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Corneal clouding is one of the manifestations of Tangier disease, an inherited disorder in which cholesterol-rich lipids are deposited in various tissues of the body. The cause of the corneal clouding is unknown. This study documents the clinical course and conjunctival biopsy findings of a 60-year-old man who was one of the earliest patients to be recognized with Tangier disease and in whom progressive corneal clouding developed in adult life. Noteworthy in the biopsy specimens were birefringent lipid particles that were predominantly present in degenerating pericytes of the conjunctival vessels.

Uveitis was induced rhesus monkeys immunized with purified retinal S-antigen. Focal retinal and subretinal infiltration, in addition to periphlebitic changes, were observed histologically. Immunized monkeys had similar cell-mediated in vitro immune responses to the S-antigen as do humans with posterior uveitis. Circulating immune complexes at the time of disease could not be detected. This primate model supports the notion that the S-antigen may play a role in human uveitis.

The Richner-Hanhart syndrome with tyrosinemia was recognized in a mentally retarded adolescent boy. The clinical manifestations, including hyperkeratosis of the volar aspects of the hands and feet, thickening of the conjunctival epithelium, and corneal opacities, as well as biochemical aberrations of tyrosine metabolism, responded to specific treatment with a diet low in phenylalanine and tyrosine. Light and electron microscopical studies illustrate the underlying conjunctival pathologic changes.

Interphotoreceptor retinoid-binding protein was found to be highly uveitogenic in primates. All six monkeys immunized with bovine interphotoreceptor retinoid-binding protein developed ocular inflammation. The main clinical changes were sheathing of retinal vessels and deep well-circumscribed yellow-white lesions. Histologic changes in the retina included shortening of the outer segments and foci of inflammation, which extended through all retinal layers. Particularly profound were the choroidal changes, such as severe inflammatory infiltration, which often formed focal granulomas with epithelioid and giant cells. Some granulomas had the structure of Dalen-Fuchs nodules. These structures and other histologic changes in the monkeys closely resemble those in uveitic conditions in humans, such as sympathetic ophthalmia or Vogt-Koyanagi-Harada syndrome. These findings show that antigen that localizes specifically in the retina may initiate an immunopathogenic process affecting mainly the choroid.

The effect of bright light on the retinas of developing albino rats was studied electron microscopically. The newly formed outer-segment lamellar membranes of newborn rats raised in continuous bright light appear to be less sensitive to the damaging effects of light, compared to those of rats raised under normal light conditions for at least two weeks. It seems to take about two days before the membranes show damage from continuous exposure to fluorescent lamps. The same brightness damages the adult outer segments within a few hours. Despite the severe damage to the outer segments, the rest of the retina develops normally for one month, and then the photoreceptor cells undergo degeneration. The retinas that have been exposed to bright light for two weeks after birth show considerable damage, but these retinas regenerate in six months.

Immune intraocular inflammation was induced in primates with homologous retinal outer segments. Perivascular retinitis, uveitis, and edema of the optic nerve head were the prominent acute clinical features. Acute and chronic inflammation was seen in the central and peripheral retinal vessels and granulomatous infiltration was present in the choroid of the uvea. Selective degeneration of the outer segments of the photoreceptor cells of the retina with sparing of the inner segments and of the adjacent pigment epithelium was confirmed by light and electron microscopy. This study strongly suggests that photoreceptor outer segments are highly and specifically immunogenic. The inciting antigen has yet to be identified. Implication of rhodopsin will have to await further studies since it exists as the essential protein in the outer segment.

An eye from a patient with systemic sarcoidosis and active ocular involvement was studied by the use of monoclonal antibodies and the immunoperoxidase technique to identify the subtypes of infiltrating cells and the presence of lymphokines. Large numbers of lymphoid cells reacting with anti-pan T cell (Leu-4) and anti-T helper/inducer (Leu-3a) subsets were observed around and within sarcoid granulomas. Only rare T suppressor/cytotoxic cells (Leu-2a) were observed. B lymphocytes and plasma cells were present in a few foci. Within the granuloma, T lymphocytes, macrophages, and epithelioid cells showed membrane labeling for interleukin 2 receptors and interferon gamma. We demonstrate the in vivo expression of interleukin 2 receptors and the release of interferon gamma by mononuclear phagocytes and T lymphocytes in ocular sarcoidosis, and we theorize about the activated T helper cell-derived lymphokines in macrophage activation and sarcoid granuloma formation in the eye.

The pigment epithelium of the normal monkey was studied by scanning and transmission electron microscopy. Appearance of microvilli of the cell are demonstrated and compared topographically. The apical surface of the pigment epithelium consists of densely distributed fine microvilli. No thick portion of the villi or the cell borders are seen in normal conditions. The attachment of the epithelium and the outer segment is extremely firm and breakage of the microvilli or outer segments occurs easily in the attempt to separate these two layers.

The human and monkey orbicularis muscle has fibers that are more uniform in size and structure than those of rectus muscles. They have distinct myofibrils, a moderate number of mitochondria, and a well-developed transverse T-tube system. The levator muscle also has relatively uniform fibers, but the myofibrils are less distinct than those of the orbicularis. Especially noteworthy is the unusual arrangement whereby Muller muscle arises directly from the undersurface of the levator muscle, causing an intimate intermingling of smooth and striated fibers. Muller muscle then inserts on the tarsus, whereas the levator muscle extends by an aponeurosis into the septa of the orbicularis muscle. In surgical specimens from patients with ptosis, the levator fibers show varying degrees of abnormality, whereas Muller fibers are normal.

Retinas of the paranatal period contain two types of cell clusters that are generally believed to play a role in the developing vasculature. The more posterior cluster consists of angioblastic cells, which undergo lumenization to form the definitive vessels. Anterior to this cluster and separated from it by a distinct boundary are clusters of spindle cells extending a variable distance toward the periphery. These clusters of spindle cells maintain a fixed position relative to the angioblastic masses, without any admixture of the two. The precise function of the spindle cells in the vascularizing process has been a subject of controversy. We found evidence to identify them as glia and to suggest that their role is to provide an energy source for the developing retina as the hyaloid vessels recede and until the retinal vessels take over this function. It further appears that congenital failure of the vessels to develop may result in a persistence of these spindle cells, in the form of hyperplastic glia in the inner layers of the retina. Our study included normal eyes from full-term and premature infants and eyes from patients with retinopathy of prematurity (oxygen-related retinopathy), anencephaly, and other congenital anomalies.