The canine eye: pectinate ligaments and aqueous outflow resistance

The contribution of the pectinate ligaments to total aqueous outflow resistance was studied in 30 excised canine eye pairs by means of constant-pressure aqueous perfusion. Incision of these ligaments over one and two quadrants of the angle circumference increased the facility of aqueous outflow significantly more than could be attributed to normal "washout" alone. Neither mechanical nor enzymatic disruption of angle glycosaminoglycans could fully account for this phenomenon. The pectinate ligaments may therefore contribute to the canine aqueous outflow barrier by compartmentalizing the glycosaminoglycans in the spaces of Fontana. In addition, these ligaments, analogous to iris processes in the human, prevent widening of the canine angle and hold the filtration structures in a relatively compressed state, a situation that can be reversed by ligament incision.