Subconjunctival hemorrhage: overview and management

Subconjunctival hemorrhage is a commonly presenting clinical problem for the optometrist. Although it is usually benign, it can be caused by a variety of entities, each with their own important sequelae. It is necessary to perform a comprehensive work-up of a patient with this problem including a thorough case history to rule out trauma, infection, medications, or systemic disease as the causative agent. The anatomy of the conjunctiva is reviewed, examination procedures are described, management issues are discussed, and case reports are presented.

Leukotrienes cause eosinophil emigration into conjunctival tissue

The ability of LTB4, LTC4, the 5S,6R and 5R,6S LTD4 stereoisomers, and LTE4 to evoke leukocyte infiltration into the conjunctiva was demonstrated in the guinea pig by histological and light microscopy techniques. LTD4 and LTE4 demonstrated a dose-dependent and predominantly eosinophilic infiltrate over the selected dose range (10 ng to 1000 ng), while there was only a minimal response to LTC4. LTB4 produced marked eosinophil infiltrates only at the highest dose; scattered neutrophil infiltrates were also noted at the high dose of LTB4. The 5R,6S LTD4 stereoisomer did not evoke any leukocyte infiltration. The SRS-A antagonist, FPL 55712, abolished peptidoleukotriene-induced eosinophil emigration, and indomethacin pre-treatment had no inhibitory effect, indicating direct mediation of this response by LTs. Histamine caused a comparable eosinophilia over a dose range of 10 micrograms to 1000 micrograms. LT-induced eosinophil emigration was directed to the conjunctival epithelium; the cells appeared intact and no tissue damage was observed. These results may have relevance in the areas of allergic conjunctivitis and asthma research.

[Scanning electron microscopy image of the cells of the conjunctival epithelium in specimens from impression cytology]

Impression cytology specimens of the conjunctiva can be examined by scanning electron microscopy. If a cellulose-acetate filter is pressed onto the conjunctiva, the microvilli-bearing epithelium becomes so firmly attached to the fine meshwork of the filter that the most superficial conjunctival cell layers adhere to the filter. When the filter is removed intercellular connections are destroyed without any damage to the cell membranes being detectable in the SEM image. Since the surface of the corneal epithelium is spread out on the filter and is firmly attached to it the lateral bond between the cells is preserved. Shrinkage is minimal. The posterior surface of the epithelial cells, facing the observer, consists of smooth, porous cell membranes. The nuclei of many cells are clearly distinguishable. Since it can be directly compared with light-microscopic specimens, the SEM image can help provide answers to morphological and pathological questions, and may represent a useful diagnostic aid.

[Human corneal fibroblasts and a human conjunctival cell line (Chang) produce a thymocyte-activating factor (TAF) in vitro]

A variety of distinct cells such as fibroblasts, epidermal cells, glioblastoma cells and corneal epithelial cells have been shown to produce Interleukin 1-like thymocyte-activating factors. Under in vitro conditions these cytokines influence a multiplicity of different cell types, including lymphocytes, fibroblasts, PMN and hepatocytes. In the present study human corneal fibroblasts, as well as the human epitheloid conjunctival Chang cell line were found to produce thymocyte-activating factors (TAF). The molecular weight of the corneal fibroblasts-TAF was found in the 670 kD region, with minor peaks of activity at 30, 17 and 4 kD. TAF from the Chang-cell line eluted at 15-25 kD. Chromatofocusing revealed the pI of the fibroblast-TAF to be at 6.7 and 5.2 and the pI of the conjunctival cells to be at 7.0, 5.3 and 5.0. The latter cells produced prostaglandin E2 upon stimulation. The immunomodulating properties of these cytokines make an important in vivo role in the pathogenesis of inflammatory corneal and conjunctival diseases probable.

Biochemical transformation of bulbar conjunctiva into corneal epithelium: an electrophoretic analysis

When the entire corneal epithelium of the rabbit is mechanically removed, the denuded corneal stroma is completely resurfaced in 5-10 days with cells of conjunctival origin. The conjunctival cells differ from the corneal epithelial cells both morphologically and biochemically; however, within approximately 6 weeks, the conjunctival cells are converted into functional cornea epithelial cells. Using high-resolution agarose-gel electrophoresis, we compared the soluble proteins from functional conjunctiva (CON), functional corneal epithelium (EPI), and 'regenerating' corneal epithelium at eight intervals ranging from 24 hr to 6 weeks post-scraping. Comparison of CON and EPI patterns shows nine major mobility classes of proteins that fall into three subgroups: A = anodal, B = intermediate, and C = cathodal. The nine major classes have marked similarity in distribution and mobility, which may account for the apparent ease with which CON can transform into EPI during regeneration. Electrophoretic patterns of soluble proteins from regenerating epithelium suggest that the regeneration process occurs in three distinct phases: 24-72 hr post-scraping is a period of de-differentiation, 72 hr to 1 week is a period of reorganization, and 1-6 weeks is a period of differentiation. Specific protein groups are identified that represent fast-transforming, slow-transforming, conjunctival-specific, and corneal-specific proteins. Certain of these protein groups can be associated with particular stages in the regenerative process.

[Corneal epithelial cells and human conjunctival cell line (Chang) produce an interleukin 3-like factor]

Tissue mast cells play a central role in the pathogenesis of allergic eye diseases. In the study reported here the authors investigated whether human corneal epithelial cells and a human epitheloid conjunctival cell line (Chang) can produce an interleukin 3 (IL 3)-like mast cell-activating factor. The activity was detected at a m.w. of 15 and 30 kD, the isoelectric points were located at a pH of 7.85, 7.15 and 6.75. The authors believe that this cytokine, which is produced by epithelial cells of the cornea and conjunctiva, might play an important role in the pathogenesis of allergic ocular diseases.

Fluorouracil (5-FU) and cytarabine (ara-C) inhibition of corneal epithelial cell and conjunctival fibroblast proliferation

We evaluated the antiproliferative properties of fluorouracil (5-FU) and cytarabine (ara-C) in a tissue culture model of rabbit corneal epithelial cells and conjunctival fibroblasts. Cells were treated with fluorouracil or cytarabine for five days. Corneal epithelial cell proliferation was inhibited to 50% of control proliferation by 0.6 mg/L of fluorouracil or 30 micrograms/L of cytarabine. Proliferation of conjunctival fibroblasts was inhibited to 50% of control by 0.5 mg/L of fluorouracil or 50 micrograms/L of cytarabine. The antiproliferative effect of 10 mg/L of fluorouracil was not blocked by thymidine. The inhibition of proliferation produced by 100 or 1,000 micrograms/L of cytarabine was blocked by 2'-deoxycytidine at concentrations of 10(-5) M and 10(-4) M, respectively. The antiproliferative effects of fluorouracil and cytarabine appear similar for both cell types. Blockage of cytarabine-related ocular toxic effects may be possible with 2'-deoxycytidine.

Effect of anaphylaxis on conjunctival goblet cells

Rats undergoing ocular anaphylaxis induced by systemic or local injection of antigen, topical application of antigen, or topical application of compound 48/80 were evaluated conjunctival goblet cell changes that might be related to anaphylaxis. The number of goblet cells in 1 micron, alkaline Giemsa-stained sections averaged 500/mm2 of epithelium in normal rats; this number was not significantly changed in any of the experimental groups. Goblet cells in control rats occasionally demonstrated evacuation of their contents (less than 1%) or upward displacement of the intracellular bolus of mucus (about 1%); these percentages were not increased in anaphylaxis. Topical application of 2.0 micrograms of histamine induced an intracellular displacement of mucus in both control animals and animals undergoing anaphylaxis. These findings suggest that in ocular anaphylaxis the amount of histamine released may be insufficient to produce such intracellular changes. Our results indicate that in ocular anaphylaxis in the rat, there is no light microscopic evidence of increased mucus discharge from conjunctival goblet cells. Increased mucus in secretions of patients with ocular allergic syndromes may not be attributable to anaphylactic mechanisms alone.

Cell proliferation in condensing scleral ectomesenchyme associated with the conjunctival papillae in the chick embryo

The role of cell proliferation in the formation of scleral ectomesenchymal condensations underlying the conjunctival papillae was examined with in vivo tritiated thymidine labelling in chick embryos ranging in age from 8 days 0 h to 10 days 12 h. Percentages of labelled nuclei were determined in both ectomesenchyme and the deeper fibrous sclera for short-term and continuous tritiated thymidine incubations. During formation of the ectomesenchymal condensations the percentages of labelled nuclei were consistently higher within the condensations than in corresponding non-condensing ectomesenchyme between papillae. The consistent differences of labelling percentages observed within the condensing versus non-condensing ectomesenchyme were not found in the fibrous sclera at any stage. All areas of both the ectomesenchyme and fibrous sclera showed decreases in the percentages of labelled nuclei from 8 days 0 h to 10 days 12 h, although the decline in the ectomesenchymal condensations beneath papillae occurred more slowly than in areas between papillae. The data suggest that the conjunctival papillae directly influence the proliferation in the subjacent condensing ectomesenchyme but have no effect on the ectomesenchyme between papillae or any region of the deeper fibrous sclera. The observations of this investigation are discussed in relation to other studies of the development of the pre-ossicular mesenchyme.

Collagen gel for ocular surface

A replacement ocular surface requires a substrate that is easily manipulated surgically, does not cause an inflammatory reaction, and is nontoxic to epithelial cells. This work evaluates the usefulness of a collagen gel as a substrate for corneal epithelial cells by determining the ocular toxicity of the gel and the ability of the gel to support and maintain corneal epithelial cells in vitro. Collagen gels, made from Vitrogen, were easily manipulated and were well-tolerated in rabbit eyes for up to 6 wk (n = 3). Epithelial sheets placed on collagen gels and incubated at 37 degrees C for up to 13 days remained well-apposed to the gels and appeared normal, but thinned, from five to three layers. The basal cells extended cytoplasmic blebs into the gels, but only one sheet of five sheets showed basement membrane deposition by 6-13 days. Thus, the collagen gels appear to meet the criteria defined above and may be a suitable substrate in biofabricated ocular surfaces.

5-Fluorouracil toxicity to the ocular surface epithelium

The antimetabolite, 5-fluorouracil (5-FU), has been used to control proliferation of retinal pigment epithelial cells and fibrocytes, and is currently the subject of a multicenter clinical trial of its value in the control of scarring after glaucoma operations. To evaluate possible ocular surface toxicity, the effect of 5-FU on the mitotic rate and differentiation of the ocular surface epithelium in rabbits was measured. 5-FU was instilled into eyes with 10-mm diameter central epithelial wounds and into nonwounded eyes at a dose of 9 mg per day for 4 days. Saline treated control wounded eyes healed within 4 days (n = 5) while 40% (4 of 10) of the 5-FU treated wounded eyes had defects at 4 days. The normal mitotic rate of the corneal epithelium was 1.0 +/- 0.3 (n = 4) tritiated thymidine labeled cells per 100 basal corneal epithelial cells after 2.5 hr incubation. Saline treated control wounded eyes had an increased mitotic rate, 7.1 +/- 1.3 (n = 5) labeled cells per 100 basal corneal epithelial cells after 2.5 hr incubation. Topical 5-FU decreased both of those rates to about 1% of normal. The normal conjunctival epithelial mitotic rate was 1.8 +/- 0.4 (n = 4) labeled cells per 60 basal cells after per 2.5 hr incubation. This rate was the same in wounded eyes, but was decreased in eyes treated with 5-FU. Thus, 5-FU (9 mg/day topically) has serious toxic effects to ocular surface epithelium which must be carefully considered if this drug is to be used clinically.

Histochemical analysis of secretory vesicles in nongoblet conjunctival epithelial cells

An Alcian-blue/Periodic acid Schiff reagent (AB/PAS) pH dependent staining method was used to identify the mucus content of secretory vesicles of non-goblet epithelial cells of the human conjunctiva. Twenty subjects were selected for biopsy of the midcentral upper tarsal conjunctiva: 10 subjects had no contact lens wearing experience, and 10 subjects wore contact lenses. Human respiratory epithelium was used as a control for the staining procedure. Four-micron paraffin sections of conjunctival and control tissues were stained with Alcian blue at pH 2.5 and 1.0 and counterstained with PAS. Non-goblet epithelial cell secretory vesicles contained neutral mucin, sialmucin, and sulphomucin. This study provides evidence for a 'second' mucus system of the conjunctiva, that this system is in the non-goblet epithelial cells, and that the mucus of this system has sulphomucins, sialomucins and neutral mucins.

Removal of viable sheets of conjunctival epithelium with dispase II

A technique (based on Gipson and Grill, Invest Ophthalmol Vis Sci 23:269, 1982) has been developed to obtain pure, viable, intact sheets of rabbit conjunctival epithelium free of the underlying basement membrane. After preparing a full thickness eye wall resection, Dispase, grade II (neutral protease-Bacillus polymyxa), 1.2 Units/ml MEM is injected intrasclerally. The conjunctiva and sclera are pinned in agar and incubated in the dispase with MEM for 1 hour. A 2 X 3 mm sheet of conjunctival epithelium can be dissected bluntly. Light microscopy shows a two- to three-layered epithelium with many goblet cells. Transmission electron microscopy reveals blebbing at the freed basal epithelial cell membrane, intact desmosomes, and intact goblet cells. The conjunctival sheets were cultured on epithelial-scraped corneal stromal carriers in vitro. Numerous goblet cells were present up to 12 hours on 4-mm carriers and 24 hours on 1-mm carriers. With this technique, pure populations of conjunctival epithelium can be isolated for further characterization and tissue culture.

Goblet cell density and vascularization during conjunctival transdifferentiation

After debridement of the entire corneal epithelium with n-heptanol, two groups of rabbit corneas were segregated according to the extent of corneal neovascularization. Using a new topographic goblet-cell counting method and routine histology, the authors have reexamined the process of conjunctival transdifferentiation and compared the changes of goblet-cell density and morphology between nonvascularized and vascularized groups for a follow-up period of 167 days. Analysis of the total goblet-cell density disclosed that no goblet cells appeared on the corneal surface during the entire period of reepithelialization. After that, two phases were identified with respect to goblet-cell density: phase I (day 0-17) and phase II (after day 17). In phase I, both groups had a similar surge of goblet cells, with the peak occurring between days 7 and 11, suggesting little correlation with vascularization. Morphologic studies indicated the presence of a prominent centripetal cellular migration. In phase II, the nonvascularized group showed a rapid decline in goblet-cell density, and as a result the morphologic transdifferentiation into a cornea-like epithelium was completed on day 43. The changes of goblet cells to a smaller size and the presence of a more acidic mucin in the centrifugal receding zone, suggested that transdifferentiation on nonvascularized corneas is a process involving changes of cellular differentiation. In contrast, the vascularized group maintained a high plateau of goblet-cell density and an epithelium with conjunctival characteristics until day 167. This result disclosed that retardation of conjunctival transdifferentiation by corneal vascularization was in phase II. The possible role of vascularization in the modulation of conjunctival transdifferentiation is discussed.

Effect of antineoplastic drugs on fibroblast proliferation in rabbit aqueous humor

An assay is described to test the ability of antineoplastic agents to slow fibroblast growth. The effect of bleomycin sulfate, cytosine arabinoside (cytarabine), and 5-fluorouracil on suppression of fibroblast proliferation in 20% rabbit aqueous humor was studied in vitro. All of the drugs exhibited some suppression of fibroblast proliferation at differing doses. The choice of target cell, however, was an important factor in the dose responses obtained.

Cellular structure of the conjunctival epithelium of rabbits

In rabbits, five different cell types were distinguished within the superficial cell layer of the conjunctival epithelium according to their ultrastructural appearance of cell organelles. These cell types also show a characteristic distribution within the various regions of the lids. The second cell type which is not found in the conjunctiva of primates is characterized by large osmiophilic granules. It is assumed that these cells are particularly important for the production of the lipid layer of the tear film preventing the rabbit cornea from evaporation.

Conjunctival epithelial wound healing

In vivo conjunctival epithelial healing in albino rabbits was investigated by light microscopy following both n-heptanol and trephined conjunctival wounding. Reepithelialization occurred faster following n-heptanol treatment (3 days) versus trephination (6-7 days). No goblet cells were present in the migrating epithelium during reepithelialization. After 1 day of wounding, goblet cells disappeared several millimeters peripheral to the wound margin in both types of wounds. Goblet cells first reappeared peripherally 1 week after wounding before they appeared in the central wound area. These observations indicate that a large area of conjunctival epithelium surrounding a wound is involved with repair of that wound. Since the goblet cell content of conjunctival epithelium appears to change as a result of the stresses of epithelial repair, the goblet cell population may reflect the presence of reparative or proliferative processes in the ocular surface.

Possible mechanisms for the loss of goblet cells in mucin-deficient disorders

By studying the pathological changes in human conjunctival flaps and the conjunctival transdifferentiation in rabbits, we have identified and correlated two pathological processes with the loss of goblet cells: (1) loss of vascularization, and (2) intense inflammation. Loss of vascularization may be correlated with the loss of goblet cells in the chronic cicatricial stage of various mucin-deficient disorders, whereas inflammation may be responsible for their absence in the acute inflammatory stage. The exact interrelationship between these two processes remains unknown. The loss of goblet cells appears to be an early sign of a spectrum of squamous metaplasia, an abnormality of epithelial differentiation. We therefore speculate that loss of vascularization and intense inflammation may have an important effect on epithelial differentiation.

Application of lectins for detection of goblet cell carbohydrates of the human conjunctiva

Paraffin-embedded and frozen biopsies from the human conjunctival epithelium were examined by fluorescence microscopy after labeling with eight fluorescein-conjugated lectins: wheat germ agglutinin; soybean agglutinin; peanut agglutinin; Ricinus communis agglutinin-1; Limulus polyphemus agglutinin; Ulex europaeus agglutinin-1; Dolichos biflorus agglutinin; concanavalin A. The lectins were used as specific molecular probes to detect carbohydrate composition of glycoproteins secreted from the conjunctival goblet cells. The labeling pattern of goblet cells and conjunctival epithelial surfaces with various lectins suggested that N-acetyl-glucosamine, galactose, N-acetyl-galactosamine and sialic acid are contained in goblet cells and contribute to the formation of tear mucus glycoprotein. Fucose and mannose, which are present in the tear mucus, were not detectable in goblet cells.

The surface of the conjunctiva in domestic ruminants. A scanning electron microscopic investigation

The surface of the conjunctiva was investigated in goats, sheep and bovines. The lid-facing surface of the nictitating membrane carries a serrated crest. At a low magnification the areas covered by a stratified squamous epithelium appear as a mosaic. In the superior and inferior conjunctival fornices the mucous membrane has a uniform appearance. Areas of goblet cells have an irregular appearance. Four functional stages can be observed in the goblet cells. At a high magnification the superficial cells of the palpebral and bulbar conjunctiva are covered by microplicae. In the fornix conjunctival microvilli project over the superficial cells.

Diurnal variation of some cytological characteristics of the conjunctiva

Variation of conjunctival cells of healthy non-contact lens wearing subjects is described using an impression biopsy technique over a period of nine waking hours. The total cell count was found to be highest on waking, falling to about half that value during the first 3 h, attributable almost exclusively to the change in the neutrophil count. A further slower decrease and finally a small increase in some cellular components was noted.

Conjunctival goblet cell frequency after alkali injury is not accurately reflected by aqueous tear mucin content

Goblet cell counts have been used to evaluate the suitability of conjunctiva as a source of ocular surface epithelial cells. However, since tear mucin content can be determined without tissue excision, it seemed that the concentration of those compounds might be a useful indicator of conjunctival vitality. To test the extent to which aqueous tear composition reflects conjunctival goblet cell frequency, goblet cell frequency and aqueous tear mucin content were measured after alkali injury in rabbits. Mild alkali injury (0.1 N NaOH for 30 sec) caused a transient but substantial decrease in goblet cells (to 25% of normal at day 7) with a return to normal by six weeks. Tear mucin content was decreased to a lesser degree, from a normal value of 6.4 +/- 0.47 nmol oligosaccharide per microliter (n = 10) to a minimal value of 4.7 +/- 0.64 (n = 7) (73% of normal) at day 7, returning to normal 4 weeks after injury. Thus, the direction of the change was the same, but the magnitudes were quite different. These results suggest that conjunctival goblet cell frequency is not accurately reflected by aqueous tear mucin content, and therefore, that tear mucin content cannot be used directly as an indicator of conjunctival health.

Experimental intraocular proliferation and neovascularization

An experimental model of massive periretinal proliferation and intraocular neovascularization, produced in rabbits by the intravitreal injection of 250,00 cultured heterologous fibroblasts, showed no significant difference in the detachment rate (69% to 100%) or neovascularization rate (45% to 88%) between the animals injected with autologous cells and those injected with heterologous cells. Dermal fibroblasts produced a slightly higher detachment rate than conjunctival fibroblasts and were equally effective after reconstitution and subculture from liquid nitrogen storage in 7% dimethyl sulfoxide. Heterologous cells produced no clinical or histologic evidence of rejection when compared with autologous cells in the same animal and had the following advantages: (1) elimination of several biopsies and extended cell culture time; (2) a ready source of cryopreserved cells is available; (3) multiple injections of many animals can be performed within a short time; (4) in vivo and in vitro drug testing can be correlated on the same cell line.

Regulation by vitamin A of envelope cross-linking in cultured keratinocytes derived from different human epithelia

When keratinocytes derived from different squamous epithelia are cultured in the absence of vitamin A, they form cross-linked envelopes during the last stage of terminal differentiation. Addition of the vitamin inhibits envelope formation, but the degree of inhibition is not the same for different keratinocyte subtypes. In the presence of low concentrations of retinyl acetate, conjunctival keratinocytes form virtually no cross-linked envelopes; esophageal and vaginal keratinocytes are less sensitive to the vitamin, and epidermal keratinocytes are the least sensitive. The suppression of cross-linked envelope formation is not associated with a proportional decrease in the concentration of involucrin, a precursor of the envelope, but occurs at the level of cross-linking itself, a process dependent on an increase in the intracellular concentration of calcium ions. Keratinocytes in which spontaneous envelope cross-linking has been prevented by retinyl acetate promptly form cross-linked envelopes if Ca2+ is introduced into the cytoplasm.

Goblet cell response to vitamin A treatment for corneal xerophthalmia

In 11 patients with active corneal xerophthalmia, conjunctival biopsies were obtained at various intervals after massive-dose systemic vitamin A therapy. Goblet cells began to repopulate the inferonasal quadrant of the conjunctivas after two weeks, and they reached normal concentrations after one month. Corneal healing proceeded much more rapidly than that, suggesting that a full complement of mucus-secreting conjunctival goblet cells is not essential for restoration and maintenance of normal corneal appearance.

Langerhans cells of the ocular surface

Recent evidence has been collected by several investigators defining a distinct population of dendritic cells (Langerhans cells) of mesenchymal origin residing in the epidermal surfaces of many mammalian species. These cells play a dominant role in the processing of antigens presented through cutaneous surfaces and carry a Class II histocompatability antigen felt to be of central importance in the afferent arm of allograft rejection. They also possess many of the characteristics of macrophages active in the efferent arm of immunologic responses. An equivalent subset of dendritic cells (Langerhans cells) in ocular surface epithelium of the human, mouse rat, and guinea pig has been identified by enzyme histochemistry, immunofluorescence, and electron microscopy. Ocular surface Langerhans cells proliferate in the setting of corneal inflammation (remote and recent) and are depleted by topical and systemic corticosteroids. Ocular surface Langerhans cells may play a central role in ocular contact hypersensitivity, corneal allograft rejection, and ocular surface immune surveillance.

Cell surface variations of the human upper tarsal conjunctiva

Fifteen specimens of the upper tarsal conjunctiva were obtained from subjects with biomicroscopically normal conjunctivae. Ten specimens were examined by scanning electron microscopy and five by transmission electron microscopy. This examination was performed to examine cells with variant surface morphologic appearance that may be signs of the initial changes typical of those seen in the diseased conjunctiva. Although most specimens had cells with a characteristic uniform distribution of microvilli, seven specimens had cells with nonuniform microvillar patterns. In these seven specimens, less than 5% of the cells showed these changes. Cell surface variations marked by reduced cell diameters and alterations in the microvillar distribution were categorized into two groups: cells with microvilli that were grouped together to form tufts of varying height and number, and cells with a single, centralized group of microvilli. These variations were seen with increased frequency in disease, and it is postulated that the microvillar changes described in this study represent a continuum of adaptive responses of cells to insult and disease.

Specialized cell types and their regional distribution in the conjunctival epithelium of the cynomolgus monkey

In the superficial layer of the conjunctival epithelium of cynomolgus monkeys, five different cell types were found. The cell types were distinguished by ultrastructural criteria (e.g., cell organelles and cytoplasma) and are defined as follows: type I are the goblet cells; type II is characterized by the content of small electron-dense granules type III is particularly rich in Golgi material, type IV contains a specifically large amount of ER; type V shows an exceptionally large number of mitochondria. The quantitative evaluation of these cell types in 15 areas of the conjunctiva of 3 animals revealed a characteristic pattern of regional distribution, which may reflect the otherwise unknown functional significance of most of these cell types.

Change with age in limbal conjunctival epithelial Langerhans cells

The distribution of Langerhans cells (LC) in corneal and conjunctival epithelial flat mounts obtained from outbred albino Swiss-Webster mice of various ages was examined by histochemical methods. The LC stain positively with ATPase and were negative to DOPA-oxidase. Mouse pup limbal conjunctival epithelium showed one or two LC/mm2. LC began to significantly increase in number by day 31 and ranged from 150-205/mm2 in 7-48 week old mice. A slight decrease in LC was seen in 12 and 24 month old mice.

Langerhans cells in the normal conjunctiva and peripheral cornea of selected species

The distribution of Langerhans cells (LCs) in human corneal and conjunctival epithelial sheets was investigated by histochemical, immunofluorescence, and immuno-electron microscopic methods. The LCs stained positive with ATPase and with antibodies to HLA-DR antigen and were negative to DOPA-oxidase. Human conjunctiva showed 250 to 300 LCs/mm2 compared to 15 to 20/mm2 in the peripheral third of the corneal epithelium, approximately similar of LCs were present in Lewis rat, fewer cells in guinea pigs and mice, and no detectable cells in the chick.

Involucrin synthesis and tissue assembly by keratinocytes in natural and cultured human epithelia

Different stratified squamous epithelia, whether they bear a stratum corneum or not, are shown by immunofluorescence to possess the precursor protein of the cross-linked envelope that is characteristic of epidermal s. corneum. This protein, involucrin, is not present in the deepest epithelial cells but appears in the course of their outward migration. The boundary at which involucrin first appears can sometimes by correlated with a visible boundary between zones of large and small cells. Cultured keratinocytes, derived from all stratified squamous epithelia (epidermal, corneal, conjuctival, esophageal, lingual, and vaginal), form colonies that grow together to form a stratified epithelium. The cells of the basal layer are nearly always free of detectable involucrin, but, in contrast to the natural epithelium, this protein usually makes its appearance in the cells immediately above the basal layer. When a cultured epithelium derived from epidermal keratinocytes is detached and applied as a graft to animals, the cells flatten and the distinctness of the basal layer is at first reduced; but with time the organization of the epithelium becomes more characteristic of epidermis. Cell size and shape become more orderly along the cell migration pathway, and involucrin first appears at some distance from the basal layer, instead of in immediately suprabasal cells, as in the cultured epithelium. The progeny of dissociated and cultured keratinocytes are therefore able, when grafted, to reassemble an epidermis in which the timing of specific gene expression is restored to that of the original tissue.

Corneal re-epithelialization from the conjunctiva

After debridement of the entire corneal epithelium, epithelial cells of conjunctival origin cover the exposed corneal surface. Four to five weeks later, these cells undergo a morphologic transformation to normal-appearing corneal epithelium. To study this transformation the entire corneal epithelium was removed from rabbits with the use of n-heptanol, after which the histologic appearance of and the number of goblet cells in the regenerated epithelium were noted. Five stages of transformation were seen. Immediately after healing, the epithelium consisted of one to two squamous cell layers with no goblet cells apparent at the light microscope level (stage 1). In the following weeks goblet cells appeared at the limbal edge of the cornea (stage 2), reached a uniform distribution across the cornea (stage 3), and subsequently receded toward the limbus (stage 4), leaving an epithelium with normal corneal morphologic appearance (stage 5). To see if there was an ongoing centripetal cell migration from the conjunctiva across the cornea after initial healing, the central corneal epithelium was isolated from the periphery by a ring of glue. Such isolation resulted in a thinning of the central epithelium and a thickening of the peripheral epithelium. These studies suggest that (1) the transformation into corneal epithelium lags behind defect closure by 4 to 5 weeks, (2) goblet cells do not initially migrate as recognizable cells, and (3) there is a continuous centripetal cell motion even after the initial defect closure is accomplished.

Density of goblet cells in vernal conjunctivitis and contact lens-associated giant papillary conjunctivitis

Using light microscopy, the density of goblet epithelial cells was determined in the conjunctival epithelium of ten patients with vernal conjunctivitis, ten patients with contact lens-associated giant papillary conjunctivitis, and ten normal subjects. The median density was 13,000/cu mm for vernal conjunctivitis, 11,000/cu mm for giant papillary conjunctivitis, and 11,000/cu mm for normal subjects, a statistically insignificant difference. Increased mucus in vernal conjunctivitis and contact mucus in vernal conjunctivitis and contact lens-associated giant papillary conjunctivitis is not accounted for by an increased density of goblet cells per cubic millimeter. It is probably caused by the greater surface area and thickness of epithelium, with a concomitant increase in the total number of goblet cells and increased mucus from nongoblet epithelial cells.

Impression cytology in conjunctivitis

A technique is described for studying the cellular response in various conjunctival disorders. A round plastic disc (Thermanox) is pressed against the patient's conjunctive, and the material adhering to the disc is stained with a modified Wright's stain (Diff-Quik) for light microscopy. This method compares favourably with the classic conjunctival scraping method. The advantages of the impression technique are that no local anesthetic is needed for abtaining conjunctival samples, it is painless and can readily be used in children, repeated samples can be taken within a short time, the staining procedure can be completed within 15 seconds, and the discs can be processed for electron microscopic studies of the cellular samples.

In vitro growth of some fastidious adenoviruses from stool specimens

Sixty-seven stool specimens from 51 children, positive for adenoviruses by electron microscopy and negative for growth in human-embryo kidney cells, were tested for growth in Chang conjunctiva cells. Twenty-eight specimens caused a cytopathic effect over more than one passage in these cultures, and several adenovirus strains grew better at 33 degree C than at 37 degree C. Most of the culture-positive specimens also induced the development of adenovirus antigens in KB cells detectable by a group-specific indirect immunofluorescence test. Twenty-four of the 25 fastidious strains tested were antigenically related and were distinct from the established serotypes commonly isolated from stools.

Semiquantitative cytologic analysis of fluid washed through the lacrimal passage

A quantitative cytologic analysis of the sediment of 5 ml of saline (0.9%) washed through the lacrimal drainage system of 25 normal and 84 diseased eyes revealed that the cytological picture reflects the conditions in the lacrimal passages and not in the conjunctiva. Neutrophilia was seen to become increasingly frequent with slowing down of the flow through the lacrimal passage, estimated on the basis of dye dilution in the lacrimal river and dye dilution in the fluid washed through the lacrimal drainage system, and also by the spontaneous passing of the dye to the nasopharynx. Neutrophilia was present in no more than 8% of normal eyes, as against 69% of eyes with epiphora, 83% with infectious conjunctivitis, 40% with conjunctivitis sicca, and 50% with chronic simple conjunctivitis. Neither lymphocytosis nor eosinophilia was seen in any normal eyes. Erythrocytes were admixed artificially by washing through and probing. Granules were absent in normal eyes, but present in 5% of the diseased eyes, while hairs were found in 4 and 14%, respectively, and the fungus Alternaria in 4 and 1%.

Extended wear of Hydrocurve II55 soft contact lenses

Nine myopic subjects (eighteen eyes) were fit with Hydrocurve II55 soft lenses and completed an average of seven months of extended wear with comfort and no significant side effects. Significant changes included horizontal meridian subjective refraction (myopia increased 0.26 D), PEK horizontal central power (0.23 D steepening), and PEK horizontal shape factor (increased .10). Papillary hypertrophy increased in 14 of 18 eyes but no subject had a giant papillary response. Conjunctival sample showed an increase in cellular infiltrates. Corneal aesthesiometry showed a significant increase in sensitivity. A safe, effective regimen for extended wear with normal myopic eyes was developed. Fitting and follow-up recommendations were made.

Effect of cigarette smoke on the surface structure of the conjunctival epithelium

Syrian golden hamsters were exposed to cigarette smoke in an intermittent smoke exposure device, and the surface structure of the tarsal conjunctiva was compared with that of sham-smoked and cage-held controls. Scanning electron microscopy revealed distortion and loss of microvilli of the conjunctival cells in the smoke-exposed animals.

[Histological studies of goblet cell counts in human conjunctiva (author's transl)]

In 121 healthy subjects of all age groups the goblet cells were counted by means of conjunctival biopsies; none of these individuals showed any inflammatory or degenerative changes in their eye lids, conjunctivae or corneas. Three groups were distinguished: a small group with relatively few, a large group with an average number and a third small groups with a relatively large number of goblet cells. The number of goblet cells was usually between 26 and 40 to the square mm, but fluctuated to a great extent in all three groups. On determining age distribution, the average goblet cell counts were found to be astonishingly similar: they did not vary significantly in the different age groups. At most, one could say the goblet cell count is slightly lower from age 61 onward.

Mass cells in ocular tissues of normal rats and rats infected with Nippostrongylus brasiliensis

In orbital exenteration specimens from 14 rats, 93% of the mast cells were found in the lids, the limbus, and the conjunctiva, 5% in the orbital tissues, and less than 1% in the globe. The density of mast cells was highest in lid (2843/mm3), limbus (2822/mm3), and orbit (2184/mm3) and lowest in bulbar conjunctiva (794/mm3), ciliary body (512/mm3), and sclera (176/mm3). There was no significant difference in the distribution or density of mast cells in orbital exenteration specimens from normal rats compared with rats infected with the worm Nippostrongylus brasiliensis. We concluded that certain ocular structures are rich in mast cells, which suggests that these structures might be susceptible to injury mediated by mast cell products.

Phagocytosis of latex microspheres by the epithelial cells of the guinea pig conjunctiva

The capability of conjunctival epithelial cells to phagocytize particulate foreign matter was studied experimentally in the guinea pig. Perilimbal conjunctival epithelium was prepared for transmission electron microscopy by perfusion fixation 4 and 24 h after instillation of latex microspheres (0.79 mu in diameter) into the lower conjunctival fornix. A varying number of microspheres were internalized by the superficial epithelial cells in both cases. The intracellular microspheres, single (at 4 and 24 h) or aggregated (only at 24 h), were always membrane-enclosed, corresponding to primary phagosomes. Some indications of secondary phagosomes were seen as well. In the 24 h specimens, microspheres were present also in the intermediate epithelial cells, implying a transfer from superficial to deeper cells. Thus, superficial as well as intermediate epithelial cells of the guinea pig conjunctiva are capable of active phagocytosis of inert particles.

The morphology of human conjunctival mucus

Normal human conjuctival mucus was examined by permeable membrane filter (Millipore) surface biopsy and instillation of India ink. It exists in solution in the tear film, as clusters of granules, as granular sheets, and as strands, the latter often arranged as a network. This mucus network entraps exfoliated epithelial cells, miscellaneous surface debris, carbon particles (from the India ink) and bacteria, and stains positively for lipid. Blinking causes both collapse of this mucus network into a single strand and movement of this strand to the medial canthus, where it compacts and is pushed onto the skin surface. There it dries and either falls off or is removed by rubbing. It is suggested that the formation and collapse of this mucus network represents a system for removing exfoliated surface cells and debris, infection and foreign particles, and lipid-contaminated mucus from the surface of the normal eye.

Morphological changes in the human conjunctival epithelium. II. In keratoconjunctivitis sicca

A clinicopathological correlation was performed on 24 patients suffering from keratoconjunctivitis sicca (KCS). Examination of conjunctival biopsies by light and transmission electron microscopy revealed stratification of the conjunctival epithelium with separation of the superficial cell layers, and this was directly proportional to the clinical severity of the disease. Counts of goblet cells were found to be inversely proportional to the degree of stratification. The goblet cells were morphologically identical to, but significantly fewer in number than, those found in normal conjunctival tissue. A reduction in epithelial cell stratification and separation and an increase in goblet cell density were closely related to nasolacrimal duct occlusion--an operation performed only in the severe examples of KCS in this series. The possible causes of 'mucous' plaques and 'filaments' are discussed in relation to these phenomena. Moreover, there is a dramatic reduction and deformation in the microplicae on the surface of the conjunctival epithelium. The significance of this was considered in relation to tear film stability.

Number of inflammatory cells in the normal conjunctiva

We counted inflammatory cells per cubic millimeter in both the epithelium and the substantia propria of samples from upper tarsal conjunctiva of 15 normal subjects and from lower forniceal conjunctiva of ten normal subjects. The upper limit of normal for number of cells was nearly 500,000/mm3. Lymphocytes accounted for about 70% of the inflammatory cells. Neutrophils and lymphocytes were almost always present in both the epithelium and the substantia propria. Plasma cells and mast cells were present in the substantia propria of all subjects, but never in the epithelium. Neither eosinophils nor basophils were found in any specimen. We concluded that conjunctiva of the white and quiet eye usually contains heavy infiltrates of inflammatory cells.

Unusual intracytoplasmic inclusions in a case of idiopathic scleritis

Large cells containing prominent, refractile PAS-positive inclusions were found in cytological smears prepared from scrapings of the conjunctiva of an elderly diabetic patient with idiopathic scleritis progressing to scleromalacia perforans. Electron-microscopic study of these inclusions revealed them to be intracellular accumulations of dense, flocculent mucoid material within vacuoles whose interior surface was frequently decorated with microvilli. Similar inclusions have been reported in a number of neoplasms in nonocular tissue. The significance of these findings with regard to the patient's condition is not understood.

[Contact biomicroscopy in examination of blood vessels of the eye (author's transl)]

The vessels of the conjunctiva and iris were studied in 20 gray and albino rabbits. The luminescent contact microscope (MLC-1) was used, at maximum magnification 174 x for visual observation and 33 x for photography. The particular advantage of contact biomicroscopy is that it makes possible detailed observation not only of the superficial network, but also of the deep network of conjunctival vessels. Both the blood flow and the distribution of formal elements in vessel lumina can be observed.

Cultured epithelial cells of cornea, conjunctiva and skin: absence of marked intrinsic divergence of their differentiated states

Keratinocytes of three different epithelia grown in cell culture express a large number of differentiation markers with either no differences or relatively small differences, depending on the species. Much of the distinctive phenotype of these epithelia in vivo must be due to external modulation and relatively little, at least in the case of the human, to permanent intrinsic divergence during development.