Conjunctival and corneal reactions in rabbits following short- and repeated exposure to preservative-free tafluprost, commercially available latanoprost and 0.02% benzalkonium chloride

Evaluation of the effects of latanoprost and benzalkonium chloride on the cell viability and nonpolar lipid profile produced by human meibomian gland epithelial cells in culture

Purpose

The purpose of this study was to explore the effects of a PGF2α analog, latanoprost, and its preservative, benzalkonium chloride (BAK), on the cell viability and lipidomic expression of immortalized human meibomian gland epithelial cells (HMGECs).

Methods

Differentiated HMGECs were exposed to latanoprost (0.05 to 50 µg/ml), BAK (0.2 to 200 µg/ml), or combined latanoprost-BAK (0.05-0.2 to 50-200 µg/ml). EP- and FP-type receptors, the cognate receptors of PGE2 and PGF2α, were inhibited, thereby sparing and isolating the function of each receptor to one condition. Cell viability was assessed by ATP quantitation, and lipid extracts were analyzed by ESI-MSMSALL with a Triple TOF 5600 Mass Spectrometer (SCIEX, Framingham, MA) using SCIEX LipidView 1.3.

Results

Latanoprost and BAK were found to be lethal to HMGECs at the highest concentrations (p < 0.001 for both). The cytotoxicity of latanoprost was mediated through FP- and EP-independent mechanisms. Both latanoprost and BAK significantly modulated the lipidomic expression of several cholesteryl esters (8% and 30%, respectively) and triacylglycerols (10% and 12%, respectively). The combined latanoprost-BAK agent appeared to be no more toxic and to only negligibly alter the lipid profile relative to its individual components.

Conclusions

The use of latanoprost and BAK in glaucoma may alter the viability of the meibomian glands and their lipid expression in vivo. Sublethal concentrations of BAK appear to modulate meibum lipid expression, particularly in relation to sterol biosynthesis. Non-preserved latanoprost had less cytotoxicity at lower doses and fewer lipidomic effects compared to BAK, further strengthening the argument in favor of BAK-free pharmaceutical preparations.

A Novel Riboflavin Formulation for Corneal Delivery Without Damaging Epithelial Cells

Purpose

This study aimed to evaluate the trans-epithelial permeability enhancement and cell damage caused by a novel riboflavin composition for corneal delivery.

Methods

We developed a trans-epithelial formulation of riboflavin for corneal delivery using 1,2-dioleoyl-3-dimethylammonium-propane (DODAP) and isostearic acid (ISA). The permeation enhancement was evaluated using an in vitro corneal epithelial cell culture system by measuring the amount of transferred riboflavin with high-performance liquid chromatography. Riboflavin permeation of MedioCROSS TE, a commercially available riboflavin formulation containing benzalkonium chloride, was also evaluated and compared to that of the DODAP/ISA formulation by changing the riboflavin concentration. The trans-epithelial electrical resistance (TEER) was measured after exposure to the samples in an in vitro corneal epithelial cell culture system to assess cytotoxicity.

Results

The DODAP/ISA formulation demonstrated greater permeation when used together than when each component was used individually. The permeation enhancement effect of the DODAP/ISA formulation was almost the same as that of MedioCROSS TE. However, when a 10-fold higher riboflavin concentration was used in the DODAP/ISA formulation, the permeation enhancement effect surpassed that of MedioCROSS TE. After 24 hours of exposure, the TEER of the DODAP/ISA formulation was higher than that of MedioCROSS TE, indicating that the DODAP/ISA formulation was less cytotoxic than MedioCROSS TE.

Conclusions

This study indicated that the DODAP/ISA formulation could serve as a less cytotoxic alternative to MedioCROSS TE. Further studies are required to determine the clinical efficacy and safety of the DODAP/ISA formulation in vivo.

Translational Relevance

This study may provide alternative procedures for corneal collagen crosslinking with less of a cytotoxic effect on corneal epithelial cells.

Cytotoxic, Apoptotic, and Oxidative Effects of Preserved and Preservative-Free Brimonidine in a Corneal Epithelial Cell Line

Purpose: This study aims to compare the cytotoxic, apoptotic, and oxidative effects of preserved and preservative-free forms of brimonidine 0.15% on the human corneal epithelial cell (HCEC) line. Methods: Time-dependent cytotoxicity studies were performed with the Alamar Blue method. For apoptotic studies, PE Annexin V and 7-amino-actinomycin (7-AAD) staining and flow cytometry were performed. Messenger RNA (mRNA) expressions of Bax, Bcl-2, and caspase-3, -9, -12, and protein expressions of Bax and Bcl-2 were evaluated by quantitative real-time polymerase chain reaction and Western blot method, respectively. Results: Cell viability was 76.4% with the preserved solution and 36.05% with the preservative-free solution at the fifth minute. No significant difference was observed with either solution at the 15-min mark, whereas cell viability did not change significantly after 1 h. In the apoptosis evaluation, it was observed that the preservative-free solution increased the early apoptotic activity to a greater degree (P < 0.05). Preservative-free solution also induced gene expression of proapoptotic Bax, caspase-9 and -12, and protein expression of Bax while reducing the protein expression of anti-apoptotic Bcl-2 (P < 0.0001). Preserved solution induced only the gene expression of caspase-12, and reduced the protein expression of Bcl-2 (P < 0.0001). No significant difference was observed in the reactive oxygen species (ROS) levels of either solution compared with the control group (P > 0.05). Conclusion: It was demonstrated that the preserved solution is less cytotoxic to the HCEC line in the early period, has less early apoptotic activity, and does not significantly increase ROS levels.

Recombinant Human Thymosin β4 (rhTβ4) Modulates the Anti-Inflammatory Responses to Alleviate Benzalkonium Chloride (BAC)-Induced Dry Eye Disease

Dry eye disease (DED) is a multifactorial ocular disorder that interferes with daily living and reduces quality of life. However, there is no most ideal therapeutic treatment to address all the deleterious defects of DED. The purpose of this study was to investigate the ability of recombinant human thymosin β4 (rhTβ4) to promote healing in a benzalkonium chloride (BAC)-induced mice DED model and the anti-inflammatory effects involved in that process. Eye drops consisting of 0.05% and 0.1% rhTβ4 were used for treatment of DED. Tear volume and corneal staining scores were measured after 7 days. Periodic acid-Schiff staining for gobleT cells in conjunctiva, immunohistochemical staining for CD4⁺ T cells, TUNEL assay for apoptotic positive cells in cornea and conjunctiva, qRT-PCR and ELISA assays for multiple cytokines were performed. All clinical parameters showed improvement in both the 0.05% and 0.1% rhTβ4 groups. Specifically, topical application of rhTβ4 significantly increased conjunctival gobleT cells and reduced apoptotic cells in conjunctiva. Mechanically, the rhTβ4 groups showed significantly reduced inflammatory cytokine levels and CD4⁺ T cells in conjunctiva by blocking NF-κB (nuclear factor kappa B) activation, suggesting that 0.05–0.1% rhTβ4 eye drops may be used as a potential therapeutic treatment for DED.

Dynamic Contrast Microscopic Optical Coherence Tomography As a Novel Method for Assessing Corneal Epithelium During Exposure to Benzalkonium Chloride

Purpose

Microscopic optical coherence tomography (mOCT) has an imaging resolution of 1 µm in all voxel dimensions, but individual epithelial cells are difficult to resolve due to lack of scattering contrast. Adding dynamic contrast processing to mOCT (dmOCT) results in color images that enable visualization of individual cells and possibly give information on cellular function via the calculation of a motility coefficient. We propose this technique as a novel method of evaluating the ocular surface after exposure to a toxic chemical, benzalkonium chloride (BAK).

Methods

Ex vivo cross-section images were acquired with a custom-built, frequency-domain mOCT system. Eyes were explanted from healthy adult C57BL/6 mice and imaged every 30 minutes with five sets of dmOCT scans at each imaging time. Total epithelium and stroma thicknesses were measured from a single mOCT B-scan, and measures of color changes (hue) and the motility coefficient were acquired from dmOCT scans.

Results

After 30-minute exposures to 0.005% BAK, local motility decreased and total epithelium thickness increased compared to controls. For basal epithelium cells, local motility decreased after 60-minute exposures, and the hue shifted red after 90-minute exposures. Stroma thickness did not significantly swell until 150-minute exposures to BAK.

Conclusions

dmOCT allows us to view the behavior of the cornea epithelium under toxic stress due to BAK, revealing parallel swelling of the extracellular matrix and changes in local subcellular motion.

Translational Relevance

The evaluation of the cornea epithelium using dmOCT is helpful to our understanding of the toxic effects of BAK.

Experimental Models, Induction Protocols, and Measured Parameters in Dry Eye Disease: Focusing on Practical Implications for Experimental Research

Dry eye disease (DED) is one of the major ophthalmological healthcare challenges worldwide. DED is a multifactorial disease characterized by a loss of homeostasis of the tear film, and its main pathogenesis is chronic ocular surface inflammation related with various cellular and molecular signaling cascades. The animal model is a reliable and effective tool for understanding the various pathological mechanisms and molecular cascades in DED. Considerable experimental research has focused on developing new strategies for the prevention and treatment of DED. Several experimental models of DED have been developed, and different animal species such as rats, mice, rabbits, dogs, and primates have been used for these models. Although the basic mechanisms of DED in animals are nearly identical to those in humans, proper knowledge about the induction of animal models is necessary to obtain better and more reliable results. Various experimental models (in vitro and in vivo DED models) were briefly discussed in this review, along with pathologic features, analytical approaches, and common measurements, which will help investigators to use the appropriate cell lines, animal, methods, and evaluation parameters depending on their study design.

Confocal Microscopy and Anterior Segment Optical Coherence Tomography Imaging of the Ocular Surface and Bleb Morphology in Medically and Surgically Treated Glaucoma Patients: A Review

Glaucoma patients often suffer from ocular surface disease (OSD) caused by the chronic administration of topical anti-glaucoma medications, especially in cases of long-term therapy with preserved or multiple drugs. Additionally, glaucoma surgery may determine ocular surface changes related to the formation and location of the filtering bleb, the application of anti-mitotic agents, and the post-operative wound-healing processes within the conjunctiva. Recently, several studies have evaluated the role of advanced diagnostic imaging technologies such as in vivo confocal microscopy (IVCM) and anterior segment-optical coherence tomography (AS-OCT) in detecting microscopic and macroscopic features of glaucoma therapy-related OSD. Their clinical applications are still being explored, with recent particular attention paid to analyzing the effects of new drug formulations and of minimally invasive surgical procedures on the ocular surface status. In this review, we summarize the current knowledge about the main changes of the ocular surface identified at IVCM and AS-OCT in glaucoma patients under medical therapy, or after surgical treatment.

Assessment of ocular surface disease in glaucoma patients with benzalkonium chloride-preserved latanoprost eye drops: a short-term longitudinal study

PURPOSE

To prospectively evaluate the effect of benzalkonium chloride (BAK)-preserved latanoprost on ocular surface damage and identify the associated risk factors among treatment-naive glaucoma patients.

METHODS

The basal Schirmer's test results, corneal Oxford staining score, non-invasive keratograph tear-breakup time, oculus hyperemia index score (objective metrics), and ocular surface disease index (OSDI) questionnaire (subjective metric) were evaluated at baseline, 1 month, and 4 months after receiving latanoprost eye drops. Associated risk factors were assessed by multivariate linear regression.

RESULTS

Seventy-four eyes (44 patients) were enrolled. Basal Schirmer's test tear-flow and Oxford scores gradually deteriorated (β = -0.14, P = 0.001 and β = 0.1, P < 0.001, respectively). The percentage of unstable tear-film (breakup time < 10 s) increased significantly at 4 months (6.21% vs 9.11%, P = 0.042). Hyperemic scores increased significantly at 1 month and normalized at 4 months (P = 0.01 and P = 0.16, respectively); total OSDI scores tended to improve (β = -0.76, P = 0.06). Older age was associated with additional corneal Oxford staining (P = 0.005); female sex was associated with increased unstable tear-film scores (P = 0.01). Artificial tear use was associated with a smaller decrease in basal Schirmer's test values (P = 0.01) and a smaller increase in unstable tear-film scores (P = 0.02).

CONCLUSIONS

Preserved latanoprost eye drops affected ocular surface changes in glaucoma patients through decreased basal tear secretion. Artificial tears represent an early intervention in vulnerable glaucoma patients with reduced tear secretion and impaired tear-film stability.

In vivo immune cell dynamics in the human cornea

In vivo confocal microscopy (IVCM) allows the evaluation of the living human cornea at the cellular level. The non-invasive nature of this technique longitudinal, repeated examinations of the same tissue over time. Image analysis of two-dimensional time-lapse sequences of presumed immune cells with and without visible dendrites at the corneal sub-basal nerve plexus in the eyes of healthy individuals was performed. We demonstrated evidence that cells without visible dendrites are highly dynamic and move rapidly in the axial directions. A number of dynamic cells were observed and measured from three eyes of different individuals. The total average displacement and trajectory speeds of three cells without visible dendrites (N = 9) was calculated to be 1.12 ± 0.21 and 1.35 ± 0.17 μm per minute, respectively. One cell with visible dendrites per cornea was also analysed. Tracking dendritic cell dynamics in vivo has the potential to significantly advance the understanding of the human immune adaptive and innate systems. The ability to observe and quantify migration rates of immune cells in vivo is likely to reveal previously unknown insights into corneal and general pathophysiology and may serve as an effective indicator of cellular responses to intervention therapies.

Poly(2-hydroxyethyl methacrylate)/β-cyclodextrin-hyaluronan contact lens with tear protein adsorption resistance and sustained drug delivery for ophthalmic diseases

A series of poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogels containing cross-linked β-cyclodextrin-hyaluronan (β-CD-crHA), with tear protein adsorption resistance and sustained drug delivery, were developed as contact lens materials for eye diseases. β-CD-HA was synthesized from aminated β-CD and HA and then crosslinked within pHEMA hydrogel using polyethylenimine as a crosslinker. The synthesized β-CD-HA was characterized by ¹H NMR analysis, and β-CD-crHA immobilized in pHEMA hydrogel was confirmed by FT-IR, SEM, and AFM analyses. The incorporation of β-CD-crHA significantly improved the surface hydrophilicity, water uptake ability, oxygen permeability, and flexibility of pHEMA hydrogel, but did not compromise light transmission. pHEMA/β-CD-crHA hydrogels not only decreased the tear protein adsorption because of the electrostatically mutual repulsion and the improved hydrophilicity, leading to the reduced adhesion of Staphylococcus aureus on the hydrogel surface, but also enhanced the encapsulation capacity and the sustainable delivery of diclofenac due to the formation of inclusion complexes between β-CD and drugs. All the hydrogels were nontoxic to 3T3 mouse fibroblasts by in vitro cell viability analysis. Among these hydrogels with different β-CD-crHA contents, pHEMA/β-CD-crHA₁₀ hydrogel showed the lowest water contact angle of 52 °, the highest water content of 65%, the largest Dk value of 36.4 barrer, and the optimal modulus of 1.8 MPa, as well as a good light transmission of over 90%. The in vivo conjunctivitis treatment of rabbits for 72 h indicated that drug-loaded pHEMA/β-CD-crHA₁₀ hydrogel presented a better therapeutic effect than both one dose administration of drug solution per day and drug-loaded pHEMA hydrogel. Thus, pHEMA/β-CD-crHA₁₀ hydrogel is a promising contact lens material for ophthalmic diseases. STATEMENT OF SIGNIFICANCE: Topical eye drops are currently the most popular treatment for ophthalmic diseases, but frequent dosing is necessary to acquire the desirable clinical effect at the expense of systemic side-effects. Drug-loaded contact lenses, as an alternative of eye drops, possess many good performances and show potential applications. However, the sustained drug delivery and the tear protein adsorption resistance are still challenging for contact lenses. Hence, we developed a novel pHEMA/β-CD-crHA hydrogel by incorporating β-CD-crHA crosslinked network into pHEMA hydrogel. Besides the improvements in surface hydrophilicity, water uptake ability, oxygen permeability, and flexibility, pHEMA/β-CD-crHA hydrogel also reduced the adsorption of tear proteins and the adhesion of Staphylococcus aureus, enhanced the drug encapsulation, and prolonged the drug delivery, with better effect in the conjunctivitis treatment of rabbits. Thus, pHEMA/β-CD-crHA hydrogel is a potential contact lens material for treating ophthalmic diseases.

Chronic dry eye induced corneal hypersensitivity, neuroinflammatory responses, and synaptic plasticity in the mouse trigeminal brainstem

Background

Dry eye disease (DED) is a multifactorial disease associated with ocular surface inflammation, pain, and nerve abnormalities. We studied the peripheral and central neuroinflammatory responses that occur during persistent DED using molecular, cellular, behavioral, and electrophysiological approaches.

Methods

A mouse model of DED was obtained by unilateral excision of the extraorbital lachrymal gland (ELG) and Harderian gland (HG) of adult female C57BL/6 mice. In vivo tests were conducted at 7, 14, and 21 days (d) after surgery. Tear production was measured by a phenol red test and corneal alterations and inflammation were assessed by fluorescein staining and in vivo confocal microscopy. Corneal nerve morphology was evaluated by nerve staining. Mechanical corneal sensitivity was monitored using von Frey filaments. Multi-unit extracellular recording of ciliary nerve fiber activity was used to monitor spontaneous corneal nerve activity. RT-qPCR and immunostaining were used to determine RNA and protein levels at d21.

Results

We observed a marked reduction of tear production and the development of corneal inflammation at d7, d14, and d21 post-surgery in DED animals. Chronic DE induced a reduction of intraepithelial corneal nerve terminals. Behavioral and electrophysiological studies showed that the DED animals developed time-dependent mechanical corneal hypersensitivity accompanied by increased spontaneous ciliary nerve fiber electrical activity. Consistent with these findings, DED mice exhibited central presynaptic plasticity, demonstrated by a higher Piccolo immunoreactivity in the ipsilateral trigeminal brainstem sensory complex (TBSC). At d21 post-surgery, mRNA levels of pro-inflammatory (IL-6 and IL-1β), astrocyte (GFAP), and oxidative (iNOS2 and NOX4) markers increased significantly in the ipsilateral trigeminal ganglion (TG). This correlated with an increase in Iba1, GFAP, and ATF3 immunostaining in the ipsilateral TG of DED animals. Furthermore, pro-inflammatory cytokines (IL-6, TNFα, IL-1β, and CCL2), iNOS2, neuronal (ATF3 and FOS), and microglial (CD68 and Itgam) markers were also upregulated in the TBSC of DED animals at d21, along with increased immunoreactivity against GFAP and Iba1.

Conclusions

Overall, these data highlight peripheral sensitization and neuroinflammatory responses that participate in the development and maintenance of dry eye-related pain. This model may be useful to identify new analgesic molecules to alleviate ocular pain.

Tear Film Osmolarity, Ocular Surface Disease and Glaucoma: A Review

Glaucoma is the second leading cause of blindness in the world, affecting more than 60 million people globally. In order to reduce the progression of the disease, both medical and surgical treatments are used. Frequent side effects of both treatments include a range of modifications of the ocular surface grouped as the Ocular Surface Disease (OSD), which include Dry Eye Disease (DED). DED and other OSD negatively impact on the success of anti-glaucoma treatments and reduce the adherence to medical therapies. Tear film osmolarity (TFO) is a relatively novel test which has become a hallmark of DED. The aim of this paper was to review the association between OSD, DED and glaucoma in view of published TFO data, and to discuss future fields of research and treatments on the topic of glaucoma iatrogenic damage.

Benzalkonium chloride-induced direct and indirect toxicity on corneal epithelial and trigeminal neuronal cells: proinflammatory and apoptotic responses in vitro

Benzalkonium chloride (BAK), a quaternary ammonium compound widely used as disinfecting agent as well as preservative in eye drops is known to induce toxic effects on the ocular surface with inflammation and corneal nerve damage leading to dry eye disease (DED) in the medium-to-long term. The aim of this study was to evaluate in vitro the toxicity of a conditioned medium produced by corneal epithelial cells previously exposed to BAK (BAK-CM) on trigeminal neuronal cells. A human corneal epithelial (HCE) cell line was exposed to 5.10^-3% BAK (i.e. 0.005% BAK) for 15 min and let recover for 5 h to prepare a BAK-CM. This BAK concentration is the lowest one found in eye drops. After this recovery period, BAK effect on HCE cells displayed cytotoxicity, morphological alteration, apoptosis, oxidative stress, ATP release, CCL2 and IL6 gene induction, as well as an increase in CCL2, IL-6 and MIF release. Next, a mouse trigeminal ganglion primary culture was exposed to the BAK-CM for 2 h, 4 h or 24 h. Whereas BAK-CM did not alter neuronal cell morphology, or induced neuronal cytotoxicity or oxidative stress, BAK-CM induced gene expression of Fos (neuronal activation marker), Atf3 (neuronal injury marker), Ccl2 and Il6 (inflammatory markers). Two and 4 h BAK-CM exposure promoted a neuronal damage (ATF-3, phospho-p38 increases; phospho-Stat3 decreases) while 24 h-BAK-CM exposure initiated a prosurvival pathway activation (phospho-p44/42, phospho-Akt increases; ATF-3, GADD153, active Caspase-3 decreases). In conclusion, this in vitro model, simulating paracrine mechanisms, represents an interesting tool to highlight the indirect toxic effects of BAK or any other xenobiotic on corneal trigeminal neurons and may help to better understand the cellular mechanisms that occur during DED pathophysiology.

EFFECT OF LUBRICANTS ON CORNEAL THICKNESS AFTER VITRECTOMY

PURPOSE

This study examines the impact of corneal surface lubricants used during pars plana vitrectomy on corneal edema.

METHODS

This prospective, observational, clinical study occurred at an academic institution. Participants were individuals aged 18 years and older who had already consented to undergo pars plana vitrectomy, without pre-existing corneal pathology. A corneal lubricant was chosen by the surgeon. Corneal thickness was measured preoperatively and postoperatively using pachymetry and anterior segment optical coherence tomography (AS-OCT). Main outcome measure was change in corneal thickness as measured by pachymetry.

RESULTS

Forty-one patients completed the study protocol. The 23 subjects in the SHCS group had a significantly smaller increase in corneal thickness as measured by pachymetry compared with the 18 subjects in the HPMC group (29.9 μm vs. 58.1 μm, P value 0.02). When measured by anterior segment optical coherence tomography, the SHCS group had a smaller increase in corneal thickness compared with the HPMC group (0.04 mm vs. 0.06 mm, P value 0.09) but did not reach significance.

CONCLUSION

SHCS is associated with reduced postoperative increase in corneal pachymetry as compared to HPMC.

Anterior-Segment Optical Coherence Tomography and Scanning Electron Microscopy to Evaluate Corneal Epithelial Changes in Patients Undergoing Glaucoma Therapy

PURPOSE

To measure corneal epithelial thickness (CET) in patients with glaucoma using anterior-segment optical coherence tomography and to evaluate CET changes in relation to corneal epithelial microvilli analyzed by scanning electron microscopy (SEM).

METHODS

Twenty-two eyes (16 patients) being treated with preservative-containing topical medications and 12 normal eyes underwent anterior-segment optical coherence tomography imaging using RTVue-100. The CET maps generated corresponded to a 6-mm diameter area of cornea that was divided into 17 sectors. We compared the CETs of each sector obtained in the glaucomatous group with those obtained in the control group.

RESULTS

Glaucomatous eyes were divided into 2 groups based on the number of microvilli on SEM: group 1 (6 eyes) = grades 1 and 2 at SEM (range: 500-3000) and group 2 (10 eyes) = grades 3 and 4 at SEM (range: 0-500). Four CET sectors were significantly thinner in group 1 than in normal eyes: central (P = 0.012), superior (P = 0.005), temporal paracentral (P = 0.003), and temporal midperipheral (P = 0.023). No significant differences were observed between group 2 and normal eyes. CET sectors were significantly thinner in group 1 than in group 2 only in the superior (P = 0.024) and superior-temporal paracentral (P = 0.020) sectors. CET progressively increased in patients with glaucoma as the number of corneal epithelial microvilli decreased.

CONCLUSIONS

CET and corneal epithelial microvilli are new parameters with which to evaluate early stages of corneal epithelial changes during glaucoma therapy. In advanced stages of corneal epithelial damage, SEM evaluation reveals ultrastructural epithelial changes that may not be observed on CET measurements.

Toxic Keratoconjunctivitis

Toxic keratoconjunctivitis (TK) is an underrecognized complication of ophthalmic drug use and various environmental or occupational exposures. A detailed history and clinical examination are important to identify the offending agent(s). Common drug-related causes of TK include preservatives in ophthalmic medications, topical antimicrobials, and topical anesthetics. Alternatives to benzalkonium chloride as well as preservative-free formulations should be considered in patients requiring long-term topical medication. More advanced cases of TK may require preservative-free topical steroids and/or antibiotics, and occasionally surgical intervention. Early recognition and appropriate management of TK may help prevent permanent ocular and visual damage.

In Vivo Scanning Laser Confocal Microscopy of Conjunctival Goblet Cells in Medically-controlled Glaucoma

AIM

The aim of this study was to evaluate the goblet cell density (GCD) of conjunctiva in medically-controlled glaucoma using laser scanning confocal microscopy (LSCM).

MATERIALS AND METHODS

Fifty-five glaucomatous patients were enrolled and divided into two groups: Group 1 (27 eyes), controlled with one medication; and group 2 (28 eyes), controlled with two medications. Seventeen patients with dry eye disease (DED) and 17 healthy individuals served as controls. Patients completed the Ocular Surface Disease Index (OSDI) questionnaire and underwent determination of tear film break-up time (BUT), corneal staining, and Schirmer test I. For the GCD assessment, 12 high-quality images were acquired from the upper conjunctival epithelium (superior nasal, superior central, and superior temporal sectors).

RESULTS

Overall, GCD was significantly reduced in both glaucoma groups and those with DED compared to healthy controls (p<0.001), with values markedly lower in group 2 compared to group 1 (p<0.05). GCD was not significantly different between those with DED and group 2. A significant negative correlation was found of GCD with OSDI and with BUT (p<0.001; R=-0.795 and R=-0.756, respectively).

CONCLUSION

Glaucoma therapy leads to a marked reduction of GCs, especially in the associative regimens. Given the negative correlation with tear film function tests, GCD reduction may play a pivotal role in the pathophysiology of the glaucoma-related disease of the ocular surface.

Comparison of Efficacy and Ocular Surface Disease Index Score between Bimatoprost, Latanoprost, Travoprost, and Tafluprost in Glaucoma Patients

Aim

The purpose of this study is to evaluate and compare the efficacy of 4 prostaglandin analogues (PGAs) and to determine the incidence of ocular surface disease in newly diagnosed, primary open-angle glaucoma (POAG) patients started on one of those 4 PGAs: bimatoprost (benzalkonium chloride, BAK, 0.3 mg/mL), latanoprost (BAK 0.2 mg/mL), travoprost (polyquad), and tafluprost (BAK-free).

Patients and Methods

In this single-center, open-label trial, 32 patients newly diagnosed with POAG were randomly started on one of the four PGAs. All patients underwent a complete ophthalmological exam at presentation and at 1, 3, and 6 months of follow-up. Dry eye disease (DED) was assessed using the original Ocular Surface Disease Index (OSDI) questionnaire, in order to evaluate the impact of the drops on the quality of life of patients.

Results

The mean age was 60.06 years ± 11.76. All four drugs equally and significantly reduced the intraocular pressure (IOP) with respect to the baseline IOP. There was a trend for a slightly greater reduction of IOP with bimatoprost, but the difference was not found to be statistically significant when compared to other PGAs. OSDI scores were significantly superior for travoprost (10.68 ± 5.73) compared to the other three drugs (p < 0.05). Latanoprost caused the most significant eyelash growth and iris discoloration. Conjunctival hyperemia and superficial keratitis occurrence were similar in the four groups.

Conclusion

All prostaglandin analogues equally and significantly reduce the IOP in patients with POAG. According to the results of the OSDI score, latanoprost seems to be the least tolerated among the four drugs.

In Vivo Analysis of Prostaglandins-induced Ocular Surface and Periocular Adnexa Modifications in Patients with Glaucoma

BACKGROUND/AIM

Prostaglandin analogues (PGAs) are a first-line medical treatment for glaucoma because of their powerful intraocular pressure (IOP) lowering effect, few systemic side-effects (SEs), and the once daily administration. Despite the high systemic safety profile, the chronic use of PGAs may induce periocular and ocular surface (OS)-related side effects, which affect a significant proportion of glaucomatous patients. In this review, we summarize the current knowledge about SEs of PGAs on periocular structures and OS, and their implications in clinical practice.

MATERIALS AND METHODS

A comprehensive literature search on the PubMed platform was performed. Two hundred fifty articles fulfilling key words were identified, of which 180 were excluded since they did not concern the effects of PGAs on the periocular tissues and OS, or because of their limited relevance. The following key words were used and combined, to narrow-down the literature: "prostaglandin" and "ocular surface," which identified 184 unique publications, of which 68 were selected; "prostaglandin" and "periocular" which identified 46 unique publications, of which 11 were selected. An additional search was conducted using "prostaglandin" and "Meibomian glands (MGs)", which identified twenty unique publications, of which 8 were selected. Thus, a total of 70 articles were chosen based on their relevance and were included in this review.

RESULTS

Prostaglandin-associated peri-orbitopathy, skin pigmentation and hypertrichosis, eyelash growth, and MGs dysfunction are the most frequent modifications of periocular tissues. They are induced by the tissue accumulation of PGAs, and FP receptor stimulation. Without preservatives, PGAs act as stimulators of conjunctival goblet cells, which are the main source of ocular surface mucoproteins, and seem to increase conjunctival epithelium microcysts proposed as in vivo hallmark of the trans-scleral aqueous humour outflow. Additional PGA-induced modifications can be recognized in the cornea, corneo-scleral limbus, conjunctival stroma and, conjunctiva-associated lymphoid tissue, mainly appearing as inflammatory changes. OS epithelia desquamation, chemosis, apoptosis, dendritic cell activation, conjunctival or episcleral vasodilation, and sub-basal nerve plexus disruption were also described in patients receiving preserved PGAs.

CONCLUSION

PGAs induce several modifications of the OS structures and adnexa; nonetheless, none of them significantly reduces the local safety profile of this class of drugs. Moreover, the OS changes do not affect the IOP lowering efficacy of PGAs. On these bases, local SEs of PGAs should not discourage clinicians in using this class of medications because of their efficacy, the systemic safety profile, and the better adherence.

A dose-escalation ex vivo study on the effects of intracameral benzalkonium chloride in rabbits

Background

Rabbits are currently not a good model for studying diseases of the corneal endothelium because their corneal endothelial cells (CECs) maintain a high proliferative capacity throughout almost all their life. Addressing this particular feature might allow the use of this species for such a purpose. The aim of this study was to evaluate the corneal endothelial injury after intracameral benzalkonium chloride (BAC) injection into rabbit eyes ex vivo, and to establish the most suitable starting dose for an in vivo study aimed at developing an animal model of corneal endothelial disease.

Results

Forty rabbit eyes obtained postmortem by transconjunctival enucleation were divided into 8 groups according to the injected compound: Control (no injection), BSS, and increasing BAC concentrations (0.005%, 0.01%, 0.025%, 0.05%, 0.1% and 0.2%). At 0, 6, 24 and 48 h, ophthalmologic examination of the anterior segment, pachymetry and specular microscopy were performed, and corneas were finally vital-stained and observed under the light microscope to assess the CECs morphology and mortality rate. When compared to BSS, CECs density started to decrease significantly at 0.025% BAC concentration, while mean cell area, corneal edema and corneal thickness began to increase significantly at 0.05%, 0.005% and 0.1% BAC concentrations, respectively. Concentrations of 0.05% BAC and above caused significant increases in CECs pleomorphism (decreased hexagonality) and mortality, compared to control and BSS.

Conclusions

Ex vivo intracameral BAC injection induces corneal endothelial toxicity in rabbits. However, confirmatory in vivo studies are required to develop the desired model, with 0.05% BAC being a suggested starting point.

Vitamin A Palmitate and Carbomer Gel Protects the Conjunctiva of Patients With Long-term Prostaglandin Analogs Application

PURPOSE

To investigate the protective effects of vitamin A palmitate and carbomer gel on the morphology of conjunctival epithelium and density of goblet cells (GCs) in patients on long-term prostaglandin analogs (PGAs) application.

METHODS

In this prospective cohort study, 23 primary open-angle glaucoma patients and 7 normal-tension glaucoma patients prescribed PGAs for >1 year were enrolled into 3 identical clinical trials and randomized into 3 groups (10 per group). Patients were treated twice daily with vitamin A palmitate eye gel 0.1%, or carbomer eye gel 0.2%, or no additional application of these 2 drugs. Ocular surface disease index questionnaires, Schirmer 1 test without anesthesia, tear break-up time test, and GCs density assessment by in vivo confocal microscopy and conjunctival impression cytology analysis were performed at baseline and at months 1, 3, and 6 of the study.

RESULTS

Both vitamin A palmitate and carbomer gel led to a significant improvement in ocular surface disease index questionnaires score and prevented the gradual decline in tear break-up time. Vitamin A palmitate significantly increased the GC density after treatment. The GC density assessed by in vivo confocal microscopy positively correlated with that measured by conjunctival impression cytology.

CONCLUSIONS

Vitamin A palmitate and carbomer eye gel can effectively relieve dry eye symptom caused by long-term application of PGAs by increasing the GCs density and thereby reducing the toxicity to the conjunctiva. Vitamin A palmitate and carbomer eye gel may be valuable alternatives for glaucoma patients who prescribed long-term PGAs.

The Conjunctiva-Associated Lymphoid Tissue in Chronic Ocular Surface Diseases

Ocular surface diseases (OSDs) represent a widely investigated field of research given their growing incidence and the negative impact on quality of life. During OSDs, cytokines generated by damaged epithelia trigger and deregulate the lymphoid cells composing the eye-associated lymphoid tissues, inducing an immune-mediated chronic inflammation that amplifies and propagates the disease during time. The conjunctiva-associated lymphoid tissue (CALT), given its particular position that permits immune cells covering the cornea, might play a crucial role in the development of OSDs. Despite the recognized inflammatory role of mucosa-associated lymphoid tissues in other stations taking contact with the external environment (gut or bronchus), CALT did not gain the deserved consideration. In the last years, the diffusion of the in vivo confocal microscopy (IVCM) stimulated the interest to CALT, especially in dry eye, ocular allergy, and glaucoma. Though the initial stimuli were different, IVCM documented similar changes, represented by increased lymphoid cells within the diffuse layer, follicles and interfollicular spaces. These findings, which need to be validated by immunohistology, support the CALT stimulation during OSDs. However, while an involvement of the CALT in OSDs is hypothesizable, the exact role of this structure in their pathogenesis remains unclear and warrants further investigations.

The Effects of Latanoprost With Benzalkonium Chloride Versus Travoprost With SofZia on the Ocular Surface

PURPOSE

To assess ocular surface changes in participants using latanoprost with benzalkonium chloride (Xalatan) and travoprost with SofZia (Travatan Z).

METHODS

In this prospective, open-label, nonrandomized cohort study, participants were classified into two groups: group 1 (n=28) naive to glaucoma therapy, group 2 (n=27) on previous Xalatan monotherapy in both eyes. Both groups started (or continued) Xalatan in the right eye and Travatan Z in the left eye. Baseline, 1-, and 2-month measurements of tear breakup time (TBUT), corneal staining score, conjunctival staining score, conjunctival hyperemia score, tear production, and intraocular pressure were obtained. The Ocular Surface Disease Index questionnaire measured participants' comfort and dryness symptoms. Medication preference was recorded.

RESULTS

Data were collected from 55 participants. Tear breakup time at baseline and 1-month follow-up in group 1 was significantly longer than that of group 2 (P=0.005). At 2 months, there was no significant difference in TBUT between the two groups (P=0.779). Tear production in group 1 at all three time points was significantly higher than group 2 (P<0.05). Conjunctival staining score at 2 months in group 1 was significantly higher than group 2 (P=0.031). There was no significant difference in other parameters between the groups at any other time point. No significant difference in any parameter was found between Xalatan and Travatan Z (intragroup comparison).

CONCLUSIONS

Significant differences in ocular surface characteristics were detected between groups, but no significant difference was detected between participants treated with Xalatan and Travatan Z.

Sodium perbarate and benzalkonium chloride induce DNA damage in Chang conjunctival epithelial cells

Content and objective: To investigate and compare the toxic effects of benzalkonium chloride (BAC) and new type oxidative preservative sodium perborate (NaBO₃) on DNA damage, reactive oxygen species (ROS), and cell survival in immortalized human Chang conjunctival cells.

MATERIALS AND METHODS

Cells were exposed to BAC and NaBO₃ in concentrations of 0.00001-0.001% for 30 min. Cell viability was measured by the MTT test. Alkaline comet assay was used to detect DNA damage. Mitochondrial membrane potential (MMP), cell apoptosis, and ROS production were detected by flow cytometry analysis.

RESULTS

Significant changes in the relative cell survival rate in cells were observed after exposure to 0.0005-0.001% BAC for 30 min (p < 0.001). DNA damage and intracellular ROS were observed in a dose-dependent manner with BAC exposure (p < 0.001). However, 0.001% BAC induced less ROS than 0.0005% BAC. A decrease in MMP was also recorded. NaBO₃ did not induce the decrease in cell survival and MMP in low concentration but could induce DNA damage and ROS generation in a 0.001% concentration (p < 0.001).

DISCUSSION AND CONCLUSIONS

BAC can induce DNA damage in human conjunctival epithelial cells; this effect may be related to oxidative stress. Although NaBO₃ did not induce a significant decrease in cell survival and MMP, DNA damage and ROS generation were still detected in high concentration. New type oxidative preservative has less toxicity than the old type, but it still has the tendency of producing genotoxic changes in an in vitro test system.

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.

Pharmacokinetics, Efficacy, and Safety of the Preservative-free Fixed Combination of Tafluprost 0.0015% and Timolol 0.5% in Healthy Volunteers: A Phase I Comparison vs. the Corresponding Preservative-free Monotherapies

PURPOSE

Plasma concentrations of tafluprost acid and timolol were compared after single (Day 1) and repeated (Day 8) instillations of once-daily tafluprost 0.0015%-timolol 0.5% preservative-free (PF) fixed-dose combination (FDC), once-daily PF tafluprost 0.0015%, and twice-daily PF timolol 0.5%.

PATIENTS AND METHODS

Fifteen healthy volunteers were randomized to this double-masked, single-center, three-period cross-over study. A wash-out interval of at least 4 weeks separated each three 8-day dosing period. Blood samples were drawn on the first and last day of each dosing period, prior to the morning dose, as well as 5, 10, 15, 30, and 45 min, and 1, 1.5, 2, 4, 8, and 12 h post-dosing. Sample plasma concentrations of tafluprost acid and/or timolol were determined and maximum concentration (C max), area under the concentration-over-time curve from time zero to the last time point with a quantifiable measurement (AUC0-last), and time to maximum concentration were calculated. Intraocular pressure (IOP), adverse events, and ocular/systemic safety variables were also evaluated.

RESULTS

Plasma concentrations of tafluprost acid were low, with similar levels measured subsequent to either single or repeated dosing of PF FDC and PF tafluprost. On both sampling days, concentrations peaked at 10 min after the dose, and were cleared from the blood circulation by 30 min; average C max ranged from 17 to 24 pg/mL, and AUC0-last from 3 to 5 pg*h/mL. Plasma concentrations of timolol were comparable after the first dose of PF FDC or PF timolol. Concentrations peaked at 15 min post-dose and diminished in a similar manner after 2 h; average C max was 800 pg/mL and AUC0-last 3900 pg*h/mL. As expected, PF timolol produced a higher Day 8 pre-dose timolol concentration than PF FDC (235 vs. 37 pg/mL; p < 0.001, respectively). The Day 8 post-dose changes in timolol concentrations were relative to this pre-dose difference. All study treatments were well tolerated and safe. PF FDC seemed to provide the best IOP reduction.

CONCLUSIONS

PF FDC demonstrated good IOP-lowering efficacy and displayed similar pharmacokinetic characteristics to the monotherapy agents. Exposure to timolol was reduced via the halved dosing.

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.

Ocular Tolerability of Preservative-Free Tafluprost and Latanoprost: in vitro and in vivo Comparative Study

Objective:

Detrimental effects of the preserved prostaglandin analogs (PGAs) have been thoroughly documented in the published literature. The current work studied two preservative-free (PF) prostaglandin eye drops: PF tafluprost and PF latanoprost. The aim of the study was to compare these two PF formulations in vitro for viability of the human corneal epithelial (HCE-T) cells and in vivo for ocular tolerability of the rabbit eye.

Method:

Viability of the HCE-T cells was measured by the MTS assay. The SV40-immortalized HCE-T cells were exposed to 100 µL of the drug solutions (at their commercial concentrations) or the culture medium. Ocular irritation was evaluated after repeated instillation of the drug solutions in Japanese white rabbits (Kbl:JW).

Results:

A significant loss of HCE-T cell viability was observed in vitro immediately after the exposure to PF latanoprost formulation but not immediately after the exposure to PF tafluprost formulation. Congruently, PF latanoprost induced in vivo more irritation on the rabbit eye than PF tafluprost.

Conclusion:

Comparing these two PF formulations in vitro and in vivo, it is considered that ocular tolerability of PF tafluprost is better than PF latanoprost. Taking into account the composition of these two PF PGA formulations, the solubilizing agent macrogolglycerol hydroxystearate 40 (MGHS40) contained in PF latanoprost formulation is a plausible cause for the negative effects.

Effect of preservative-free tafluprost on intraocular pressure, pupil diameter, and anterior segment structures in normal canine eyes

OBJECTIVE

This study was designed to evaluate the changes in intraocular pressure (IOP), pupil diameter (PD), and anterior segment parameters using ultrasound biomicroscopy (UBM) after instillation of preservative-free (PF) tafluprost in normal dogs.

PROCEDURES

Six beagle dogs were used. PF tafluprost was instilled in one randomly selected eye, and PF artificial tear was instilled in the other eye (control). IOP and PD were measured every 15 min for the first hour, every 2 h for the next 17 h, and at 24 h and 36 h postinstillation (PI). Anterior segment parameters including geometric iridocorneal angle (ICA), width of the entry of the ciliary cleft (CCW), length of the ciliary cleft, area of the ciliary cleft, and depth of the anterior chamber were measured with UBM before and after PF tafluprost instillation.

RESULTS

Compared with the control group, IOP was significantly lower from 4 h PI to 24 h PI and PD was significantly smaller from 30 min PI to 18 h PI (P < 0.05). Among UBM parameters, ICA and CCW significantly decreased and increased after PF tafluprost instillation, respectively (P < 0.05). Other parameters showed no significant changes.

CONCLUSIONS

Instillation of PF tafluprost lowered IOP and induced miosis in normal canine eyes. Alterations in ICA and CCW occurred simultaneously, which probably affected the outflow of aqueous humor. PF tafluprost could be considered an alternative prostaglandin analog in the treatment of canine glaucoma.

Ocular inflammation induces trigeminal pain, peripheral and central neuroinflammatory mechanisms

Ocular surface diseases are among the most frequent ocular pathologies, with prevalence ranging from 20% of the general population. In addition, ocular pain following corneal injury is frequently observed in clinic. The aim of the study was to characterize the peripheral and central neuroinflammatory process in the trigeminal pathways in response to cornea alteration induced by chronic topical instillations of 0.2% benzalkonium chloride (BAC) in male C57BL/6J mice. In vitro BAC induced neurotoxicity and increases neuronal (FOS, ATF3) and pro-inflammatory (IL-6) markers in primary mouse trigeminal ganglion culture. BAC-treated mice exhibited 7days after the treatment reduced aqueous tear production and increased inflammatory cell infiltration in the cornea. Hypertonic saline-evoked eye wipe behavior was enhanced in BAC-treated animals that exhibited increased FOS, ATF3 and Iba1 immunoreactivity in the trigeminal ganglion. Ocular inflammation is associated with a significant increase in IL-6 and TNF-α mRNA expression in the trigeminal ganglion. We reported a strong increase in FOS and Iba1 positive cells in particular in the sensory trigeminal complex at the ipsilateral interpolaris/caudalis (Vi/Vc) transition and Vc/upper cervical cord (Vc/C1) regions. In addition, activated microglial cells were tightly wrapped around activated FOS neurons in both regions and phosphorylated p38 mitogen-activated protein kinase was markedly enhanced specifically in microglial cells during ocular inflammation. Similar data were obtained in the facial motor nucleus. These neuroanatomical data correlated with the increase in mRNA expression of pro-inflammatory (TNF-α, IL-6, CCL2) and neuronal (FOS and ATF3) markers. Interestingly, the suppression of corneal inflammation 10days following the end of BAC treatment resulted in a marked attenuation of peripheral and central changes observed in pathological conditions. This study provides the first demonstration that corneal inflammation induces activation of neurons and microglial p38 MAPK pathway within sensory trigeminal complex. These results suggest that this altered activity in intracellular signaling caused by ocular inflammation might play a priming role in the central sensitization of ocular related brainstem circuits, which represents a significant factor in ocular pain development.

In Vivo Effects of Preservative-free and Preserved Prostaglandin Analogs: Mouse Ocular Surface Study

Purpose

Chronic use of topical hypotensive agents induces several side effects caused by preservatives. The purpose of this study was to evaluate the effects of prostaglandin analogs with varying concentrations of benzalkonium chloride (BAC), preservative-free (PF), and alternative preservatives on mouse corneal tissue.

Methods

Thirty-five, 8- to 10-week-old female C57BL/6 mice (five mice for each group) were used for this study. To the control group, we applied normal saline, and to each drug-treated group we applied 0.02% BAC, bimatoprost 0.01% (with BAC 0.02%), latanoprost 0.005% (with BAC 0.02%), travoprost 0.004% (with 0.001% polyquad) or tafluprost 0.0015% with/without 0.001% BAC, once a day (9 p.m.) for 4 weeks. Corneal fluorescein staining was evaluated in all groups. After harvest, the corneal tissues were embedded in paraffin and then Hematoxylin-Eosin stain was performed for histopathological examination. Immunofluorescence staining was done against TNF-α, IL-6, HLA DR, pJNK, and pAkt.

Results

In corneal fluorescein staining, severe punctate epithelial keratitis was seen in the groups of 0.02% BAC, 0.02% BAC containing bimatoprost 0.01% and latanoprost 0.005%. The surface desquamation, irregular surface, loss of cell borders, anisocytosis and stromal shrinkage were observed in the groups of BAC-containing eye drops. Moreover, the groups treated with BAC-containing eye drops have high inflammatory markers, significantly decreased cell viability-related signal, pAkt, and higher apoptosis-inducing signal, pJNK, than the control group. On the other hand, travoprost 0.004% and PF tafluprost 0.0015% have less cellular morphologic changes, lower inflammation, and higher cellular viability than BAC-containing formulations.

Conclusions

Corneal damage, increased inflammation and apoptosis and low cell viability were observed in BAC-containing groups. PF or alternatively preserved glaucoma medications seem to be a reasonable and viable alternative to those preserved with BAC.

Effects of Four Formulations of Prostaglandin Analogs on Eye Surface Cells. A Comparative Study

We evaluated the cytotoxic effects of four prostaglandin analogs (PGAs) used to treat glaucoma. First we established primary cultures of conjunctival stromal cells from healthy donors. Then cell cultures were incubated with different concentrations (0, 0.1, 1, 5, 25, 50 and 100%) of commercial formulations of bimatoprost, tafluprost, travoprost and latanoprost for increasing periods (5 and 30 min, 1 h, 6 h and 24 h) and cell survival was assessed with three different methods: WST-1, MTT and calcein/AM-ethidium homodimer-1 assays. Our results showed that all PGAs were associated with a certain level of cell damage, which correlated significantly with the concentration of PGA used, and to a lesser extent with culture time. Tafluprost tended to be less toxic than bimatoprost, travoprost and latanoprost after all culture periods. The results for WST-1, MTT and calcein/AM-ethidium homodimer-1 correlated closely. When the average lethal dose 50 was calculated, we found that the most cytotoxic drug was latanoprost, whereas tafluprost was the most sparing of the ocular surface in vitro. These results indicate the need to design novel PGAs with high effectiveness but free from the cytotoxic effects that we found, or at least to obtain drugs that are functional at low dosages. The fact that the commercial formulation of tafluprost used in this work was preservative-free may support the current tendency to eliminate preservatives from eye drops for clinical use.

Excipients of preservative-free latanoprost induced inflammatory response and cytotoxicity in immortalized human HCE-2 corneal epithelial cells

Various preservative-free eye drop formulations for glaucoma treatment have been marketed intending to decrease ocular surface side effects and improve tolerability. However, preservative-free eye drops including different solubilizers to dissolve the antiglaucoma drugs may induce detrimental effects in the eye. In this study, we exposed human corneal epithelial cells (HCE-2) for 1, 6, 12, 24 and 48 hours to the first preservative-free (PF) tafluprost (Taflotan^®), the recently-launched preservative-free (PF) latanoprost (Monoprost^®), preservative benzalkonium chloride (BAK) and the excipient macrogolglycerol hydroxystearate 40 (MGHS40) using dilutions 0.1%, 0.3%, 1.0%, 3.0% and 10.0% of the original products. The cells also were exposed to undiluted PF tafluprost and PF latanoprost once a day for 9 days. Cellular morphology was examined by light microscopy and cell proliferation by Ki-67 fluorescent staining with cell viability being determined by erythrosine staining and the release of lactate dehydrogenase (LDH). Mitochondrial metabolic activity was evaluated with the colorimetric MTT assay. The secretion of interleukin 6 (IL-6) was measured with ELISA. HCE-2 cells displayed no significant morphological changes after PF tafluprost treatment, but PF latanoprost caused clear cell loss. Moreover, PF latanoprost, BAK and MGHS40 evoked cellular damage and inflammation with increasing concentrations and time. Furthermore, undiluted daily PF latanoprost application significantly increased LDH release and IL-6 secretion as compared to PF tafluprost. MGHS40 was observed to be associated with the toxicity of PF latanoprost. Excipients in ocular drops should receive more attention in the future, since they seem to trigger similar detrimental effects in cells as preservatives.

A 6-month study comparing efficacy, safety, and tolerability of the preservative-free fixed combination of tafluprost 0.0015% and timolol 0.5% versus each of its individual preservative-free components

Introduction

The efficacy, safety and tolerability of the preservative-free (PF) fixed combination (FC) of tafluprost 0.0015% and timolol 0.5% (once daily) were compared to those of the individual components (PF tafluprost 0.0015% once daily and PF timolol 0.5% twice daily) in patients with open-angle glaucoma or ocular hypertension inadequately controlled on prior timolol or prostaglandin monotherapy for 6 months.

Methods

A stratified, double-masked, randomized, multicenter phase III study was conducted. A total of 189 prior timolol users were randomized within the timolol stratum (TS) to receive either FC (n = 95) or timolol 0.5% (TIM; n = 94). Furthermore, a total of 375 prior prostaglandin analog (PGA) users were randomized within the prostaglandin stratum (PS) to receive either FC (n = 188) or tafluprost 0.0015% (TAF; n = 187). To be eligible for participation in the study, the patients were required to have an intraocular pressure (IOP) of ≥22 mmHg when on timolol (TIM) or of ≥20 mmHg when on PGA in either treated eye at the screening and end-of-run-in visits. In addition to these, the study included visits at baseline, 2 and 6 weeks, 3 and 6 months and at a post-study visit. IOP was measured at 8 a.m., 10 a.m., 4 p.m., and 8 p.m.

Results

In the TS, a significant reduction from baseline IOP was seen with FC and TIM throughout the study. Average diurnal IOP change from baseline at month 3 was −8.55 mmHg (32%) for FC and −7.35 mmHg (28%) for TIM. The model-based treatment difference (FC–TIM) was −0.885 mmHg [95% confidence interval (CI) −1.745 to −0.024; p = 0.044] demonstrating the superiority of FC over TIM. In the PS, a significant reduction in IOP was seen with both FC and TAF throughout the study. The average diurnal IOP change from baseline at month 3 was −8.61 mmHg (33%) for FC and −7.23 mmHg (28%) for TAF. The model-based treatment difference (FC–TAF) was −1.516 mmHg (95% CI −2.044 to −0.988; p < 0.001) demonstrating the superiority of FC over TAF. In the TS, related ocular adverse events (AEs) were more frequent for patients treated with FC compared to TIM (16.8% versus 6.4%), whereas related non-ocular AEs were more frequent with TIM compared to FC (2.1% versus 0.0%). In the PS, AEs were similarly distributed between FC and TAF. The frequency of conjunctival hyperemia of FC was low (6.4%).

Conclusion

The preservative-free fixed combination of tafluprost and timolol provided a substantial and significant IOP reduction in both strata. The IOP reduction was superior to both tafluprost 0.0015% and timolol 0.5% when given as monotherapies. Overall, the study treatments were safe and well tolerated.

Funding

Santen Oy, Tampere, Finland.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-014-0163-3) contains supplementary material, which is available to authorized users.

Comparison of the ocular surface changes following the use of two different prostaglandin F2α analogues containing benzalkonium chloride or polyquad in rabbit eyes

OBJECTIVE

The aim of this study is to compare the effect of prostaglandin analogues preserved with either 0.015% or 0.001% benzalkoium chloride (BAK); or 0.001% polyquad (PQ) on the ocular surface of rabbit eyes.

METHODS

Forty white rabbits were randomized to receive four-times daily instillation of either 0.0015% tafluprost (TF) preserved with 0.001% BAK (TF-BAK); 0.004% travoprost (TR) with 0.015% BAK (TR-BAK) or 0.001% PQ (TR-PQ); or preservative-free artificial tears in one eye for a 4-week period. Tear samples collected from the 40 rabbits were analyzed by enzyme-linked immunosorbent assays (ELISA) to identify the presence of inflammatory cytokines: interleukin (IL)-1β and IL-6 on day 14. Subsequently, harvested cornea and bulbar conjunctiva were evaluated using light and transmission electron microscopy (TEM).

RESULTS

IL-6 was significantly increased in TF-BAK and TR-BAK groups compared to controls and TR-PQ group (p = 0.005); however, IL-1β level was not significantly different among four groups (p = 0.360). Rabbits treated with TR-BAK showed decreased goblet cell density of bulbar conjunctiva and increased pyknotic change and vacuolization of corneal epithelial cells on light microscopy; similar change occurred but was less severe in TF-BAK group. The TR-PQ group showed similar results as the controls. The destruction of the microvillar architecture of bulbar conjunctiva and cornea was most prominent in the TR-BAK group.

CONCLUSIONS

Preservatives included in the anti-glaucoma eye-drops showed different ocular surface changes according to the concentration and type in the rabbits. Prostaglandin analogues preserved with higher level of BAK may cause more harmful effects on the ocular surface than PQ-preserved medications.

In vivo laser scanning confocal microscopy of the ocular surface in glaucoma

Over the past decade, knowledge about the ocular surface in glaucoma has significantly increased through the use of in vivo laser scanning confocal microscopy (LSCM). This in vivo imaging method can show modifications at the cellular level induced by anti-glaucoma drugs on ocular surface structures and adnexa in the eye. High-quality images of the conjunctiva, cornea, limbus, meibomian glands, and lymphoid structures during therapy can be obtained. In addition, LSCM opened new fields of research on the patho-physiology of aqueous humor (AH) hydrodynamics in untreated, and in medically or surgically treated glaucomatous patients. In these conditions, an enhancement of the trans-scleral AH outflow contributed to clarification of the mechanism of action of different anti-glaucoma medications and surgical approaches. Finally, the use of LSCM represented a huge advance in evaluation of bleb functionality after filtration surgery, defining the hallmarks of AH filtration through the bleb-wall and distinguishing functional from nonfunctional blebs. Thus, signs seen with LSCM may anticipate clinical failure, guiding the clinician in planning the appropriate timing of the various steps in bleb management. In this review we summarize the current knowledge about in vivo LSCM of the ocular surface in glaucoma.

Bimatoprost 0.01% vs bimatoprost 0.03%: a 12-month prospective trial of clinical and in vivo confocal microscopy in glaucoma patients

PURPOSE

To evaluate the safety of two commercially available formulations of bimatoprost eye drops: 0.03 and 0.01% ophthalmic solutions.

METHODS

This was a randomized, prospective, parallel-group, open-label, cohort study. A total of 60 glaucoma patients (60 eyes) under bimatoprost 0.03% monotherapy since at least 1 year were enrolled. Selected patients were randomized to receive a single drop of bimatoprost 0.01% (n=30) or bimatoprost 0.03% (n=30) ophthalmic solutions for 12 months. Statistical analysis was performed using paired t-test and repeated measures ANOVA test.

RESULTS

Global clinical score (the sum of pruritus, stinging/burning, blurred vision, sticky eye sensation, eye dryness sensation, and foreign body sensation) significantly decreased in the bimatoprost 0.01% group from baseline 4.7 ± 3.8 to 2.9 ± 2.3 (P < 0.001) and 2.5 ± 2.0 (P < 0.001) at 6-month and 12-month follow-ups, respectively. Comparison between groups showed differences at both follow-up visits (P = 0.003 and P < 0.001, respectively). In vivo confocal microscopy revealed a significant increase in goblet cell density in the bimatoprost 0.01% group compared with the bimatoprost 0.03% group (P<0.001 at both follow-up visits). All functional parameters and conjunctival hyperemia improved in the bimatoprost 0.01% group at each follow-up visit (P < 0.05) and in comparison with bimatoprost 0.03% (P < 0.05).

CONCLUSION

The results of this trial suggest that bimatoprost 0.01% eye drops seem to decrease the ocular discomfort with respect to bimatoprost 0.03% eye drops.

Apoptosis in the iris and trabecular meshwork of medically treated and untreated primary open angle glaucoma patients

AIM

To compare the trabecular meshwork (TM) and iris apoptosis of treated and untreated primary open angle glaucoma (POAG) patients.

METHODS

Eight treatment-naive, newly diagnosed (group 1) and 11 medicaly treated (group 2) patients with POAG were included in the study. Each patient underwent a limbus-based trabeculectomy. The TM and peripheral iris specimens were dissected out and were snap-frozen in liquid nitrogen and stored at -80°C until they were assayed. Apoptosis in each group was assesed by TUNEL method.

RESULTS

The mean patient age was 60.6±5.8 years (53-68 years) vs 58.9±8.9 years (47-70 years) in group 1 and group 2 (P=0.859). The mean treatment time in group 2 was 22.2±7.3 months (12-34 months). Apoptotic indexes in TM and iris were significantly higher in POAG patients using medication (group 2) compared to treatment-naive POAG patients (group 1) (P=0.004, 0.015; respectively).

CONCLUSION

Long term administration of topical antiglaucoma medications causes additional toxic effects on TM.

In vitro effects of preservative-free and preserved prostaglandin analogs on primary cultured human conjunctival fibroblast cells

PURPOSE

Long-term use of topical medication is needed for glaucoma treatment. One of the most commonly prescribed classes of hypotensive agents are prostaglandin analogs (PGs) used as both first-line monotherapy; as well as in combination therapy with other hypotensive agents. Several side effects of eye drops can be caused by preservatives. The purpose of this study was to evaluate the effects of PGs with varying concentrations of benzalkonium chloride (BAC), alternative preservatives, or no preservatives on human conjunctival fibroblast cells.

METHODS

Primary human conjunctival fibroblast cells were used in these experiments. Cells were exposed to the following drugs: BAC at different concentrations, bimatoprost 0.01% (with BAC 0.02%), latanoprost 0.005% (with BAC 0.02%), tafluprost 0.0015% with/without 0.001% BAC and travoprost 0.004% (with 0.001% Polyquad) for 15 and 30 minutes. Cell cytotoxicity was evaluated by phase-contrast microscopy to monitor morphological changes of cells, Counting Kit-8 (CCK-8) assay to cell viability, and fluorescent activated cell sorting (FACS) analysis to measure apoptosis.

RESULTS

BAC caused cell shrinkage and detachment from the plate in a dose-dependent manner. Morphological changes were observed in cells treated with bimatoprost 0.01% and latanoprost 0.005%. However, mild cell shrinkage was noted in cells treated with tafluprost 0.0015%, while a non-toxic effect was noted with travoprost 0.004% and preservative-free tafluprost 0.0015%. CCK-8 assay and FACS analysis showed all groups had a significantly decreased cell viability and higher apoptosis rate compared with the control group. However, travoprost 0.004% and preservative-free tafluprost 0.0015% showed lower cytotoxicity and apoptosis rate than other drugs.

CONCLUSIONS

This in vitro study revealed that BAC-induced cytotoxicity is dose-dependent, although it is important to emphasize that the clinical significance of toxicity differences observed among the different PGs formulations has not yet been firmly established. Alternatively preserved or preservative-free glaucoma medications seem to be a reasonable and viable alternative to those preserved with BAC.

Conjunctival goblet cells density and preservative-free tafluprost therapy for glaucoma: an in vivo confocal microscopy and impression cytology study

PURPOSE

To evaluate the density of conjunctival goblet cells (GCs) in glaucomatous patients treated with preservative-free (PF) tafluprost, using laser scanning confocal microscopy (LSCM) and impression cytology (IC).

METHODS

Thirty glaucomatous patients (30 eyes) naive for therapy and thirty healthy subjects (30 eyes) were enrolled. Conjunctiva was examined by means of Heidelberg Retina Tomography/Rostock cornea module. Afterwards, the specimens for IC were obtained. Patients were randomized to PF-tafluprost (Group 1) or preserved latanoprost (Group 2) and controls to the vehicle of latanoprost (Group 3) or physiological buffered saline solution (Group 4). Both LSCM and IC were performed at baseline, and after the 1st and 6th months of therapy, GC density (GCD) (cells/mm(2) ) was the main outcome measurement.

RESULTS

  Baseline. Mean GCD was 240.69 ± 25.43 and 232.65 ± 23.52, for LSCM, and 162.10 ± 23.44 and 164.71 ± 21.03 for IC in Group 1 and 2, respectively. GC density values were not significantly different in Group 3 and 4 (p > 0.05%). Month one. Mean GCD increased to 284.16 ± 43.88 and 230.62 ± 48.32 in Group 1 (p < 0.001) and to 297.86 ± 26.87 and 221.78 ± 43.02 in Group 2 (p < 0.05), measured with LSCM and IC, respectively. In Group 3, GCD decreased to 205.88 ± 25.04 and 139.54 ± 17.37 measured with LSCM and IC, respectively (p < 0.05). Month six. Mean GCD did not change in Group 1 (p > 0.05) whereas it decreased in Group 2 (p < 0.05), compared to month 1. In Group 3, GCD further decreased to 166.32 ± 22.31 and 120.76 ± 11.66, measured with LSCM and IC, respectively (p < 0.05); in Group 4, mean GCD did not change during the study period (p > 0.05).

CONCLUSIONS

Treatment with PF tafluprost was associated with an increase in conjunctival GCD in glaucomatous eyes naïve for therapy. Further studies are mandatory to verify this finding because its validation may have important consequences in the medical management of glaucoma.

Aliphatic β-nitroalcohols for therapeutic corneoscleral cross-linking: corneal permeability considerations

PURPOSE

Our recent tissue cross-linking studies have raised the possibility of using aliphatic β-nitroalcohols (BNAs) for pharmacologic, therapeutic corneal cross-linking. The present study was performed to determine the permeability of BNAs and to explore the use of permeability-enhancing agents.

METHODS

Ex vivo rabbit corneas were mounted in a typical Franz diffusion chamber. BNA permeability was determined by assaying the recipient chamber over time using a modification of the Griess nitrite colorimetric assay. The apparent permeability coefficient (Ptot) was determined for 2 mono-nitroalcohols [2-nitroethanol (2ne) and 2-nitro-1-propanol (2nprop)], a nitrodiol [2-methyl-2-nitro-1,3-propanediol (MNPD)], and a nitrotriol [2-hydroxymethyl-2-nitro-1,3-propanediol (HNPD)]. Permeability-enhancing effects using benzalkonium chloride (BAC) (0.01% and 0.02%), ethylenediaminetetraacetic acid (0.05%), and a combination of 0.01% BAC + 0.5% tetracaine were also studied.

RESULTS

The Ptot (±SE) values (in centimeters per second) were as follows: 4.33 × 10 (±9.82 × 10) for 2ne [molecular weight (MW) = 91 Da], 9.34 × 10 (±2.16 × 10) for 2nprop (MW = 105 Da), 4.37 × 10 (±1.86 × 10) for MNPD (MW = 135 Da), and 8.95 × 10 (±1.93 × 10) for HNPD (MW = 151 Da). Using the nitrodiol, permeability increased approximately 2-fold using 0.01% BAC, 5-fold using 0.02% BAC, and 5-fold using the combination of 0.01% BAC + 0.5% tetracaine. No effect was observed using 0.05% ethylenediaminetetraacetic acid.

CONCLUSIONS

The results indicate that the corneal epithelium is permeable to BNAs, with the apparent permeability corresponding to MW. The findings are consistent with previous literature indicating that the small size of these compounds (<10Å) favors their passage through the corneal epithelium via the paracellular route. This information will help to guide dosing regimens for in vivo topical cross-linking studies.

Preservative-free tafluprost in the treatment of naive patients with glaucoma and ocular hypertension

PURPOSE

The study reported here investigated the efficacy, tolerability, and safety of the preservative-free prostaglandin analog tafluprost 0.0015% in treatment-naive patients.

PATIENTS AND METHODS

Data were collected in two non-interventional, prospective, multicenter, observational, open-label studies of identical design that were conducted in Germany and the Czech Republic. All subjects received preservative-free tafluprost 0.0015% once daily. Intraocular pressure (IOP) levels were recorded for each eye at untreated baseline and 3 months after initiation of medical treatment. The primary outcome was change in mean IOP from baseline to month 3. In the primary open-angle glaucoma (POAG) and ocular hypertension (OH) patient subgroups, analyses were stratified by the level of baseline IOP: ≥20 to 23 mmHg versus ≥24 mmHg. In addition, responder rates and the achievement of pre-specified IOP levels at month 3 were evaluated. Local tolerance of preservative-free tafluprost was evaluated by the patients at final visit. Overall satisfaction with the medical treatment was evaluated by both patients and physicians. All adverse events were recorded.

RESULTS

A total of 579 treatment-naive patients with POAG (n = 349), OH (n = 105), normal tension glaucoma (n = 71), exfoliative glaucoma (n = 27), or other glaucomas (n = 27) were included in this observational study. Mean IOP level at baseline for all patients was 23.6 ± 4.0 mmHg. Mean IOP at month 3 was 16.8 ± 2.9 mmHg (-28.8% vs baseline). At month 3, significant reductions in mean IOP (P < 0.001) were seen in all patients and all subgroups. Preservative-free tafluprost lowered mean IOP significantly in patients with POAG and OH with IOP levels ≥ 20 to 23 mmHg from 21.9 ± 1.1 mmHg at baseline to 16.5 ± 2.2 mmHg, and in the subgroup with IOP levels ≥ 24 mmHg from 26.2 ± 2.4 mmHg to 17.9 ± 2.4 mmHg. In the subgroups of patients with POAG and OH, an IOP response ≥20%, ≥30%, and ≥40% was achieved by 83.4%, 44.1%, and 12.8%, respectively. Overall, patients with higher baseline IOP values showed a better response than patients with lower baseline IOP levels. Preservative-free tafluprost was well tolerated and safe. After 3 months, 97.9% of all patients remained on therapy.

CONCLUSION

In this real-world observational study, treatment with once-daily preservative-free tafluprost proved efficacious, well tolerated, and safe in treatment-naive patients.