Collagen fibrillar network in the optic nerve head of normal monkey eyes and monkey eyes with laser-induced glaucoma - A scanning electron microscopic study

Purpose. To examine the three-dimensional organization of collagen fibrils in the lamina cribrosa of normal monkey eyes and monkey eyes with laser-ind uced glaucoma. Methods. Intraocular pressure elevation and glaucomatous optic discs were o btained in one eye of three adult monkeys by repeated applications of argon laser to the chamber angle. The monkey eyes were enucleated, and the colla gen fibrillar network was investigated by scanning electron microscopy afte r cell maceration with 10% sodium hydroxide and conductive staining. Results. In normal monkey eyes, round to oval shaped regular laminar pores through which axon bundles exited were observed in the lamina cribrosa. The straight, column-like pores or openings were formed by multilayered lamina r plates that aligned vertically in parallel with the optic nerves. The sur face of the laminar plates was covered by delicate, loosely arranged collag en fibrils. The inner surface of the pores was smooth, made up of well-pack ed collagen fibers. In glaucomatous eyes, the laminar pores were clogged by tightened collagen fibrils. The inner surface of the pores was irregular, and the pores were narrowed or distorted. Conclusions. Alterations in the three-dimensional organization of collagen fibrils were demonstrated in the optic nerve head of glaucomatous monkey ey es. The architectural changes may affect the flexibility and resilience req uired of the lamina cribrosa in supporting optic nerve fibers.