The mode of water flow in the Tenon's capsule and the subconjunctival tissue was studied in the rabbit. Carbon-black ink injected under the Tenon's capsule was found to move along the plane of the capsule posteriorly toward the optic nerve sheath and also along the direction of the corneal limbus, but a very little amount moved through the layers of the capsule. The flow rates of physiological saline through the capsule were determined under various hydrostatic pressures, and the water flow conductivity through the capsule averaged 8.8 +/- 5.5 X 10(-12) cm4 dyne-1 sec-1 in 7 eyes. The Tenon's capsule offered a considerable resistance to water flow through its layers. The upper conjunctiva was dissected to the limbus and the wound was closed 1) after subconjunctival injection of saline and 2) after injection of concentrated sodium hyaluronate. One month later, a needle connected to a saline reservoir was inserted into the subconjunctival tissue of the treated area and the rate of water flow into the tissue was determined under various hydrostatic pressures. The results were compared with those in the normal eye. The water flow rate was significantly less in the treated eye than in the normal eye. The eyes treated with sodium hyaluronate tended to show a higher flow rate than those treated with saline. Histological examinations revealed that an intensive scar formation took place in the dissected area, indicating that scar formation greatly reduces water flow in the Tenon's capsule and subconjunctival tissue.