients with exophthalmos of various aetiology an abnormal difference in intraocular pressure between the eyes was found, but only 3 of them (2%) had glaucoma; this frequency equals the glaucoma frequency in an average population. In 3 out of 10 patients with tenonitis/scleritis posterior an elevated intraocular pressure was found, in contrast with the normal intraocular pressure found in 20 patients with orbital pseudotumour. Six patients with secondary vascular glaucoma due to elevated episcleral venous pressure of unknown origin were examined; 3 of them had unilateral, the other 3 bilateral, typical lesions. All were female and above the age of 40 years. In contrast with the findings in other investigations, in 3 of these 6 patients orbital neuro-ophthalmological lesions were found.