Bulbar Conjunctival Epithelium Research Articles

Cytologic features of the bulbar conjunctiva in patients with primary open-angle glaucoma-associated dry eye disease

Purpose: To examine the features of the bulbar conjunctiva in patients who developed dry-eye disease (DED) after drug treatment for primary open-angle glaucoma (POAG). Methods: Impression cytology was performed by applying twice a strip of cellulose acetate filter to the ocular surface to remove the superficial epithelial layers of the temporal bulbar conjunctiva. The strips were removed with a peeling motion in a few seconds, and the samples were immediately fixed in 95% ethyl alcohol, stained with hematoxylin and eosin, mounted on glass slides and coverslipped for light microscopy. Squamous metaplasia was graded according to Nelson’s grading system on the basis of cell morphology, staining and integrity as well as the nucleus-to-cytoplasm ratio. This study included a case group of 80 patients (mean age, 63.8 +- 6.7 years) with POAG-associated DED, with the group being divided into four subgroups. Subgroups 1 and 2 were composed of 40 patients each, with glaucoma duration of less or more than 5 years, respectively. Subgroups a and b were composed of 40 patients each, with a number of topical ocular hypotensive drugs used equal to one or at least two, respectively. The control group was composed of 20 apparently healthy volunteers (mean age, 67.9 +- 8.9 years). All patients underwent a routine eye examination. Results: All patients with glaucoma had symptoms of DED with Ocular Surface Disease Index (OSDI) scores of at least 15. In subgroup 1, 60% had Nelson’s grade 1 and 40%, Nelson’s grade 2 squamous metaplasia. In subgroup 2, 10% had Nelson’s grade 1; 60%, Nelson’s grade 2 and 30%, Nelson’s grade 3 squamous metaplasia. In subgroup a, 20% had Nelson’s grade 1; 60%, Nelson’s grade 2 and 30%, Nelson’s grade 3 squamous metaplasia. In subgroup b, 10% had Nelson’s grade 1; 60%, Nelson’s grade 2 and 30%, Nelson’s grade 3 squamous metaplasia. Conclusion: Changes in the bulbar conjunctival epithelium corresponded to Nelson’s grade 2 or 3 squamous metaplasia in 80% of patients who developed DED after drug treatment for POAG. The severity of squamous metaplasia correlated with the duration of glaucoma and, consequently, longer use of hypotensive eye drops (r1 = 0.15, p1 = 0.02, p2 = 0.01). Findings of the current study and international guidelines argue for the use of the medications containing no preservatives or potentially toxic components in long-term therapy against glaucoma.

Localization of phosphatidylinositol phosphate 5 kinase γ, phospholipase β3 and diacylglycerol kinase ζ in corneal epithelium in comparison with conjunctival epithelium of mice

Based on the theory that the phosphoinositide (PI) signal is involved in the physiology of cornea and conjunctiva, we examined the localization in the mouse anterior ocular epithelia of immunoreactivities for phosphatidylinositol 4-phosphate 5-kinase (PIP5K), phospholipase C (PLC) and diacylglycerol kinase (DGK), enzymes that work sequentially in PI cycle. Immunoreactivity for PIP5Kγ in the corneal epithelium, including the limbus, was distinct in adults in contrast to faint or negligible immunoreactivity in the conjunctival epithelium in neonatal mice. This adult localization pattern was first recognized at the postnatal time of eyelid opening. Immunoreactivity for PLCβ3 was rather equally distinct throughout the entire corneal and conjunctival epithelia in adults. DGKζ-immunoreactive nuclei were mainly localized in the basal half domain of the corneal epithelium but in both basal and apical domains of the conjunctival epithelium in adults. This nuclear immunoreactivity was at weak or negligible levels in the peripheral and limbus cornea and in a considerable portion of the bulbar conjunctival epithelium continuous with the limbus. The adult patterns for PLCβ3 and DGKζ were already present at birth. The present findings suggest the following possibilities on the functional significance of the three enzyme molecules. PIP5Kγ is involved in cornea-specific functions such as bright-field vision, including corneal transparency, and in the stability of epithelial junctions, for which there seems to be a much higher requirement in the corneal epithelium than in the conjunctival epithelium. PLCβ3 is involved from birth in as-yet undefined functions exerted ubiquitously from birth in both corneal and conjunctival epithelia. DGKζ is involved in regulation from birth of the transcription in epithelial cells, including apoptosis as well as regulation of mitosis of epithelial cells in both cornea and conjunctiva, with the transcription involvement more apparent in the conjunctiva, although it does not work in stem cells of the corneal limbus.

Rapid bioprinting of conjunctival stem cell micro-constructs for subconjunctival ocular injection

Ocular surface diseases including conjunctival disorders are multifactorial progressive conditions that can severely affect vision and quality of life. In recent years, stem cell therapies based on conjunctival stem cells (CjSCs) have become a potential solution for treating ocular surface diseases. However, neither an efficient culture of CjSCs nor the development of a minimally invasive ocular surface CjSC transplantation therapy has been reported. Here, we developed a robust in vitro expansion method for primary rabbit-derived CjSCs and applied digital light processing (DLP)-based bioprinting to produce CjSC-loaded hydrogel micro-constructs for injectable delivery. Expansion medium containing small molecule cocktail generated fast dividing and highly homogenous CjSCs for more than 10 passages in feeder-free culture. Bioprinted hydrogel micro-constructs with tunable mechanical properties enabled the 3D culture of CjSCs while supporting viability, stem cell phenotype, and differentiation potency into conjunctival goblet cells. These hydrogel micro-constructs were well-suited for scalable dynamic suspension culture of CjSCs and were successfully delivered to the bulbar conjunctival epithelium via minimally invasive subconjunctival injection. This work integrates novel cell culture strategies with bioprinting to develop a clinically relevant injectable-delivery approach for CjSCs towards the stem cell therapies for the treatment of ocular surface diseases.

Ocular Surface Epithelial Thickness Evaluation in Dry Eye Patients: Clinical Correlations.

Purpose. To evaluate the relationship between corneal and conjunctival epithelium thickness and ocular surface clinical tests in dry eye disease (DED) patients. Patients and Methods. Fifty-four patients with DED and 32 control subjects were included. Each patient underwent an ocular surface evaluation using the ocular surface disease index (OSDI), tear film break-up time (TBUT), corneal and conjunctival staining, tear film lipid layer analysis, and Schirmer test. The central corneal (CET), limbal (LET), and bulbar conjunctival epithelium thickness (BET) were acquired using spectral-domain optical coherence tomography (SD-OCT). Results. Compared to control subjects, mean BET was significantly thicker and mean LET was significantly lower in the DED group. There was no significant difference in mean CET between the two groups. The mean LET was correlated with OSDI and TBUT. The inferior LET was correlated with OSDI, Schirmer I test, TBUT, Oxford score, and corneal sensitivity. Mean BET was correlated with OSDI and TBUT, but not with Schirmer I test and Oxford score. Conclusions. In dry eye patients, a thinner limbal epithelium and a thicker bulbar conjunctival epithelium were observed. These changes were correlated to the severity of dry eye symptoms and tear film alterations.

Ocular Surface Epithelial Thickness Evaluation with Spectral-Domain Optical Coherence Tomography

To use in vivo spectral-domain optical coherence tomography (SD-OCT) to measure corneal, limbal, and bulbar conjunctival epithelial thickness. A total of 156 eyes of 79 subjects were enrolled in four groups: young control (YC group), < 40 years; middle-aged control (MAC group), > 40 years; patients with dry eye syndrome (KCS group); and patients with glaucoma or ocular hypertension treated with intraocular pressure (IOP)-lowering medication (G group). The central corneal epithelium (CE) thickness, and the limbal (LE) and bulbar conjunctival epithelium (BCE) thickness in four quadrants were measured using SD-OCT. The mean thicknesses of the CE, LE, and BCE of the YC group were 48.3 ± 2.9 μm, 83.0 ± 14.3 μm, and 42.0 ± 7.5 μm, and for the MAC group were 48.8 ± 3.0 μm, 84.3 ± 10.1 μm, and 42.2 ± 7.9 μm, respectively. The ocular surface epithelial thickness was not significantly different between the YC and MAC groups. CE thicknesses were not significantly different between the KCS, G, and control groups. The mean LE thicknesses were significantly lower in the KCS and G groups compared with the MAC group. The mean BCE was significantly thicker in the KCS and G groups compared with the MAC group. Anterior segment SD-OCT can provide a noninvasive evaluation of ocular surface epithelial thickness. LE and BCE thickness was modified in dry eye patients and patients using IOP-lowering eye drops, whereas aging seemed to have no effect.

Ocular surface epithelial thickness evaluation with spectral‐domain optical coherence tomography in patients with dry eye syndrome

AbstractPurpose To use spectral‐domain optical coherence tomography (SD‐OCT) to measure corneal, limbal and bulbar conjunctival epithelial thickness in patients with dry eye syndrome.Methods A total of 111 eyes of 56 subjects were enrolled in 3 groups: (1) young control (YC group), &lt; 40 years; (2) middle‐aged control (MAC group), &gt; 40 years; (3) patients with dry eye syndrome (KCS group). The central corneal epithelium (CE) thickness, and the limbal (LE) and bulbar conjunctival epithelium (BCE) thickness in four quadrants were measured using a SD‐OCT. All patients underwent a complete examination of the ocular surface including Schirmer test, TBUT and fluorescein staining.Results The ocular surface epithelial thickness was not significantly different between the YC and MAC groups. CE thicknesses were not significantly different between the KCS (49.0 ± 4.1 µm) and control groups (48.3 ± 2.9 µm in YC and 48.8 ± 3.0 µm in MAC). The mean LE thickness was significantly lower in the KCS group (77.3 ± 17.2 µm) compared to the MAC group (84.3 ± 10.1 µm, p=0.031). The mean BCE was significantly thicker in the KCS group (50.4 ± 11.1 µm) compared to the MAC group (42.2 ± 7.9 µm, p=0.005). In the KCS group, the BCE thickness was significantly higher in the superior and inferior quadrants compared to nasal and temporal. The mean BCE thickness was significantly higher in ocular surface severity grades 3 and 4 (53.3 ± 12.1 µm) compared to grades 1 and 2 (45.7 ± 7.2 µm) (p=0.031).Conclusion SD‐OCT can provide a non invasive in vivo evaluation of ocular surface epithelial thickness. Limbal and conjunctival epithelium thicknesses were modified in dry eye patients whereas aging seemed to have no effect.

Evaluation of Conjunctival Graft Thickness after Pterygium Surgery by Anterior Segment Optical Coherence Tomography

Background: To evaluate changes in thickness of the conjunctival graft after pterygium surgery by anterior segment optical coherence tomography (AS-OCT).Materials and Methods: Eleven eyes of 11 patients with primary nasal pterygium underwent excision followed by free conjunctival autograft. Imaging with AS-OCT was performed at 1 week, 1 month and 3 months after surgery to measure thickness of the conjunctival graft at 1, 2 and 3 mm posterior to the scleral spur. As the control, thickness of the normal bulbar conjunctival epithelium in the temporal area was also measured at the same locations.Results: Average thickness of the graft decreased from 458 ± 171 µm at 1 week after surgery to 306 ± 64 µm at 1 month (p < 0.0001). Although the graft thickness decreased to 291 ± 124 µm at 3 months postoperatively, the difference between 1-month and 3-month values was not statistically significant (p = 0.94). Average thickness of the normal conjunctival epithelium was 58 ± 13 µm, 60 ± 19 µm and 61 ± 12 µm at 1 week, 1 month and 3 months after surgery, respectively, with no statistically significant difference. Graft thickness was significantly greater than thickness of the normal conjunctival epithelium at various time points (p < 0.05).Conclusion: Evaluation by AS-OCT showed that there was significant thickening of the conjunctival graft at 1 week after pterygium surgery which continued to decrease up to 3 months. Quantitative data by AS-OCT allows accurate evaluation of the conjunctival changes over time.

Potential localization of putative stem/progenitor cells in human bulbar conjunctival epithelium

Although the conjunctival fornix appears to contain the greatest proportion of stem cells, it is likely that pockets of conjunctival epithelial stem cells may also exist throughout the conjunctival epithelium. This study was to investigate the potential localization of putative stem/progenitor cells in the human bulbar conjunctival epithelium by evaluating 6 keratins and 13 molecules that have been previously proposed stem cell associated or differentiation markers. We found that cornea specific cytokeratin (CK) 3 was not expressed by the bulbar conjunctival epithelial cells. In contrast, CK4 and CK7 were expressed by the superficial cells of bulbar conjunctival epithelium. CK14 and CK15 were confined to the basal cell layer. CK19 was strongly expressed by all layers of the bulbar conjunctival epithelium. The expression patterns of molecular markers in the basal cells of human bulbar conjunctival epithelium were found to be similar to the corneal epithelium. Basal conjunctival epithelial cells strongly expressed stem cell associated markers, including ABCG2, p63, nerve growth factor (NGF) with its receptors tyrosine kinase receptor A (TrkA) and neurotrophin low-affinity receptor p75NTR, glial cell-derived neurotrophic factor (GDNF) with its receptor GDNF family receptor alpha 1 (GFRalpha-1), integrin beta1, alpha-enolase, and epidermal growth factor receptor (EGFR). The differentiation associated markers nestin, E-cadherin and involucrin were not expressed by these cells. These findings indicate that the basal cells of bulbar conjunctival epithelium shares a similar expression pattern of stem cell associated markers to the corneal epithelium, but has a unique pattern of differentiation associated cytokeratin expression.

Confocal Microscopy of the Bulbar Conjunctiva in Contact Lens Wear

The aim of this study was to investigate the capabilities of laser scanning confocal microscopy (LSCM) for undertaking qualitative and quantitative investigations of the response of the bulbar conjunctiva to contact lens wear. LSCM was used to observe and measure morphological characteristics of the bulbar conjunctiva of 11 asymptomatic soft contact lens wearers and 11 healthy volunteer subjects (controls). The appearance of the bulbar conjunctiva is consistent with known histology of this tissue based on light and electron microscopy. The thickness of the bulbar conjunctival epithelium of lens wearers (30.9 +/- 1.1 microm) was less than that of controls (32.9 +/- 1.1 microm) (P < 0.0001). Superficial and basal bulbar conjunctival epithelial cell densities in contact lens wearers were 91% and 79% higher, respectively, than that in controls (P < 0.0001). No difference was observed in goblet and Langerhans cell density between lens wearers and controls. Conjunctival microcysts were observed in greater numbers, and were larger in size, in lens wearers compared with controls. The effects of contact lens wear on the human bulbar conjunctiva can be investigated effectively at a cellular level using LSCM. The observations in this study suggest that contact lens wear can induce changes in the bulbar conjunctiva such as epithelial thinning and accelerated formation and enlargement of microcysts, increased epithelial cell density, but has no impact on goblet or Langerhans cell density.

Distribution of amyloid and BIG‐H3 in the cornea and limbus of a patient with lattice corneal dystrophy. Unique findings in donated eyes

Abstract Purpose The lattice corneal dystrophies (LCDs) are hereditary diseases involving the formation of opaque or refractile, amyloid‐containing filaments in the corneal stroma. We report the distribution of amyloid and big‐h3 protein in cornea and limbus in a patient suffering with LCD. Methods An 84 year‐old patient with lattice corneal dystrophy died and donated her eyes for further study. The corneal and limbal tissue of the patient processed for light and electron microscopy. The primary polyclonal antibody big‐h3 was located by secondary, goat anti‐rabbit antibody conjugated with gold. Results In cornea amyloid deposits were observed below epithelium, and in the anterior and middle stroma. The epithelium was thin and invaginated by the amyloid deposits. In the limbus, large numbers of amyloid deposits were observed in sub‐epithelial region, and in the mid and deep stroma. Subepithelial amyloid was also present in the substantia propria beneath the bulbar conjunctival epithelium. The amyloid deposits contained very thin amyloid fibrils and strongly stained with big‐h3 antibody. There were also numerous long spacing collagen fibrils observed in the mid stroma, which also labelled with the antibody. Conclusion This is the first report of structural changes in the peripheral cornea and limbus in LCD. It is thought that mutated big‐h3 protein diffuse into the stroma from the corneal epithelium to form amyloid deposits. The presence of amyloid and big‐h3 at the limbus and in the adjacent bulbar conjunctiva and perilimbal cornea, suggests that Big‐h3 is overproduced in these regions, which are normally free from clinically detectable disease.

Corneal, Limbal, and Conjunctival Epithelial Thickness from Optical Coherence Tomography

To compare human central corneal, limbal and bulbar conjunctival epithelial thickness in vivo using an Optical Coherence Tomographer (OCT). Thirteen healthy human subjects participated in this study. An OCT (Carl Zeiss, Meditec, Dublin, CA) was used to image central cornea, temporal corneo-scleral limbus and bulbar conjunctiva of the left eye. Two images were taken at each location. Thirty central measurements were averaged from each image for quantifying epithelial thickness. In addition to the central cornea and limbal region, a band corresponding to bulbar conjunctival "epithelium" is apparent in OCT images, with respective thicknesses of 54.7 +/- 1.9 microm (mean +/- SD), 79.6 +/- 7.4 microm and 44.9 +/- 3.4 microm that are statistically significant different (repeated measures analysis of variance p < 0.01, post hoc test shows all p < 0.01). This study demonstrates that it is possible to image the epithelial tissue in humans in vivo using optical coherence tomography, and in these subjects, the corneo-limbal epithelium is the thickest, while the bulbar conjunctival epithelium is the thinnest and the corneal epithelium has intermediate thickness.

Clusters of Corneal Epithelial Cells Reside Ectopically in Human Conjunctival Epithelium

The ocular surface is covered by two biologically distinct epithelia: corneal and conjunctival. The expression of keratin12 (K12) is currently considered a hallmark of cornea-type differentiation. In the current study, the biological features of K12-positive cells in human bulbar conjunctival epithelium were examined. Human conjunctival tissues were subjected to investigate the K12-positive cells in conjunctiva by immunostaining, in situ hybridization, Western blot analysis, reverse transcriptase-polymerase chain reaction (RT-PCR), and fluorescence-activated cell sorting (FACS). Gene expression profiling of these cells was performed with introduced amplified-fragment length polymorphism (iAFLP). To determine the presence of stem- or progenitor cells, immunostaining and colony-forming assays were performed. Western blot analysis, RT-PCR revealed that K12 was expressed in conjunctival epithelium. Immunostaining analysis showed that K12-positive cells reside mainly in clusters in conjunctival epithelium. FACS analysis showed that 0.2% to 1.7% of conjunctival epithelial cells collected from the inferior bulbar conjunctiva were K12 positive. iAFLP analysis revealed that the gene expression patterns of these cells were highly similar to that of corneal epithelial cells. p63 and ABCG2 were expressed beneath the K12-positive cells. Some colony-forming cells expressed K12. The K12-positive cells appear to be ectopically residing, self-maintaining corneal epithelial cells in the conjunctival epithelium.

Localization of ocular P2Y 2 receptor gene expression by in situ hybridization

The objective of this study was to determine the cellular localization of P2Y 2 receptor gene expression in rabbit and primate ocular tissues using the technique of non-isotopic in situ hybridization. Fresh frozen whole eye from a New Zealand white rabbit and whole eye and eyelid from a rhesus macaque were cut into 5 μm thick sections and mounted onto glass slides. In situ hybridization was performed on ocular cryosections using digoxigenin-labeled P2Y 2 receptor riboprobes. Alkaline phosphatase-conjugated anti-digoxigenin antibody was used to localize riboprobe hybridization, which was subsequently visualized by staining with a precipitating alkaline phosphatase substrate. Cytoplasmic staining indicative of antisense riboprobe hybridization to P2Y 2 receptor mRNA was observed in the palpebral and bulbar conjunctival epithelium, including goblet cells, the corneal epithelium, and in meibomian gland sebaceous and ductal cells. Staining was also observed in both layers of the ciliary body epithelium, subcapsular epithelium of the lens, and corneal endothelium. In the posterior eye, staining was observed in various layers of the retina, including ganglion cell, inner nuclear, inner segment and retinal pigment epithelium layers, in the optic nerve head, and in a variety of structures within the choroid. No specific staining of sense riboprobe was seen on any of the ocular structures. These results demonstrate that the P2Y 2 receptor gene is expressed in a variety of ocular cells types and suggest that P2Y 2 receptors are associated with diverse physiological functions throughout the eye.

Proliferation and apoptosis in the epithelium of the developing human cornea and conjunctiva

To determine the distribution of proliferating and apoptotic cells in the human cornea during prenatal and early postnatal development, we examined sections of the bulbar conjunctiva, the limbus as well as the central and peripheral cornea between 11 weeks of gestation and 6 months after birth. The objective was to localize dividing cells by proliferating cell nuclear antigen-like immunoreactivity (PCNA-LI) and apoptotic cells by terminal transferase-mediated nick-end labeling (TUNEL). Before the 17 th gestational week, PCNA-LI was absent in all 4 regions examined, indicating negligible cell proliferation during early development. After 20 weeks, strong PCNA-labeling was observed in all regions examined suggestive of high proliferative activity not only in the limbus and the bulbar conjunctiva, but also in the central and peripheral cornea. This rise in proliferative activity was followed by a steady decline: after 28 weeks, anti-PCNA staining gradually disappeared in the central and peripheral cornea, so that, at 6 months after birth, it was confined to the limbus and the bulbar conjunctiva, resembling the picture described for the adult cornea. TUNEL-positive cells were virtually absent in all 4 regions examined before the 38 th gestational week. Apoptotic cells only started to appear at 38 weeks; at this stage, they were confined to the bulbar conjunctival epithelium. At 6 months after birth, TUNEL-positive cells were observed in the bulbar conjunctival epithelium and the entire cornea; the limbus, however remained devoid of apoptotic cells throughout the entire prenatal and early postnatal period. The present study for the first time localizes proliferating and apoptotic cells in the epithelium of the developing human cornea. Three stages of development can be distinguished: Minimal proliferation (until 17 th week), vigorous proliferation over the entire cornea including the limbus and the bulbar conjunctiva (until 28 th week) and gradual decrease in proliferative activity (after 28 th week) accompanied by the appearance of apoptotic cells.

Expression of involucrin by ocular surface epithelia of patients with benign and malignant disorders

Purpose. Keratinization of the ocular surface epithelium is associated with various disorders impairing vision. We immunohistochemically determined whether the ocular surface epithelia express involucrin, and whether its expression pattern may differ in benign vs. malignant disorders. Expression of cytokeratins was also examined to provide further information relative to the epithelial differentiation. Methods. We evaluated 17 specimens; 6 specimens of the normal ocular surface epithelia, 3 specimens from cases of conjunctival intraepithelial neoplasia (CIN), 6 of conjunctival squamous cell carcinoma (SCC) and 2 of conjunctivae from cases of superior limbic keratoconjunctivitis (SLK). Results. Corneal epithelium exhibited intracellular immunoreactivity for involucrin. Four of the 6 specimens of bulbar conjunctival epithelium showed involucrin immunoreactivity in the perimembranous region, whereas the fornical conjunctiva was negative. Cornified envelope in SLK specimens was positive for involucrin. The CIN showed its immunoreactivity in the perimembranous region in all levels of the hyperproliferative epithelium without keratinization, i.e., similar to the bulbar conjunctiva. The neoplastic cells of well-differentiated SCC showed involucrin in the perimembranous region, and those of moderately- to poorly-differentiated SCC have involucrin in their cytoplasm. The expression pattern of cytokeratins was unrelated to grade of malignancy in ocular SCC. Conclusion. The epithelia of normal subjects and of CIN expresses involucrin without keratinization. In contrary, the keratinized SLK epithelium markedly expresses involucrin in the cornified envelope. The subcellular immunolocalization of involucrin in the ocular SCC may help in evaluating the differentiation, i.e., malignancy, of neoplastic cells.

Aquaporins in complex tissues: distribution of aquaporins 1–5 in human and rat eye

Multiple physiological fluid movements are involved in vision. Here we define the cellular and subcellular sites of aquaporin (AQP) water transport proteins in human and rat eyes by immunoblotting, high-resolution immunocytochemistry, and immunoelectron microscopy. AQP3 is abundant in bulbar conjunctival epithelium and glands but is only weakly present in corneal epithelium. In contrast, AQP5 is prominent in corneal epithelium and apical membranes of lacrimal acini. AQP1 is heavily expressed in scleral fibroblasts, corneal endothelium and keratocytes, and endothelium covering the trabecular meshwork and Schlemm's canal. Although AQP1 is plentiful in ciliary nonpigmented epithelium, it is not present in ciliary pigmented epithelium. Posterior and anterior epithelium of the iris and anterior lens epithelium also contain significant amounts of AQP1, but AQP0 (major intrinsic protein of the lens) is expressed in lens fiber cells. Retinal Müller cells and astrocytes exhibit notable concentrations of AQP4, whereas neurons and retinal pigment epithelium do not display aquaporin immunolabeling. These studies demonstrate selective expression of AQP1, AQP3, AQP4, and AQP5 in distinct ocular epithelia, predicting specific roles for each in the complex network through which water movements occur in the eye.

Localizations of epidermal growth factor receptor and proliferating cell nuclear antigen during corneal wound healing

The localization of epidermal growth factor receptor and proliferating cell nuclear antigen was demonstrated immunohistochemical to be similar in the corneal, limbal, and bulbar conjunctival epithelium, i.e., located adjacent to the artificially made corneal epithelial defect. In the course of regeneration of the corneal epithelium soon after the wounding, both epidermal growth factor receptor and proliferating cell nuclear antigen were expressed in the epithelial cells in the limbal area adjacent to the epithelial defect. After the defect was covered with several layers of regenerated epithelium, the main site of the expression of epidermal growth factor receptor and proliferating cell nuclear antigen moved to the basal layer of regenerated epithelium. The present study indicated that epidermal growth factor receptor, as expressed on the epithelial cell surface, can be considered to play an important role in epithelial cell proliferation, which is an indispensable process in corneal wound healing.

Conjunctival cytology in asymptomatic wearers of soft contact lenses.

Conjunctival epithelium was systematically investigated with impression cytology in clinically asymptomatic wearers of soft contact lenses who had been using their lenses for several years. Severe abnormalities were observed, which had so far only been seen in diseases of the ocular surface mainly in dry eye syndromes. All patients showed evidence of squamous metaplasia with distinctly enlarged, flattened cells without evidence of keratinization. They also showed frequent nuclear abnormalities, primarily a high percentage of snakelike-appearing condensations of nuclear chromatin (snakes). The goblet cell density observed was relatively low. Snakes were for the first time detected outside the known localization (upper bulbar conjunctiva, 12 o'clock position) and could be demonstrated throughout the whole bulbar conjunctival epithelium. It is suggested that the changes observed are due to chronic mechanical irritation by the contact lens, as indicated by their topographical distribution and as proven by their reversibility after omission of contact lens wear.