A randomized crossover study comparing trehalose/hyaluronate eyedrops and standard treatment: patient satisfaction in the treatment of dry eye syndrome

Artificial Tears: A Systematic Review

Artificial tears are the mainstay of dry eye disease management, but also have a role in corneal abrasion and wound healing, pain and inflammation management, conjunctivitis, keratitis, contact lens rewetting and removal, and foreign body removal. A systematic review of randomized controlled trials (PROSPERO registration CRD42022369619) comparing the efficacy of artificial tears in patients with dry eye to inform prescribing choices using Web of Science, PubMed and Medline databases identified 64 relevant articles. There is good evidence that artificial tears improve symptoms of dry eye disease within a month of regular use, applied about four times a day, but signs generally take several months to improve. Not all patients with dry eye disease benefit from artificial tears, so if there is no benefit over a month, alternative management should be considered. Combination formulations are more effective than single active ingredient artificial tears. Artificial tears containing polyethylene glycol are more effective than those containing carboxymethylcellulose/carmellose sodium and hydroxypropyl methylcellulose. Those classified as having evaporative dry eye disease, benefit from artificial tears with liposomes, especially of higher concentration. The data available is limited by the definition of dry eye disease applied in published studies being variable, as well as the disease severity examined and compliance with artificial tears being rarely quantified.

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.

Use of Artificial Tears in Patients Undergoing Treatment with Anti-VEGF Intravitreal Injections

Purpose

To analyze the use of artificial tears in patients undergoing treatment with anti-vascular endothelial growth (anti-VEGF) intravitreal injections.

Methods

Thirty-four eyes undergoing anti-VEGF treatment were analyzed. Each patient underwent a subjective and objective evaluation of the ocular surface, using the Ocular Surface Disease Index (OSDI), Dry Eye Questionnaire (DEQ)-5, tear meniscus height (TMH), first and average non-invasive Keratograph Break-Up Time (NIKBUT), bulbar conjunctival redness, meibography and the Vision Break-Up Time (VBUT). Patients attended 5 visits (days 0, 7, 30, 37, and 60). All patients continued with their intravitreal injection treatment during the study (days 0, 30, and 60). Patients did not receive any artificial tear treatment during the first month of the study, and at the baseline visit they were randomly assigned to one of two study groups to receive either the Systane Hydration or the Viscofresh 10mg/mL formulation. Patients were instructed to instill one drop of the assigned study treatment 3 times a day for 30 days during the second month of the study.

Results

According to the Mixed Models for Repeated Measures analysis, there is not enough statistical evidence for any of the parameters examined to determine significant differences between being treated with artificial tears and not being treated (p > 0.05). There is, however, a tendency toward improved outcomes in some parameters when artificial tears were used. OSDI, DEQ-5, TMH, and meibography were not affected by either the type of artificial tear used or by the time (from day 30 to day 60; p > 0.05), but the NIKBUT and VBUT values increased over time during this period regardless of which treatment the patient was receiving.

Conclusion

The use of artificial tears may help to keep the tear film stable Future studies with larger samples should be conducted to elucidate whether the tendency reported in our study becomes significant.

Clinical Efficacy, Tolerability and Safety of a New Multiple-Action Eyedrop in Subjects with Moderate to Severe Dry Eye

Background: To assess the clinical efficacy, tolerability and safety of a new-generation ophthalmic solution containing cross-linked hyaluronic acid 0.15% trehalose 3%, liposomes 1% and sterylamine 0.25% (Trimix® Off Health Italia, Firenze, Italy) (CXHAL) versus trehalose 3% (Thealoz®, Thea Pharmaceuticals, Clermont-Ferrand, France) (TRS) in subjects with moderate to severe dry eye disease (DED). Patients and methods: In this prospective, observational cohort study, 41 subjects with moderate to severe dry eye were enrolled and divided into two age- and sex-matched groups. Group 1 was treated with CXHA eye drops, and group 2 was treated with TRS eye drops four times daily for 2 months. All subjects were evaluated at baseline (V0) and at day 60 ± 3 (V1). The examination comprised Best Corrected Visual Acuity (BCVA) and Symptom Assessment in Dry Eye (SANDE). Tear osmolarity was evaluated using the TearLab Osmolarity System®; Keratograph 5M (Oculus, Wetzlar, Germany) was performed to assess tear meniscus height (TMH), fluorescein tear break-up time (TBUT) and corneal and conjunctival fluorescein staining and meibography; furthermore, slit lamp evaluation was performed for eyelid erythema and edema, conjunctival chemosis and hyperemia and Meibomian gland secretion quality. Results: All patients completed the treatment. BCVA remained stable in both groups, and no adverse events were reported. After 2 months, both groups showed statistically significant improvements for SANDE (p = 0.001 and p = 0.012, respectively), TBUT values (p < 0.001 and p < 0.001, respectively) and staining (p = 0.004 and p = 0.001, respectively) as compared to baseline values. Group 1 showed a statistically significant improvement in SANDE frequency and tear osmolarity (p = 0.02 and p = 0.001, respectively), whereas chemosis was significantly reduced in group 2. The amount of TBUT improvement was statistically higher in group 1 compared to that in group 2 (p = 0.041). Conclusion: A new-generation multiple-action ophthalmic solution was safe and clinically effective in the treatment of moderate and severe dry eye, with significant improvements in the main ocular surface parameters.

Ophthalmic Complications and Managements of Sulfur Mustard Exposure: A Narrative Review

Sulfur mustard (SM) is a lethal chemical agent that affects many organs, particularly the eyes, respiratory system and skin. Even asymptomatic patients with documented SM vapor exposure may develop organ disorder many years later. Patients with even minor signs in the acute stage may experience late complications that necessitate surgery. Early decontamination and conservative measures could help the patients and decrease the complications. Despite decades of research, there is still no effective treatment for either acute or long-term SM-induced ocular complications. Even after multiple medications and surgical procedures, the majority of patients continue to have symptoms. For dry eye, punctual occlusion, autologous eye drops, and aggressive lubrication are used; for persistent epithelial defects (PED), tarsorrhaphy, amniotic membrane transplant, and stem cell transplantation are used; for total limbal stem cell deficiency (LSCD), living-related conjunctivolimbal allograft and keratolimbal allograft are used; for corneal vascularization, steroids, non-steroidal anti-inflammatory drugs, and anti-vascular endothelial growth factor prescribed; and for corneal opacities, corneal transplantation is done. Platelet rich plasma and topical drops containing stem cell transplantation for LSCD, photodynamic therapy paired with subconjunctival or topical anti-vascular endothelial growth factors for corneal vascularization, topical curcumin and topical ciclosporin-A for dry eye, and orbital fat-derived stem cells for PED are all alternative treatments that can be suggested. Despite the experimental and clinical research on the complications of SM exposure over the past decades, there is still no effective treatment for eye complications. However, supportive medical and surgical management has been applied with relatively good outcome.

Stereoselective Construction of Orthogonally Protected, N-O Interlinked Disaccharide Mimetics Using N-Substituted β-Aminooxy Donors

Orthogonally protected N-substituted β-aminooxy sugars can be stereoselectively synthesized from sugar epoxides and nitrones derived from aromatic aldehydes. Both the ether- and ester-protected sugar epoxides can be employed. The synthesized aminooxy sugars could be reacted with aldehyde bearing/free reducing sugars under the heating condition to afford N-O-linked 1,1-/1,5/1,6-disaccharide mimetics in a good yield.

Hyaluronic Acid/Trehalose Ophthalmic Solution in Reducing Post-Cataract Surgery Dry Eye Signs and Symptoms: A Prospective, Interventional, Randomized, Open-Label Study

The purpose of this prospective study was to evaluate the efficacy of the perioperative use of a hyaluronic acid (HA) and trehalose ophthalmic solution (Thealoz^® Duo) in reducing post-cataract surgery dry eye signs and symptoms in patients with mild/moderate dry eye disease (DED). One hundred and twenty patients, scheduled for unilateral cataract surgery, were randomized into three groups: (1) group A: HA/trehalose three times/day in the preoperative week and for 5 postoperative weeks; (2) group B: HA/trehalose for only 5 postoperative weeks; (3) group C: no artificial tears. In groups A and B, OSDI (Ocular Surface Disease Index) questionnaire scores were significantly lower than group C at all the postoperative visits; in group A they were significantly lower than group B on the day of surgery, with similar results in the first and fifth weeks after surgery. In groups A and B, break-up time (BUT) was significantly higher than group C during the postoperative period (p ≤ 0.001). In comparison to the preoperative values, BUT in group A remained stable 7 days after surgery; however, in groups B and C, it significantly decreased. In conclusion, the HA/trehalose ophthalmic solution effectively reduced post-cataract surgery DED signs and symptoms in patients with mild/moderate DED, particularly if also administered in the preoperative period.

Trehalose-Induced Remodelling of the Human Microbiota Affects Clostridioides difficile Infection Outcome in an In Vitro Colonic Model: A Pilot Study

Within the human intestinal tract, dietary, microbial- and host-derived compounds are used as signals by many pathogenic organisms, including Clostridioides difficile. Trehalose has been reported to enhance virulence of certain C. difficile ribotypes; however, such variants are widespread and not correlated with clinical outcomes for patients suffering from C. difficile infection (CDI). Here, we make preliminary observations on how trehalose supplementation affects the microbiota in an in vitro model and show that trehalose-induced changes can reduce the outgrowth of C. difficile, preventing simulated CDI. Three clinically reflective human gut models simulated the effects of sugar (trehalose or glucose) or saline ingestion on the microbiota. Models were instilled with sugar or saline and further exposed to C. difficile spores. The recovery of the microbiota following antibiotic treatment and CDI induction was monitored in each model. The human microbiota remodelled to utilise the bioavailable trehalose. Clindamycin induction caused simulated CDI in models supplemented with either glucose or saline; however, trehalose supplementation did not result in CDI, although limited spore germination did occur. The absence of CDI in trehalose model was associated with enhanced abundances of Finegoldia, Faecalibacterium and Oscillospira, and reduced abundances of Klebsiella and Clostridium spp., compared with the other models. Functional analysis of the microbiota in the trehalose model revealed differences in the metabolic pathways, such as amino acid metabolism, which could be attributed to prevention of CDI. Our data show that trehalose supplementation remodelled the microbiota, which prevented simulated CDI, potentially due to enhanced recovery of nutritionally competitive microbiota against C. difficile.

The Efficacy and Safety of Trehalose in Primary Trabeculectomy with Mitomycin C: A Report of Early Findings

Objective

To compare bleb morphology and tear tests of glaucoma patients who used trehalose and those who did not use after primary trabeculectomy with mitomycin C (MMC) during the early post-operative period.

Methods

This retrospective study included two groups: Group 1 using Trehalose + hyaluronic acid (THA) after primary trabeculectomy with MMC (n = 19) and Group 2 undergoing primary trabeculectomy with MMC (n = 16). The preoperative and postoperative intraocular pressure (IOP), the results of Schirmer, and tear break-up time tests were analyzed. Postoperative bleb morphology was also evaluated at the 1st day, and 1st and 2nd weeks, and 1st and 2nd months.

Results

There was no statistically significant difference in preoperative IOP, Schirmer test or tear break-up time between groups. The mean horizontal extent of the blebs was significantly wider in Group 1 at the first week (p= 0.02). Bleb vascularization was also found to be lower in Group 1 at the second week (p= 0.001). The mean bleb height and horizontal extent were significantly higher in Group 1 at the first month (p=0.02, p= 0.03, respectively). The mean bleb horizontal extent was significantly higher in Group 1 at the second month (p= 0.03).

Conclusion

The use of trehalose improved surgical success of primary trabeculectomy with MMC in terms of IOP control, post-operative complications, and bleb morphology during the early postoperative period. Trehalose might contribute to wound healing which led to an ideal bleb.

Trehalose/sodium hyaluronate eye drops in post-cataract ocular surface disorders

Purpose

Prospective, randomised, open-label, comparative study to evaluate efficacy of trehalose/sodium hyaluronate eye drops for post-operative discomfort and tear film stability in patients undergoing cataract surgery.

Methods

Patients with healthy ocular surface, subclinical, or mild dry eye were enrolled. Tear breakup time (TBUT), Schirmer test, dry eye symptoms, corneal fluorescein staining (CFS), and ocular surface disease (OSDI) evaluation were performed pre-operatively and at two and four weeks after surgery. Patients were assigned to receive trehalose/sodium hyaluronate eye drops b.i.d (Group A), or 0.9% unpreserved sodium chloride eye drops b.i.d for 4 weeks (Group B).

Results

One hundred and thirty-five patients were randomised, 66 patients in Group A (73.2 ± 4.5 years) and 69 patients in Group B (74.3 ± 3.8 years), 60.8% females. Fifteen patients (8 Group A) were lost at follow-up. Pre-operatively, no between-group differences were observed, and TBUT increased in Group A between the pre-operative and 2 and 4 week evaluations and was higher in group A than in Group B at 4 weeks. Schirmer test and CFS showed an improvement only in Group A four weeks post-operatively. In Group A an improvement was observed after two and four weeks in foreign body and puncture sensation, whilst a difference in blinking discomfort was observed after four weeks. In Group B we observed an improvement in puncture sensation two and four weeks after surgery. Mean OSDI scores differences between the two groups were significant at four weeks.

Conclusions

Trehalose/sodium hyaluronate eye drops were effective in reducing signs and symptoms of dry eye and improving tear film stability

Randomized controlled trial of trehalose: An efficient autophagic bioprotectant in the management of dry eye disease

PURPOSE:

To compare the therapeutic effect of sodium hyaluronate (SH)–trehalose (Trehalube, Microlabs, Bangalore, India, SH 0.1% and trehalose 3%) or SH (0.1% Hylotears, Raymed, Chandigarh, India) alone in patients with dry eye disease (DED).

MATERIALS AND METHODS:

Patients were randomized into two groups: SH-trehalose (SH 0.1% and trehalose 3%) or SH (0.1% Hylotears) alone. The Ocular Surface Disease Index (OSDI) questionnaire was used to assess patient's symptoms. Patients were followed up at 4 and 8 weeks, and OSDI score, tear film break-up time (TBUT), tear film height (TFH), Schirmer's test, and conjunctival staining were evaluated at each visit.

RESULTS:

A total of 384 patients were included in the study, 192 patients in each arm. The mean age of participants was 37.62 + 14.4 years and 225 were women (56%). The improvement in Schirmer's test was significantly better in the SH-trehalose group at 8 weeks (5.26 + 4.3 mm, 95% confidence interval = 4.6–5.9 mm) compared to the SH group (3.71 + 3.9, 95% confidence interval = 3.15–4.28 mm). The TBUT and TFH showed slight improvement at 4 weeks in both groups, but not at 8 weeks. There were no group differences at all-time points in terms of conjunctival staining and OSDI-based grades of DED.

CONCLUSION:

It was found that treating dry eye with SH-trehalose leads to greater improvement in the Schirmer's values and TBUT after 8 weeks of sustained use in patients with DED, and this was more pronounced in those with severe DED.

Trehalose for Ocular Surface Health

Trehalose is a natural disaccharide synthesized in various life forms, but not found in vertebrates. An increasing body of evidence demonstrates exceptional bioprotective characteristics of trehalose. This review discusses the scientific findings on potential functions of trehalose in oxidative stress, protein clearance, and inflammation, with an emphasis on animal models and clinical trials in ophthalmology. The main objective is to help understand the beneficial effects of trehalose in clinical trials and practice, especially in patients suffering from ocular surface disease. The discussion is supplemented with an overview of patents for the use of trehalose in dry eye and with prospects for the 2020s.

Polysaccharides in Ocular Drug Delivery

Polysaccharides, such as cellulose, hyaluronic acid, alginic acid, and chitosan, as well as polysaccharide derivatives, have been successfully used to augment drug delivery in the treatment of ocular pathologies. The properties of polysaccharides can be extensively modified to optimize ocular drug formulations and to obtain biocompatible and biodegradable drugs with improved bioavailability and tailored pharmacological effects. This review discusses the available polysaccharide choices for overcoming the difficulties associated with ocular drug delivery, and it explores the reasons for the dependence between the physicochemical properties of polysaccharide-based drug carriers and their efficiency in different formulations and applications. Polysaccharides will continue to be of great interest to researchers endeavoring to develop ophthalmic drugs with improved effectiveness and safety.

Trehalose/hyaluronate eyedrop effects on ocular surface inflammatory markers and mucin expression in dry eye patients

Aim

To assess the ocular surface parameters, inflammatory marker level in tears, and mucin expression in conjunctival epithelium before and after treatment with trehalose/hyaluronate tear substitute in dry eye (DE) patients.

Patients and methods

Fifteen DE patients were evaluated in an open-label, pilot study at enrollment, after 2 days of washout (baseline) and after 1 and 2 months (endpoint) of treatment with a trehalose/hyaluronate tear substitute (one drop/eye/three times daily). Data for symptoms of discomfort (Ocular Surface Disease Index and Visual Analogue Scale pain score), tear film (Schirmer test I, tear film breakup time), ocular surface damage (corneal National Eye Institute) and conjunctival van Bijsterveld scores, impression cytology scored by Nelson’s grade and goblet cells (GCs) number/mm² analysis, and MUC4 immunostaining, and inflammation (interleukin [IL]-1β, IL-6, and IL-8 levels) were measured.

Results

Significant changes at endpoint as compared to baseline were found for Ocular Surface Disease Index score (respectively, mean±SD, 22.2±2.9 vs 38.7±12.7), Visual Analogue Scale score (3.4±1.3 vs 6.6±1.4), tear film breakup time (8.6±1.28 vs 6.17±1.9 seconds), corneal staining (National Eye Institute grade 1.23±0.64 vs 3.37±0.49), conjunctival staining (1.73±1.14 vs 4.17±0.91), impression cytology (Nelson grade 1.10±0.20 vs 1.63±0.54), and GC density (139.9±22.0 vs 107.8±16.2 GC/mm²). IL-1β, IL-6, and IL-8 tear levels showed a significant decrease at endpoint as compared to baseline (respectively, pg/mL tears: 12.3±6.9, 26.6±25.2, 743.5±477.7 vs 33.6±17.3, 112.0±24.3, 1,139.2±671.7).

Conclusions

A decrease in ocular discomfort symptoms, surface damage, and tear cytokine levels was shown after 2 months’ treatment with trehalose/hyaluronate tear substitute in DE patients, along with a significant GC density recovery. These results may be associated with the synergic action of both trehalose and hyaluronic acid in targeting different entries of the DE vicious loop.

Reflections on Dry Eye Syndrome Treatment: Therapeutic Role of Blood Products

Dry eye syndrome (DES) is a multifactorial, frequent, pathology characterized by deficient tear production or increased evaporation of tears and associated with ocular surface alteration and inflammation. It mostly affects, but not exclusively, older individuals and leads to varying degrees of discomfort and decreased quality of life. Although the typical treatments of DES rely on using artificial tears, polyunsaturated fatty acids, integrin antagonists, anti-inflammatory agents, or on performing punctal occlusion, recently, standardized blood-derived serum eye drops (SED) are generating much interest as a new physiological treatment option. The scientific rationale in using SED for treating or releasing the symptoms of DES is thought to lie in its composition in multiple factors that resembles that of tears and contributes to the healing and protection of the ocular surface. This manuscript seeks to provide relevant background information on the management of DES, and on the increasing role that various types of SED or platelet lysates, from autologous or allogeneic origins, are playing in the improved therapeutic management of this pathology. The increasing role played by blood establishments in producing better-standardized SED is also addressed.

Effects of 3% trehalose as an adjuvant treatment after LASIK

PURPOSE

To evaluate the effect of 3% trehalose as an adjuvant in the standard treatment after laser-assisted in situ keratomileusis.

DESIGN

Interventional prospective comparative single-blind study.

SETTING

Department of Ophthalmology, Hospital Quirón Zaragoza, Spain.

METHODS

A total of 26 eyes (13 patients) were included, of which 12 eyes (group 1) received conventional treatment with lubricant drops of hyaluronic acid (0.15%) and 14 eyes (group 2) received, additionally, an ophthalmic solution of 3% trehalose. Pre- and postoperative quality-of-life tests and vital stains, tear breakup time, and osmolarity measurements were made.

RESULTS

We obtained statistically significant differences between the groups in the Symptom Assessment in Dry Eye test in all visits with respect to severity, and in the postoperative day 1 visit with respect to frequency, in all cases favoring the trehalose treatment. The values of osmolarity were not significantly different between groups. However, we did find significant differences in the Oxford scale in day 90 for the trehalose treatment (P<0.001), and in the National Eye Institute scale in day 30 (P=0.02).

CONCLUSION

The results of this exploratory study indicate that the adjuvant treatment with 3% trehalose could be superior with respect to the standard treatment, with improvements in the objective and subjective parameters of tear quality.

Trehalose efficacy in dry eye syndrome treatment after phacoemulsification

Purpose to estimate the efficacy of “artificial tear” preparation on the trehalose base in dry eye syndrome treatment in cataract patients after phacoemulsification.Materials and methods: in 40 patients with incipient cataract phacoemulsification with IOL implantation was performed. During 1 week, all patients received eye gel with dexpanthenol in addition to postoperative therapy. Then, all patients were divided into two groups (randomization using envelopes): in the main group, the gel was replaced by Thealoz®, in the control group, the gel was discontinued. Special investigation tests (OSDI score, TBUT test, conjunctival hyperemia, corneal confocal tomography) were performed before surgery, in one week and one month after it. Statistical analysis was performed using SAS 9.4 program.Results: all investigated parameters had significant differences with time and between groups (р < 0.001). TBUT test result decreased in one week after surgery from 7.4 ± 2.1 to 4.6 ± 1.9 sec in the main group and from 7.5 ± 2.3 to 4.4 ± 2 sec in the control group. Return to baseline results in the control group was slowed down and made 6.4 ± 2.8 sec (compared with 7.9 ± 2.4 sec in the main one). In the trehalose group, OSDI score ameliorated from 35.1 ± 8.7 (in one week) to 14.2 ± 5.3 (in one month), in the control group, from 40.1 ± 11.5 to 24.8 ± 9. Conjunctival hyperemia was also less pronounced in the main group in one month after surgery: 0.45 ± 0.6 (1.6 ± 0.7 in one week), in the control group, these indices were equal to 1.7 ± 0.5 (in one week) and 1.3 ± 0.7 (in one month).Conclusions: Thealoz® use as a part of combined postoperative therapy helps to effectively fight against dry eye syndrome main signs and enhances treatment tolerance.

Over the counter (OTC) artificial tear drops for dry eye syndrome

BACKGROUND

Over the counter (OTC) artificial tears historically have been the first line of treatment for dry eye syndrome and dry eye-related conditions like contact lens discomfort, yet currently we know little regarding the overall efficacy of individual, commercially available artificial tears. This review provides a much needed meta-analytical look at all randomized and quasi-randomized clinical trials that have analyzed head-to-head comparisons of OTC artificial tears.

OBJECTIVES

To evaluate the effectiveness and toxicity of OTC artificial tear applications in the treatment of dry eye syndrome compared with another class of OTC artificial tears, no treatment, or placebo.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2015, Issue 12), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to December 2015), EMBASE (January 1980 to December 2015), Latin American and Caribbean Health Sciences (LILACS) (January 1982 to December 2015), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov), the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en) and the US Food and Drugs Administration (FDA) website (www.fda.gov). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 4 December 2015. We searched reference lists of included trials for any additional trials not identified by the electronic searches.

SELECTION CRITERIA

This review includes randomized controlled trials with adult participants who were diagnosed with dry eye, regardless of race and gender. We included trials in which the age of participants was not reported, and clinical trials comparing OTC artificial tears with another class of OTC artificial tears, placebo, or no treatment. This review did not consider head-to-head comparisons of artificial tears with another type of dry-eye therapy.

DATA COLLECTION AND ANALYSIS

We followed the standard methodological procedures expected by Cochrane. Two authors independently screened the search results, reviewed full-text copies for eligibility, examined risk of bias, and extracted data. We performed meta-analysis for trials that compared similar interventions and reported comparable outcomes with sufficient data. We summarized all other included trial results in the text.

MAIN RESULTS

We included 43 randomized controlled trials (3497 participants with dry eye). Due to the heterogeneity of study characteristics among the included trials with respect to types of diagnostic criteria, interventions, comparisons, and measurements taken, our ability to perform meta-analyses was limited. The review found that, in general, there was uncertainty whether different OTC artificial tears provide similar relief of signs and symptoms when compared with each other or placebo. Nevertheless, we found that 0.2% polyacrylic acid-based artificial tears were consistently more effective at treating dry eye symptoms than 1.4% polyvinyl alcohol-based artificial tears in two trials assessing this comparison (175 participants). All other included artificial tears produced contradictory between-group results or found no between-group differences. Our review also found that OTC artificial tears may be generally safe, but not without adverse events. Overall, we assessed the quality of evidence as low due to high risks of bias among included trials and poor reporting of outcome measures which were insufficient for quantitative analysis. Furthermore, we identified an additional 18 potentially eligible trials that were reported only in clinical trial registers with no associated results or publications. These trials reportedly enrolled 2079 total participants for whom no data are available. Such lack of reporting of trial results represents a high risk of publication bias.

AUTHORS' CONCLUSIONS

OTC artificial tears may be safe and effective means for treating dry eye syndrome; the literature indicates that the majority of OTC artificial tears may have similar efficacies. This conclusion could be greatly skewed by the inconsistencies in study designs and inconsistencies in reporting trial results. Additional research is therefore needed before we can draw robust conclusions about the effectiveness of individual OTC artificial tear formulations.