Comparison of hypotonic and isotonic solutions containing sodium hyaluronate on the symptomatic treatment of dry eye patients

A comparison between hyaluronic acid and other single ingredient eye drops for dry eye, a review

Dry eye disease (DED) is a highly prevalent and debilitating condition. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan that has a long history as a safe and effective DED treatment. HA is frequently used as a comparator when assessing other topical DED treatments. This study aims to summarise and critically evaluate the literature describing all isolated active ingredients that have been directly compared with HA in the treatment of DED. A literature search was conducted in Embase using Ovid on the 24th of August 2021 and in PubMed including MEDLINE on the 20th of September 2021. Twenty-three studies met the inclusion criteria, 21 of which were randomised controlled trials. Seventeen different ingredients representing six treatment categories were compared with HA treatment. Most measures showed no significant difference between treatments, suggesting either equivalency of treatments or that studies were underpowered. Only two ingredients were represented in more than two studies; carboxymethyl cellulose treatment appears equivalent to HA treatment, while Diquafosol treatment appears superior to HA treatment. Drop-frequency varied from one to eight drops daily. No single study explained the choice of drop frequency. Nine studies used a HA concentration of 0.1% which may be below therapeutic levels. Nine studies reported using preserved formulations, six of them with differences in preservatives between the compared groups. Thirteen studies were financially linked to industry. No major complications were reported. Studies were not designed to find differences in treatment effects for different types or severities of DED. HA is a good comparator treatment when assessing other DED treatments, although consensus after decades of use is still lacking for best choice of concentration, molecular weight and drop tonicity. Well-designed studies are needed to determine an evidence-based standard for HA treatment to be used as comparator.

Hyaluronic acid in the treatment of dry eye disease

Dry eye disease (DED) is a highly prevalent and debilitating condition affecting several hundred million people worldwide. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan commonly used in the treatment of DED. This review aims to critically evaluate the literature on the safety and efficacy of artificial tears containing HA used in DED treatment. Literature searches were conducted in PubMed, including MEDLINE, and in Embase via Ovid with the search term: "(hyaluronic acid OR hyaluronan OR hyaluronate) AND (dry eye OR sicca)". A total of 53 clinical trials are included in this review, including eight placebo-controlled trials. Hyaluronic acid concentrations ranged from 0.1% to 0.4%. Studies lasted up to 3 months. A broad spectrum of DED types and severities was represented in the reviewed literature. No major complications or adverse events were reported. Artificial tears containing 0.1% to 0.4% HA were effective at improving both signs and symptoms of DED. Two major gaps in the literature have been identified: 1. no study investigated the ideal drop frequency for HA-containing eyedrops, and 2. insufficient evidence was presented to recommend any specific HA formulation over another. Future investigations assessing the optimal drop frequency for different concentrations and molecular weights of HA, different drop formulations, including tonicity, and accounting for DED severity and aetiology are essential for an evidence-based, individualized approach to DED treatment.

Development of an osmoprotective microemulsion as a therapeutic platform for ocular surface protection

Self-emulsified osmoprotective ophthalmic microemulsions (O/A) were prepared by combining betaine/leucine, clusterin/oleanolic acid, and hyaluronic acid or Dextran. The microemulsions contained an internal oily phase (1.2%), an external aqueous phase (96.3%), cosolvents (1%), and surfactants (1.5%). Physicochemical characterization and in vivo and in vitro tolerance were analyzed. The formulations' osmoprotective in vitro activity was assayed in a hyperosmolar model in human corneal cells. Average internal phase sizes were 16-26 nm for the microemulsions including Dextran. Addition of hyaluronic acid increased the size range (25-39 nm). Addition of osmoprotectants did not change nanodroplet size. The formulations were isotonic (280-290 mOsm/L) with neutral pH (≈7) and zeta potential (-10 to 0 mV), low surface tension (≈35-40mN·m^-1), and low viscosity (≈1 mPa·s), except for the microemulsions containing hyaluronic acid (≈4-5 mPa·s). SEM and cryo-TEM showed that all formulations exhibited sphere-shaped morphology with good cell tolerance (≈100%) and were stable at 8 °C for 9 months. Osmoprotective formulations were well tolerated in vitro and in vivo, protecting cells from hypertonic stress. We therefore developed stable microemulsions compatible with the ocular surface that could constitute a novel tool for treatment of ophthalmic diseases.

A randomized multicenter clinical evaluation of sequential application of 0.3% and 0.15% hyaluronic acid for treatment of dry eye

PURPOSE

We report the clinical efficacy of sequential applications of 0.3% and 0.15% unpreserved hyaluronic acid (HA) for the treatment of dry eye disease (DED).

STUDY DESIGN

Randomized clinical trial.

METHODS

Patients over 19 years of age with DED level 2 or higher, corneal fluorescein staining (CFS) score > 1, and tear break-up time (TBUT) < 10 s were included. Seventy-six patients were randomly assigned to the 0.15% HA group, 0.3% HA group, or combination group. Each group applied two drops of 0.15% or 0.3% HA, or a single drop of both 0.3% and 0.15% HA. Patients were evaluated using the ocular surface disease index (OSDI), CFS and conjunctival fluorescein stain score, TBUT, and blurring/discomfort after application at baseline, 4 weeks, and 8 weeks.

RESULTS

The combination group had the greatest improvement in CFS score from baseline to 8 weeks, compared with the 0.15% and 0.3% HA group (p < 0.001). The combined CFS-OSDI responder rates of the combination group (CFS score = 0 and OSDI ≥ 50% improvement at 8 weeks) were significantly higher than those of the 0.15% and 0.3% groups (p = 0.037). At 4 and 8 weeks, blurring after application in both the 0.3% and combination groups was significantly higher than in the 0.15% group, despite no difference between the 0.3% and combination groups. There were no differences in CFS and conjunctival staining score, TBUT, or OSDI within the three groups at baseline, 4 weeks, and 8 weeks.

CONCLUSIONS

Sequential application of 0.3% and 0.15% HA improved symptoms/signs in moderate to severe DED patients.

Mono- and Dicationic DABCO/Quinuclidine Composed Nanomaterials for the Loading of Steroidal Drug: 32 Factorial Design and Physicochemical Characterization

Oil-in-water nanoemulsions (NEs) are considered a suitable nanotechnological approach to improve the eye-related bioavailability of lipophilic drugs. The potential of cationic NEs is prominent due to the electrostatic interaction that occurs between the positively charged droplets with the negatively charged mucins present in the tear film. This interaction offers prolonged NEs residence at the ocular surface, increasing the drug absorption. Triamcinolone acetonide (TA) is one of the first pharmacologic strategies applied as an intravitreal injection in the treatment of age-related macular degeneration (AMD). Newly synthesized quaternary derivatives of 1,4-diazabicyclo[2.2.2]octane (DABCO) and quinuclidine surfactants have been screened with the purpose to select the best compound to formulate long-term stable NEs that combine the best physicochemical properties for the loading of TA intended for ocular administration.

Effects of Eye Drops Containing Hyaluronic Acid-Nimesulide Conjugates in a Benzalkonium Chloride-Induced Experimental Dry Eye Rabbit Model

Dry eye syndrome (DES) is a common ocular disease worldwide. Currently, anti-inflammatory agents and immunosuppressive drugs, such as cyclosporine A, have been widely used to treat this chronic condition. However, the multifactorial etiology of DES, poor tolerance, low bioavailability, and prolonged treatment to response time have limited their usage. In this study, nimesulide, a cyclooxygenase (COX)-2 selective inhibitor, was conjugated with hyaluronic acid (HA), and the HA-nimesulide conjugates were expected to increase the solubility and biocompatibility for alleviating the DES in the benzalkonium chloride (BAC)-induced goblet cell-loss dry eye model. The therapeutic efficacy of HA-nimesulide was assessed using fluorescein staining, goblet cell density by conjunctival impression cytology, and histology and immunohistochemistry of corneal tissues. Compared to commercial artificial tears and Restasis®, the HA-nimesulide conjugates could promote goblet cell recovery and enhance the regeneration of the corneal epithelium. Importantly, immunofluorescent staining studies demonstrated that the HA-nimesulide conjugates could decrease the number of infiltrating CD11b-positive cells after two weeks of topical application. In the anti-inflammatory test, the HA-nimesulide conjugates could inhibit the production of pro-inflammatory cytokines and prostaglandin E2 (PGE2) in the lipopolysaccharide (LPS)-stimulated Raw 264.7 cell model. In conclusion, we demonstrated that HA-nimesulide conjugates had anti-inflammatory activity, and promoted goblet cell recovery and corneal epithelium regeneration when used as topical eye drops; accordingly, the HA-nimesulide conjugates could potentially be effective for the treatment of DES.

Formulation Considerations for the Management of Dry Eye Disease

Dry eye disease (DED) is one of the most common ocular surface disorders characterised by a deficiency in quality and/or quantity of the tear fluid. Due to its multifactorial nature involving several inter-related underlying pathologies, it can rapidly accelerate to become a chronic refractory condition. Therefore, several therapeutic interventions are often simultaneously recommended to manage DED efficiently. Typically, artificial tear supplements are the first line of treatment, followed by topical application of medicated eyedrops. However, the bioavailability of topical eyedrops is generally low as the well-developed protective mechanisms of the eye ensure their rapid clearance from the precorneal space, thus limiting ocular penetration of the incorporated drug. Moreover, excipients commonly used in eyedrops can potentially exhibit ocular toxicity and further exacerbate the signs and symptoms of DED. Therefore, formulation development of topical eyedrops is rather challenging. This review highlights the challenges typically faced in eyedrop development, in particular, those intended for the management of DED. Firstly, various artificial tear supplements currently on the market, their mechanisms of action, as well as their application, are discussed. Furthermore, formulation strategies generally used to enhance ocular drug delivery, their advantages and limitations, as well as their application in commercially available DED eyedrops are described.

Physicochemical Properties of Hyaluronic Acid-Based Lubricant Eye Drops

Purpose

To assess the physicochemical properties of hyaluronic acid (HA)-based artificial tears.

Methods

The average molecular weight (MW) and polydispersion index (PDI) of HA in 18 commercially available artificial tears were determined by light scattering/high-performance liquid chromatography. Osmolality, pH, viscosity, and sodium concentration were determined using an osmometer, pH meter, rheometer, and inductively coupled plasma mass spectrometer, respectively.

Results

The MW of HA varied considerably between formulations. The PDI was >2.0 in two formulations (2.28 and 4.94), suggesting the presence of a copolymer and/or HA size variability. Three formulations exhibited viscosity exceeding the blur threshold at different shear rates. Viscosity at low shear rates was generally highest in formulations containing high-MW HA. Correlations were found between observed viscosity and a predictive/calculated value, except for four copolymer-containing formulations, and osmolality (range, 154–335 mOsm/kg) and sodium concentration (range, 22–183 mM), with two exceptions. Compared with organic osmolytes, adding sodium decreased viscosity, particularly at lower shear rates.

Conclusions

In the context of the literature, our findings suggest that for most patients with dry eye disease, the ideal HA-based artificial tear should include high-MW HA with a low PDI and exhibit enhanced viscosity at low shear rate (without exceeding the blur threshold). The inclusion of synergistic copolymers and a low sodium concentration may increase viscosity, but whether any of these physicochemical properties or correlations can predict clinical efficacy will require further investigation.

Translational Relevance

Understanding the properties of HA-based artificial tears will support the development of unique formulations that target specific ocular surface conditions.

Efficacy of eyedrops containing cross-linked hyaluronic acid and coenzyme Q10 in treating patients with mild to moderate dry eye

PURPOSE

Dry eye disease (DED) is a common condition causing substantial burden. A randomized, controlled, single-masked study was performed in 40 patients with mild to moderate DED to evaluate the efficacy and safety of a collyrium based on crosslinked hyaluronic acid (XLHA) with coenzyme Q10 (CoQ10).

METHODS

Enrolled subjects were divided into 2 groups: group A, treated with XLHA + CoQ10; and group B, treated with hyaluronic acid (HA). Eyedrops were administered 4 times daily for 3 months. The Ocular Surface Disease Index (OSDI) questionnaire, tear break-up time (TBUT), corneal and conjunctival staining, and meibomian gland assessment (MGD) were evaluated; furthermore, corneal aesthesiometry, in vivo corneal confocal microscopy, visual acuity, intraocular pressure (IOP), and fundus examination were performed.

RESULTS

At the end of treatment, OSDI score significantly decreased in groups A and B (p<0.01 and p<0.05, respectively); the decrease was significantly higher in group A. Corneal staining decreased in both groups, with lower scores in group A. The MGD was significantly ameliorated in group A patients. No differences were found for corneal aesthesiometry or TBUT. Epithelial cell reflectivity was significantly reduced only in group A. For keratocytes and stromal matrix parameters, there was a significant improvement in group A. No changes were found for visual acuity, IOP, or fundus examination.

CONCLUSIONS

The XLHA + CoQ10 treatment showed greater effectiveness in DED compared to HA alone, probably due to the longer permanency on ocular surface and the antioxidant activity of CoQ10. Therefore, XLHA + CoQ10 eyedrops could represent a new possibility in dry eye treatment.

Novel Artificial Tears Containing Cross-Linked Hyaluronic Acid: An In Vitro Re-Epithelialization Study

Dry eye syndrome is a common disease which can damage the corneal epithelium. It is treated with eye drops to stimulate tear production and hydrate the corneal surface. The most prescribed artificial tear remedies contain hyaluronic acid (HA), which enhances epithelial wound healing, improving tissue health. To the best of our knowledge, only a few recent studies have investigated cross-linked HA (HA-CL) in eye drops for human applications. This work consists in an in vitro evaluation of the re-epithelialization ability of two different preparations containing a recently synthetized HA cross-linked with urea: 0.02% (w/v) HA-CL (solution 1, S1), and 0.4% (w/v) HA-CL (solution 2, S2). The study was conducted on both 2D human corneal cells (HCEpiC) and 3D reconstructed tissues of human corneal epithelium (HCE). Viability by 3(4,5-dimethylthiazol-2)2,5-diphenyltetrazolium bromide (MTT) test, pro-inflammatory cytokine release (interleukin-8, IL-8) by ELISA, and morphology by hematoxylin and eosin (HE) staining were evaluated. In addition, to understand the molecular basis of the re-epithelialization properties, cyclin D1 levels were assessed by western blot. The results showed no cellular toxicity, a slight decrease in IL-8 release, and restoration of epithelium integrity when the wounded 3D model was treated with S1 and S2. In parallel, cyclin D1 levels increased in cells treated with both S1 and S2.

Comparison of 0.3% Hypotonic and Isotonic Sodium Hyaluronate Eye Drops in the Treatment of Experimental Dry Eye

PURPOSE

To compare the efficacy of 0.3% hypotonic and isotonic sodium hyaluronate (SH) eye drops in the treatment of experimental dry eye.

METHODS

Experimental dry eye was established in female C57BL/6 mice by subcutaneous scopolamine injection and an air draft. The mice were divided into three groups (n = 15): control, preservative-free 0.3% isotonic SH, and preservative-free 0.3% hypotonic SH. The tear volume, tear film break-up time, and corneal fluorescein staining scores were measured 5 and 10 days after treatment. After conjunctival tissues were excised at 10 days, the levels of interleukin (IL)-6, IL-17, interferon (IFN)-γ, and IFN-γ inducible protein-10 were determined using the multiplex immunobead assay. In addition, PAS staining and flow cytometry were performed to evaluate the counts of conjunctival goblet cells and CD4+ IFN-γ+ T cells.

RESULTS

Mice treated with 0.3% hypotonic SH showed a significant decrease in corneal staining scores (P = 0.04) and the levels of IL-6 (16.7 ± 1.4 pg/mL, P = 0.02) and IFN-γ (46.5 ± 11.5 pg/mL, P = 0.02) compared to mice treated with 0.3% isotonic SH (IL-6; 32.5 ± 8.8 pg/mL, IFN-γ; 92.0 ± 16.0 pg/mL) at day 10. Although no significant difference in CD4+ IFN-γ+ T cell numbers was observed, goblet cell counts were higher in the hyopotonic SH group than in the isotonic SH group (P = 0.02).

CONCLUSIONS

When compared to 0.3% isotonic SH eye drops, 0.3% hypotonic SH eye drops can be more effective by improving corneal staining scores, decreasing inflammatory molecules, and increasing goblet cell counts for experimental dry eye. These data suggest that hypotonic artificial tears may be useful as an adjunctive treatment for inflammatory dry eye.

Safety and Efficacy of Cortisol Phosphate in Hyaluronic Acid Vehicle in the Treatment of Dry Eye in Sjogren Syndrome

PURPOSE

Evaluation of 0.3% cortisol phosphate eye drops in hyaluronic acid vehicle in the treatment of dry eye in Sjogren Syndrome.

METHODS

This prospective, single-center, masked (single blind), randomized controlled study included 40 female patients divided into 2 groups, group 1 treated with Idracemi, 0.3% cortisol phosphate eye drops twice a day, and group 2 treated with Cortivis, 0.3% cortisol phosphate in hyaluronic acid vehicle, with the same posology. Screening (day -7), randomization (day 0), follow-up (day 7), and termination (day 28) visits were conducted. Symptoms (VAS) questionnaire, tear film breakup time, corneo-conjunctival stain, intraocular pressure (IOP) measurement, and fundus examination were performed at each visit. Conjunctival impression cytology for human leukocyte antigen-DR (HLA-DR) expression at visit 1 and 4 was also performed.

RESULTS

No changes in IOP or fundus examination were observed in either group at each time point. Group 1 showed at day 28 a statistically significant amelioration of symptoms and reduction of HLA-DR expression. Group 2 showed at day 7 statistically significant improvement of corneal and conjunctival stain versus baseline and versus group 1; the symptom score was statistically significantly better than baseline and versus group 1 after 28 days too. The HLA-DR expression and the epithelial cell area were statistically significantly reduced versus baseline and versus group 1 at the same time.

CONCLUSIONS

Cortisol phosphate proved to be safe and effective in treating dry eye in Sjogren Syndrome patients in both formulations. However, the formula with hyaluronic acid vehicle proved to be more effective. Both formulations were very well tolerated.

Cationic Thiolated Poly(aspartamide) Polymer as a Potential Excipient for Artificial Tear Formulations

Dry eye disease is a relatively common ocular problem, which causes eye discomfort and visual disorders leading to a decrease in the quality of life. The aim of this study was to find a possible excipient for eye drop formulations, which is able to stabilize the tear film. A cationic thiolated polyaspartamide polymer, poly[(N-mercaptoethylaspartamide)-co-(N-(N′,N′-dimethylaminoethyl)aspartamide)] (ThioPASP-DME), was used as a potential vehicle. Besides satisfying the basic requirements, the chemical structure of ThioPASP-DME is similar to those of ocular mucins as it is a protein-like polymer bearing a considerable number of thiol groups. The solution of the polymer is therefore able to mimic the physiological properties of the mucins and it can interact with the mucus layer via disulphide bond formation. The resultant mucoadhesion provides a prolonged residence time and ensures protective effect for the corneal/conjunctival epithelium. ThioPASP-DME also has an antioxidant effect due to the presence of the thiol groups. The applicability of ThioPASP-DME as a potential excipient in eye drops was determined by means of ocular compatibility tests and through examinations of the interactions with the mucosal surface. The results indicate that ThioPASP-DME can serve as a potential eye drop excipient for the therapy of dry eye disease.

Osmolarity of prevalent eye drops, side effects, and therapeutic approaches

PURPOSE

Little is known about how the osmolarity of ophthalmic formulations affects the ocular surface. Because hyperosmolar eye drops could be therapeutic for treating corneal edema, this article presents an ex vivo model of corneal edema for testing ophthalmic drugs based on their osmolarity. The respective osmolarity of common eye drops found in the German market is also analyzed here.

METHODS

For modeling corneal edema, an Ex Vivo Eye Irritation Test was used to simulate an ocular anterior chamber with a physiological corneal barrier. To induce corneal edema, the anterior chamber was supplied with a hypoosmolar medium (148 mOsm/L) for 24 hours. Preserved and preservative-free 5% sodium chloride (hyperosmolar Omnisorb and Ocusalin 5% UD) were used for 1 hour, on 5 corneas each, to test their efficiency to reduce corneal edema in this model. Corneal thickness was determined by optical coherence tomography. Osmolarity of 87 common eye drops was measured by freezing point osmometry.

RESULTS

Ex vivo, the tested hypoosmolar condition induced corneal edema from 450 μm (±50 μm) at baseline to 851 μm (±94 μm, P < 0.0001). Omnisorb and Ocusalin 5% UD significantly reduced the corneal thickness by 279 μm (±28 μm, P < 0.001) for Omnisorb and 258 μm (±29 μm, P < 0.001) for Ocusalin 5% UD. Forty-three (49%) of the tested products had an osmolarity below and 44 (51%) above the physiological tear osmolarity of 289 mOsm/L. Osmolarity values of less than 200 mOsm/L were found in lubricant drops. The highest osmolarity was detected in Omnisorb (1955 mOsm/L).

CONCLUSIONS

The Ex Vivo Eye Irritation Test has proven to be a reliable novel model of corneal edema for evaluating osmotic eye drops. Osmolarity measurements revealed a wide range from hypotonic to hypertonic formulations for commonly marketed ophthalmic drugs.

Viscoelastic interactions between polydeoxyribonucleotide and ophthalmic excipients

This study investigated the interaction between polydeoxyribonucleotide (PDRN) and several ionic and nonionic isotonic agents, thickeners and a preservative that were employed as excipients in ophthalmic preparations. Interaction of each individual excipient and PDRN aqueous solution was evaluated by analyzing their rheological properties. Rheological properties of PDRN solutions were evaluated by dynamic oscillatory shear tests and values of elastic modulus (G'), viscous modulus (G″) and loss tangent (tan δ) were used to assess the relative changes in viscoelastic properties. At given concentrations, sodium chloride was found to show alteration in viscoelastic properties of PDRN solution while nonionic isotonic agents like d-glucose and d-sorbitol did not alter them. Similarly, nonionic water soluble polymers like polyvinylpyrrolidone (PVP) and hydroxypropyl methylcellulose (HPMC) also did not interact with PDRN to alter the viscoelastic properties. However, there were changes observed when carbopol 940 was used as a thickener. Therefore, PDRN was found to interact with ionic excipients and the interactions were negligible when nonionic materials were examined, which suggests that nonionic excipients are suitable to be formulated with PDRN.

Efficacy of hypotonic 0.18% sodium hyaluronate eye drops in patients with dry eye disease

PURPOSE

The aim of this study was to evaluate the efficacy of hypotonic 0.18% sodium hyaluronate (SH) eye drops under the clinical settings of the dry eye workshop treatment guideline for mild dry eye disease (DED).

METHODS

This analysis included 60 patients with DED. Patients with level 1 DED were treated with either isotonic 0.1% SH (group 1) or with hypotonic 0.18% SH eye drops (group 2). Patients with level 2 DED were treated with 0.1% fluorometholone, 0.05% cyclosporine A, and either isotonic 0.1% SH (group 3) or hypotonic 0.18% SH (group 4) eye drops. Tear film breakup time (TBUT), Schirmer test, corneal staining with fluorescein, and ocular surface disease index score were recorded at baseline, 1 month, and 3 months after treatment.

RESULTS

In group 2, TBUT at 3 months (P = 0.03) and corneal staining scores at 1 and 3 months (P ≤ 0.03) were significantly improved after the treatment compared with baseline scores, whereas these parameters were not changed during the follow-up period in group 1. In groups 3 and 4, TBUT and corneal staining scores at 1 and 3 months, and ocular surface disease index score and Schirmer test results at 3 months after the treatment showed significant improvements compared with the baseline score (P < 0.05). Group 4 patients showed an extended TBUT and an improved corneal staining score (P ≤ 0.01) at 3 months after treatment, compared with the values of group 3.

CONCLUSIONS

Hypotonic 0.18% SH eye drops seemed to be effective in improving tear film stability and ocular surface integrity compared with isotonic 0.1% SH eye drops in patients with mild DED.

Use of preservative-free hyaluronic acid (Hylabak(®)) for a range of patients with dry eye syndrome: experience in Russia

Artificial tear preparations are important in the management of dry eye syndrome. We present the findings from four recently published studies conducted in Russia assessing Hylabak(®) (marketed as Hyabak(®) in Europe), a preservative-free hyaluronic acid preparation, for the treatment of dry eye syndrome. All studies had an open, noncomparative design, but one compared the findings with those from 25 patients treated with Tear Naturale(®) in previous studies. A total of 134 children and adults were enrolled, and the etiologies of dry eye syndrome included contact lens use, intensive office work, adenovirus eye infection, postmenopausal status, persistent meibomian blepharitis, Sjögren's syndrome, phacoemulsification with intraocular lens implantation, and refractive surgery. The patients were treated with Hylabak for 2 weeks to 2 months. All studies showed that Hylabak resulted in marked improvement as assessed by subjective sensations/complaints, Schirmer's test, Norn's test, impression cytology and biomicroscopy, staining, and tear osmolarity. Greater benefits were also reported compared with Tear Naturale, including a faster onset of action. Hylabak was well tolerated. In conclusion, Hylabak provided rapid and safe relief from the signs and symptoms of dry eye syndrome, as well as improvement in objective measures, in a wide range of patients.

Effects of amino acids enriched tears substitutes on the cornea of patients with dysfunctional tear syndrome

PURPOSE

To evaluate the effect of aminoacid enriched artificial tears on the ocular surface of patients with dysfunctional tear syndrome (DTS).

METHODS

Forty patients were divided into two groups: group 1 treated for 90 days with sodium hyaluronate (SH) 0.15% 1 drop × 5 times/day; group 2 treated for 90 days with SH 0.15% + aminoacids mixture 1 drop × 5 times/day. Symptom score questionnaire, tear break-up time (TBUT), corneal fluorescein stain, Shirmer's I test and confocal microscopy were performed at baseline and after 30 and 90 days. Confocal images underwent morphometric analysis.

RESULTS

Both treatments improved symptoms after 1 month. Group 2 patients showed at 1 month an improvement of TBUT and corneal stain, maintained throughout the study. Also Shirmer's I test improved after 3 months. In group 1, an improvement of TBUT and corneal stain was observed after 3 months. The morphometric analysis of confocal images demonstrated at month 1 an improvement of nerve tortuosity in group 2; after 3 months both groups showed a significant improvement versus baseline. The epithelium showed, in both groups, a reduction in hyperreflective large cells starting from 1 month; the area of the cells was significantly reduced after 3 months, with a significant higher reduction in group 2. The perineural stromal opacity was significantly increased after 3 months, particularly in group 2.

CONCLUSION

This is the first study addressing corneal changes after amino acids administration in a DTS population. The treatment with amino acids enriched SH can be considered a useful tool in the treatment of DTS.

Role of hyperosmolarity in the pathogenesis and management of dry eye disease: proceedings of the OCEAN group meeting

Dry eye disease (DED), a multifactorial disease of the tears and ocular surface, is common and has a significant impact on quality of life. Reduced aqueous tear flow and/or increased evaporation of the aqueous tear phase leads to tear hyperosmolarity, a key step in the vicious circle of DED pathology. Tear hyperosmolarity gives rise to morphological changes such as apoptosis of cells of the conjunctiva and cornea, and triggers inflammatory cascades that contribute to further cell death, including loss of mucin-producing goblet cells. This exacerbates tear film instability and drives the cycle of events that perpetuate the condition. Traditional approaches to counteracting tear hyperosmolarity in DED include use of hypotonic tear substitutes, which have relatively short persistence in the eye. More recent attempts to counteract tear hyperosmolarity in DED have included osmoprotectants, small organic molecules that are used in many cell types throughout the natural world to restore cell volume and stabilize protein function, allowing adaptation to hyperosmolarity. There is now an expanding pool of clinical data on the efficacy of DED therapies that include osmoprotectants such as erythritol, taurine, trehalose and L-carnitine. Osmoprotectants in DED may directly protect cells against hyperosmolarity and thereby promote exit from the vicious circle of DED physiopathology.

Cytoprotective effect of hyaluronic acid and hydroxypropyl methylcellulose against DNA damage induced by thimerosal in Chang conjunctival cells

BACKGROUND

To investigate genotoxicity of the preservative thimerosal (Thi), and the cytoprotective and antioxidant effects of hyaluronic Acid (HA) and hydroxypropyl methylcellulose (HPMC) on Chang conjunctival cells.

METHOD

Cells were divided into three groups. One group was exposed to Thi at various concentrations (0.00001 %∼0.001 %) for 30 min; the other two groups were pretreated with 0.3 % HA or 0.3 % HPMC for 30 min before the Thi exposure. After cell viability was evaluated, alkaline comet assay and detection of the phosphorylated form of the histone variant H2AX (γH2AX) foci were used to determine DNA damage. Reactive oxygen species (ROS) production was assessed by the fluorescent probe, 2', 7'-dichlorodihydrofluorescein diacetate (DCFH-DA).

RESULTS

A significant change of cell viability was observed after exposure to 0.001 % Thi for 30 min. DNA single- and double-strand breaks were significantly increased in a dose-dependent manner with Thi exposure. In addition, intracellular ROS induced by Thi was dose-dependent, except at 0.001 % less ROS was induced than at 0.0005 %. However, cells pretreated with 0.3 % HA or 0.3 % HPMC showed significantly increased cell survival, decreased DNA damage, and decreased ROS production compared to cells exposed to Thi alone. Pretreatment with 0.3 % HA was found to be even more protective than 0.3 % HPMC.

CONCLUSION

Thi can induce DNA damage in human conjunctival epithelial cells, probably due to oxidative stress. HA and HPMC are protective agents that have antioxidant properties and can decrease DNA damage induced by Thi. Pretreatment of 0.3 % HA may be more protective of the ocular surface than 0.3 % HPMC.

TRPV1 activation is required for hypertonicity-stimulated inflammatory cytokine release in human corneal epithelial cells

PURPOSE

To determine whether hypertonic stress promotes increases in inflammatory cytokine release through transient receptor potential vanilloid channel type 1 (TRPV1) signaling pathway activation in human corneal epithelial cells (HCECs).

METHODS

Hyperosmotic medium was prepared by supplementing isotonic Ringers solution with sucrose. Ca2+ signaling was measured in fura2-AM-loaded HCECs using a single-cell fluorescence imaging system. Western blot analysis evaluated the phosphorylation status of EGFR, ERK, p38 MAPK, and nuclear factor (NF)-κB. ELISA assessed the effect of TRPV1 activation on the release of IL-6 and IL-8.

RESULTS

A 450 mOsm hypertonic stress elicited 2-fold Ca2+ transients that were suppressed by the TRPV1-selective antagonists capsazepine and JYL 1421. Such transients were enhanced by PGE2. Hypertonicity-induced EGF receptor (EGFR) transactivation was suppressed by preincubating HCECs with capsazepine, matrix metalloproteinase 1 (MMP1) inhibitor TIMP-1, broad-spectrum MMP inhibitor GM 6001, heparin-bound (HB)-EGF inhibitor CRM 197, or EGFR inhibitor AG 1478. ERK and p38 MAPK and NF-κB activation after EGFR transactivation occurred in tonicity and in a time-dependent manner. Hypertonicity-induced increases in IL-6 and IL-8 releases were suppressed by exposure to capsazepine, AG 1478, ERK inhibitor PD 98059, p38 inhibitor SB 203580, or NF-κB inhibitor PDTC.

CONCLUSIONS

Hypertonic stress-elicited TRPV1 channel stimulation mediates increases in a proinflammatory cytokine IL-6 and a chemoattractant IL-8 by eliciting EGFR transactivation, MAPK, and NF-κB activation. Selective drug modulation of either TRPV1 activity or its signaling mediators may yield a novel approach to suppressing inflammatory responses occurring in dry eye syndrome.

Comparative studies of various hyaluronic acids produced by microbial fermentation for potential topical ophthalmic applications

This work presents a comparative study of various hyaluronic acids (HA) produced by fermentation of either Bacillus subtilis or Streptococcus towards the selection of an optimal molecular weight (MW) HA for the preparation of topical ophthalmic formulations. The influence of HA MW on water binding capacity, sterile filtration, rheological properties, precorneal residence time and ocular tolerance of ophthalmic solutions was investigated. Molecular weight did not affect hydration of hyaluronic acid according to differential scanning calorimetry (DSC). In general, medium MW HA (0.6-1 MDa) resulted in solutions that were superior in terms of sterile filtration and kinematic viscosity requirements compared to high MW HA (>1 MDa). Moreover, all HA-based solutions exhibited well-defined viscoelastic properties that depend on MW. Gamma scintigraphic data indicated that HA MW at 0.1% concentration (w/v) and HA origin did not significantly affect the corneal residence time on rabbit eyes. A 0.3% solution of high MW HA had a prolonged residence time in the precorneal area compared to a medium MW HA at the same concentration. Finally, an in vivo ocular irritation test based on confocal laser scanning ophthalmoscopy (CLSO) conclusively showed the excellent tolerance of both Bacillus-derived HA and Streptococcus-derived HA after topical instillation onto the corneal surface. Overall, this comprehensive work highlights the superiority of medium MW hyaluronic acid for topical ophthalmic formulations based on their physico-chemical and biological properties, tolerance and handling. Such solutions are expected to enhance tear film stability, to allow for maximum comfort, and to exhibit high residence times, while being biocompatible and easy to sterile filter.

Efficacy of different dry eye treatments with artificial tears or ocular lubricants: a systematic review

PURPOSE

To objectively review the outcome of clinical studies where rose bengal stain (RB) has been used as an outcome measure to assess the efficacy of artificial tears (AT) in patients with dry eye.

METHODS

From peer-reviewed articles published between 1947 and 2008, information was sought on dry eye status, as reported using a grading scheme, after use of RB as a diagnostic test, before and after use of a specific regimen of artificial tears or ocular lubricants for approximately 30 days. Mean baseline scores and post-treatment scores were calculated, along with the net change and the percentage change in the RB scores.

RESULTS

From a total of 33 suitable data sets, published between 1985 and 2006, the group mean pre-treatment RB score was 4.25 +/- 1.55 (+/-S.D.), which decreased to 2.84 +/- 1.24 after 30 days of treatment. This represented a net change of -1.43 (95% CI of -1.04 to -1.45). For use of traditional AT (saline, hypromellose, etc), the net change was -0.95, it was -1.33 for use of carbomer (polyacrylic acid) gels and -2.10 for hyaluronic acid (HA) products. These changes represented net improvements of 25.9 +/- 18.4%, 38.0 +/- 20.7% and 41.8 +/- 16.3% respectively. The greater change with HA was not associated with a lower final outcome score, but with higher pre-treatment scores.

CONCLUSIONS

Based on RB grading schemes used by numerous different clinicians over many years, treatment of dry eye with artificial tears or ocular lubricants can be expected to improve the condition of the exposed ocular surface. Assuming no improvement without treatment, a 30 days treatment period can be projected to produce an overall improvement of around 25%, but with no unambiguous statistical differences between product types.

Tear Dynamics Model

PURPOSE

Quantitative understanding of tear dynamics may help in developing better ophthalmic drug delivery vehicles and dry eye treatments. This paper attempts to develop a comprehensive model that can predict the effect of physiological parameters on various issues related to tear dynamics.

METHODS

The model is based on mass balances of water and solutes such as glucose, sodium, potassium, and chloride. The mass balances require models for the drainage of fluid through the canaliculi and the transport of tears and solutes through the conjunctiva. The model parameters are obtained by simulating Ussing-chamber experiments. The differential equations for the unsteady balances are solved numerically.

RESULTS

The model predicts that under normal conditions, the tear volume, tear osmolarity and potential are 7.1 microl, 297.6 mM, and -15.1 mV, respectively. The model also predicts that the conjunctiva is secretory and contributes about 25% of the total tear production. We also predict the effect of evaporation on tear physiology and show that an increase in evaporation increases osmolarity, reduces tear volume, and increases conjuctival secretion. Additionally, the new tear dynamics model helps assess the effect of osmolarity of the instilled drops, insertion of punctum plugs and use of moisture chamber as treatments for dry eyes. Furthermore, the model is used to predict the effect of modulation of specific transport pathways, which is proposed as a potential remedy for dry eyes, on conjuctival secretion and total tear volume.

CONCLUSIONS

Most of the predicted results agree with the reported experimental results, at least qualitatively. However, some predictions disagree with experiments suggesting that further improvements in the model are needed. The model developed in this paper can improve our understanding of tear dynamics and also serve as a tool to evaluate the efficacy of various modalities at treating dry eyes.

Short term effects of topical cyclosporine and viscoelastic on the ocular surfaces in patients with dry eye

Purpose

To compare the short term effects of topical 0.05% cyclosporine (CsA) and a mixture of 0.08% chondroitin sulfate and 0.06% sodium hyaluronate (CS-HA) on dry eye ocular surfaces.

Methods

36 patients with moderate to severe dry eye (5 mm/5 min or less with Schirmer's test or tear break up time (BUT) less than 6 seconds), were treated with topical application of CS-HA on one eye and CsA on the other 4 times a day for 6-8 weeks. BUT, Schirmer's test without anesthesia, and conjunctival impression cytology (CIC; goblet cell density, nucleus to cytoplasmic ratio, and epithelial cell morphology) were evaluated and compared between eyes before and after treatment (repeated measurement of ANOVA).

Results

After treatment, BUT and tear wettings were significantly prolonged in each group. Topical CsA treated eyes had greater increase in BUT (p=0.026); there was no significant difference in tear wetting (p=0.132). While the 3 parameters of CIC improved in both groups, goblet cell density was significantly higher in eyes treated with CsA (p=0.033).

Conclusions

While both CS-HA and 0.05% CsA eyedrops improve ocular surfaces, topical CsA may have a better effect on enhancing tear film stability and goblet cell density.

Formulation considerations of intranasal corticosteroids for the treatment of allergic rhinitis

OBJECTIVE

To examine how various aspects of an intranasal corticosteroid (INS) formulation may influence the efficacy, tolerability, and patient preference and adherence to INS therapy.

DATA SOURCES

A PubMed search of the literature was conducted for studies on allergic rhinitis published between January 1977 and January 2006 using the keywords intranasal corticosteroid, preservatives, benzalkonium chloride, and tonicity.

STUDY SELECTION

Prospective studies, retrospective studies, and case reports were selected for inclusion in this review.

RESULTS

Currently available INSs are effective first-line treatments for allergic rhinitis. Differences in patient preference for a particular INS are largely attributable to sensory attributes of the nasal spray, which arise from characteristics of the formulation. Additives and preservatives can cause tolerability issues by irritating the mucosal membranes and causing nasal drying, or they can confer an unpleasant odor or taste to an INS formulation. The relative osmotic pressure, or tonicity, of an INS can modulate nasal absorption and retention, thereby potentially influencing the clinical efficacy. Characteristics such as delivery device and spray volume can affect a patient's perception and experience with a particular INS. Newer INSs, such as ciclesonide, are in development for the treatment of allergic rhinitis, and consideration of the formulation characteristics of these agents is an important part of the development process.

CONCLUSIONS

INSs are an effective treatment option for patients with allergic rhinitis; however, there is room for formulation improvement. Optimization of formulation may increase the efficacy, tolerability, and patient preference and adherence to INSs.

Correlation between dry eye and rheumatoid arthritis activity

PURPOSE

To evaluate the incidence of dry eye in rheumatoid arthritis (RA) patients with or without Sjögren syndrome (SS), and to investigate the correlation between dry eye and RA activity.

DESIGN

Prospective case-control study.

METHODS

In 72 RA patients, the severity of dry eye was assessed by the Schirmer test, tear break-up time, rose bengal staining, and fluorescein staining. The RA activity was evaluated by the Lansbury index (LI), which is based on the duration of morning stiffness, erythrocyte sedimentation rate (ESR), grip strength, and joint score.

RESULTS

Ten percent of patients met the Japanese criteria for SS. No difference in dry eye tests or LI was observed between SS patients and non-SS patients. Even in the non-SS group, 90% of patients were diagnosed with probable dry eye. In SS patients, positive correlations were observed between LI and Schirmer test (P = .048), ESR and Schirmer test (P = .035), ESR and rose bengal staining (P = .001), and grip strength and rose bengal staining (P = .047). No such correlations were observed in the non-SS patients.

CONCLUSIONS

Dry eye is common in RA patients, including those without SS. We found that there was a correlation between LI and Schirmer test in RA patients with SS, but no correlation when the entire group was analyzed. Dry eye always should be taken into consideration regardless of the RA activity, because the severity of dry eye is independent of RA activity.

Effectiveness of sodium hyaluronate eyedrops in the treatment of dry eye

BACKGROUND

Dry eye is a common condition, affecting approximately 10-20% of the adult population. Artificial tears are often effective in relieving symptoms in mild and moderate dry eye by replenishing deficient tear volume. Sodium hyaluronate has been proposed as a component in artificial tears, due to its viscoelastic rheology. This paper reports on a study carried out to assess the efficacy of two recently developed eyedrops containing 0.1% and 0.3% sodium hyaluronate (SH) in the treatment of moderate dry eye.

METHODS

Thirteen subjects were recruited with moderate dry eye. Forty microlitres of 0.1% SH, 0.3% SH, or 0.9% saline were instilled in both eyes, and the subjects' symptom intensity and non-invasive break-up time (NIBUT) were measured at 5, 15, 30, 45, and 60 min, and then hourly, until 6 h after drop instillation. This was repeated twice following an interval of 7(+/-1) days, but with a different treatment so that at the end of the final visit each subject had trialled all products. Drop allocation was randomized and double-masked.

RESULTS

Both symptoms and NIBUT improved with all treatments. These changes were of a larger magnitude and longer duration with the SH containing eyedrops than with saline. SH of 0.3% tended to perform better than 0.1% SH and achieved statistical significance (P=0.04) for NIBUT when considered over the whole 6-h study period.

CONCLUSIONS

Sodium hyaluronate of 0.1% and 0.3% reduces symptoms of ocular irritation and lengthens NIBUT in subjects with moderate dry eye more effectively than saline, in terms of peak effect and duration of action.

A convenient rabbit model of ocular epithelium damage induced by osmotic dehydration

Dry eye is an ocular disease clinically associated with corneal epithelium damage and arises acutely or chronically from dehydration of the ocular surface. We provide herein a novel in vivo model of corneal epithelium damage, in which the corneal surface was entirely covered with a sugar powder to provoke the rapid removal of corneal surface liquid. In this animal model, such corneal damage as can be fluorometrically detected was observed immediately after 20-minute hyperosmotic treatment, reached a maximum 6 hours later, and then gradually declined to complete recovery at Hour 126. Recovery of the damaged corneas produced by hyperosmotic stress was significantly accelerated by treatment with 0.1% sodium hyaluronate, a dry eye remedy in Japan. Thinning or partial erosion of the epithelial cell layers was histopathologically demonstrated in and around the sugar powder-applied area but the posterior stromal cell layer remained intact, indicating that the present rabbit in vivo model may be used to conveniently screen therapeutics against acute ocular diseases with corneal epithelium damage. In addition, microscopic observations of TUNEL-stained thin-sections of the damaged corneas indicated that apoptotic cell death, but not any inflammatory reactions, may be at least partially responsible for the hyperosmolarity-induced destruction of the corneal epithelium.

Sodium hyaluronate eye drops of different osmolarity for the treatment of dry eye in Sjögren's syndrome patients

AIM

To study the effect of the treatment of dry eye in Sjögren's syndrome patients with hypotonic or isotonic hyaluronate eye drops.

METHODS

40 Sjögren's syndrome patients were divided in two groups and treated as follows: group 1 with hypotonic (150 mOsm/l) 0.4% hyaluronate eye drops; group 2 with isotonic 0.4% hyaluronate eye drops. The eye drops were instilled six times a day for 90 days. Grading of subjective symptoms, break up time (BUT), corneal fluorescein staining, conjunctival rose bengal staining, Schirmer's I test, and conjunctival impression cytology were carried out at 0 and 15, 30, 90 days from the beginning of the study. Patients were examined in a blind fashion. For the statistical analysis the Student's t test, Mann-Whitney U test, and chi(2) test were performed.

RESULTS

Symptoms were statistically significantly improved at day 15 in both groups but group 1 patients had a global score statistically significantly better group 2 (p=0.02). At day 15 group 1 patients had an improvement from baseline values of BUT (p=0.003), fluorescein, and rose bengal score (p=0.000001 and p=0.0004 respectively). Group 2 patients had, at day 15, an improvement of BUT and fluorescein score compared to baseline values (p=0.05 and p=0.0001 respectively). A comparison between the two groups showed better results for group 1 patients at day 15 for rose bengal stain (p=0.01) and for BUT (p=0.05) and fluorescein score (p=0.0003) at day 90. The conjunctival impression cytology showed that group 1 had a statistically significant better total score than group 2 starting from day 15 and lasting throughout the study (p<0.02). Also group 2 patients showed an improvement from baseline values starting from day 30 (p=0.000005).

CONCLUSION

Hyaluronate eye drops are useful for treating severe dry eye in Sjögren's syndrome patients. The use of a formulation with pronounced hypotonicity showed better effects on corneoconjunctival epithelium than the isotonic solution.

Long term treatment with sodium hyaluronate-containing artificial tears reduces ocular surface damage in patients with dry eye

BACKGROUND/AIMS

Several studies have reported that sodium hyaluronate is able to improve both symptoms and signs in patients with dry eye but none have demonstrated an improvement of conjunctival epithelial cell abnormalities of the ocular surface. The aim of this study was to explore the effect of sodium hyaluronate-containing eye drops on the ocular surface of patients with dry eye during long term treatment.

METHODS

A randomised double blind study was undertaken in 86 patients with medium to severe dry eye (that is, rose bengal and/or fluorescein test score of at least 3, tear film break up time <10 seconds, or Schirmer's test <5.5 mm). Patients were treated with either preservative-free sodium hyaluronate or saline for 3 months at a dose of one drop 4-8 times a day. Bulbar impression cytology, slit lamp examinations, and subjective symptoms were evaluated after 1, 2, and 3 months. Impression cytology was considered the primary efficacy parameter of the study.

RESULTS

The efficacy analysis was performed on a total of 44 patients who were able to fully adhere to the protocol. After 3 months of treatment sodium hyaluronate improved impression cytology score (p = 0.024 v baseline). At the same time also the difference with respect to placebo was statistically significant (p = 0.036). Study medication was well tolerated and no treatment related adverse events occurred during the study.

CONCLUSIONS

Sodium hyaluronate may effectively improve ocular surface damage associated with dry eye syndrome.