Treatment Practices and Outcomes of Meibomian Gland Dysfunction at a Tertiary Center in Southern India.

OBJECTIVE: To describe the current treatment practices for meibomian gland dysfunction (MGD) at a tertiary eye center, together with the subjective outcomes and compliance behaviors of patients. METHODS: This retrospective cohort study reviewed medical records for MGD severity grading, treatment prescribed, and follow-up schedule. In addition, participants were surveyed to gauge subjective outcomes and treatment adherence. RESULTS: Eight hundred ten patients were diagnosed with "MGD" or "meibomitis" and had a total of 14 different treatment combinations prescribed. In 3.0% of cases, there was no treatment specified. As MGD severity increased, it became more likely that management would be applied and this was also associated with significantly longer treatment durations (P=0.02) and shorter follow-up periods (P<0.001). Posttreatment subjective outcomes and treatment adherence surveys had a response rate of 36.7% and 24.1% respectively. Overall, 53.5% reported sustained improvement, 40.7% no improvement, and 5.7% experienced temporary relief. Although no treatment regimen seemed to be more efficacious than others, patients showed greater adherence when using topical reagents compared with lid hygiene measures (P≤0.002). CONCLUSION: Clinicians, in this large tertiary eye center, use a wide range of treatment regimens to manage MGD. This suggests the need for development of standard management protocols. Whether alone, or in combination, no MGD treatment significantly improved subjective symptoms, a result that may be influenced by compliance behaviors. Use of topical reagents (eye drops or ointment) seemed to be associated with the best compliance. Future focus on more effective MGD treatments is needed to improve practical outcomes.

Measurement of consensual accommodation in vision-impaired eyes.

PURPOSE: To measure the accommodative response in unsighted or profoundly vision impaired (PVI) eyes when accommodation is elicited in the fellow, sighted eye. METHODS: Eighty-eight unilaterally PVI subjects (UPS) and 97 bilaterally sighted subjects (BSS) (10 to 45 years) were enrolled. Subjects had clear ocular media for auto-refraction and could steadily fixate targets with the sighted eye. For BSS, a long-pass filter was placed in front of one eye to simulate unilateral blindness. Both eyes were measured with a Shin-Nippon auto-refractor while fixating a 4/40 letter at 4 m and then an N8 letter at 40 cm and at 33 cm. Accommodation was calculated as the difference between distance and near refraction. RESULTS: Only subjects with repeatable alignment between measurements were included in the analyses (64 UPS, 95 BSS). Results were analyzed using t test and a generalized linear mixed model including age, sightedness, distance spherical equivalent, and accommodation as factors. The t test found no significant difference between eyes for UPS (p = 0.981 at 40 cm and p = 0.663 at 33 cm). For BSS, the sighting eye produced statistically significant but only slightly greater amounts of accommodation than the filtered eye (0.098 diopters [D], p = 0.002 at 40 cm and 0.189 D, p < 0.001 at 33 cm). The generalized linear mixed model found no difference between BSS and UPS in terms of difference in accommodation between eyes (p = 0.128 at 40 cm and p = 0.157 at 33 cm). CONCLUSIONS: The PVI eyes of unilaterally PVI individuals display similar accommodative response to their fellow, sighted eyes when accommodation is elicited by near target of up to 3 D to the fellow eye. However, the difference in accommodative response between PVI and fellow, sighted eye is related to the amount of accommodation elicited.

Decrease in hyperosmotic stress-induced corneal epithelial cell apoptosis by L-carnitine.

PURPOSE: To characterize the osmoprotective properties of L-carnitine on human corneal epithelial cell volume and apoptosis during hyperosmotic stress. METHODS: Human corneal limbal epithelial (HCLE) cells were exposed to culture medium at 300 mOsm (isotonic) or 500 mOsm (hyperosmotic) with or without L-carnitine (10 mM). Induction of apoptosis was detected by quantifying the proteolytic activity of caspase-8, caspase-9, and caspase-3/7 using caspase activity assays, the expression of tumor necrosis factor (TNF)-α with enzyme-linked immunosorbent assay, and annexin V/propidium iodide staining of HCLE cells evaluated with confocal microscopy and flow cytometry. Cell volume changes in response to hyperosmotic stress were analyzed using flow cytometry. RESULTS: After the HCLE cells were exposed to hyperosmotic medium (500 mOsm), the percentage of shrunken cells and damaged/dead cells (stained positively for annexin V and/or propidium iodide) was six- and three-fold, respectively, higher than that under isotonic conditions (300 mOsm). This was paralleled by an increase in TNF-α concentration in media and caspase-8, -9, and -3/7 activities (six-, four-, ten-, and twelve-fold, respectively; all showing p < 0.001). Addition of L-carnitine during hyperosmotic stress partly restored cell volume and significantly reduced the concentration of TNF-α released (p = 0.005) and caspase-9 activity (p = 0.0125). Addition of L-carnitine reduced the percentage of hyperosmolarity-induced damaged/dead cells to levels observed under isotonic conditions. CONCLUSIONS: L-carnitine can regulate human corneal epithelial cell volume under hyperosmotic stress and ameliorate hyperosmotic stress-induced apoptosis.

Betaine stabilizes cell volume and protects against apoptosis in human corneal epithelial cells under hyperosmotic stress.

Elevated tear osmolarity is one of the key pathological factors in dry eye leading to ocular discomfort associated with damage to the ocular surface and inflammation. The aim of this study was to determine the capacity of the organic osmolyte, betaine, to act as an osmoprotectant against hypertonic stress-induced human corneal epithelial cell shrinkage and apoptosis using in vitro cell culture models. Human corneal limbal epithelial (HCLE) cells exposed to culture medium for 16 h at 300 mOsm (isotonic) or 500 mOsm (hyperosmotic) in the presence or absence of betaine (5 or 10 mM) were evaluated for cell volume changes; cell viability; and apoptosis. Betaine (10 mM) ameliorated hyperosmotically induced reduction of cell volume (from 27% reduction to 11%) and resulted in increased mitochondrial activity (by 17%) and an increase in viable cell numbers (by 12%) compared to controls (exposure to hyperosmotic medium without betaine). Hyperosmotically shocked HCLE cells in the presence of betaine (10 mM) halved the number of damaged cells (apoptotic/necrotic) compared to cells in the absence of betaine. The presence of betaine (at 5 or 10 mM) significantly reduced the activity of caspase-8, -9 and -3/7 and release of TNF-α was also reduced by 34% or 55% after exposure of HCLE to 500 mOsm in the presence of 5 or 10 mM betaine, respectively. Using polyclonal antibody against Betaine/GABA transporter 1 (BGT-1), we detected the presence of BGT-1 in HCLE. We demonstrated that the transport of betaine was facilitated by increased osmolarity. In conclusion, betaine stabilized corneal epithelial cell volume under hyperosmotic stress and limited hyperosmotic stress-induced HCLE apoptosis.

A preliminary study of changes in tear film proteins in the feline eye following nictitating membrane removal.

OBJECTIVE: To investigate the influence of nictitating membrane (third eyelid) removal on selected proteins in feline tears. ANIMAL STUDIED: Domestic short-haired cats (7-17 months; 2.6-5.2 kg) were used. PROCEDURES: Eye-flush tears were collected periodically for up to 18 weeks from both eyes of animals with nictitating membranes removed, but nictitating gland left intact, (n = 4) or with nictitating membranes intact (n = 4). Tear comparisons were based on total protein content (TPC) using micro bicinchoninic acid assay, immunoglobulin A (IgA), and matrix-metalloproteinase (MMP)-9 measurements using sandwich enzyme-linked immunosorbent assay (ELISA) and tear gelatinase activity using gelatin zymography. Expression of MMP-2 and -9 in nictitating membranes removed at baseline (week 0) and eyes collected at 18 weeks were also investigated in histological sections using immunoperoxidase for visualization. RESULTS: Nictitating membrane removal did not significantly change TPC and MMP-9 in tears within the first 4 weeks. MMP-9 was not detected by ELISA in tears from eyes without nictitating membranes from week 5 onwards. IgA (%IgA of TPC) data varied between animals. Gelatin zymography showed increased MMP-2 and -9 activity in tears from eyes without nictitating membranes at week 1 and a decrease following week 2 post-surgery. MMP-2 and -9 were immunolocalised to conjunctival goblet cells of removed nictitating membranes and to the conjunctival epithelium, respectively. After 18 weeks, the distribution of MMPs in tissue was comparable between eyes with and without nictitating membranes. CONCLUSIONS: Based on this preliminary study, nictitating membrane removal appeared to cause long-term changes in expression of tear proteins, including reduced MMP-9 expression.

Transport of L-carnitine in human corneal and conjunctival epithelial cells.

PURPOSE: Previously we demonstrated expression and localization of carnitine/organic cation transporters, OCTN1 and OCTN2, in human corneal and conjunctival epithelia. The present study aimed to examine the characteristics of L-carnitine transporters in cultured human limbal corneal (HCLE) and conjunctival epithelial (HCjE) cells. METHODS: Time-course, Na(+)-dependence, kinetics, energy- and pH- dependence of L-carnitine transport were investigated by monitoring L-[(3)H]carnitine uptake into HCLE and HCjE cells. To determine the specificity of action, competition and inhibition studies were performed. RESULTS: The uptake of L-carnitine into HCLE and HCjE cells was saturable and time-dependent. An Eadie-Hofstee plot showed two distinct components: a high- and a low- affinity carnitine transport system in HCLE and/or HCjE cells. L-carnitine transport was significantly inhibited by the metabolic inhibitors (sodium azide, dinitrophenol, iodoacetic acid). The L-carnitine analogs (D-carnitine, acetyl-L-carnitine and γ-butyrobetaine), tetraethylammonium (TEA), 2-amino-2-norbornane carboxylic acid (BCH), strongly inhibited uptake of L-[(3)H]carnitine. Uptake of L-[(3)H]carnitine also required the presence of Na(+) in the external medium and the uptake activity was maximal at pH 5.5. The anti-OCTN2 antibody blocked L-carnitine uptake in both HCLE and HCjE cells whereas the anti-OCTN1 antibody did not significantly block L-carnitine uptake. CONCLUSIONS: L-carnitine is transported into HCLE and HCjE cells by an active carrier mediated transport system that is time-, Na(+)-, energy- and pH- dependent. The carnitine/organic cation transporter OCTN2 appears to play a dominant role in this process.

Care regimen and lens material influence on silicone hydrogel contact lens deposition.

PURPOSE: To quantitatively detect proteins and cholesterol extracted from worn silicone hydrogel contact lenses and determine the effect of various lens care solutions on deposit accumulation. METHODS: Contact lenses, made from different polymers and worn on a daily wear schedule with different lens care solutions, were collected. Lipid and protein deposits were extracted by methanol:chloroform (1:1, v/v) and protein extraction solution (containing urea and surfactant), respectively. Lipid extracts were separated and cholesterol quantified using thin layer chromatography. Protein extracts were quantified using standard techniques. RESULTS: Among all lenses tested, Balafilcon A lenses exhibited greatest extracted cholesterol (4.1 to 8.2 microg/lens) and total protein (5.4 to 23.2 microg/lens). AQuify was the most effective solution in reducing extracted deposits, especially extracted protein, from Balafilcon A lenses. AQuify and Opti-Free RepleniSH solutions were most effective in reducing extracted cholesterol from Senofilcon A and Galyfilcon A lenses, respectively. Use of Opti-Free Express solution resulted in more extracted protein from Lotrafilcon B lenses than use of other solutions. Generally, Lotrafilcon B, Senofilcon A, and Galyfilcon A lenses accumulated relatively low amount of proteins. Lotrafilcon B lenses accumulated the least amount of cholesterol deposit among all lenses tested regardless of solution used. CONCLUSIONS: Lens polymer (possibly associated with surface characteristics) is a prominent factor affecting lipid and protein accumulation. Within a lens polymer type, lens care solutions exhibit varying effectiveness in reducing protein and lipid accumulation.

Proteomic analysis of protein deposits on worn daily wear silicone hydrogel contact lenses.

PURPOSE: Previous studies have demonstrated deposition of tear proteins onto worn contact lenses. In this study, we used proteomic techniques to analyze the protein deposits extracted from worn daily wear silicone hydrogel contact lenses in combination with different lens care solutions. METHODS: Worn lenses were collected and protein deposits extracted using urea and surfactant. Protein extracts were desalted, concentrated, and then separated using one-dimensional gel electrophoresis. Individual protein components in extracts were identified using liquid chromatography combined with tandem mass spectrometry (LC-MS-MS) after trypsin digestion. RESULTS: One-dimensional gel electrophoresis revealed that lysozyme and other small proteins (around 20 kDa) were the most abundant proteins in the extracts. LC-MS-MS revealed a wide array of proteins in lens extracts with lysozyme and lipocalin 1 being the most commonly identified in deposit extracts. CONCLUSIONS: Worn contact lenses deposit a wide array of proteins from tear film and other sources. Protein deposit profiles varied and were specific for each contact lens material.

Genetic factors and molecular mechanisms in dry eye disease.

Dry eye disease (DED) is a complex condition with a multifactorial etiology that can be difficult to manage successfully. While external factors are modifiable, treatment success is limited if genetic factors contribute to the disease. The purpose of this review is to compile research describing normal and abnormal ocular surface function on a molecular level, appraise genetic studies involving DED or DED-associated diseases, and introduce the basic methods used for conducting genetic epidemiology studies.

Carboxymethylcellulose binds to human corneal epithelial cells and is a modulator of corneal epithelial wound healing.

PURPOSE: In this study, the ability of carboxymethylcellulose (CMC), used in artificial tear formulations, to interact with corneal-epithelial-cells (HCECs) and facilitate corneal epithelial wound healing was investigated. METHODS: HCECs were incubated with fluorescein-labeled CMC (F-CMC). CMC-epithelial binding was measured by spectrophotometry. The effect on F-CMC binding by hyaluronic acid (HA) or glucose was measured after preincubation in HA, mAb to CD44, or glucose, or mAb to GluT-1. F-CMC binding to fibronectin or collagen was measured by incubating proteins with F-CMC. The wound widths were measured 18 hours after confluent HCECs were scratch wounded. The ability of CMC to induce cell chemotaxis, proliferation, or migration was measured by quantitative assay. The efficacy of CMC in promoting epithelial wound healing was also tested in a rabbit epithelial scrape-wound model. RESULTS: CMC remained bound to the HCECs for 2 hours. Preincubation of HCECs with glucose or mAb to GluT-1, but not with HA or mAb to CD44, reduced the binding of CMC to HCECs from 43.7% to 67.2% or 10.9% to 25.3%, respectively. CMC bound significantly to fibronectin (3.1-fold) or collagen (9.3-fold) compared with the control (BSA), and such binding enhanced cell adhesion. CMC stimulated re-epithelialization of HCECs scratched in vitro and in vivo rabbit cornea epithelial scrape wounds. CMC stimulated cell migration but not proliferation. CONCLUSIONS: CMC probably binds to HCECs through interaction of its glucopyranose subunits with glucose transporters. CMC binding to the matrix proteins stimulated HCEC attachment, migration, and re-epithelialization of corneal wounds.