Structural proteins of the neonatal and adult lamina cribrosa.

Optic nerve heads from three premature infants and six adults were studied immunohistochemically to compare the extracellular proteins in the lamina cribrosa of young and old human eyes. In both age groups, antibodies to the basement membrane components laminin and collagen type IV were associated with blood vessels and laminar beam margins. In the adult eyes, interstitial collagen types I and III were heavily distributed within the laminar beams. Antibodies to fibrillin, the microfibrillar portion of elastin, labeled discrete, heavy bands oriented longitudinally within these beams. The beams of the neonatal lamina cribrosa contained much less interstitial collagen, with a predominance of collagen type III. Neonatal elastic tissue bands were less numerous and distinct within the laminar beams. These biochemical differences between the young and old lamina cribrosa may, in part, explain different clinical behaviors of the optic nerve head in congenital and adult glaucoma.

The extracellular matrix of the human optic nerve.

The nerve fibers of the optic nerve are enclosed and segmented by extracellular matrix. With immunostains, we localized collagen types I through VI, laminin, and fibronectin in frozen sections of the extracellular matrix of the prelaminar, laminar, and retrolaminar human optic nerve. The internal limiting lamina of the optic nerve has an extracellular composition similar to the thicker adjacent retinal internal limiting lamina. We confirmed that the lamina cribrosa contains type IV collagen and laminin, whereas the sclera does not. The septa of the retrolaminar optic nerve appear as vascular inward extensions of the pia mater. The glial tube that lines the optic nerve extends forward from the retrolaminar optic nerve through the lamina cribrosa to end anteriorly at the retinal pigment epithelium. It does not separate the optic nerve from the adjacent sensory retina.

Quantitative analysis of labelled inner retinal proteins in experimental optic neuritis.

In order to determine if axonal transport changes in chronic experimental allergic encephalomyelitis (EAE) were due to blockade or increased discharge of fast transported proteins from the inner retina, we examined the presence of pulse labeled proteins in autoradiograms of the optic nerve head, retinal ganglion cell and nerve fiber layers of juvenile strain-13 guinea pigs with chronic EAE and normal controls. Quantitative analysis of silver grains, performed six and twenty-four hours following the intravitreal injection of tritiated leucine, showed a decrease in inner retinal radioactivity in those with EAE, whereas no difference was detected between the two groups after three days. Grain counts within the optic nerve heads of guinea pigs with EAE were reduced at all time intervals studied. These results are consistent with an increase in discharge of fast transported proteins from retinal ganglion cells into optic nerve axons and support our previous observations of increased radioactivity at the foci of optic nerve demyelination.

An immunocytochemical comparison of Müller cells and astrocytes in the cat retina.

Immunocytochemical localization, at the light and electron microscopic levels, of five different known glial proteins was used to compare Müller cells with astrocytes in the adult cat retina. Retina from two different areas of the eye was examined. A region of retina on the border of the optic nerve was used because of its large population of astrocytes, and a region away from the optic nerve was used to examine Müller cells (astrocytes are sparse in this region). Antibodies to cellular retinaldehyde binding protein and glutamine synthetase labeled the Müller cells but not the astrocytes, while labeling with anti-carbonic anhydrase C, anti-alpha crystallin and anti-glial fibrillary acidic protein was found in both Müller cells and astrocytes.

Changes in the content and composition of collagen in the glaucomatous eye--basis for a new hypothesis for the genesis of chronic open angle glaucoma--a preliminary report.

The pressure theory is still predominant in explaining the pathophysiology of the chronic open angle glaucoma. An insufficient drainage system resulting in an increased intraocular pressure is the basis for this theory. The pressure will exert an effect upon the optic disc which either directly on the nerve fibres or indirectly via the vascular system will result in a characteristic optic atrophy. The collagen fibres, both in the trabecular meshwork of the anterior chamber and in the lamina cribrosa of the optic disc, form a mesh through which the aqueous humour and the nerve fibres, respectively, pass through the wall of the eye. A hypothesis explaining the pathophysiology of this disease, and based on the assumption that there is a primary change in the collagen molecules, resulting in a weaker structure than normal both in the trabeculae and in the laminae, is forwarded. The structures analysed for the content of hydroxyproline, hydroxylysine and proline were the trabecular meshwork, the sclera and the lamina cribrosa. Three categories of autopsy eyes were studied, i.e. normal eyes, glaucomatous eyes, and eyes under a suspicion of glaucoma. In the normal eyes, the collagen composition in the trabecular meshwork was different from that in the sclera and the lamina cribrosa. There is also a difference in the composition between the sclera and the lamina cribrosa. In glaucoma, the content and/or the composition of the collagen molecules in the lamina were significantly changed. In the eyes under suspicion of glaucoma the same changes as in the glaucomatous eyes could be demonstrated. However, 5 of the 7 eyes in this category had no demonstrable nerve atrophy. The findings suggest that the change in collagen pattern is primary. This study has not demonstrated which types of collagen are present or the physical properties of this collagen. Further tests to demonstrate the different types of collagen and their rigidity are planned.

Hemorrhages with optic nerve drusen. A differentiation from early papilledema.

The distinction between early papilledema and drusen of the optic disk may be made more difficult by the presence of hemorrhages. We report five patients with drusen of the optic disk and associated hemorrhages. The distinguishing characteristics of both conditions are described.

Analog vs. digital photogrammetry for optic cup analysis.

This report compares the reproducibility of analog and digital photogrammetry for topographical analysis of the optic cup. Ten simultaneous stereophotographs of each of three optic discs were taken with the Zeiss fundus camera plus a twin-prism stereoseparator. Digital processing produced photogrammetric contours of the optic cup and estimates of its geometry. Optic cup contours from the same stereopairs were also drawn with an analog stereoplotter and were analyzed by manual planimetry. The reproducibility of digital photogrammetry and analysis for estimation of cup depth, cup width, cup cross sectional area, and cup volume was concluded to be generally superior to the reproducibility of analog photogrammetry and manual analysis.

Drusen of the optic disc. A retrospective study in cadaver eyes.

A retrospective study of 737 consecutive necropsies yielded 15 cases of drusen of the optic nerve head, an incidence of 20-4 cases per thousand. This represents the highest incidence yet reported. The histopathological features of drusen of the nerve head included elevation of the nerve head, compression of optic nerve fibres, partial optic atrophy, cytoid bodies, disc haemorrhages, juxtapapillary retinal scarring with haemosiderin deposition, calcification, and iron deposition within drusen.