The collagen architecture of the sclera--SEM and immunohistochemical studies

The arrangement of the collagen fibrils of the sclera was analyzed at defined areas by using SEM with regard to morphological alterations in cases of glaucoma and to postoperative astigmatism after cataract operations. Adult eyes with no apparent pathological changes were studied. In the lamina cribrosa the collagen fibrils are arranged circularly around the points of passage of the axons and vessels. In the region of the muscle attachments the tendinous collagen fibrils intersect the bundles of collagen fibrils of the sclera at right angles. The collagen fibrils form a reticular structure on the external surface of the sclera. A main route of alignment can only be identified in a few places. The collagen fibrils are aligned in a rhombic pattern on the internal surface of the sclera. The immunohistochemical analysis revealed collagen types I and III in the sclera, while collagen types I, III and IV were found in the lamina cribrosa.