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PubMed2001

The lipid layer: the outer surface of the ocular surface tear film.

The outer layer of the tear film--the lipid layer--has numerous functions. It is a composite monolayer composed of a polar phase with surfactant properties and a nonpolar phase. In order to achieve an effective lipid layer, the nonpolar phase, which retards water vapor transmission, is dependent on a properly structured polar phase. Additionally, this composite lipid layer must maintain its integrity during a blink. The phases of the lipid layer depend on both lipid type as well as fatty acid and alcohol composition for functionality. Surprisingly, the importance of the composition of the aqueous layer of the tear film in proper structuring of the lipid layer has not been recognized. Finally, lipid layer abnormalities and their relationship to ocular disease are beginning to be clarified.

Humans↗
PubMed1985

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.

Animals↗
PubMed2004

Ocular surface epithelium induces expression of human mucosal lymphocyte antigen (HML-1) on peripheral blood lymphocytes.

BACKGROUND/AIMS: Peripheral blood CD8+ lymphocytes that home to mucosal surfaces express the human mucosal lymphocyte antigen (HML-1). At mucosal surfaces, including the ocular surface, only intraepithelial CD8+ lymphocytes express HML-1. These lymphocytes are retained in the intraepithelial compartment by virtue of the interaction between HML-1 and its natural ligand, E-cadherin, which is expressed on epithelial cells. The purpose of this study was to determine whether ocular surface epithelial cells (ocular mucosa) could induce the expression of human mucosal lymphocyte antigen on peripheral blood lymphocytes. METHODS: Human corneal and conjunctival epithelial cells were co-cultured with peripheral blood lymphocytes. Both non-activated and activated lymphocytes were used in the experiments. After 7 days of incubation, lymphocytes were recovered and analysed for the antigens CD8/HML-1, CD4/HML-1, CD3/CD8, CD3/CD4, CD3/CD25, CD8/CD25, and CD4/CD25 by flowcytometry. RESULTS: Significant statistical differences were observed in the CD8/HML-1 expression when conjunctival epithelial cells were co-cultured with non-activated and activated lymphocytes (p = 0.04 for each) and when corneal epithelial cells were co-cultured with non-activated lymphocytes (p = 0.03). Significant statistical difference in CD4/HML-1 expression was observed only when conjunctival epithelial cells were co-cultured with activated lymphocytes (p = 0.02). CONCLUSION: Ocular surface epithelial cells can induce the expression of human mucosal lymphocyte antigen on CD8+ (and to some extent on CD4+) lymphocytes. This may allow the retention of CD8+ and CD4+ lymphocytes within the epithelial compartment of the conjunctiva and play a part in mucosal homing of lymphocytes.

Antigens, CD↗
PubMed2004

Amniotic membrane transplantation in ocular surface disorders.

The term ocular surface disorders indicate a close relationship between the conjunctival and corneal epithelium in many corneal and external diseases. The human amniotic membrane has a thick basement membrane and an avascular stromal matrix and its first ophthalmic use was reported by deRoth for conjunctival surface reconstruction. It was subsequently used for different ophthalmic reasons. Amniotic membrane transplantation can be used in a number of conditions eg, as a graft to replace damaged ocular surface stromal matrix or as a patch to prevent unwanted inflammatory insults from gaining access to the damaged ocular surface. Amniotic membrane can be utilised in persistent of recurrent corneal epithelial and stromal defects; in cases of corneal perforation due to ulcer or melting; after conjunctival excision for acquired melanosis, neoplasia, etc; in cases of pemphigoid, Stevens-Johnson syndrome, chemical bums; in cases of symblepharon, in dry eyes or in large leaking filtering blebs.

Amnion↗
PubMed2006

Dynamics of ocular surface topography.

PURPOSE: To investigate fluctuations in the ocular surface, we used high-speed videokeratoscopy (50 Hz) to measure the dynamics of the ocular surface topography. METHODS: Ocular surface height difference maps were computed to illustrate the changes in the tear film in the inter-blink interval. Topography data were used to derive the ocular surface wavefront aberrations up to the fourth radial order of the Zernike polynomial expansion. We examined the ocular surface dynamics and temporal changes in the ocular surface wavefront aberrations in the inter-blink interval. RESULTS: During the first 0.5 s following a blink, the ocular surface height at the upper edge of the topography map increased by about 2 mum. Temporal changes occurred for some ocular surface wavefront aberrations and appeared to be related to changes in the distribution of tear film. CONCLUSION: In the clinical measurement of ocular surface topography using videokeratoscopy or optics of the eye using wavefront sensors, care should be taken to avoid the initial tear film build-up phase following a blink to achieve more consistent results.

Adult↗
PubMed1994

Risk factors in the development of ocular surface epithelial dysplasia.

BACKGROUND: Ocular surface epithelial dysplasia involves a spectrum of diseases ranging from only minor eye irritation to blindness and potentially death. METHODS: A case-control study involving 60 patients with ocular surface epithelial dysplasia treated between 1972 and 1991 and 60 age- and sex-matched individuals was conducted to compare relative ultraviolet light exposures over their lifetimes. A standardized self-administered ultraviolet exposure questionnaire was used for assessment. RESULTS: Risk factors identified include phenotypic features such as fair skin (odds ratio [OR], 5.4; 95% confidence interval [CI], 1.1, 25.6), pale iris (OR, 1.8; 95%; CI, 0.9, 3.8), and propensity to sunburn (OR, 3.8; 95% CI, 0.7, 19.7), history of previous skin cancers removed (OR, 15; 95% CI, 2.0, 113.6), and being outdoors more than 50% of time in the first 6 years of life while living 30 degrees or less from the equator (OR, 7.5; 95% CI, 1.8, 30.6). CONCLUSION: These risk factors suggest that ocular surface epithelial dysplasia is an ultraviolet light-related disease.

Adult↗
PubMed2002

[Ocular surface reconstruction by tissue engineering].

Ocular surface reconstruction by tissue engineering using somatic stem cells is a second-generation modality. In order to treat bilaterally affected, severe ocular surface disorders, we investigated the transplantation of two types of cultivated mucosal epithelia: allogenic corneal epithelial stem cells, and autologous oral mucosal epithelial cells. For this, first, we summarized the clinical results of allogenic keratoepithelioplasty and limbal transplantation. In addition, we showed that the immunological shift from Th1 to Th2 by using keyhole limpet hemocyanin was effective in suppressing the incidence of immunological rejection. Second, we investigated the transplantation of cultivated human corneal epithelial stem cells onto amniotic membrane. The cultivated sheet was created by co-culture with 3T3 fibroblasts, using the air-lift method, in cultivating the corneal epithelial stem cell on the amniotic membrane. These cultivated cells demonstrated positive keratin 3 and 12 specific to in vivo corneal epithelium, tight junction related proteins, and telomerase activity. The transplanted allogenic human corneal epithelial sheet survived on the corneal surface in all cases, and was quite effective for achieving ocular surface stability in the acute phase of Stevens-Johnson syndrome, ocular cicatricial pemphigoid, or chemical injury. However, a few cases developed immunological rejection or opportunistic infection. Third, to establish the transplantation of the autologous cultivated oral mucosal epithelial sheet, we performed animal experiments using rabbits. In vitro oral mucosal epithelial sheet showed histology similar to that of in vivo corneal epithelial sheet. It expressed positive keratin 3 as well. Since the autologous transplantation of this sheet survived on the ocular surface with the recovery of corneal transparency, a cultivated oral mucosal epithelium may become a substitute for corneal epithelium. Fourth, we created a cultivated human corneal endothelial cell sheet on amniotic membrane using a similar technique, and transplanted it to a rabbit eye as a xenograft. The transplanted corneal endothelial cell density was over 3,000 cells/mm2, and it was actively functioning even after the transplantation. Lastly, to explore cell markers for corneal epithelial stem cells, we established a technique using laser micro-capture, and introduced amplified fragment length polymorphism (AFLP), identifying several candidate molecules as stem cell markers.

Animals↗
PubMed2006

Expression in human ocular surface tissues of the GalNAc-transferases that initiate mucin-type O-glycosylation.

PURPOSE: Mucins are highly glycosylated proteins that act as lubricants, protectants, and mediators of signal transduction. The UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (ppGaNTase) family members initiate mucin-type O-glycosylation. Because O-glycosylation provides mucins with the viscoelastic properties required for proper mucin function, ppGaNTase expression is vital to the maintenance of healthy epithelial surfaces including the ocular surface. Differences of expression of ppGaNTase isoforms might be factors influencing susceptibility to dry eye disease. Therefore, we determined the expression of the ppGaNTase isoforms in normal human ocular surface tissues and the conjunctival epithelium from patients with aqueous-deficient dry eye. METHODS: Expression of ppGaNTase isoforms was quantitated by real-time reverse transcriptase polymerase chain rection (RT-PCR). RESULTS: Conjunctiva and cornea expressed multiple ppGaNTase isoforms, with isoforms T12 and T4 being the most strongly expressed in conjunctiva and T12 and T3 in the cornea. In contrast, lacrimal gland expressed fewer isoforms and had lower total ppGaNTase expression. Brush cytology was found to be superior to impression cytology for harvesting conjunctival epithelium in terms of ease of use, safety, and reproducibility of results. Similar to whole conjunctiva, the strongest isoforms in conjunctival epithelial cells were T12 and T4, followed by T3, T1, T5, and T2. No significant differences of ppGaNTase expression were found between the conjunctival epithelium of dry eye and normal control groups. CONCLUSION: Human ocular surface tissues express multiple ppGaNTase isoforms, suggesting a requirement for glycosylating diverse mucin-type substrates. However, there is no evidence to date to suggest that differences of ppGaNTase expression levels might contribute to susceptibility to dry eye disease.

Conjunctiva↗
PubMed2003

[Classification of ocular surface disease. Part 1].

The ocular surface consists of the lid margin, conjunctiva and cornea which together with the tear system represent a functional entity. The diagnosis of ocular surface disease can be very difficult due to the similarity of various disease entities. The classification should be made on the pathological and pathophysiological characteristics of ocular surface disease. The first part of the classification comprises diseases of the lid margin, the tear system as well as diseases of the conjunctiva. Both the clinical presentation as well as the underlying pathophysiological and pathological characteristics of the most important ocular surface diseases are reviewed.

Conjunctival Diseases↗
PubMed2006

MUC1 splice variants in human ocular surface tissues: possible differences between dry eye patients and normal controls.

Mucins are highly glycosylated proteins that are vital to the maintenance of healthy epithelial surfaces including the ocular surface. Mucins act as lubricants, protectants, and mediators of signal transduction. The majority of the O-glycosylation sites on the transmembrane mucin MUC1 are found in a highly polymorphic core region containing a variable number of tandem repeats (VNTR). MUC1 alleles can be divided into size classes that contain small (30-45) or large (60-90) numbers of repeats. Although at least 12 splice variants of MUC1 have been found in other tissues, no splice variants have been reported in human ocular surface tissues. We have used RT-PCR to identify MUC1 splice variants that were then confirmed by sequencing. We here report the presence in some samples of human cornea, conjunctiva, and lacrimal gland of MUC1/B which features canonical splicing between exons 1 and 2 and MUC1/A, a transcript that retains 27bp from the 3' end of intron 1 and is predicted to add 9 amino acids to the MUC1 sequence upstream of the tandem repeat region. Cornea and conjunctiva both contain the MUC1/SEC splice variant that lacks the transmembrane domain and, therefore, results in a soluble, secreted form of MUC1. Cornea and conjunctiva also contain MUC1/Y and MUC1/Z(X) variants that lack the tandem repeat region. Cornea, conjunctiva, and lacrimal gland also contain a previously undescribed MUC1 variant transcript, termed MUC1/YI, that retains 99bp from the 5' end and 27bp from the 3' end of the first intron, resulting in a frame shift and premature stop codon. This transcript is predicted to produce a novel 27 amino acid peptide after signal peptidase cleavage. Analysis of brush cytology samples revealed that the percentage of dry eye patients expressing the MUC1/A variant in the conjunctival epithelium is lower than in normal control donors. Western blotting confirmed that MUC1/A is associated with alleles containing the large size class of tandem repeats. Therefore, we propose that one factor in susceptibility to dry eye disease may be the lengths of the MUC1 VNTR in conjunctival epithelium based on the rationale that longer VNTR provide better lubrication and greater protection of the ocular surface against inflammation.

Alternative Splicing↗
PubMed1983

Cellulose acetate impressions of the ocular surface. Dry eye states.

Cellulose acetate impressions of the ocular surface were obtained for normal eyes, eyes with blepharoconjunctivitis, eyes with keratoconjunctivitis sicca, and eyes with primary ocular surface disease. Normal eyes and eyes with blepharoconjunctivitis had morphologically normal epithelium and goblet cells on the bulbar and palpebral ocular surfaces. Eyes with primary ocular surface disease had abnormal ocular surface impressions (decreased, abnormal, or absent goblet cells with abnormal epithelial cells) on both the bulbar and palpebral ocular surfaces. Conversely, eyes with keratoconjunctivitis sicca had substantial abnormalities of the epithelium and goblet cells only on the bulbar ocular surface, suggesting an environmental role in this disease process.

Adult↗
PubMedDate not supplied

Ocular surface squamous neoplasia.

Ocular surface squamous neoplasia presents as a spectrum from simple dysplasia to carcinoma in situ to invasive squamous cell carcinoma involving the conjunctiva as well as the cornea. It is a distinct clinical entity, although it has been known by a variety of different names throughout the literature. Most commonly it arises in the limbal region, occurring particularly in elderly males who have lived in geographic areas exposed to high levels of ultraviolet-B radiation. Symptoms range from none to severe pain and visual loss. The development of preoperative diagnostic techniques, such as impression cytology, are of value in clinical decision making and follow-up management. Simple excision with adequate margins is currently the best established form of treatment despite trials of other modalities. The course of this disease may be evanescent, but is more frequently slowly progressive and may require exenteration and occasionally may lead to death.

Carcinoma in Situ↗
PubMed2006

UV absorption in human oral mucosal epithelial sheets for ocular surface reconstruction.

BACKGROUND: Ocular surface reconstruction with autologous oral mucosal epithelium has attracted attention as a novel treatment strategy that avoids allograft rejection. OBJECTIVES: To evaluate the absorption of ultraviolet (UV) A or B irradiation by human oral mucosal epithelium cultured on human amniotic membrane. METHODS: Human oral mucosal and limbal epithelial cells were co-cultured on amniotic membrane with inactivated 3T3 fibroblasts. The cell sheets were also subjected to UV-A (365 nm) or UV-B (302 nm) irradiation at energy levels ranging from 50 to 800 microW/cm2, and the UV absorption rate was measured with a UV irradiation meter. RESULTS: Cultured oral mucosal epithelium had a structure with 3-5 layers of cells, consistent with the histological features of cultured corneal limbal epithelium after 4 weeks. The decrease in UV-A absorption of cultivated oral mucosal epithelium ranged from 25 to 36% of that for cultured corneal epithelium. The increase in UV-B absorption by cultured oral mucosal epithelium between 200 and 800 microW/cm2 was approximately 145% of that for cultured corneal limbal epithelium. CONCLUSION: Our data demonstrated that cultured oral mucosal epithelium has low UV-A and high UV-B absorption capacity as compared with those of cultured corneal epithelium, suggesting that oral mucosal epithelium can compensate for UV absorption of corneal epithelium.

3T3 Cells↗
PubMed2003

[Creating a specific diagnostic and quality-of-life questionnaire for patients with ocular surface disease].

INTRODUCTION: Ocular surface diseases (OSD) affect about 15% of the population over 65 years of age. Nevertheless, OSD knowledge in the scientific community remains poor, and the healthcare system does not adequately recognize this disorder. However, many patients with OSD suffering from chronic pain experience substantial alteration in their quality of life (QoL). PURPOSE: Our work aimed at developing a patient self-evaluation questionnaire specific to OSD. This questionnaire could thus become a useful diagnostic tool that ophthalmologists could employ in daily practice in order to better understand patients'complaints and thereby correctly treat their disease. It also may serve as an evaluation tool in medical research. This article describes the phases of item generation, validation by experts, and identification of dimensions in the QoL section. METHODS: The questionnaire was developed in French by a group of experts including clinicians and methodologists. It comprised two parts: one on diagnostic aid, and the other on subjective perception of the disease (symptoms, perception of treatment, quality of life). The questionnaire was tested on five patients. It was then modified according to the patients' suggestions and tested again on 20 patients. After a second review by the scientific committee, a pilot questionnaire suitable for systematic use in quantitative studies was prepared. A cross-sectional observational study then identified the statistical dimensions of the QoL section, which led to a reduction in the total number of items. RESULTS: The resulting operational version of the questionnaire included four sections CONCLUSION: The next study will test the reproducibility of the operational version of the OSD questionnaire obtained after the item reduction phase.

Adult↗
PubMed2004

Evaporation from the ocular surface.

Evaporation from the ocular surface is dramatically reduced by the lipid layer which covers it. With this layer intact, evaporation represents a small loss of water for which the lacrimal gland easily compensates. When tear production is compromised evaporation becomes important, especially since evaporation in almost all ocular surface disease states and any surface perturbation, including contact lens wear, increases evaporation significantly. How the barrier function of the lipid layer accomplishes this reduction in evaporation is not understood and is probably quite complex as is the structure of the lipid layer. Improving this barrier function remains an important and elusive goal.

Animals↗
PubMed2006

[Lacrimal film and the ocular surface].

Abnormalities of the ocular surface affect a large proportion of the general population. Symptoms depend on whether the lids, the corneoconjunctival surface, or the lacrimal layer are involved. The latter results from the balance of a fragile mixture of water, lipids, and mucus. Different circumstances can lead to the disruption of the lacrimal layer associated with dry-eye symptoms, eventually leading to inflammation. Alterations observed during dry-eye disease, meibomian dysfunction, allergic conjunctivitis, contact lens wear infectious conjunctivitis, or after refractive surgery are reviewed. Patient relief depends on a reliable analysis of the mechanism involved in the ocular surface disease.

Conjunctiva↗