Measurement of episcleral venous pressure.

Using materials available in any ophthalmology clinic, we constructed a useful and reliable instrument for measuring episcleral venous pressure. The instrument, a modification of the pressure chamber method of Seidel, utilizes a latex membrane and an air-filled chamber. These modifications facilitated ease of preparation for the measurement. Episcleral venous pressure in normal subjects was 9.0 +/- 1.6 mm Hg (mean +/- S.D.). Measurement of episcleral venous pressure facilitated diagnosis of diseases such as arteriovenous fistula and superior vena caval obstruction, which block drainage of venous blood from the orbit.