In vivo detection of clinically non-apparent ocular surface inflammation in patients with meibomian gland dysfunction-associated refractory dry eye symptoms: a pilot study.

PURPOSE: The utility of in vivo confocal microscopy (IVCM) in the investigation of palpebral conjunctival and corneal inflammation in patients with meibomian gland dysfunction (MGD)-associated refractory dry eye symptoms following gland expression, despite objective clinical improvement. METHODS: A retrospective, observational pilot study was conducted evaluating five patients with MGD-associated refractory dry eye symptoms and three control groups: symptomatic untreated MGD patients (n=3), treatment-responsive MGD patients with improved symptoms (n=3) and asymptomatic healthy normals (n=11). Ocular surface disease index (OSDI) scores, tear break-up time (TBUT), the number of meibomian glands yielding liquid secretion (MGYLS), palpebral conjunctival epithelial and substantia propria immune cell (EIC, SIC), and corneal dendritic cell (DC) densities were measured. RESULTS: Despite clinical improvement (TBUT: 6.4±1.2 s to 10.1±2.1 s, P=0.03; MGYLS: 3.5±0.8 glands to 7.0±1.1 glands, P=0.13) and a normal clinical examination post treatment, MGD patients remained symptomatic. IVCM revealed increased immune cells in the palpebral conjunctiva (refractory MGD EIC=592.6±110.1 cells/mm2 untreated MGD EIC=522.6±104.7 cells/mm2, P=0.69; responsive MGD EIC=194.9±119.4 cells/mm2, P<0.01; normals EIC=123.7±19.2 cells/mm2, P< 0.001), but not the cornea (refractory MGD DC=60.9±28.3 cells/mm2; normals DC=25.9±6.3 cells/mm2; P=0.43). EIC did not correlate with TBUT (Rs=-0.26, P=0.33). OSDI scores correlated with both EIC (Rs=0.76, P<0.001) and TBUT (Rs=-0.69, P<0.01) but not SIC. Intraglandular immune cells were also seen. CONCLUSION: MGD-associated refractory symptoms and the symptom-sign disparity may be explained by clinically non-apparent, active inflammation of the palpebral conjunctiva as detected by IVCM. These patients may benefit from anti-inflammatory therapy.

Correlation of lipid layer thickness measurements with fluorescein tear film break-up time and Schirmer's test.

PURPOSE: This study correlates measurement of lipid layer thickness (LLT) with two frequently used dry eye tests, fluorescein break-up time (FBUT) and Schirmer's test with anaesthesia (STA). METHODS: Subjects (n = 44 eyes) with symptoms of dry eye and positive results for dry eye with either FBUT or STA or both were selected. Quantification of LLT was performed by the observation of colour interference patterns in zones of specular reflection using a custom-designed instrument. RESULTS: All correlations among pairs of tests were strong and exhibited a significance of P < 0.000: STA with FBUT, Pearson's correlation 0.653; STA with LLT, 0.764; FBUT with LLT, 0.751. When LLT was high, ie > or = 120 nm, which occurred in 14 eyes, STA was also elevated in those eyes and FBUT was high in 13 of the 14 eyes. When LLT was low, ie < or = 60, which occurred in 22 eyes, STA was below normal in 14 of the 22 eyes, and FBUT was below normal in 15 of the 22 eyes. These clinical observations paralleled the statistical findings computed from the entire data set. CONCLUSIONS: The correlations demonstrated in this study support the premise (1) that measurement of LLT is a reliable test for the diagnosis of dry eye, and (2) that aqueous deficiency and lipid deficiency, as they apply to dry eye disorders, are not mutually exclusive.

Comparison of fluorescein break-up time measurement reproducibility using standard fluorescein strips versus the Dry Eye Test (DET) method.

PURPOSE: To compare the repeatability of fluorescein break-up time (FBUT) measurements determined with either a standard fluorescein strip or the Dry Eye Test (DET) modified fluorescein strip methods. METHODS: This was a prospective, randomized contralateral study of 100 patients, in which FBUT measurements were determined with a standard FUL-GLO fluorescein strip (Akorn, Inc., Buffalo Grove, IL, U.S.A.) in one eye and a DET strip (Akorn, Inc., Buffalo Grove, IL, U.S.A.) for the contralateral eye. Three consecutive measurements were made immediately after fluorescein instillation. The second eye was evaluated 1 minute after completion of the first eye. Data from patients with FBUT values less than 20 seconds were included in the data analysis, because measurements greater than 20 seconds are not diagnostically significant. RESULTS: Seventy-five patients met enrollment and FBUT measurement criteria. For three consecutive FBUT measurements, the DET values were within 3 seconds for 72 of the 75 patients (96%). Eighty percent of patients reported no sensation with the DET strip, 20% reported mild sensation, and no patient reported moderate sensation. With FUL-GLO strips, measurements were within 3 seconds for 53 of the 75 patients (71%) (p <0.005). The standard fluorescein strip method elicited reports of no sensation from 31% of patients, mild sensation from 60%, and moderate sensation from 9% (p <0.001). CONCLUSIONS: The DET strip provides a significant reduction in sensation upon application, improved single measurement reliability, and enhanced measurement precision, compared with a conventional fluorescein strip.

Survey of preferred tests for diagnosis of the tear film and dry eye.

PURPOSE: To survey practitioners in the tear film/dry eye field for their preferred diagnostic methods for the evaluation of the tear film and dry eye syndrome. METHODS: A survey was given to 36 optometrists and 41 ophthalmologists with backgrounds in the area of tear film and dry eye syndrome to find their preferred test if only one diagnostic option was available for tear film evaluation. Second, third, and fourth choices were also recorded, as well as any additional comments. RESULTS: Sixty-eight practitioners completed the survey. No one single test was a dominant first choice of the majority of respondents in either profession. History and/or dry eye questionnaire was the most frequent response to the question addressing the use of only one test (28%). The second most frequently chosen test was fluorescein break-up time (FBUT) (19%), followed by fluorescein staining (13%), and rose bengal (10%). The Schirmer test was most frequently included as one of the four choices (62%), although it was the first choice of only 9%. CONCLUSION: The importance of multiple tests in the evaluation of tear film disorders is overwhelmingly acknowledged, with patient history/dry eye questionnaires, FBUT, ocular surface staining, and the Schirmer test being the preferred diagnostic tools.

Histopathology of the ocular surface after eye rubbing.

PURPOSE: This study demonstrates the effects of eye rubbing on ocular surface tissue. METHODS: Rabbits (3-4 kg; n = 24) were killed at 0, 4-h, 8-h, and 12-h intervals after a 5-min period of eye rubbing. Ocular surface tissues were studied by light and scanning electron microscopy. Contralateral eyes served as controls. Eye rubbing was accomplished by using digital pressure over the closed eyelid with a force sufficient to appreciate by palpation the orbital rim. Biomicroscopic examination revealed marked vascular injection of the conjunctiva. Ocular surface tissues studied included the lid margins, the upper and lower tarsal conjunctivae, the bulbar conjunctiva, and the cornea. RESULTS: Changes in the ocular surface included dramatic alteration in the upper tarsal conjunctiva when compared with controls. The cornea and bulbar and lower tarsal conjunctiva were not altered when compared with control tissues, except for some increase in exfoliating cells in the cornea. The surface epithelial cells of the upper tarsal conjunctiva had a spheroidal structure and were markedly elevated, the microprojections were altered, and there was evidence of increased cellular exfoliation. These changes were most pronounced at the 0 and 4-h time points, less noticeable at 8 h, and no appreciable changes were observed when compared with control tissues at 12 h. CONCLUSION: This study demonstrates that eye rubbing causes surface alterations in the stratified cuboidal to columnar epithelial surface of the upper tarsal conjunctiva while sparing the stratified squamous epithelial surface of the distal lid margins and cornea.

Meibomian gland phospholipids.

The content of the meibomian gland lipid exprimate is known, but little is known about the phospholipids that comprise the glandular cells. The purpose of the present study is to identify and quantitate the phospholipid complement of the meibomian gland cells that produce the lipid secretion of meibomian oil and which is vital to tear film stability. Eyelids (n = 50) were excised from rabbits, and after surgical removal of surrounding tissues, the tarsal plates with and without expressing meibomian oil were extracted and phospholipids of the plates quantified by 31P nuclear magnetic resonance (NMR). Seventeen phospholipids were quantified from tarsal plates expressed of oil and tarsal plates containing meibomian oil: alkylacylphosphatidylcholine (AAPC), dihydrosphingomyelin (DHSM), dimethylphosphatidylethanolamine, diphosphatidylglycerol (cardiolipin), ethanolamine plasmalogen (EPLAS), lysoethanolamine plasmalogen, lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylserine, phosphatidic acid, phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol, phosphatidylinositol, phosphatidylserine, sphingomyelin (SM), sphingosylphosphorylcholine. The six zwitterionic and neutral phospholipids, DHSM, EPLAS, PE, SM, AAPC, and PC together comprise 79.5% of the total meibomian gland phospholipid profile (in meibomian oil this value is 84.2%). The zwitterionic and neutral phospholipids dominate meibomian gland phospholipid profiles. Since the meibomian gland cells undergo holocrine secretion and form the meibomian glad secretion, such a composition is consistent with the hypothesis that a chemically stable lamellar surfactant layer phospholipids bind non-polar meibomian oil to the aqueous layer of the tear film.

Effect of periocular humidity on the tear film lipid layer.

The purpose of this study was to determine the relationship between the tear film and humidity by examining whether alterations in periocular humidity influence the thickness of the tear film lipid layer. Thirteen dry eye subjects presenting with a baseline lipid layer thickness of < or = 60 nm were fitted with modified swim goggles in which the right eye (OD) was exposed to conditions of high humidity and the left eye (OS) remained exposed to ambient room conditions. The lipid layer was monitored over a 60-min time course with goggles on and for an additional 60 min following goggle removal. The OD lipid layer increased significantly in thickness within 5 min of exposure to conditions of high humidity (p < 0.0001), reaching a maximum increase of 66.4 nm after 15 min of goggle wear (p < 0.0001). This maximum increase to a lipid layer thickness of 120.5 nm was maintained at the 30- and 60-min goggle time points. No significant change was detected OS. Following goggle removal, OD values declined but remained significantly elevated over the OS lipid layer thickness throughout the 60-min postgoggle period. Moderate to total relief of dry eye symptoms was reported during goggle wear and generally persisted at a reduced level for 1-3 h following goggle removal. Increased periocular humidity results in an increase in tear film lipid layer thickness, possibly by providing an environment that is more conducive to the spreading of meibomian lipid and its incorporation into the tear film.

Tear film lipid layer formation: implications for contact lens wear.

An overview of the relation between lipid layer formation and contact lens wear is provided, with particular emphasis on factors that influence the delivery and spreading of lipid on the tear film. The disruption of the lipid layer by a contact lens is discussed, as well as factors that may enhance the stability of the prelens tear film lipid layer.

Phospholipids in meibomian gland secretion.

The bulk of the lipid layer overlying the aqueous portion of the precorneal tear film is composed of polar and nonpolar components. The nonpolar lipids have been the subject of numerous studies; however, the polar lipids have remained relatively uncharacterized. The polar lipids are thought to contain surfactant phospholipids that are critical to the spreading of a lipid film over the aqueous layer, by providing an interface between this layer and the nonpolar lipids. The purpose of the present study is to identify and quantitate the phospholipid complement of meibomian gland secretion which provides the tear film with phospholipids. Meibomian gland secretion was collected from rabbits and phospholipids identified and quantitated by 31P nuclear magnetic resonance spectroscopy. Ten phospholipids were detected from meibomian gland secretion: diphosphatidylglycerol, dihydrosphingomyelin, ethanolamine plasmalogen, phosphatidylethanolamine (PE), phosphatidylserine, sphingomyelin, lysophosphatidylcholine, phosphatidylinositol, alkylacylphosphatidylcholine, and phosphatidylcholine (PC). The two major phospholipids were PC and PE, together comprising nearly 60% of the total phospholipid profile. The nature and relative concentrations of the meibomian gland secretion phospholipids are congruous with a surfactant role at the aqueous-lipid interface and, considering the physical chemistry of the tear film, suggest that the phospholipids should be organized in a very flat or planar configuration.

Tear film lipid layer thickness as a function of blinking.

Alterations in the tear film lipid layer as a function of blinking were investigated using a custom-designed specular reflection monitoring system. The tear film lipid layer of 104 subjects under conditions of normal ("baseline") blinking and "forceful" blinking was quantitated on the basis of specific interference colors. Deliberate, forceful blinking was found to significantly increase the lipid layer thickness (LLT) of the tear film. The magnitude of increase was found to be correlated with the baseline LLT values; individuals with baseline LLT values of 75-150 nm demonstrated a mean increase in LLT of 33 nm following forceful blinking, whereas subjects with baseline LLT values < or = 60 nm experienced a mean increase of 19 nm. The difference in the magnitude of increase between the groups was highly significant (p = 0.0001). The data suggest that, in addition to playing a role in the spreading of lipid across the tear film, the blinking mechanism may be important in the maintenance of the lipid layer by augmenting the expression of lipids from the meibomian glands.

Tear film-contact lens interactions.

Contemporary contact lenses, when considered in perspective, are remarkably effective; the remaining primary challenge, however, appears to be the relationship of the contact lens to the tear film. The number of contact lens wearers in the United States is no longer increasing, perhaps the result of discomfort which may occur initially, preventing contact lens wear, or which may develop over a period of years, resulting in termination of wear. Contemporary lenses can usually provide comfort if tear film integrity can be maintained. The environmental humidity is a critical component in the formation and thickness of the lipid layer for both the preocular and the prelens tear films, thus influencing tear film stability and evaporation. A common clinical observation is the gradual development of discomfort over 10 or more years of contact lens wear by patients who initially are totally asymptomatic. This discomfort, probably the result of compromise to the tear film occurring with age, frequently leads to discontinuation of contact lens wear. Intermittent discontinuation of contact lens wear may also occur as the result of seasonal discomfort when the relative humidity is low, or when the nature of the visual demand, as in extended VDT operation, inhibits blinking. The fragile tear film and its relation to contact lenses is readily understood by two quotations: "The human tear film is rather unstable, but it is regenerated by frequent blinking", and "When a contact lens is placed in the eye, the lens alters the normal structure of the tear film and affects its rate of evaporation.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Surface deposits on worn hard contact lenses.

Giant papillary conjunctivitis (GPC) is associated with deposits on contact lenses. We used scanning electron microscopy to study the anterior surface of 30 hard contact lenses, both cleaned and not cleaned, worn by patients with GPC and with keratoconus and by asymptomatic subjects. Uncleaned lenses worn by asymptomatic subjects for one day had deposits on about 5% of the surface. In most cases, the deposits were removed completely by one cleaning. Uncleaned lenses worn by patients with GPC or keratoconus had deposits on about 90% of the surface. Most of these deposits were removed by one cleaning. However, residual deposits after cleaning were greater on lenses from patients with keratoconus than on those from patients with GPC. Lenses from asymptomatic subjects rarely had residual deposits after cleaning. We found that the types of deposits on worn soft and hard contact lenses are similar, that there are fewer deposits on hard lenses than on soft lenses, and that deposits on hard lenses, unlike those on soft lenses, generally can be removed by one cleaning.