[Mechanical characteristics of the bovine choroid]

We studied the mechanical relationship between the tension and the length of stretch of bovine choroids. Longitudinal and circular choroidal strips (4 mm x 6 mm) were prepared at 3 different locations (I. ora serrata, II. anterior to the equator, III. posterior to the equator). Using a force transducer and a potentiometer, changes in the tension and the length of stretch were recorded simultaneously. At a tension of 600 mg, longitudinal strips stretched more than circular strips at all 3 locations (p < 0.05). Longitudinal strips all stretched to almost the same length (about 1.3 mm), but circular strips stretched less in the order of I, II and III. These results suggest that there are mechanical characteristics in the bovine choroid allowing it to stretch more in the longitudinal direction than in the circular direction.