Review: Myopia control strategies recommendations from the 2018 WHO/IAPB/BHVI Meeting on Myopia.

Myopia is a major public health problem, particularly in East Asia. In this summary report, we present key findings and recommendations on strategies for myopia control discussed during the meeting jointly organised by the WHO Regional Office for the Western Pacific, the International Agency for the Prevention of Blindness and the Brien Holden Vision Institute. First, myopia prevalence was reported to be increasing, with up to 80% of junior school students with myopia in East Asia. However, common challenges in implementing myopia control strategies on a national level included lack of school screening programme, and paucity of accurate prevalence data. Second, there continues to be broad public misconception about myopia and myopia control, including lack of parental awareness and resistance to wearing spectacles. Third, best practices for myopia management were shared, and recommendations for policy implementation are presented in this review. Key recommendations from this meeting include increased public education to raise parent and teacher awareness; encouragement of increased outdoor time of 2-3 hours per day for schoolchildren-as a practical public health intervention that has been shown to potentially reduce onset and progression of myopia. Governments and non-governmental organisations are encouraged to collaborate, especially education and health ministries to develop national myopia prevention programme. Lastly, it is important to emphasise that the key recommendations, such as increasing outdoor time for schoolchildren, are specific for East Asian nations in the Western Pacific region and may not be entirely applicable for Western nations.

Simulation in Ophthalmic Training.

Vision impairment and blindness arise both as a cause, and a consequence, of poverty. Achievement of the United Nations Sustainable Development Goals in providing universal access and equity in eye care, both within and between among countries, remains challenging. A severe shortage of eye care providers is creating unnecessary blindness and vision impairment in developing communities worldwide. Education and training develops and strengthens the capacity of emerging nations to contribute to global eye health and the World Health Organization Development Goals in an effective and sustainable way. Although relative to other medical professions, adoption of simulation in ophthalmic training has been relatively slow, simulation potentially offers reduced training costs, increased accessibility, objective measurement of training outcomes, and improvements in patient safety during and after clinician training, all of which can help address the global burden of vision impairment and blindness. Simulation training offers advantages over apprenticeship models, the traditional mode of transferring knowledge and skills in medicine and health, which suffers from imperfect transference due to inherent biases, heuristic and idiosyncratic expectations of experts, and subjective measures of outcomes. Simulation does not completely do away with these confounders because it is made to fit into established curricula, making it difficult to measure effectiveness of the simulation in isolation. The power of simulation training for resource-limited regions and countries is immense in offering cost-effective training in-country; however, it is important that any such tools are developed within the context of the limitations in situ.

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.

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.

Characterization of protease IV expression in Pseudomonas aeruginosa clinical isolates.

Expression of protease IV by Pseudomonas aeruginosa during ocular infections contributes significantly to tissue damage. However, several P. aeruginosa strains isolated from ocular infections or inflammatory events produce very low levels of protease IV. The aim of the present study was to characterize, genetically and phenotypically, the presence and expression of the protease IV gene in a group of clinical isolates that cause adverse ocular events of varying degrees, and to elucidate the possible control mechanisms of expression associated with this virulence factor. Protease IV gene sequences from seven clinical isolates of P. aeruginosa were determined and compared to P. aeruginosa strains PAO1 and PA103-29. Production and enzyme activity of protease IV were measured in test strains and compared to that of quorum-sensing gene (lasRI) mutants and the expression of other virulence factors. Protease IV gene sequence similarities between the isolates were 97.5-99.5 %. The strains were classified into two distinct phylogenetic groups that correlated with the presence of exo-enzymes from type three secretion systems (TTSS). Protease IV concentrations produced by PAOΔlasRI mutants and the two clinical isolates with a lasRI gene deficiency were restored to levels comparable to strain PAO1 following complementation of the quorum-sensing gene deficiencies. The protease IV gene is highly conserved in P. aeruginosa clinical isolates that cause a range of adverse ocular events. Observed variations within the gene sequence appear to correlate with presence of specific TTSS genes. Protease IV expression was shown to be regulated by the Las quorum-sensing system.

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.

Contact lens deposits, adverse responses, and clinical ocular surface parameters.

PURPOSE: To correlate clinical responses during contact lens wear with the amount of protein or cholesterol extracted from lenses after wear. METHODS: Clinical parameters, including adverse response rates and corneal staining, and symptomatology rating during lens wear were collected from a series of clinical tests comprising four different silicone hydrogel lenses with four different multipurpose solutions. To test for correlates, the amount of total protein or cholesterol extracted from lenses after daily wear were compared statistically to clinical parameters. RESULTS: The amount of protein (p = 0.008) or cholesterol (p = 0.01) extracted from lenses was higher for those subjects who showed solution-induced corneal staining. Amount of protein extracted was correlated (p < 0.01) with conjunctival staining (R = -0.23), lens front surface wetting (r = 0.14), and lens fit tightness (R = -0.20). These clinical parameters accounted for 48% of lens protein deposition. The amount of cholesterol extracted from lenses was much more weakly associated with clinical variables. Amount of protein or cholesterol extracted from lenses was not associated with the production of any corneal infiltrative or mechanical adverse event during wear and was only very weakly correlated with insertion comfort of lenses. CONCLUSIONS: These results suggest that there may be no physiologically relevant consequence of cholesterol depositing on silicone hydrogel lenses. The amount of protein that deposits onto silicone hydrogel lenses during wear may have more affect on lens performance on-eye. However, the correlations were generally small and may still not indicate any causative relevant physiological response. Further work is required to determine whether there is any direct causative effect to support these correlative findings.

Role of carnitine in disease.

Carnitine is a conditionally essential nutrient that plays a vital role in energy production and fatty acid metabolism. Vegetarians possess a greater bioavailability than meat eaters. Distinct deficiencies arise either from genetic mutation of carnitine transporters or in association with other disorders such as liver or kidney disease. Carnitine deficiency occurs in aberrations of carnitine regulation in disorders such as diabetes, sepsis, cardiomyopathy, malnutrition, cirrhosis, endocrine disorders and with aging. Nutritional supplementation of L-carnitine, the biologically active form of carnitine, is ameliorative for uremic patients, and can improve nerve conduction, neuropathic pain and immune function in diabetes patients while it is life-saving for patients suffering primary carnitine deficiency. Clinical application of carnitine holds much promise in a range of neural disorders such as Alzheimer's disease, hepatic encephalopathy and other painful neuropathies. Topical application in dry eye offers osmoprotection and modulates immune and inflammatory responses. Carnitine has been recognized as a nutritional supplement in cardiovascular disease and there is increasing evidence that carnitine supplementation may be beneficial in treating obesity, improving glucose intolerance and total energy expenditure.

Polymorphisms in the Pseudomonas aeruginosa type III secretion protein, PcrV - implications for anti-PcrV immunotherapy.

The type III secretion system of Pseudomonas aeruginosa, responsible for acute infection, is composed of over twenty proteins that facilitate cytotoxin injection directly into host cells. Integral to this process is production and secretion of PcrV. Administration of a recently developed, anti-PcrV immunoglobulin, either as a therapeutic or prophylactic has previously demonstrated efficacy against laboratory strains of P. aeruginosa in a murine model. To determine if this therapy is universally applicable to a variety of P. aeruginosa clinical isolates, genetic heterogeneity of pcrV was analyzed among strains collected from three geographically distinct regions; United States, France and Japan. Sequence analysis of PcrV demonstrated limited variation among the clinical isolates examined. Strains were grouped according to the presence of non-synonymous single nucleotide polymorphisms. Representative isolates from each mutant group were examined for the ability of anti-PcrV to bind the protein secreted by these strains. The protective effect of anti-PcrV IgG against each strain was determined using an epithelial cell line cytotoxicity assay. The majority of strains tested demonstrated reduced cytotoxicity in the presence of anti-PcrV IgG. This study provides insights into the natural sequence variability of PcrV and an initial indication of the amino acid residues that appear to be conserved across strains. It also demonstrates the protective effect of anti-PcrV immunotherapy against a multitude of P. aeruginosa strains from diverse global regions with a variety of mutations in PcrV.

In vitro adsorption of tear proteins to hydroxyethyl methacrylate-based contact lens materials.

OBJECTIVES: Investigations of polymer interactions in single protein solutions is a necessary step in the elucidation of in vivo early binding events during protein deposition on hydroxyethyl methacrylate-based contact lens materials. Quantity and tenacity of binding of significant tear components to groups I and IV contact lenses was assessed. Competitive binding by these components was also examined. METHODS: Adsorption on FDA groups I and IV hydrogel lenses was monitored using I-labeled protein. Lenses were incubated in increasing concentrations of radiolabeled single species proteins in solution. For competition experiments, concentration of each radiolabeled protein was held constant and the adsorption/sorption challenged with increasing concentrations of nonlabeled proteins. Lenses were soaked in phosphate-buffered saline to determine desorption. RESULTS: Group IV lenses bound large amounts of lysozyme, whereas group I lenses bound highest amounts of albumin. Albumin binding to both lens types was relatively strong and could not be competed from binding by other proteins lysozyme, lactoferrin, and mucin. Mucin at high concentrations tended to positively cooperate with the binding of lactoferrin and albumin to all lenses. CONCLUSIONS: Binding of proteins to hydroxyethyl methacrylate-based hydrogel lens surfaces is affected by charge and polymer components, and perhaps manufacturing processes. Albumin binds strongly to lens surfaces, and this may play an adverse role during contact lens wear.

Expression and localization of carnitine/organic cation transporter OCTN1 and OCTN2 in ocular epithelium.

PURPOSE: The existence of an organic cation transport process in rabbit cornea and conjunctiva that mediates absorption of carnitine has previously been suggested. This study was conducted to determine the expression and localization of the carnitine/organic cation transporter (OCTN1 and OCTN2) in corneal or conjunctival epithelium. METHODS: Reverse transcriptase-polymerase chain reaction (RT-PCR) was used for OCTN1 and OCTN2 mRNA expression in cultured human corneal-limbal epithelial (HCLE) or human conjunctival epithelial (HCjE) cells. Immunofluorescence staining with polyclonal antibody against human OCTN1 or OCTN2 was performed to investigate transporter expression in ocular epithelial cells or rabbit corneal and conjunctival epithelium. Polarity of the transporter expression was determined using Western blot analysis of the apical or basal membrane proteins extracted from the cultured cells. Apical or basal uptake of [H(3)]-L-carnitine was determined using the polarized epithelial cells grown onto collagen-coated porous filter support. RESULTS: OCTN1 and OCTN2 mRNA expression was detected in HCLE and HCjE cells of rabbits and humans. OCTN1 and OCTN2 were predominately localized in the apical membranes of the cells. HCLE and HCjE cells were able to take up L-carnitine; most carnitine uptake occurred through the apical surfaces. CONCLUSIONS: This report is the first to document OCTN1 and OCTN2 expression in human corneal and conjunctival epithelial cells. These findings suggest potential involvement of OCTN1 and OCTN2 in the transport of carnitine in ocular tissues.

Carboxymethyl cellulose stimulates rabbit corneal epithelial wound healing.

PURPOSE: Previously, we reported carboxymethyl cellulose (CMC) binding to human corneal epithelial cells and promoting corneal epithelial wound closure in vitro. Using an animal model, the efficacy of CMC in promoting corneal wound healing was examined. MATERIALS AND METHODS: Following corneal epithelial wounding of NZ white rabbits, CMC (0.2% or 1.0%) or control vehicle (PBS) was administered topically (4 times daily for 3 days) to wounded and unwounded eyes with or without contact lens wear. Wound healing in response to the treatments was measured as percentage reduction of fluorescein-stained wound area 0 to 72 hr post-wounding. Corneas were examined histologically and expression of zonula occludens-1 (ZO-1) tight-junction was detected by immunohistochemistry. RESULTS: Percentage wound reduction in CMC-treated groups was significantly greater than controls (p < 0.05) at 24 and 32 hr. Complete wound closure was observed by 48 hr in 100% of CMC-treated eyes compared to 45% of vehicle-treated eyes. CMC also promoted wound closure dose-dependently. Epithelial cells formed an intact layer following CMC-treatment whereas vehicle-treated cells were less ordered. Strong ZO-1 expression in corneal epithelia of CMC-treated eyes was observed at 72 hr. Contact lens wear appeared to delay wound closure compared to without lens wear during CMC-treatment (p = 0.001). CONCLUSIONS: CMC promoted dose-dependent corneal epithelial wound healing. CMC stimulated ZO-1 expression, indicating accelerated corneal epithelial resistance barrier regeneration.

Promoter-, cell-, and ligand-specific transactivation responses of the VDRB1 isoform.

The vitamin D receptor (VDR) mediates the effects of 1,25(OH)(2)D(3), the active form of vitamin D. The human VDRB1 isoform differs from the originally described VDR by an N-terminal extension of 50 amino acids. Here we investigate cell-, promoter-, and ligand-specific transactivation by the VDRB1 isoform. Transactivation by these isoforms of the cytochrome P450 CYP24 promoter was compared in kidney (HEK293 and COS1), tumor-derived colon (Caco-2, LS174T, and HCT15), and mammary (HS578T and MCF7) cell lines. VDRB1 transactivation in response to 1,25(OH)(2)D(3) was greater in COS1 and HCT15 cells (145%), lower in HEK293 and Caco-2 cells (70-85%) and similar in other cell lines tested. By contrast, on the cytochrome P450 CYP3A4 promoter, 1,25(OH)(2)D(3)-induced VDRB1 transactivation was significantly lower than VDRA in Caco-2 (68%), but comparable to VDRA in HEK293 and COS1 cells. Ligand-dependence of VDRB1 differential transactivation was investigated using the secondary bile acid lithocholic acid (LCA). On the CYP24 promoter LCA-induced transactivation was similar for both isoforms in COS1, whereas in Caco-2 and HEK293 cells VDRB1 was less active. On the CYP3A4 promoter, LCA activation of VDRB1 was comparable to VDRA in all the cell lines tested. Mutational analysis indicated that both the 1,25(OH)(2)D(3) and LCA-regulated activities of both VDR isoforms required a functional ligand-dependent activation function (AF-2) domain. In gel shift assays VDR:DNA complex formation was stronger in the presence of 1,25(OH)(2)D(3) than with LCA. These results indicate that regulation of VDRB1 transactivation activity is dependent on cellular context, promoter, and the nature of the ligand.

Vitamin D receptor B1 and exon 1d: functional and evolutionary analysis.

The vitamin D receptor (VDR) shares a conserved structural and functional organization with other nuclear receptor (NR) superfamily members. For many NRs, N-terminal variant isoforms that display distinct cell-, stage- and promoter-specific actions have been identified. The novel VDR isoform VDRB1, with a 50 amino acid N-terminal extension, is produced from low abundance transcripts that contain exon 1d of the human VDR locus. There is evidence for the conservation of this exon in other mammalian and avian species. The transactivation differences between VDRB1 and the original VDR, clarified here, provide insights into mechanisms that may contribute to functional differences and potentially distinct physiological roles for these two VDR isoforms.