Evaluation of biomarkers of inflammation in response to benzalkonium chloride on corneal and conjunctival epithelial cells

Mass spectrometry (MS)-based metabolomics of plasma and urine in dry eye disease (DED)-induced rat model

Dry eye disease (DED) is an ophthalmic disease associated with poor quality and quantity of tears, and the number of patients is steadily increasing. The aim of this study was to determine plasma and urine metabolites obtained from DED scopolamine animal model where dry eye conditions (DRY) are induced. It was also of interest to examine whether DED (scopolamine) rat model was exacerbated by treatment with benzalkonium chloride (BAC). Subsequently, plasma and urine metabolites were analyzed using liquid chromatography (LC) and gas chromatography (GC)-mass spectrometry (MS), respectively. Data demonstrated that DED indicators such as tear volume, tear breakup time (TBUT), and corneal damage in the DED groups (DRY and BAC group) differed from those of control (CON). Similar results were noted in inflammatory factors such as interleukin (IL-1β), IL-6, and tumor necrosis factor (TNF)-α. In the partial least squares-discriminant analysis (PLS-DA) score plots, the three groups were distinctly separated from each other. In addition, the related metabolites were also associated with these distinct separations as evidenced by 9 and 14 in plasma and urine, respectively. Almost all of the selected metabolites were decreased in the DRY group compared to CON, and the BAC group was lower than the DRY. In plasma and urine, lysophosphatidylcholine/lysophosphatidylethanolamine, organic acids, amino acids, and sugars varied between three groups, and these metabolites were related to inflammation and oxidative stress. Data suggest that treatment with scopolamine with/without BAC-induced DED and affected the level of systemic metabolites involved in inflammation and oxidative stress.

Enhancing the hypotensive effect of latanoprost by combining synthetic phosphatidylcholine liposomes with hyaluronic acid and osmoprotective agents

The first line of glaucoma treatment focuses on reducing intraocular pressure (IOP) through the prescription of topical prostaglandin analogues, such as latanoprost (LAT). Topical ophthalmic medicines have low bioavailability due to their rapid elimination from the ocular surface. Nanotechnology offers innovative ways of enhancing the ocular bioavailability of antiglaucoma agents while reducing administration frequency. This study aims to combine LAT-loaded synthetic phosphatidylcholine liposomes with hyaluronic acid (0.2% w/v) and the osmoprotectants betaine (0.40% w/v) and leucine (0.90% w/v) (LAT-HA-LIP) to extend the hypotensive effect of LAT while protecting the ocular surface. LAT-HA-LIP was prepared as a mixture of 1,2-dioleoyl-sn-glycero-3-phosphocholine and 1,2-dimyristoyl-sn-glycero-3-phosphocholine, cholesterol and α-tocopherol acetate. LAT-HA-LIP exhibited high drug-loading capacity (104.52 ± 4.10%), unimodal vesicle sizes (195.14 ± 14.34 nm) and a zeta potential of -13.96 ± 0.78 mV. LAT-HA-LIP was isotonic (284.00 ± 1.41 mOsm L-1), had neutral pH (7.63 ± 0.01) and had suitable surface tension (44.07 ± 2.70 mN m-1) and viscosity (2.69 ± 0.15 mPa s-1) for topical ophthalmic administration. LAT-HA-LIP exhibited optimal in vitro tolerance in human corneal and conjunctival epithelial cells. No signs of ocular alteration or discomfort were observed when LAT-HA-LIP was instilled in albino male New Zealand rabbits. Hypotensive studies revealed that, after a single eye drop, the effect of LAT-HA-LIP lasted 24 h longer than that of a marketed formulation and that relative ocular bioavailability was almost three times higher (p < 0.001). These findings indicate the potential ocular protection and hypotensive effect LAT-HA-LIP offers in glaucoma treatment.

Preservatives and ocular surface disease: A review

Ocular surface disease (OSD) is a complex condition that can cause a range of symptoms (e.g, dryness, irritation, and pain) and can significantly impact the quality of life of affected individuals. Iatrogenic OSD, a common finding in patients with glaucoma who receive chronic therapy with topical ocular antihypertensive drugs containing preservatives such as benzalkonium chloride (BAK), has been linked to damage to the ocular surface barrier, corneal epithelial cells, nerves, conjunctival goblet cells, and trabecular meshwork. Chronic BAK exposure activates inflammatory pathways and worsens symptoms, compromising the success of subsequent filtration surgery in an exposure-dependent manner. In eyes being treated for glaucoma, symptomatic treatment of OSD may provide some relief, but addressing the root cause of the OSD often necessitates reducing or, ideally, eliminating BAK toxicity. Strategies to decrease BAK exposure in patients with glaucoma encompass the use of preservative-free formulations or drugs with alternative and less toxic preservatives such as SofZia®, Polyquad, potassium sorbate, or Purite®. Though the benefits of these alternative preservatives are largely unproven, they might be considered when financial constraints prevent the use of preservative-free versions. For patients receiving multiple topical preserved drugs, the best practice is to switch to nonpreserved equivalents wherever feasible, regardless of OSD severity. Furthermore, nonpharmacological approaches, including laser or incisional procedures, should be considered. This review explores the effects of BAK on the ocular surface and reviews strategies for minimizing or eliminating BAK exposure in patients with glaucoma in order to significantly improve their quality of life and prevent complications associated with chronic exposure to BAK.

The Effect of Topical Rebamipide 2% in Managing Dry Eye Following Cataract Surgery

Purpose: To evaluate the potential advantages of using topical rebamipide 2% to manage dry eye following cataract surgery.Methods: Patients who underwent cataract surgery (phacoemulsification and intraocular lens insertion) were evaluated for dry eye 1 week postoperatively. Randomly selected patients were divided into the rebamipide group, who received 2% rebamipide eye drops, and the control group, who did not receive rebamipide. Various dry eye-related tests, including Schirmer’s test, the tear break-up time (TBUT), ocular surface staining, tear film osmolarity, tear lipid layer thickness, and the ocular surface disease index (OSDI) were performed in both groups 1 week, and 1 and 2 months postoperatively.Results: In the rebamipide group, we observed significant improvement in TBUT, the ocular surface staining score, and OSDI at 2 months postoperatively, as compared to 1 week (<i>p</i> = 0.002, 0.014, and 0.013, respectively). Schirmer’s test, tear film osmolarity, and tear lipid layer thickness remained unchanged in the rebamipide group. Throughout the entire follow-up period, the rebamipide group had a significantly prolonged TBUT (1 month: <i>p</i> = 0.007, 2 months: <i>p</i> = 0.000), and lower ocular surface staining score (1 month: <i>p</i> = 0.000, 2 months: <i>p</i> = 0.000), as compared to the control.Conclusions: Following cataract surgery, the use of rebamipide eye drops produced improvements in TBUT, ocular surface staining scores, and OSDI. This suggests that rebamipide offers benefits in managing dry eye that can occur after cataract surgery.

Mucoadhesive phenylboronic acid-grafted carboxymethyl cellulose hydrogels containing glutathione for treatment of corneal epithelial cells exposed to benzalkonium chloride

Benzalkonium chloride (BAK) is the most commonly-used preservative in topical ophthalmic medications that may cause ocular surface inflammation associated with oxidative stress and dry eye syndrome. Glutathione (GSH) is an antioxidant in human tears and able to decrease the proinflammatory cytokine release from cells and reactive oxygen species (ROS) formation. Carboxymethyl cellulose (CMC), a hydrophilic polymer, is one of most commonly used artificial tears and can promote the corneal epithelial cell adhesion, migration and re-epithelialization. However, most of commercial artificial tears provide only temporary relief of irritation symptoms and show the short-term treatment effects. In the study, 3-aminophenylboronic acid was grafted to CMC for increase of mucoadhesive properties that might increase the precorneal retention time and maintain the effective therapeutic concentration on the ocular surface. CMC was modified with different degree of substitution (DS) and characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Phenylboronic acid (PBA)-grafted CMC hydrogels have interconnected porous structure and shear thinning behavior. Modification of CMC with high DS (H-PBA-CMC) shows the strong bioadhesive force. The optimal concentration of GSH to treat corneal epithelial cells (CECs) was evaluated by cell viability assay. H-PBA-CMC hydrogels could sustained release GSH and decrease the ROS level. H-PBA-CMC hydrogels containing GSH shows the therapeutic effects in BAK-damaged CECs via improvement of inflammation, apoptosis and cell viability. After topical administration of developed hydrogels, there was no ocular irritation in rabbits. These results suggested that PBA-grafted CMC hydrogels containing GSH might have potential applications for treatment of dry eye disease.

Triclosan and its alternatives, especially chlorhexidine, modulate macrophage immune response with distinct modes of action

Since European regulators restricted the use of bacteriocidic triclosan (TCS), alternatives for TCS are emerging. Recently, TCS has been shown to reprogram immune metabolism, trigger the NLRP3 inflammasome, and subsequently the release of IL-1β in human macrophages, but data on substitutes is scarce. Hence, we aimed to examine the effects of TCS compared to its alternatives at the molecular level in human macrophages. LPS-stimulated THP-1 macrophages were exposed to TCS or its substitutes, including benzalkonium chloride, benzethonium chloride, chloroxylenol, chlorhexidine (CHX) and cetylpyridinium chloride, with the inhibitory concentration (IC10-value) of cell viability to decipher their mode of action. TCS induced the release of the pro-inflammatory cytokine TNF and high level of IL-1β, suggesting the activation of the NLRP3-inflammasome, which was confirmed by non-apparent IL-1β under the NLRP3-inhibitor MCC950 treatment d. While IL-6 release was reduced in all treatments, the alternative CHX completely abolished the release of all investigated cytokines. To unravel the underlying molecular mechanisms, we used untargeted LC-MS/MS-based proteomics. TCS and CHX showed the strongest cellular response at the protein and signalling pathway level, whereby pathways related to metabolism, translation, cellular stress and migration were mainly affected but to different proposed modes of action. TCS inhibited mitochondrial electron transfer and affected phagocytosis. In contrast, in CHX-treated cells, the translation was arrested due to stress conditions, resulting in the formation of stress granules. Mitochondrial (e.g. ATP5F1D, ATP5PB, UQCRQ) and ribosomal (e.g. RPL10, RPL35, RPS23) proteins were revealed as putative key drivers. Furthermore, we have demonstrated the formation of podosomes by CHX, potentially involved in ECM degradation. Our results exhibit modulation of the immune response in macrophages by TCS and its substitutes and illuminated underlying molecular effects. These results illustrate critical processes involved in the modulation of macrophages' immune response by TCS and its alternatives, providing information essential for hazard assessment.

Pharmacokinetic and Ocular Toxicity Evaluation of Latanoprost Ophthalmic Solution, 0.005%, with Preservative Level Reduced to Below the Limit of Quantitation

Purpose: The systemic and ocular pharmacokinetics (PK), and ocular toxicity of benzalkonium chloride (BAK)-free TearClear latanoprost ophthalmic solution, 0.005% formulation (TC-002) were evaluated. TC-002 is designed to selectively capture BAK at the time of drug administration; therefore, the dose delivered to the eye contains no quantifiable level of preservative. Methods: The systemic and ocular PK of TC-002 were compared to a BAK containing reference listed drug (RLD, Xalatan™) over a 24-h period, after a single topical ocular dose to 1 eye of male Dutch Belted (DB) rabbits (n = 3/timepoint). Latanoprost acid concentrations were measured in plasma and ocular tissues. The ocular toxicity was evaluated in a separate study and included toxicokinetic evaluation of TC-002 after once daily topical ocular dosing into each eye of DB rabbits (n = 8/group) for at least 28 days. Toxicity endpoints included ophthalmic and clinical evaluations, necropsy, and microscopic evaluation of ocular tissues. Results: Average ratios of Cmax values for TC-002/RLD ranged from 0.6 to 1.6, and Cmax and area under the concentration-time curve of last observed concentration (AUClast) exposures to latanoprost acid were similar (<2-fold) between the 2 treatments. In the 28-day study, the Tmax was achieved in both groups in <0.5 h. There were no abnormal ocular findings. Conclusions: TC-002 with no quantifiable preservative or BAK-containing RLD exhibited similar ocular and systemic PK profiles. TC-002 was well tolerated and comparable to RLD. TC-002 retains the safety and PK characteristics of RLD without the added concern of long-term exposure of the eye to preservatives.

Latanoprost PF vs. Bimatoprost PF: Which Treats the Ocular Surface Better?

(1) Background: The current study aimed to compare two of the most frequently prescribed preservative-free (PF) antiglaucoma drops, (Latanoprost PF vs. Bimatoprost PF) in promoting OSD in patients with POAG. (2) Methods: In this prospective study, 44 eyes from 44 participants were included. In the control group we enrolled 24 eyes, 11 eyes treated only with Latanoprost PF were enrolled in the Latanoprost PF group, and 9 eyes treated only with Bimatoprost PF in the Bimatoprost PF group. In all eyes, we evaluated the ocular levels of MMP-9 using the InflammaDry kit. We also performed Schirmer's test and the TBUT test. (3) Results: We found elevated ocular levels of MMP-9 (>40 ng/mL) in the Bimatoprost PF group (88.89% of the participants) compared to the control (8.33%) and the Latanoprost PF group (27.27%), and the difference was statistically significant (p < 0.001). The Schirmer's test values were statistically significantly lower in the Bimatoprost PF group compared to the other two groups. Additionally, the TBUT values were lower in the Bimatoprost PF group compared to the control group, and the difference was statistically significant. (4) Conclusions: Latanoprost PF eye drops treat the ocular surface better and they do not induce overexpression of MMP-9, a molecule that is related to OSD.

The molecular aspect of anti-glaucomatous eye drops - are we harming our patients?

Glaucoma is one of the leading causes of irreversible blindness. Progression is halted with a reduction in intraocular pressure (IOP), which is most often achieved with eye drops. A major challenge in the topical treatment of glaucoma patients is the many side effects and the resulting reduced adherence. Side effects may of course be due to the molecular properties of the active pharmaceutical ingredients (APIs). There are currently six different APIs available: prostaglandin analogues, β-adrenergic inhibitors, α-adrenergic agonists, carbonic anhydrase inhibitors, rho-kinase inhibitors and muscarinic 3 agonists. But the additives used in eye drops are also known to cause damage to the ocular surface and to some extent also to the deeper tissues. Said additives are considered inactive molecular components and are added to secure for instance viscosity and pH value, and to prevent contamination. There has been an increasing focus on the harmful effects of preservatives, with the most commonly used preservative benzalkonium chloride (BAK) being particularly controversial. BAK has long been recognized as a toxin that increases the risk of ocular discomfort. This can affect the adherence and ultimately result in lack of disease control. Other issues include the addition of certain buffers, such as phosphates, and varying pH values. This review will address the different molecular components of the IOP-lowering eye drops and what to be aware of when prescribing topical glaucoma treatment.

Corneal neuroepithelial compartmentalized microfluidic chip model for evaluation of toxicity-induced dry eye

Part of the lacrimal functional unit, the cornea protects the ocular surface from numerous environmental aggressions and xenobiotics. Toxicological evaluation of compounds remains a challenge due to complex interactions between corneal nerve endings and epithelial cells. To this day, models do not integrate the physiological specificity of corneal nerve endings and are insufficient for the detection of low toxic effects essential to anticipate Toxicity-Induced Dry Eye (TIDE). Using high-content imaging tool, we here characterize toxicity-induced cellular alterations using primary cultures of mouse trigeminal sensory neurons and corneal epithelial cells in a compartmentalized microfluidic chip. We validate this model through the analysis of benzalkonium chloride (BAC) toxicity, a well-known preservative in eyedrops, after a single (6h) or repeated (twice a day for 15 min over 5 days) topical 5.10-4% BAC applications on the corneal epithelial cells and nerve terminals. In combination with high-content image analysis, this advanced microfluidic protocol reveal specific and tiny changes in the epithelial cells and axonal network as well as in trigeminal cells, not directly exposed to BAC, with ATF3/6 stress markers and phospho-p44/42 cell activation marker. Altogether, this corneal neuroepithelial chip enables the evaluation of toxic effects of ocular xenobiotics, distinguishing the impact on corneal sensory innervation and epithelial cells. The combination of compartmentalized co-culture/high-content imaging/multiparameter analysis opens the way for the systematic analysis of toxicants but also neuroprotective compounds.

Assessment of corneal sublayer thickness changes in glaucoma patients using optical coherence tomography and correlation of epithelial layer thinning with dry eye monitoring

BACKGROUND

In this study, we aimed to assess the central corneal epithelial thickness (CET), central corneal stromal thickness (CST), and total central corneal thickness (CCT) thinning relationships with dry eye development monitoring and underestimated measurement of intraocular pressure (IOP) in primary open-angle glaucoma (POAG) patients treated with timolol, dorzolamide, and brimonidine.

METHODS

This longitudinal cohort study included 106 patients with POAG. All patients underwent a detailed ophthalmic examination. In addition, CET, CST, and CCT were measured using anterior segment optical coherence tomography (AS-OCT). Subsequently, the cohort was divided into three groups based on the therapy administered. The Tomec group received monotherapy with benzalkonium chloride (BAK)-preserved timolol + dorzolamide fixed combination. The Alphagan group received monotherapy with purite-preserved brimonidine, and the Combigan group received monotherapy with BAK-preserved timolol + brimonidine fixed combination.

RESULTS

CET, CST, and CCT did not show a statistically significant decrease in the Alphagan group (p>0.05). However, the Tomec and Combigan groups showed significantly reduced measurements, except for stromal thickness (p<0.05). Finally, a significant positive correlation was found between changes in tear break-up time (TBUT) and CET during the follow-up period (r = 0.637, p = 0.001).

CONCLUSIONS

CET and CCT thinning were higher in the Tomec and Combigan groups than in the Alphagan group. Furthermore, although CCT reduction was significant in the Tomec and Combigan groups, its effect on IOP underestimation was approximately 1%. Furthermore, the positive correlation between CET and TBUT suggests that CET measurement with AS-OCT may also be useful in dry eye monitoring.

Efficacy of Topical 0.05% Cyclosporine A for Ocular Surface Disease Related to Topical Anti-Glaucoma Medications

Purpose: We aimed to determine the therapeutic efficacy of 0.05% topical cyclosporine A (CsA) for chronic ocular surface disease (OSD) in patients using benzalkonium chloride (BAK)-preserved antiglaucoma eye drops. Methods: A prospective, randomized, paired-eye, controlled clinical trial was conducted with participants who had been instilling at least one BAK-preserved topical antiglaucoma drug in both eyes for at least 6 months. Topical CsA was only applied in randomly selected unilateral eyes. Visual field (VF) indices, ocular surface parameters, tear meniscus height (TMH), and matrix metalloproteinase-9 (MMP-9) immunoassay were evaluated at baseline and at 2 and 4 months. Results: Seventy eyes from 35 participants were included in the study. The Schirmer I, tear breakup time, and TMH increased by 4.5 ± 8.6 mm (P < 0.01), 5.0 ± 5.3 s (P < 0.001), and 85.4 ± 159.0 μm (P < 0.01) in the treated eyes at 4 months from baseline, respectively. The ocular staining score and MMP-9 positivity in the treated eyes decreased by 2.2 ± 1.3 (P < 0.001) and 0.7 ± 0.9 points (P < 0.001), respectively, at 4 months. In untreated eyes, only TMH increased by 41.4 ± 92.1 μm (P = 0.016) from baseline to 4 months. In VF indices, the tracking failure frequency was 19.09% ± 21.62%, and the test duration was 336.0 ± 79.5 s in the treated eyes at 4 months, which were lower than 34.37% ± 23.13% (P < 0.001) and 375.9 ± 70.7 s (P < 0.05) in the nontreated eyes. Conclusion: Application of topical 0.05% CsA significantly improved the OSD parameters and the reliability indices of VF tests. This study was registered with the Clinical Research Information Service (CRIS) (number KCT0007124).

Quaternary ammonium compounds in hypersensitivity reactions

Quaternary ammonium compounds (QAC) are commonly used disinfectants, antiseptics, preservatives, and detergents due to their antibacterial property and represent the first used biocides before phenolic or nitrogen products. Their common structure consists of one or more quaternary ammonium bound with four lateral substituents. Their amphiphilic structure allows them to intercalate into microorganism surfaces which induces an unstable and porous membrane that explains their antimicrobial activity towards bacteria, fungi, and viruses. QAC are thus found in many areas, such as household products, medicines, hygiene products, cosmetics, agriculture, or industrial products but are also used in medical practice as disinfectants and antiseptics and in health care facilities where they are used for cleaning floors and walls. QAC exposure has already been involved in occupational asthma in healthcare workers or professional cleaners by many authors. They also have been suggested to play a role in contact dermatitis (CD) and urticaria in workers using cosmetics such as hairdressers or healthcare workers, inciting reglementary agencies to make recommendations regarding those products. However, distinguishing the irritant or sensitizing properties of chemicals is complex and as a result, the sensitizing property of QAC is still controverted. Moreover, the precise mechanisms underlying the possible sensitization effect are still under investigation, and to date, only a few studies have documented an immunological mechanism. Besides, QAC have been suggested to be responsible for neuromuscular blocking agents (NMBA) sensitization by cross-reactivity. This hypothesis is supported by a higher prevalence of quaternary ammonium (QA)-specific IgE in the professionally exposed populations, such as hairdressers, cleaners, or healthcare workers, suggesting that the sensitization happens with structurally similar compounds present in the environment. This review summarizes the newest knowledge about QAC and their role in hypersensitivities. After describing the different QAC, their structure and use, the most relevant studies about the effects of QAC on the immune system will be reviewed and discussed.

Novel Osmoprotective DOPC-DMPC Liposomes Loaded with Antihypertensive Drugs as Potential Strategy for Glaucoma Treatment

Glaucoma is a group of chronic irreversible neuropathies that affect the retina and the optic nerve. It is considered one of the leading causes of blindness in the world. Although it can be due to various causes, the most important modifiable risk factor is the elevated intraocular pressure (IOP). In this case, the treatment of choice consists of instilling antihypertensive formulations on the ocular surface. The chronicity of the pathology, together with the low bioavailability of the drugs that are applied on the ocular surface, make it necessary to instill the formulations very frequently, which is associated, in many cases, with the appearance of dry eye disease (DED). The objective of this work is the design of topical ocular formulations capable of treating glaucoma and, at the same time, preventing DED. For this, two liposome formulations, loaded with brimonidine or with travoprost, were Tadeveloped using synthetic phospholipids and enriched by the addition of compounds with osmoprotective activity. The proposed formulations not only presented physicochemical characteristics (size, pH, osmolarity, surface tension, and viscosity) and encapsulation efficiency values (EE% of 24.78% and ≥99.01% for brimonidine and travoprost, respectively) suitable for ocular surface administration, but also showed good tolerance in human corneal and conjunctival cell cultures, as well as an in vitro osmoprotective activity. The hypotensive effect of both liposomal formulations was evaluated in normotensive albino New Zealand rabbits, showing a faster and longer lasting reduction of intraocular pressure in comparison to the corresponding commercialized products used as control. According to these results, the hypotensive liposomal formulations combined with osmoprotective agents would result in a very promising platform for the treatment of glaucoma and the simultaneous protection of the ocular surface.

Clinicopathological Correlation of Microbial Keratitis and Ahead: Is There a Corneal Sepsis?

Microbial, infectious keratitis is a relevant indication for penetrating keratoplasty. The requirement for transplantation results in histopathological examination of the entire thickness of the cornea. Although the clinical diagnosis is not always possible to confirm, pathology can support diagnostic evidence of clinical presentation and pathogenesis. This is achieved with multiple methods from cytology, histochemistry, immunohistology, molecular pathology and in rare cases electron microscopy. These allow tissue-based detection of previous and parallel diseases and the responsible pathogens. The failure of satisfactory clinicopathological correlation raises the question whether a suspected pathogen was not ultimately responsible for destroyed corneal tissue. The pathogenesis of keratitis requiring transplantation is not yet completely understood, also on the experimental level. The development of such a keratitis can lead to a clinical symptomatology which can be described as "threatening organ dysfunction", a term used in sepsis research. Considering recent literature, possible correlations between sepsis and microbial keratitis and their relation to histopathology are discussed.

A novel osmoprotective liposomal formulation from synthetic phospholipids to reduce in vitro hyperosmolar stress in dry eye treatments

Dry eye disease (DED) is a worldwide, multifactorial disease mainly caused by a deficit in tear production or increased tear evaporation with an increase in tear osmolarity and inflammation. This causes discomfort and there is a therapeutic need to restore the homeostasis of the ocular surface. The aim of the present work was to develop a biodegradable and biocompatible liposomal formulation from the synthetic phospholipids 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) that is able to reduce the effects of hypertonic stress by helping to restore the lipid layer of the tear film. Liposomes were made using the lipid film hydration method with synthetic phospholipids (10 mg/mL) with and without 0.2% HPMC. They were characterised in terms of size, osmolarity, pH, surface tension, and viscosity. Additionally, the in vitro toxicity of the formulation at 1 and 4 h in human corneal epithelial cells (hTERT-HCECs) and human conjunctival cells (IM-HConEpiC) was determined. Furthermore, osmoprotective activity was tested in a corneal model of hyperosmolar stress. In vivo acute tolerance testing was also carried out in albino New Zealand rabbits by topical application of the ophthalmic formulations every 30 min for 6 h. All the assayed formulations showed suitable physicochemical characteristics for ocular surface administration. The liposomal formulations were well-tolerated in cell cultures and showed osmoprotective activity in a hyperosmolar model. No alterations or discomfort were reported when they were topically administered in rabbits. According to the results, the osmoprotective liposomal formulations developed in this work are promising candidates for the treatment of DED.

Evaluation of ocular surface parameters in dogs with and without meibomian gland dysfunction

BACKGROUND

Interest in meibomian gland dysfunction (MGD) is growing in veterinary medicine. However, research on MGD in dogs is lacking. The aims of this study were to compare the interferometry grades, tear meniscus height (TMH) and non-invasive tear break-up time (NIBUT) grades between dogs with and without MGD.

METHODS

Routine ophthalmic examination, interferometry, NIBUT assessment, TMH measurement and meibography were performed. Age and Schirmer tear test-1 (STT-1) results were compared between the control and MGD groups using Student's t-test. Interferometry grades, NIBUT grades and TMH were compared between the two groups using Mann-Whitney U-test.

RESULTS

There was no significant difference in age between the two groups (p = 0.279). STT-1 (p = 0.024), interferometry (p = 0.004) and NIBUT grades (p = 0.012) were significantly lower in the MGD group than in the control group. No significant difference in TMH values (p = 0.587) was observed between the two groups. While the control group included 18 and seven eyes in meiboscore 0 and 1, in MGD group, 12, eight, five and three eyes were included in meiboscore 0, 1, 2 and 3, respectively.

CONCLUSIONS

Low interferometry and NIBUT grades were associated with MGD, suggesting decreased meibum and disrupted tear film quality. TMH did not differ between the two groups. Meibography could aid in the diagnosis of MGD in severe cases, although it could not detect early MGD in the dogs in this study.

In-situ tear fluid dissolving nanofibers enable prolonged viscosity-enhanced dual drug delivery to the eye

Liquid and semi-solid formulations are the most commonly used drug delivery systems for ophthalmic diseases. Upon application into the conjunctival sac, these systems introduce a variable and unphysiologically high liquid volume to the eye, resulting in overflow and extensive nasolacrimal drainage, accounting for dosing inaccuracy and short ocular residence time. In this study, we present nanofibrous electrospun scaffolds composed of biocompatible polymers, overcoming these challenges by immediate drug release. The fibers incorporate gentamicin and dexamethasone, intended for the treatment of bacterial conjunctivitis. Upon contact with the ocular surface, the nanofibers immediately dissolve in the tear fluid, quantitatively releasing the two actives, yielding over92% drug recovery, determined with fluorimetric and chromatographic quantifications methods. Simultaneously, the viscosity of the tear fluid increases, shown by complex viscometry measurements. A newly developed ex vivo microfluidic porcine cornea model was used to evaluated ocular residence time. In contrast to fluid eye drops, the contact time was significantly prolonged and 20min after application, an increase in drug availability on the ocular surface of 342% was observed. Biocompatibility of the polymer system was demonstrated in an OECD approved in vitro cornea model. The antibacterial activity after processing was evaluated according to EUCAST guidelines, and storage stability of the system was confirmed over a 12-week period. This innovative drug delivery system poses a highly promising platform technology, overcoming challenges associated with conventional dosage forms for drug delivery to the anterior eye and thus significantly advancing therapeutic approaches.

The trabecular meshwork in glaucoma: An inflammatory trabeculopathy?

Glaucoma is an optic neuropathy in which the primary risk factor is increased intraocular pressure (IOP), attributed to increased resistance to trabecular outflow of aqueous humor (AH). This resistance is believed to result from trabecular degeneration secondary to chronic oxidative stress and cellular senescence but may also involve inflammatory mechanisms whose roles are little known. In fact, inflammatory processes play a major role in the pathophysiology of glaucoma to varying degrees, affecting all structures of the eye, including the ocular surface, the anterior and posterior segments, and even the visual pathways of the brain. These processes are thought to result from dysfunction of a regulatory, protective para-inflammation, becoming chronic and harmful in glaucoma. While the mechanisms of the retinal inflammation which accelerates the degeneration of retinal ganglion cells (RGCs) as well as the inflammation of the ocular surface aggravated by long-term use of preserved glaucoma eye drops have been described for several years, very little is known about the pathophysiology of trabecular inflammation in glaucoma. The objective of this literature review is to provide a synthesis of knowledge on the roles and mechanisms of inflammation in both the healthy and glaucomatous trabecular meshwork, as well as its role in the pathophysiology of glaucoma. Therefore, after a review of the mechanisms of cellular senescence and oxidative stress - sources of trabecular inflammation, we will approach the study of the expression and roles of the main inflammatory mediators within the trabecular meshwork. Finally, we will discuss current knowledge on the toxicity of glaucoma eye drops and their preservatives on the ocular surface and trabecular meshwork as well as their role in trabecular inflammation.

Therapie des Trockenen Auges

Die Therapie des Trockenen Auges stellt eine schwierige Aufgabe für den behandelnden Augenarzt dar. Fortschritte in unserem Verständnis der Risikofaktoren, der Ätiologie und Pathophysiologie des Trockenen Auges haben zu einer Weiterentwicklung der Behandlungsstrategien geführt. Vor Beginn der Therapie ist die korrekte Zuordnung in eine wässrig-muzinöse Tränenfilmdysfunktion (Mindersekretion), in eine lipidbedingte Tränenfilmdysfunktion (hyperevaporative Form durch eine abnormen Meibom-Drüsen-Physiologie) oder in eine variable Kombination wichtig. Unter Berücksichtigung aktueller Empfehlungen der DOG, des BVA und des TFOS DEWS II Unterausschusses wurde ein Behandlungsalgorithmus abgeleitet, der ein schrittweises Vorgehen je nach Schweregrad der Erkrankung darstellt.

Benzalkonium chloride-induced myofibroblastic transdifferentiation of Tenon's capsule fibroblasts is inhibited by coculture with corneal epithelial cells or by interleukin-10

Benzalkonium chloride (BAC) is used as a preservative in eyedrops but induces subconjunctival fibrosis that can result in failure of glaucoma surgery. Tenon's capsule fibroblasts in subconjunctival tissue interact with the corneal epithelium through tear fluid. With the use of a coculture system, we have now investigated the effect of human corneal epithelial (HCE) cells on myofibroblastic transdifferentiation of human Tenon fibroblasts (HTFs) induced by BAC (5 × 10^-6%). Immunofluorescence and immunoblot analyses revealed that the BAC-induced expression of α smooth muscle actin (αSMA) in HTFs was suppressed by coculture of these cells with HCE cells (p < 0.01). The concentration of interleukin-10 (IL-10) in culture supernatants of BAC-treated HTFs was increased by coculture with HCE cells (17.26-fold, vs. coculure, p < 0.001). Immunofluorescence and immunoblot analyses also showed that exogenous IL-10 (300 pg/ml) suppressed the BAC-induced expression of αSMA by 43.65% (p < 0.05) as well as the nuclear translocation of myocardin-related transcription factor-A (MRTF-A) by 39.32% (p < 0.01) in HTFs cultured alone. Our findings suggest that corneal epithelial cells may protect against subconjunctival fibrosis by maintaining IL-10 levels and preventing the MRTF-A-dependent transdifferentiation of HTFs into myofibroblasts.

Changes in Tear Osmolarity after Cataract Surgery

BACKGROUND

The purpose of this study was to examine changes in the ocular surface before and after phacoemulsification with small incisions and to examine the changes in tear osmolarity.

METHODS

This was a prospective, observational study involving 55 eyes of 39 patients (19 male, 20 female patients; average age 72.0±7.3 years) who had cataract surgery at a Nippon Medical School Hospital between December 2013 and June 2018. Compromised tear dynamics were determined by the Schirmer test or the tear break-up time (BUT). An abnormal ocular surface was identified by positive vital staining with fluorescein or lissamine green. Moreover, tear osmolarity (Tosm) and corneal sensitivity were measured. All assessments were done preoperatively and 1 and 4 weeks (P1W and P4W) after the surgery.

RESULTS

None of the operations had any complications. Operating time was 17.8±9.3 minutes. BUT was significantly decreased at P1W, and it recovered at P4W. The Schirmer test did not change significantly. The fluorescein staining score (FSS) increased significantly at P1W and recovered at P4W. The Lissamine green score (LSS) did not change significantly. Tear osmolarity increased significantly at P1W and did not recover at P4W. Corneal sensitivity decreased significantly at P1W and recovered at P4W.

CONCLUSION

In the present study, there were temporary changes in dry eye-related examinations including tear osmolarity after cataract surgery. In particular, tear osmolarity increased significantly 4 weeks after surgery compared to before surgery, and it showed long-term changes, unlike other factors. After cataract surgery, tear osmolarity, BUT, and FSS increase, resulting in dry eye symptoms. Therefore, it is necessary to pay attention to discomfortable eye symptoms of patients after cataract surgery.

Pharmacological evaluation of innovative eye drop formulations containing TS-polysaccaride, hyaluronic acid and glycyrrhizin for irritative ocular diseases using in vitro reconstituted human corneal epithelium model

In vitro reconstructed human corneal tissue models are closer to in vivo human corneal tissue in term of morphology, biochemical and physiological properties, and represent a valid alternative to animal use for evaluating the pharmacological effects ophthalmic topically applied medical devices. In this experimental work the in vitro reconstructed human corneal tissues have been used for assessing the potential beneficial effects of an innovative ophthalmic formulation containing hyaluronic acid, glycyrrhizin and TS-polysaccharide for the treatment of symptomatic states on the eye surface including dry eye, itching, foreign body sensation and redness due allergic reaction. Corneal tissues have been treated with benzalkonium chloride for 24 h to induce cell damage and then treated with the tested items for 16 h. After the incubation period, tissue viability, TNF-α, IL-6 and MMP-9 have been assessed. Diclofenac has been used as reference anti-inflammatory drug. The novel formulation protected the tissues against benzalkonium chloride damage, while exerted a mild but not significant reduction of the anti-inflammatory mediator TNF-α.

ACE2 Expression Is Upregulated in Inflammatory Corneal Epithelial Cells and Attenuated by Resveratrol

Purpose

The ocular surface is considered an important route for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. The expression level of the SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) is vital for viral infection. However, the regulation of ACE2 expression on the ocular surface is still unknown. We aimed to determine the change in ACE2 expression in inflamed corneal epithelium and explore potential drugs to reduce the expression of ACE2 on the ocular surface.

Methods

The expression of the SARS-CoV-2 receptors ACE2 and TMPRSS2 in human corneal epithelial cells (HCECs) was examined by qPCR and Western blotting. The altered expression of ACE2 in inflammatory corneal epithelium was evaluated in TNFα- and IL-1β-stimulated HCECs and inflamed mouse corneal epithelium, and the effect of resveratrol on ACE2 expression in HCECs was detected by immunofluorescence and Western blot analysis.

Results

ACE2 and TMPRSS2 are expressed on the human corneal epithelial cells. ACE2 expression is upregulated in HCECs by stimulation with TNFα and IL-1β and inflamed mouse corneas, including dry eye and alkali-burned corneas. In addition, resveratrol attenuates the increased expression of ACE2 induced by TNFα in HCECs.

Conclusions

This study demonstrates that ACE2 is highly expressed in HCECs and can be upregulated by stimulation with inflammatory cytokines and inflamed mouse corneal epithelium. Resveratrol may be able to reduce the increased expression of ACE2 on the inflammatory ocular surface. Our work suggests that patients with an inflammatory ocular surface may display higher ACE2 expression, which increases the risk of SARS-CoV-2 infection.

Physicochemical characterization of a DMPC-based nanoemulsion for dry eye and compatibility test with soft contact lenses in vitro

INTRODUCTION

The use of contact lenses (CL) is often associated with hallmark symptoms of dry eye disease (DED) such as red eye and dryness. Even though lipid-based artificial tears are already marketed for DED, there is little evidence that supports their use while wearing soft CL.

METHODS

An oil in water (O/W) nanoemulsion was formulated with a highly-stable oily phase composed of castor oil and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). Physicochemical characterization of the DMPC-based nanoemulsion (DMPC-NE) was performed using the Zetasizer Nano ZSP, and its long-term stability was evaluated over 24 months; in addition, the in vitro cytotoxicity of DMPC-NE was determined by Neutral Red Uptake (NRU) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Finally, the physical compatibility of the DMPC-NE with soft CL was tested by measuring the power, diameter, thickness and UV transmittance of two different types of CL.

RESULTS

DMPC-NE had a mean particle size of 86.48 ± 4.22 nm, a polydispersity index of 0.22 ± 0.01 and a zeta potential of -33.23 ± 0.93 mV that remained with no changes after 24 months. DMPC-NE formulation, free of preservatives, showed no cytotoxicity and it was compatible with the physical properties of FDA-class II and -class IV CL.

CONCLUSION

DMPC-NE is a highly stable formulation for dry eye that is safe to be used while wearing soft CL.

Anterior Segment Optical Coherence Tomography (AS-OCT) Guided Reversal of Edematous Punctal Occlusion

Aim

To evaluate the role of anterior segment–optical coherence tomography (AS-OCT) in the diagnosis of punctal stenosis and to compare punctal parameters before and after medical treatment.

Patients and Methods

The study was conducted on 40 eyes of 24 patients who had acquired inflammatory punctal stenosis and had persistent epiphora (persistent epiphora group – PEG), and 20 eyes of 10 subjects with normal punctal openings as a control group (control group – CG). We measured the outer punctal diameter (OPD), recorded the visibility of the internal punctum and punctal depth (PD) using AS-OCT, before and 1 month after treatment with preservative free methylprednisolone 5% eye drops. Punctal diameter, tear meniscus height (TMH) and Munk’s score were compared to the control group before and after treatment.

Results

The mean OPD of the PEG before treatment (455.5 ± 174 µm) was significantly smaller than that of the CG (590.9 ± 106.6 µm) (P= 0.002). The mean OPD of the PEG significantly increased to 484.6 ± 175.5 µm after treatment (P <0.001). Also, the visibility of vertical canaliculus lumen and PD were restored in 70% of eyes. The TMH was much higher in the PEG than in the CG before treatment (P<0.05). However, after treatment the difference was not statistically significant.

Conclusion

AS-OCT parameters were useful in monitoring and measuring the efficacy of medical treatment in relieving punctal edema, which subsequently resulted in reducing the epiphora symptoms.

Development of an enzyme-linked immunosorbent assay for Keap1-Nrf2 interaction inhibitors identification

Development of Keap1–Nrf2 interaction inhibitors is a promising strategy for the discovery of therapeutic agents against oxidative stress-mediated diseases. Two motifs of Nrf2, ETGE and DLG motif, are responsible for Keap1-Nrf2 binding. Previously, ETGE peptide or ETGE-derived peptide-based approaches were used to detect Keap1-Nrf2 interaction; however, these approaches are not able to monitor Keap1-DLG motif binding. We first report here a novel Enzyme-linked Immunosorbent Assay (ELISA) approach to detect the protein-protein interaction of full length Keap1 and Nrf2. In our assay, the test compounds can target either ETGE or DLG binding site, therefore facilitating the exploration of diverse Keap1-Nrf2 inhibitors. Three FDA-approved drugs, zafirlukast, dutasteride and ketoconazole, were found to inhibit the Keap1-Nrf2 interaction with IC₅₀ of 5.87, 2.81 and 1.67 μM, respectively. Additionally, these three drugs also activated Nrf2 pathway in neuroblasts and lipopolysaccharide (LPS)-challenged mice. The results presented here indicate that the ELISA approach has the capacity to identify Keap1-Nrf2 inhibitors.

•

We established a novel Enzyme-linked Immunosorbent Assay for Keap1-Nrf2 interaction inhibitors identification.

•

This ELISA is the first approach to detect the protein-protein interaction of full length Keap1 and Nrf2.

•

In this assay, the test compounds can target either ETGE or DLG binding site, therefore facilitating the exploration of diverse Keap1-Nrf2 inhibitors.

•

Zafirlukast, dutasteride and ketoconazole have been identified as inhibitors of the Keap1-Nrf2 interaction.

Optimization of the Interaction between Diclofenac and Ibuprofen with Benzalkonium Chloride to Prepare Ocular Nanosuspension

BACKGROUND

Non-steroidal anti-inflammatory drugs are most commonly used in the management of ocular inflammations. These drugs have poorly aqueous solubility and weakly acidic nature. They interact with cationic quaternary ammonium compound benzalkonium chloride, used as a preservative in ophthalmic formulations, to form insoluble complexes. To overcome this incompatibility solubilizers like polysorbate 80, lysine salts, tocopheryl polyethylene glycol succinate etc. are used which are quite irritating and affect the corneal integrity.

OBJECTIVE

The objective of the present study is to formulate nonirritating, compatible, microbiologically stable ophthalmic formulation with good corneal permeation characteristics. The interaction between diclofenac sodium or ibuprofen with benzalkonium chloride was optimized using a central composite experimental design to prepare nanosuspensions by nanoprecipitation.

METHODS

The optimized batches of nanosuspensions were evaluated for ex vivo corneal permeation study, preservative challenge test and physical stability. The optimal concentrations of benzalkonium chloride for diclofenac sodium (0.1%, w/v) and ibuprofen (0.1% w/v) nanosuspensions were determined to be 0.002%(w/v), which had a respective average particle size of 440 nm and 331 nm, respectively. The nanosuspensions of diclofenac sodium and ibuprofen provided 1.6 and 2.1- fold higher ex vivo corneal permeation than their respective conventional aqueous solution dosage forms. Further, the concentration of benzalkonium chloride used in the formulations showed adequate preservative efficacy.

RESULTS

The optimized nanosuspension formulations of diclofenac and ibuprofen were found to be physically stable and microbiologically safe with greater corneal penetration than the conventional solution dosage forms.

Meibomian gland dropout rate as a method to assess meibomian gland morphologic changes during use of preservative-containing or preservative-free topical prostaglandin analogues

PURPOSE

To investigate the usefulness of meibomian gland (MG) dropout rate in the evaluation of MG morphological change associated with the use of prostaglandin for glaucoma treatment through the association between MG and the ocular surface parameters and medication duration and presence of preservative.

METHODS

This cross-sectional study was conducted on 88 eyes of 88 patients who were diagnosed with glaucoma and used only Tafluprost as treatment. The patients were divided into four "user" groups: 1) 23 patients used preservative-free (PF) Tafluprost for 6 months; 2) 21 patients used preservative-containing (PC) Tafluprost for 6 months; 3) 23 patients used PF-Tafluprost for 24 months; 4) 21 patients used PC-Tafluprost for 24 months. Ocular surface parameters and the MG condition, including MG dropout rate and meiboscale, were evaluated. Multiple regression was used to identify associations.

RESULTS

There were significant differences in age (p = 0.003), tear breakup time (p = 0.016), lid margin abnormality (p = 0.016), expressibility (p = 0.039), meiboscale (p<0.001), and MG dropout rate (p<0.001) among the 4 groups. MG dropout rate and meiboscale showed significant differences in all post hoc analyses, except for the comparison between the PF-Tafluprost and PC-Tafluprost 6-month user groups. Medication duration, preservative status, and meiboscale were significantly correlated with MG dropout rate (p<0.001, p = 0.024, p<0.001, respectively). In the 6-month user group, preservative status significantly correlated with MG dropout rate (p = 0.015). However, in the 24-month user group, meiboscale was the only parameter significantly associated with MG dropout rate (p<0.001).

CONCLUSION

MG dropout rate in patients using Tafluprost showed a significant correlation with medication duration and preservative status. This result indicates MG dropout rate reflects MG morphologic change associated with prostaglandin.

New Classes of Polycationic Compounds as Preservatives for Ophthalmic Formulations

PURPOSE

The purpose of this research work was to develop new polycationic compounds based on pyridine and piperidine structures with high antimicrobial activities against bacteria and fungi. Furthermore, the compounds should offer a lower toxicity than the commonly used preservatives for ophthalmic formulations, such as benzalkonium chloride (BAC) and polyquaternium-1 (PQ1).

METHODS

Two polymers and three dimeric compounds were developed. Minimum inhibitory concentrations were determined for Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Aspergillus brasiliensis. The compounds were characterized regarding their impact on cell viability, cytotoxicity, epithelial integrity and surface tension. MTT and CytoTox-Glo™ assays, permeation studies with mannitol and transepithelial electrical resistance (TEER) measurements were performed on human corneal epithelial or MDCK I cells. BAC and PQ1 were used as references.

RESULTS

Three polycationic compounds exhibited high antimicrobial activity against the tested microorganisms comparable to that of BAC. Four compounds were tolerated as well as or better than PQ1. In addition, the TEER, permeability and surface tension were only affected by compounds with amphiphilic properties.

CONCLUSION

The pyridine- and piperidine-based polycationic compounds are promising candidates as new preservatives for ophthalmic formulations. Their high antimicrobial efficacy and good tolerability indicate a different mechanism of action compared to BAC.

The impact of topical intraocular pressure lowering medications on the ocular surface of glaucoma patients: A review

Purpose

To assess the literature on the effects of topical intraocular pressure (IOP)-lowering medications on the ocular surface. Ocular surface assessment in these patients is seldom a priority for most clinicians since the ultimate goal of management is to preserve vision.

Methods

A literature search of articles (English only) on the subject matter was conducted and their findings summarized.

Results

This review assesses the prevalence of dry eye symptoms in glaucoma patients on topical IOP-lowering medications. We extensively reviewed the effects of the preservatives and active ingredients in these medications on the ocular surface. In particular, the effects of benzalkonium chloride (BAK), a widely used preservative, on meibomian glands are explored. Also mentioned in this review is the association between duration of therapy and severity of dry eye symptoms. The role of the pH of medications in the development of ocular surface disease is also reviewed. Finally, we probed the occurrences of ocular allergic reactions with the use of topical IOP-lowering medications.

Conclusions

The preservatives and active agents in most topical glaucoma medications are implicated in the prevalence of ocular surface discomfort. Whilst clinicians involved in glaucoma care are encouraged to assess the ocular surface routinely, further studies are needed to demonstrate the contributions of other physiochemical properties of these medications to the development of ocular surface disease in these patients.

A standardized extract of Rhynchosia volubilis Lour. exerts a protective effect on benzalkonium chloride-induced mouse dry eye model

ETHNOPHARMACOLOGICAL RELEVANCE

In contrast to other leguminous plants generally used as food, Rhynchosia volubilis Loureiro, a small soybean with a black seed coat, has been used as a traditional oriental remedy for various human diseases in Eastern Asia. In this study, we demonstrated the protective effect of R. volubilis against dry eye disease.

AIM OF THE STUDY

We aimed to investigate whether a standardized ethanol extract of R. volubilis (EERV) can protect the cornea in a benzalkonium chloride (BAC)-induced mouse dry eye model.

MATERIALS AND METHODS

Experimental dry eye was induced by the instillation of 0.2% BAC on mouse cornea. A standardized ethanol extract of R. volubilis (EERV) was orally administered following BAC treatment. The positive control group was treated with commercial eye drops. Fluorescein staining, tear break-up time (BUT), and hematoxylin and eosin staining were evaluated on the ocular surface. Squamous metaplasia and apoptosis in the corneal epithelial layer were detected by immunostaining. Furthermore, the protein expression of cytochrome c, Bcl-2, and Bax was determined.

RESULTS

EERV treatment significantly improved fluorescein scoring, BUT, and smoothness in the cornea compared to the vehicle group. In addition, EERV inhibited squamous metaplasia and apoptosis in the cornea. The expression of cytochrome c and Bax was upregulated, while that of Bcl-2 was downregulated in the vehicle group compared with that in the control group. However, EERV treatment inhibited the expression of cytochrome c and Bax, while that of Bcl-2 was improved.

CONCLUSION

Standardized EERV could be a beneficial candidate for the treatment of dry eye disease.

Meibomian Gland Dysfunction in Patients Receiving Long-Term Glaucoma Medications

PURPOSE

The purpose of this study was to evaluate the impact of meibomian gland dysfunction (MGD) on the ocular surface of patients with medically treated glaucoma.

MATERIALS AND METHODS

This was a cross-sectional study in which 70 subjects with glaucoma on long-term (>1 year) topical hypotensive medications were recruited. MGD was defined as the presence of signs consistent with meibomian gland terminal duct obstruction. MGD was categorized between grades 1 and 4 and plus disease according to clinical severity. The ocular surface disease index (OSDI) questionnaire was completed at the time of enrollment. Ocular surface tests consisted of tear break-up time (BUT), ocular surface staining with lissamine green (LG), and Schirmer test with anesthesia. A Student t test, χ test, and Mann-Whitney U test were used in statistical comparisons. Forty-five healthy control subjects with no evidence of intraocular or ocular surface disease were also included.

RESULTS

MGD was detected in 56 (80.0%) subjects with glaucoma. Forty-seven patients (67.1%) had obstructive and 9 (12.9%) had atrophic type of MGD. Of these 56 cases, 47 (83.9%) had signs consistent with mild to moderate MGD. The ocular surface test results of patients with glaucoma with MGD and without MGD were significantly worse (P < 0.001) for all parameters compared with those of healthy controls. However, there were no significant differences between ocular surface disease index scores (P = 0.912), tear break-up time (P = 0.635), lissamine green scores (P = 0.248), and Schirmer results (P = 0.991) between patients with glaucoma with MGD and without MGD.

CONCLUSIONS

Mild to moderate MGD is frequently encountered in patients with medically treated glaucoma. However, the presence of MGD does not appear to have an additional detrimental effect on the ocular surface to that already induced by chronic topical medication use.

A Comparison of the Effects of Benzalkonium Chloride on Ocular Surfaces between C57BL/6 and BALB/c Mice

Models of benzalkonium chloride (BAC)-induced ocular disruption have been created and are widely used in various animals. This study aimed to compare the effects of BAC on the ocular surfaces of C57BL/6 and BALB/c mice. C57BL/6 and BALB/c mice were treated separately with BAC eye-drops at different concentrations. Eyes were evaluated by scoring epithelial disruption, corneal opacity and neovascularization in vivo, and by histological assays with hematoxylin/eosin (H/E) and periodic acid-Schiff stainings and by determining the expression of inflammatory factors in vitro on Days 7 and 14. The in vivo corneal epithelial disruption, corneal edema/opacity and neovascularization, which were in accordance with the results of the H/E staining and peaked at Day 7, were observed in a dose-dependent manner in the BAC-treated mice, with more severe signs in the C57BL/6 mice than the BALB/c mice. The loss of conjunctival goblet cells in the conjunctivas and the increasing expression of monocyte chemoattractant protein 1 (MCP-1), growth-regulated protein alpha (GROa) and macrophage inflammatory protein-1 alpha (MIP-1a) in the corneas were found in a dose-dependent manner in both strains of mice. Topical application of BAC can dramatically disrupt the ocular surfaces of C57BL/6 and BALB/c mice, and the disruptions were much more severe in the C57BL/6 mice that received high doses of BAC.

Therapeutic agents and biocides for ocular infections by free-living amoebae of Acanthamoeba genus

Acanthamoeba keratitis is a sight-threatening infectious disease. Resistance of the cystic form of the protozoan to biocides and the potential toxicity of chemical compounds to corneal cells are the main concerns related to long-term treatment with the clinically available ophthalmic drugs. Currently, a limited number of recognized antimicrobial agents are available to treat ocular amoebic infections. Topical application of biguanide and diamidine antiseptic solutions is the first-line therapy. We consider the current challenges when treating Acanthamoeba keratitis and review the chemical properties, toxicities, and mechanisms of action of the available biocides. Antimicrobial therapy using anti-inflammatory drugs is controversial, and aspects related to this topic are discussed. Finally, we offer our perspective on potential improvement of the effectiveness and safety of therapeutic profiles, with the focus on the quality of life and the advancement of individualized medicine.

Analysis of the effects of preservative-free tafluprost on the tear proteome

The purpose of the present study was to assess the ocular surface health status in primary open angle glaucoma (POAG) patients switching from topical application of preserved latanoprost (LT) to preservative-free tafluprost (PFT) by tear proteomic monitoring. Tear fluid of POAG patients showing dry eye symptoms, using LT and switching to PFT as well as tear fluid of healthy controls has been examined. Tear proteome dynamics was monitored over 24 weeks in a first mass spectrometric explorative analysis in a small POAG patient cohort (N = 3). Longitudinal responses of candidate proteins as well as cytokines were comparatively analyzed by microarray in a larger cohort of POAG patients (N = 16) and healthy controls (N = 15). Clinical parameters including tear breakup time (TBUT) and basal Schirmer test (BST) were recorded. Distinct post-switch level alterations could be documented in POAG tear proteins (> 1000). Cellular leakage proteins, dry eye related candidates and cytokines showed predominantly level diminishment in POAG patients and approximation to the tear protein level of healthy controls in response to PFT. Tear proteins like pyruvate kinase isozymes M1/M2 or galectin 7 displayed linear tear film level decline in POAG patients (R²≥0.9; P < 0.05) distinctly converging the healthy level. Proteomic outcome fit well with improved clinical parameters, TBUT and BST. In conclusion, tear proteomic alterations indicated ocular surface recovery regarding epithelia leakage and inflammation recession. Together with improved clinical parameters the study output proposes beneficial effects of PFT glaucoma therapy.

Comparison of the Efficacy of Fluorometholone With and Without Benzalkonium Chloride in Ocular Surface Disease

PURPOSE

The purpose of this study was to compare the cytotoxicity and antiinflammatory effect of preserved and unpreserved 0.1% fluorometholone (FML).

METHODS

Drug-induced morphological changes and cytotoxicity were examined in human corneal epithelial cells. Dry eye was induced in mice by treatment with 0.2% benzalkonium chloride (BAC) for the first 2 weeks, and then, the eyes (4 groups; Normal saline, BAC, preserved FML, and unpreserved FML) were treated thrice daily with each formulation for the next 2 weeks. Corneal tissues were embedded in paraffin and stained with hematoxylin and eosin for histopathological examination. Immunofluorescence staining was performed for tumor necrosis factor-α, interleukin-6, and human leukocyte antigen-DR. Terminal deoxynucleotidyl transferase dUTP nick end labeling assay was performed to evaluate drug-induced cytotoxicity.

RESULTS

BAC and preserved FML caused cell shrinkage and detachment from the plate in a dose-dependent manner, and cell viability decreased significantly. However, cytotoxicity was reduced on treatment with unpreserved FML. Hematoxylin-eosin staining revealed surface desquamation, irregular surface, loss of cell borders, and stromal shrinkage in the group treated with BAC. On BAC exposure, tumor necrosis factor-α, interleukin-6, and human leukocyte antigen-DR were strongly detected, and cytotoxicity was markedly increased, as evidenced by a positive result in the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Ocular surface damage and inflammation were slightly reduced on treatment with preserved FML. In comparison, unpreserved FML did not induce morphological changes; moreover, decreased cell cytotoxicity and ocular surface inflammation were observed.

CONCLUSIONS

The cytotoxicity of antiinflammatory eye drops evaluated in this study was induced by the preservative BAC. Accordingly, unpreserved FML is more effective than preserved eye drops in decreasing ocular inflammation.

Effect of benzalkonium chloride-free latanoprost ophthalmic solution on ocular surface in patients with glaucoma

Introduction

Benzalkonium chloride (BAK), included as a preservative in many topical treatments for glaucoma, induces significant toxicity and alters tear breakup time (TBUT). BAK-containing latanoprost, an ester prodrug of prostaglandin F_2α, can cause ocular adverse events (AEs) associated with BAK. The purpose of this study was to evaluate the efficacy and safety of BAK-free latanoprost.

Patients and methods

A prospective, open-label, single-arm, multicenter, 8-week study in patients with primary open-angle glaucoma or ocular hypertension taking BAK-containing latanoprost for ≥12 months was performed. Patients were switched to BAK-free latanoprost ophthalmic solution 0.005% administered once daily, and eyes were assessed after 28 and 56 days. Primary efficacy and safety variables were TBUT and treatment-emergent AEs, respectively.

Results

At day 56, 40 eyes were evaluable. Mean TBUT increased significantly from baseline (3.67±1.60 seconds) to 5.03±2.64 and 6.06±3.39 seconds after 28 and 56 days of treatment with BAK-free latanoprost (P<0.0001). Ocular Surface Disease Index^© (OSDI^©) score also decreased significantly to 12.06±13.40 and 7.06±10.75 at 28 and 56 days, respectively, versus baseline (18.09±18.61, P<0.0001). In addition, inferior corneal staining score decreased significantly to 0.53 from baseline (0.85, P=0.0033). A reduction in conjunctival hyperemia and intraocular pressure was observed at both time points. No treatment-related serious AEs were evident and 12 (26.08%) treatment-emergent AEs occurred in seven patients, with eye pain and irritation being the most frequent. No clinically significant changes in vital signs or slit lamp examinations were observed.

Conclusion

Results indicate that switching from BAK-containing latanoprost to BAK-free latanoprost resulted in significant improvements in TBUT, OSDI^© score, and inferior corneal staining score, and measurable reductions in conjunctival hyperemia score. Furthermore, BAK-free latanoprost was well tolerated with only mild-to-moderate and self-limiting AEs. BAK-free latanoprost appears to be effective in protecting ocular surface integrity in glaucoma patients but further studies are needed to confirm this beneficial effect.

The Effects of Two Non-Steroidal Anti-Inflammatory Drugs, Bromfenac 0.1% and Ketorolac 0.45%, on Cataract Surgery

PURPOSE

To compare the additive effects of two types of non-steroidal anti-inflammatory drugs (NSAIDs), bromfenac 0.1% or ketorolac 0.45%, relative to topical steroid alone in cataract surgery.

MATERIALS AND METHODS

A total 91 subjects scheduled to undergo cataract operation were randomized into three groups: Group 1, pre/postoperative bromfenac 0.1%; Group 2, pre/postoperative preservative-free ketorolac 0.45%; and Group 3, postoperative steroid only, as a control. Outcome measures included intraoperative change in pupil size, postoperative anterior chamber inflammation control, change in macular thickness and volume, and ocular surface status after operation.

RESULTS

Both NSAID groups had smaller intraoperative pupil diameter changes compared to the control group (p<0.05). There was significantly less ocular inflammation 1 week and 1 month postoperatively in both NSAID groups than the control group. The changes in central foveal subfield thickness measured before the operation and at postoperative 1 month were 4.30±4.25, 4.87±6.03, and 12.47±12.24 μm in groups 1 to 3, respectively. In the control group, macular thickness and volume increased more in patients with diabetes mellitus (DM), compared to those without DM. In contrast, in both NSAID groups, NSAIDs significantly reduced macular changes in subgroups of patients with or without DM. Although three ocular surface parameters were worse in group 1 than in group 2, these differences were not significant.

CONCLUSION

Adding preoperative and postoperative bromfenac 0.1% or ketorolac 0.45% to topical steroid can reduce intraoperative miosis, postoperative inflammation, and macular changes more effectively than postoperative steroid alone.

Semaphorin 3A controls allergic and inflammatory responses in experimental allergic conjunctivitis

AIM

To assess the efficacy of topical Semaphorin-3A (SEMA3A) in the treatment of allergic conjunctivitis.

METHODS

Experimental allergic conjunctivitis (EAC) mice model induced by short ragweed pollen (SRW) in 4-week-old of BALB/c mice, mice were evaluated using haematoxylin and eosin (H&E) staining, immunofluorescence and light microscope photographs. Early phase took the samples in 24h after instillation and late phase took the samples between 4 to 14d after the start of treatment. The study use of topical SEMA3A (10 U, 100 U, 1000 U) eye drops and subconjunctival injection of SEMA3A with same concentration. For comparison, five types of allergy eyedrops were quantified using clinical characteristics.

RESULTS

Clinical score of composite ocular symptoms of the mice treated with SEMA3A were significantly decreased both in the immediate phase and the late phase compared to those treated with commercial ophthalmic formulations and non-treatment mice. SEMA3A treatment attenuates infiltration of eosinophils entering into conjunctiva in EAC mice. The score of eosinophil infiltration in the conjunctiva of SEMA3A 1000 U-treated group were significantly lower than low-concentration of SEMA3A treated groups and non-treated group. SEMA3A treatment also suppressed T-cell proliferation in vitro and decreased serum total IgE levels in EAC mice. Moreover, Treatment of SEMA3A suppressed Th2-related cytokines (IL-5, IL-13 and IL-4) and pro-inflammatory cytokines (IFN-γ, IL-17 and TNF-α) release, but increased regulatory cytokine IL-10 concentration in the conjunctiva of EAC mice.

CONCLUSIONS

SEMA3A as a biological agent, showed the beneficial activity in ocular allergic processes with the less damage to the intraocular tissue. It is expected that SEMA3A may be contributed in patients with a more severe spectrum of refractory ocular allergic diseases including allergic conjunctivitis in the near future.

Determining the Depth of Injury in Bioengineered Tissue Models of Cornea and Conjunctiva for the Prediction of All Three Ocular GHS Categories

The depth of injury (DOI) is a mechanistic correlate to the ocular irritation response. Attempts to quantitatively determine the DOI in alternative tests have been limited to exvivo animal eyes by fluorescent staining for biomarkers of cell death and viability in histological cross sections. It was the purpose of this study to assess whether DOI could also be measured by means of cell viability detected by the MTT assay using 3-dimensional (3D) reconstructed models of cornea and conjunctiva. The formazan-free area of metabolically inactive cells in the tissue after topical substance application is used as the visible correlate of the DOI. Areas of metabolically active or inactive cells are quantitatively analyzed on cryosection images with ImageJ software analysis tools. By incorporating the total tissue thickness, the relative MTT-DOI (rMTT-DOI) was calculated. Using the rMTT-DOI and human reconstructed cornea equivalents, we developed a prediction model based on suitable viability cut-off values. We tested 25 chemicals that cover the whole range of eye irritation potential based on the globally harmonized system of classification and labelling of chemicals (GHS). Principally, the MTT-DOI test method allows distinguishing between the cytotoxic effects of the different chemicals in accordance with all 3 GHS categories for eye irritation. Although the prediction model is slightly over-predictive with respect to non-irritants, it promises to be highly valuable to discriminate between severe irritants (Cat. 1), and mild to moderate irritants (Cat. 2). We also tested 3D conjunctiva models with the aim to specifically address conjunctiva-damaging substances. Using the MTT-DOI method in this model delivers comparable results as the cornea model, but does not add additional information. However, the MTT-DOI method using reconstructed cornea models already provided good predictability that was superior to the already existing established invitro/exvivo methods.

In vitro effects of preserved and unpreserved anti-allergic drugs on human corneal epithelial cells

PURPOSE

Treatment with topical eye drops for long-standing ocular diseases like allergy can induce detrimental side effects. The purpose of this study was to investigate in vitro cytotoxicity of commercially preserved and unpreserved anti-allergic eye drops on the viability and barrier function of monolayer and stratified human corneal-limbal epithelial cells.

METHODS

Cells were treated with unpreserved ketotifen solution, benzalkonium chloride (BAC)-containing anti-allergic drugs (ketotifen, olopatadine, levocabastine) as well as BAC alone. 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to determine cell viability. Effects of compounds on barrier function were analyzed measuring transepithelial electrical resistance (TEER) to determine paracellular permeability and rose bengal assays to evaluate transcellular barrier formation.

RESULTS

The BAC-preserved anti-allergic formulations and BAC alone significantly reduced cell viability, monolayer cultures being more sensitive to damage by these solutions. Unpreserved ketotifen induced the least diminution in cell viability. The extent of decrease of cell viability was clearly dependent of BAC presence, but it was also affected by the different types of drugs when the concentration of BAC was low and the short time of exposure. Treatment with BAC-containing anti-allergic drugs and BAC alone resulted in increased paracellular permeability and loss of transcellular barrier function as indicated by TEER measurement and rose bengal assays.

CONCLUSIONS

The presence of the preservative BAC in anti-allergic eye drop formulations contributes importantly to the cytotoxic effects induced by these compounds. Stratified cell cultures seem to be a more relevant model for toxicity evaluation induced on the ocular surface epithelia than monolayer cultures.

Balancing antimicrobial efficacy and toxicity of currently available topical ophthalmic preservatives

Medical treatment of ophthalmic diseases relies primarily on the use of multidose drugs. Short term use is highly effective usually with little local toxicity. However, chronic use of these preparations not only increases the likelihood of microbial contamination and secondary ocular infection, but also of toxicity from the drug formulation itself. Increasing awareness of the toxicity of ophthalmic preservatives has led to an increasing variety of preservative schemes ranging from "self-preservation" to ionic buffer systems. Beyond outdated testing methods, the anti-microbial efficacy of most of these systems is poorly defined, potentially placing these preparations at an unknown risk of contamination by unmonitored, untested organisms. No uniformity in toxicity testing exists which further complicates the clinician's judgment of the risk-benefit of using a particular drug formulation. In this manuscript we examine in detail each of the current employed ophthalmic preservative regimens with respect to their known antimicrobial activity and potential toxicity, where known. We also survey the most popular ophthalmic preparations, detailing their preservation schemes as well as concentrations to help the clinician in choosing an appropriate formulation for the treatment of various ophthalmic diseases.

Preliminary studies on validation of calu-3 cell line as a model for screening respiratory mucosa irritation and toxicity

There is need to develop reproducible methods and experimental models for screening mucosal irritation and toxicity for drugs and pharmaceutical excipients. The aim of this study was to validate Calu-3 cell line as a model for screening respiratory irritation and toxicity of drugs and excipients. Eighteen test compounds were selected according to their irritation potential and European Centre for the Validation of Alternative Methods (ECVAM) guidelines. Cell toxicity and irritation was determined using MTT assay. Data analysis and interpretation were done using modified ECVAM approach; where replicate values met acceptance criteria if percent relative standard deviation (RSD) of the raw data is <18%. Compounds with mean relative viability values of 50% and below were classified as irritant (I); those above 50% were non-irritant (NI). At low concentration (0.2% w/v) and 1 h incubation, the Calu-3 cell culture model accurately predicted the toxicity of most test compounds. The specificity of our proposed model (percentage of in vivo non-irritants correctly predicted), concordance (percentage of compounds correctly predicted) and sensitivity (percentage of in vivo irritants correctly predicted) at 0.2% w/v and 60 min exposure were 100%, 72%, and 44%, respectively. In conclusion, the Calu-3 cell line in conjunction with MTT assay appears to be a potentially useful tool for screening drugs and excipients for respiratory mucosa irritation and toxicity. However, as the data reported in this study were solely based on MTT assay, additional studies are needed using other toxicity-/irritation-indicating methods to confirm the observed trend.