Conjunctiva

Abstract

The conjunctiva is the mucous membrane that lines the inner surface of the eyelids and curves onto the anterior surface of the eyeball, where it extends to the cornea. It is continuous with the skin at the margin of the eyelids and with the cornea at the limbus (Wolff, 1976). Thus it forms a sac between the eyelids and the globe. Despite its small size, the conjunctiva plays a vital role in both vision and immunity. It physically protects the delicate structures of the eye by serving as a mechanical barrier to foreign substances, and it provides epithelium to cover corneal wounds (Kinoshita et al., 1983). Its goblet cells secrete mucus that forms the inner layer of the tear film and is essential for normal vision. The abundant blood supply of the conjunctiva delivers protective substances such as antibodies, complement, and white blood cells to the eye to combat infections and to remove dead or damaged tissue (Dawson, 1976, 1984). Lastly, the conjunctival, intestinal, bronchiolar, and other mucous membranes constitute the mucosal immune system (Chandler and Axelrod, 1980; Wolf and Bye, 1984), found in the regions of the body most commonly invaded by microorganisms. These topics will be discussed further in the following pages. When we began our study of the conjunctiva, our primary goal was to analyze the factors involved in the onset of an infection of the external eye. The surface of the epithelium, where invading microorganisms first impinge, had not yet been thoroughly investigated. We started by reexamining the structure of the normal epithelium and present here our observations of the structure of the conjunctiva, with emphasis on its surface. Of several species that we examined, the guinea pig most closely resembles man in conjunctival structure. Therefore, conjunctiva from pathogen‐free guinea pigs was used to illustrate this review. (See Technical Considerations.) © 1996 Wiley‐Liss, Inc.

Investigations on the conjunctival goblet cells and the characteristics of the glands associated with the eye in chinchillas (Chinchilla Laniger)

“…Because of its histological appearance, the conjunctiva was divided into four zones. Several authors graded the conjunctiva of guinea pigs, 13–18 rats, 19 and mice 20 in a different way to ours; however, in the study by Gasser et al. , 9 the zoning system in guinea pigs was reported similar to ours.…”

“…Several solitary goblet cells may occur in the conjunctiva of chinchillas. Their density and distribution vary within different zones, as in guinea pigs; 9,14–18 t ‐test for independent samples was used to compare the mean goblet cell density of each conjunctival zone with those of the guinea pig (Table 4). In all four palpebral conjunctival zones, chinchillas revealed a significantly higher goblet cell density than guinea pigs, whereas the goblet cell density in all four bulbar zones is significantly higher in guinea pigs than in chinchillas (Table 4).…”

“…A comparison to other studies in guinea pigs, rats, mice, hamsters, and gerbils is difficult because the results of these studies are not quantitative. In fact, the goblet cell density in fornices of guinea pigs was often determined as moderate to high 14,15,26 . This zone is equivalent to the lymphonodular area in the chinchilla, which did not show higher densities.…”

Mechanistic modeling of ophthalmic drug delivery to the anterior chamber by eye drops and contact lenses

“…Studies examining guinea pigs by Nichols determined that the epithelial cells are responsible for the transport of ions and water [26] while the secretion of the mucus layer is a more complex process. Goblet cells secrete gel forming mucins which give the tear film many of its rheological properties while the lacrimal gland produces smaller mucins which help lubricate and protect the eye [27,28].…”

“…ACCEPTED MANUSCRIPT 26 significantly longer time to reach the steady state pressure for the interblink phase than for the blink phase, which is not predicted by the model. This difference can be partially accounted for by considering that the lower puncta was filled with a pressure measurement device whose large diameter prevented the puncta from connecting to the tear film.…”