Artificial Tears: Biological Role of Their Ingredients in the Management of Dry Eye Disease.

Dry eye disease (DED) is the most common ocular surface disease, characterized by insufficient production and/or instability of the tear film. Tear substitutes are usually the first line of treatment for patients with DED. Despite the large variety of tear substitutes available on the market, few studies have been performed to compare their performance. There is a need to better understand the specific mechanical and pharmacological roles of each ingredient composing the different formulations. In this review, we describe the main categories of ingredients composing tear substitutes (e.g., viscosity-enhancing agents, electrolytes, osmo-protectants, antioxidants, lipids, surfactants and preservatives) as well as their effects on the ocular surface, and we provide insight into how certain components of tear substitutes may promote corneal wound healing, and/or counteract inflammation. Based on these considerations, we propose an approach to select the most appropriate tear substitute formulations according to the predominant etiological causes of DED.

Lipid artificial tears at a mimetic ocular interface.

We studied the behaviour of three lipid tear products, commercialised by the same brand, as Langmuir films at the air/liquid interface to simulate the ocular environment. No significant differences were observed in the surface behaviour of two of them disclosing the same composition, but commercialised for different applications. The interaction of several subphases, namely sodium chloride, glucose, albumin and lysozyme present in the natural tear, with the lipid films was assessed at room temperature and the temperature of human tear using surface pressure-area isotherms and elastic modulus plots. There is a notable influence of sodium chloride and the proteins albumin and lysozyme on the surface pressure-area isotherm of the lipid Langmuir films. Albumin shifted this isotherm to lower areas while an opposite shift was caused by lysozyme. These studies could be useful for the formulation of new lipid-containing artificial tears, and for increasing the confidence of the customers in commercial eye care formulations.

Why chitosan could be apt candidate for glaucoma drug delivery - An overview.

Most of the people in the world are affected by glaucoma, which leads to irreversible blindness. Several patient friendly treatments are available, nevertheless medications lack an easy and efficient way of sustained delivery. To make the delivery with enhanced bioavailability, biodegradable and non-biodegradable polymers-based drug carriers are explored. However, ocular drug delivery issues have not been resolved yet due to less adhesiveness, poor penetration ability, pH, and temperature dependent burst releases. Chitosan is found to be effective for ocular drug delivery due to excellent physio-chemical properties in terms of overcoming the existing issues. In this review, we aim to highlight why it has been chosen and the holy grail for ocular drug delivery. Besides, we have comprehensively reviewed recent patents on chitosan as a platform for ocular drug delivery and future perspectives on factors, lacunae and challenges that need to be addressed for better ocular delivery methods for glaucoma management.

Preclinical Development of Artificial Tears Based on an Extract of Artemia Salina Containing Dinucleotides in Rabbits.

PURPOSE: To evaluate the preclinical efficacy of eye drops based on an extract of Artemia salina on the ocular surface of rabbits. Tear secretion, tear break-up time and corneal staining were measured. MATERIAL AND METHODS: A preclinical and short-term prospective study was performed. Twenty New Zealand white rabbits were divided into five groups, with four rabbits per group, each receiving a different concentration of Artemia salina. In each rabbit, an extract of Artemia salina (2%, 4%, 6%, 8% or 10%) was randomly instilled in one eye and saline solution (negative control) in the other eye. Tear secretion, tear break-up time and corneal staining were measured before and after the instillation of five drops per eye (one drop per hour) on the same day. RESULTS: In tear secretion, there was an increase of 43.88 ± 6.73% with 4% Artemia salina in comparison with its baseline measurement (P = .049). The rest of the groups did not show differences (P ≥ 0.05). For tear break-up time, none of the groups showed differences (P ≥ 0.05), while for corneal staining score, there was an improvement of 0.88 ± 0.83 with 4% Artemia salina (P = .038) and a deterioration of 0.50 ± 0.83 with control solution (P = .008). CONCLUSIONS: Short-term instillation of eye drops with 4% Artemia salina produced both stimulation of tear secretion and a slight improvement of physiological corneal staining. Besides, all the doses of up to 10% Artemia salina did not produce undesirable side effects on the ocular surface. Therefore, these eye drops are presented as a possible new treatment for dry eye due to their secretagogue properties and ocular surface regeneration.

Influence of Artificial Tears on Keratometric Measurements in Cataract Patients.

PURPOSE: To assess the influence of artificial tears of different viscosity on K-readings prior to cataract surgery. DESIGN: Prospective randomized crossover, before-and-after clinical study. METHODS: Setting: Department of Ophthalmology, Medical University of Vienna. PATIENT POPULATION: A total of 123 eyes of 80 patients prior to cataract surgery were assigned to 2 groups based on normal and dry eyes. INTERVENTION: Two native baseline keratometries were followed by instillation of either high- or low-viscosity eye drops. Keratometry was repeated 30 seconds, 2 minutes, and 5 minutes after instillation. MAIN OUTCOME MEASURES: Influence of eye drops of different viscosity in normal and dry eyes on short time K-readings. RESULTS: Repeatability between native baseline measurements was high (standard deviation = 0.02 mm in normal and in dry eyes). In normal and dry eyes, a statistically significant increase in measurement variability after instillation of both low-viscosity and high-viscosity eye drops was observed (P < .01). Measurement variability was most pronounced between baseline measurement and 30 seconds and diminished over time. Variability of K-readings appeared higher in dry eyes compared with normal eyes. Astigmatism changed more than 0.5 diopters in 13.2% of normal eyes and 34.4% in dry eyes using eye drops of high viscosity. CONCLUSION: Tear film-stabilizing eye drops prior to keratometry measurements influenced K-readings significantly, especially in dry eyes. A time period of more than 5 minutes should be allowed to pass after instillation of eye drops. The higher the viscosity of the eye drops, the stronger the influence and the longer its persistence.

Formulation of hyaluronan grafted with dodecanoic acid as a potential ophthalmic treatment.

This work concerns the chemical modification of medium molecular weight hyaluronan for ophthalmic applications. The synthesis of amphiphilic HA with dodecanoyl moities was carried out under mild aqueous conditions. Perfect control of the degree of substitution was obtained by varying the molar ratio of activated fatty acid used in the reaction feed. Moreover, the preparation of the derivatives was optimized to achieve the desired degree of substitution (DS = 9.0 ± 0.2 %). The prepared hyaluronan derivatives were water-soluble and exhibited self-associating properties (amphiphilicity). The structure of the prepared derivatives was elucidated by NMR spectroscopy, rheology, turbidity, SEC-MALLS, and gas chromatography (GC). The hydrophobic moieties increase the solution viscosity by physical crosslinking. Low concentration of HAC12 is needed to prepare highly viscous solutions with potential use for ophthalmic applications. Amphiphilic HA kept the biocompatibility of hyaluronan. The degree of substitution and Mw of the amphiphilic HA controls the sterilization by filtration. The protection against desiccation was tested using human keratinocytes (HaCaT) cells lines.

Cationic Emulsion-Based Artificial Tears as a Mimic of Functional Healthy Tear Film for Restoration of Ocular Surface Homeostasis in Dry Eye Disease.

Dry eye disease (DED) is a complex multifactorial disease that affects an increasing number of patients worldwide. Close to 30% of the population has experienced dry eye (DE) symptoms and presented with some signs of the disease during their lifetime. The significant heterogeneity in the medical background of patients with DEs and in their sensitivity to symptoms renders a clear understanding of DED complicated. It has become evident over the past few years that DED results from an impairment of the ocular surface homeostasis. Hence, a holistic treatment approach that concomitantly addresses the different mechanisms that result in the destabilization of the tear film (TF) and the ocular surface would be appropriate. The goal of the present review is to compile the different types of scientific evidence (from in silico modeling to clinical trials) that help explain the mechanism of action of cationic emulsion (CE)-based eye drop technology for the treatment of both the signs and the symptoms of DED. These CE-based artificial tear (AT) eye drops designed to mimic, from a functional point of view, a healthy TF contribute to the restoration of a healthy ocular surface environment and TF that leads to a better management of DE patients. The CE-based AT eye drops help restore the ocular surface homeostasis in patients who have unstable TF or no tears.

Nanoscale poly(acrylic acid)-based hydrogels prepared via a green single-step approach for application as low-viscosity biomimetic fluid tears.

The present work reports a nanotechnology strategy to prepare a low-viscosity poly(acrylic acid) (PAAc)-based tear substitute with enhanced efficacy and compliance. Specifically, nanogels composed of PAAc and polyvinylpyrrolidone (PVP) were prepared by adapting an ionizing radiation method. For this purpose, different aqueous systems: PVP/PAAc nanoparticulate complexes, PVP/acrylic acid (AAc), N-vinylpyrrolidone (N-VP)/PAAc, and N-VP/AAc were exposed to gamma rays. The dynamic light scattering technique showed that stable nanogels are only produced in a relatively high yield from the PVP/AAc system. Nanogel formation was driven by the hydrogen-bonding complexation between PVP and PAAc (formed in situ) as well as the radiation-induced cross-linking. Transparency, viscosity and mucoadhesiveness of emerged nanogels were optimized by controlling the feed composition and irradiation dose. Furthermore, neutralized nanogels were topically applied in a dry eye model and compared with a PAAc-based commercial tear substitute, namely Vidisic® Gel. The results of Schirmer's test and tear break-up time demonstrated that nanogels prepared from AAc-rich feed solutions at 20 kGy enhanced markedly the dry eye conditions. The histopathological analysis also ensured the competence of PAAc-rich nanogels to completely return the corneal epithelium to its normal state.

Assessment of Phosphate and Osmolarity Levels in Chronically Administered Eye Drops

Objectives: To assess phosphate and osmolarity levels of chronically administered eye drops commercially available in Turkey. Materials and Methods: A total of 53 topical eye drops including 18 antiglaucoma drugs, 4 nonsteroidal anti-inflammatory drugs (NSAIDs), 10 corticosteroids, 7 antihistaminics, and 14 artificial tears identified using the Vademecum Modern Medications Guideline (2018) were included in the study. Phosphate levels were assessed using Roche Cobas C501 analyzer (Roche Diagnostics GmbH, Mannheim, Germany) and the respective kits. Osmolarity was assessed using Vescor Vapro 5600 vapor pressure osmometer (Sanova Medical Systems, Vienna, Austria). Mean phosphate and osmolarity levels were obtained after averaging three measurements. Eye drops were categorized as isoosmolar, hypoosmolar and hyperosmolar based on physiologic tear osmolarity range (296.5±9.8 mOsm/L). Results: The highest phosphate concentration was found in the antiglaucoma group (20.3±35.4 mmol/L), followed by antihistaminics (17.3±17.9 mmol/L), corticosteroids (15.2±19.1 mmol/L), artificial tears (0.8±1.0), and NSAIDs (0.04±0.08). Percentage of medications in the hyperosmolar category was highest in the NSAI group (75%), followed by antihistaminics (43%), corticosteroids (20%), and antiglaucoma drugs (19%). Nearly all of the artificial tear formulations were in the hypoosmolar (71%) or isoosmolar (21%) categories. Conclusion: Approximately 40% of glaucoma medications and approximately 60% of corticosteroid and antihistaminic medications had a phosphate concentration higher than the physiologic tear phosphate level (1.45 mmol/L).

A review of the efficacy, safety and tolerability of Lacrycon® eye drops for the treatment of dry eye syndrome.

Lacrycon® is a preservative-free hypotonic artificial tear for the treatment of dry eye syndrome containing hyaluronic acid, carbomer, and glycerol. Lacrycon has been used for many years; this is the first comprehensive review of clinical efficacy and tolerability. Eight clinical studies (1992-2013) were reviewed. Comparators included phosphate-buffered saline (Phase I) and active controls (Phase II: Lacrisol™; Phase III: Gel-larmes™, Lacrisol, Hyalistil®, Vismed®, or the currently prescribed tear substitute). Administration schedules varied from 3 to 8 instillations per day for 7 to 84 days, and evaluation timepoints varied between studies. Pre-corneal retention of Lacrycon was 22% better than phosphate-buffered saline in terms of AUC (P=0.048). Patients' evaluation of efficacy was better for Lacrycon than Gel-larmes on Day 15 and 45 (P<0.05) and similar on Day 90 (P>0.05); there was no difference (P>0.05) versus Hyalistil (Day 30) or Vismed (Day 35 and 85). Functional tests were either in favor of Lacrycon (P<0.05) (fluorescein test [versus Gel-larmes/Lacrisol/Hyalistil], tear break-up time [TBUT] and rose Bengal test, Schirmer I test, and tear meniscus [versus Lacrisol]), or there was no difference between treatments (P>0.05) (fluorescein test [versus Vismed], TBUT and rose Bengal test [versus Gel-larmes], Schirmer I test [versus Gel-larmes/Lacrisol/Hyalistil/VisMed], tear meniscus [versus Lacrisol/Hyalistil], Oxford Grading Score, OSDI, van Bijsterveld score, and conjunctival hyperemia [versus Vismed]). Lacrycon was better tolerated than most comparators and had a similar safety profile to Vismed. No comparison showed favored the comparator over Lacrycon. These good efficacy, tolerability and safety data support the use of Lacrycon in dry eye syndrome.

Improvement of ferning patterns of lubricant eye drops mixed with various electrolytes and carboxymethylcellulose.

PURPOSE: To investigate the effect of the addition of electrolytes, basic tear solution (BTS), and sodium carboxymethylcellulose (SCMS) on the tear ferning (TF) patterns of Blink Contact Soothing Eye Drops® and Refresh Plus Tears®. METHOD: Samples of Blink Contact Soothing Eye Drops® and Refresh Plus Tears® (10 µL) were mixed with different volumes (3-30 µL) of several electrolytes, namely sodium chloride, potassium chloride, calcium chloride, magnesium chloride hexahydrate, sodium hydrogen carbonate, and sodium dihydrogen phosphate, BTS, and SCMS. Samples (1 µL) of the mixtures were dried on a glass slide at room temperature and the TF patterns were inspected using a light microscope, graded using the Masmali five-point grading scale and compared to the corresponding TF grades of the artificial tears. RESULTS: The TF grades of Blink Contact Soothing Eye Drops® and Refresh Plus Tears® improved from 1.2 and 1.5, respectively to 0.2 when calcium chloride was used as the electrolyte. Improvements in TF grades were also observed when other electrolytes (e.g., sodium dihydrogen phosphate), BTS, and SCMS were used. CONCLUSION: The tear ferning test can be used to evaluate the effect of the addition of electrolytes to an artificial tear in-vitro. The TF patterns of artificial tear solutions such as Blink Contact Soothing Eye Drops® and Refresh Plus Tears® can be improved with the addition of various concentrations of electrolytes, BTS, and SCMS, however further research is still needed to understand the clinical relevance of TF patterns with respect to the management of dry eye symptoms and their potential role in the development of new artificial tears.

Impact of Nanostructured Lipid Carriers as an Artificial Tear Film in a Rabbit Evaporative Dry Eye Model.

PURPOSE: To characterize formulations of nanostructured lipid carriers (NLCs) as an artificial tear film and evaluate their efficacy in protecting the ocular surface epithelial cells from desiccating stress in vivo. METHODS: The physicochemical properties of NLCs, produced with components similar to the tear film such as phosphatidylcholine and squalene, were determined. In vitro cytotoxicity of NLCs was evaluated by a short-time exposure test in porcine corneal epithelial cells using a methyl thiazol diphenyl-tetrazolium bromide assay. The residence time of NLCs in rabbit eyes and the efficacy of NLCs eye drops in protecting the rabbit corneal epithelium from desiccating stress were assessed. RESULTS: Nanosized NLCs with a mean size of ∼39 ± 5 nm and a zeta potential of -30 mV could be produced and formulated into eye drop with a pH of 6.90 ± 0.01, osmolarity of 273 ± 1 mOsm/L, and surface tension of 39 ± 1 mN/m (for air interface). Eye drop formulations of NLCs were nontoxic to porcine corneal epithelial cells. NLCs drops showed higher ocular surface retention and formed a stable corneal film compared with a saline solution. Moreover, NLCs eye drops showed greater efficacy in protecting the corneal surface against desiccating stress compared with a polymer-based commercial artificial tear. CONCLUSIONS: NLCs eye drops are biocompatible in rabbit eyes and show potential as a tear replacement vehicle for the treatment of dry eye disease.

Evaluation of an enhanced viscosity artificial tear for moderate to severe dry eye disease: A multicenter, double-masked, randomized 30-day study.

PURPOSE: In a randomized, controlled clinical trial, two lubricant artificial tear formulations with enhanced viscosity were compared: an investigational product at the time, containing carboxymethylcellulose 1.0% and glycerin 0.9% (CMC-GLY) with osmoprotectants, and a standard formula containing carboxymethylcellulose 1.0% alone (CMC). METHODS: This double-masked study recruited patients with moderate to severe dry eye at 10 US centers. After a 7-day run-in with CMC 0.5% (Refresh Tears) patients were randomized to use either CMC-GLY or CMC as needed, but at least 2 times daily for 30 days. Patients were stratified by Ocular Surface Disease Index© (OSDI) score into moderate (23-32) and severe (> 32-65) subgroups. Assessments included OSDI (primary efficacy variable), corneal and conjunctival staining, tear break-up time (TBUT), symptom surveys, and safety variables. Study visits were days 1 (baseline/randomization), 7, and 30. RESULTS: A total of 188 patients (94 CMC-GLY, 94 CMC) were enrolled. The severe subgroup had 67 CMC-GLY and 65 CMC patients. OSDI scores progressively improved and were similar at day 30 between treatment groups. At day 7, only the CMC-GLY group demonstrated significant improvements from baseline in OSDI score (all patients p < 0.001, severe p < 0.001), corneal staining (p = 0.004), and TBUT (p < 0.001). Between-group dose frequency for CMC-GLY was lower at day 7 (p = 0.031). Other efficacy results were similar between groups. The most commonly reported adverse event in both groups was blurred vision. CONCLUSIONS: Overall, the CMC-GLY artificial tear formulation was as effective as the CMC formulation. CMC-GLY demonstrated improvements at an earlier stage (day 7). Both artificial tear formulations were safe and well tolerated, with no treatment-related serious adverse events. These results support the use of the CMC-GLY artificial tear formulation as an effective treatment to reduce the symptoms and signs of dry eye disease.

An imaging system integrating optical coherence tomography and interferometry for in vivo measurement of the thickness and dynamics of the tear film.

BACKGROUND: The outermost layer of the tear film consists of a thin lipid layer (LL). The lipid layer serves as a barrier against evaporation of the aqueous component of the tear film. The ability to simultaneously image both the lipid layer thickness and overall tear film thickness is novel, and will help further understandings of mechanisms of how the lipid layer assembles and interacts with the full tear film thickness. METHODS: We developed a system that combines simultaneous optical coherence tomography (OCT) and thickness dependent fringes (TDF) interferometry for in vivo imaging of the tear film. The OCT possesses an axial resolution of 1.38 µm in tear film, providing an accurate measurement of the thickness of the overall tear film. The TDF can detect a minimal change of approximately 15 nm in LL thickness. In addition, the spatial resolution of TDF images in x-y plane is 5 µm. RESULTS: The effect of instilling artificial tears on the PCTF and PLTF was examined. In both contact lens and non-contact lens wear, it could be observed from the OCT results that instillation of artificial tears increased the thickness of the overall tear film immediately, followed by a gradual reduction thereafter. These findings were consistent with other studies. However, unlike those previous reports, the thickness of the LL in this study was quantified simultaneously with the TDF subsystem. The results showed that bulking agents such as these artificial tears were not necessarily intended to increase the LL thickness. Immediately after instillation of artificial tears, the PCTF increased from 4.4 ± 0.97 to 20.3 ± 3.6 µm. The PCTF then decreased to 8.8 ± 2.1 µm at 4 min post-instillation. The thicknesses of the LL were 62.4 ± 14.5 nm, 48.7 ± 5.3 nm, and 55.2 ± 9.8 nm at pre-drop instillation, post-drop instillation, and 4-min post-drop instillation, respectively. CONCLUSIONS: In this work, we have described a novel imaging system that integrated OCT and TDF imaging techniques, which may facilitate the study of many physiological and clinical aspects of the tear film.

Structure and microanalysis of tear film ferning of camel tears, human tears, and Refresh Plus.

Purpose: This study aimed to investigate the tear ferning pattern and chemical elements of the tear film of camel tears compared with human tears and Refresh Plus eye lubricant. Refresh Plus was used as a control because it provides a healthy ferning pattern, due to the presence of an optimum ratio of carboxymethylcellulose (CMC) sodium and electrolytes. The main research focus is elucidating the viability of camel tear film in the dry, harsh environment of the desert. Methods: The tears were collected from five camels, five male desert workers (20-25 years old) at a small village located 100 km from Riyadh, Saudi Arabia, and five male subjects (20-25 years old) from Riyadh. A small drop (1 µl) of tears was dried on a glass slide and observed under a light (Olympus BX1) and scanning electron microscope (Inspect S50, Field Electron and Ion Company [FEI]). Energy-dispersive X-ray spectroscopy (EDS) of the tear film and Refresh Plus were investigated with a JEOL 1400 scanning transmission electron microscope. Results: The camel tear film pattern was surrounded by thick, peripheral, homogenous layers containing small oily droplets, particles, and tiny branches in the tear ferning. The tear ferning of the camel was grade 0-1, whereas the tear ferning of human tears and Refresh Plus was grade 1-2. The mass percentage of chloride was highest in the camel tears. The mass percentage of potassium in the camel tears was greater than that in the human tears, but it was less than that in the Refresh Plus lubricant. Conclusions: Camel tears exhibit a better quality than human tears and Refresh Plus lubricant do. The presence of oily droplet-like structures at the periphery of tear ferning suggests that camel tear film may have a higher quality and quantity of minerals and lubricants, which may help the animal to avoid eye dryness. Future work is required to investigate the identification of the elements present in the peripheral and central part of the tear ferning.

The effect of ocular lubricants containing benzalkonium chloride on nasal mucosal flora.

PURPOSE: The effect of ocular artificial teardrop containing benzalkonium chloride (BAC) on nasal mucosa was investigated. MATERIALS AND METHODS: There were two different treatment trial groups. Each dry eye syndrome (DES) patient received the ocular lubricant treatment four times a day in both groups (one group containing BAC, the other group was not). Moistened sterile cotton-tipped applicators were placed in both nostrils and were immediately cultured prior to ocular lubricant treatment and at the end of treatment trial. The bacterial culture-positivity rate, species of bacteria, and drug sensitivity were recorded in the two groups during pre-treatment and post-treatment. RESULTS: There were 20 patients in each group with a mean age of 53.14 years (36 female, 4 male). At the beginning of the treatment trial, Staphylococcus epidermidis was the most frequently isolated organism from the nasal cavity accounting in 24/40 patients (60%). Of the 40 organisms isolated from the nares prior to treatment trial, 37 (92.5%) were sensitive to gentamycin. At the end of 1 month of treatment trial in patients who were treated with ocular lubricants containing BAC, none of the nasal cultures showed growth of any organisms. However, patients who were treated with ocular lubricants not containing BAC demonstrated persistent positive nasal cultures with the same species and the same antibiotic susceptibility profile at the end of the treatment trial period. CONCLUSION: Topically applied ocular lubricants including BAC has an anti-bacterial activity on nasal flora in DES patients.

Does the temperature of an artificial tear affect its comfort?

BACKGROUND: Refrigerated eye-drops have been advocated in cases of ocular allergies to provide a soothing effect upon instillation. This notion continues to be promoted by practitioners for artificial tears (AT) in the management of dry eye (DE) with little support in the literature. To further substantiate claims of a soothing effect of cold eye-drops, the aim of this study was to determine if refrigeration of an AT enhanced the subjective comfort upon instillation. METHODS: Participants with mild to moderate DE participated in an open label contralateral study of two weeks duration. Each participant instilled Systane Ultra (Alcon Laboratories) in the morning (between 6.00-10.00 hours) and in the evening (between 18.00-22.00 hours). Participants were asked to report the subjective comfort immediately after both of these instillations, on a scale from 1 (poor) to 10 (excellent). This was done for ambient (aAT) and refrigerated (rAT) drops. An in vitro study evaluated if there were any changes in eye-drop pH and osmolarity with refrigeration. RESULTS: Participants (n = 18, three male, 15 female, age 22-28 years, average 24.4 ± 1.6) reported mean comfort scores (± standard deviation) of 7.8 ± 0.9 and 7.6 ± 1.4, for the aAT and the rAT, respectively. Mean comfort scores (± standard deviation) for morning and evening, were 7.7 ± 1.2 and 7.8 ± 1.1, respectively. A non-parametric Friedman test of differences among repeated measures was conducted and rendered a chi-squared value of 3.74, which was not statistically significant (p = 0.29). The pH remained stable at 8.0 and the osmolality did not vary significantly with refrigeration. CONCLUSION: There is no advantage, with respect to patient perceived comfort, in refrigerating the Systane Ultra (Alcon Laboratories) AT for mild to moderate DE.

Can artificial tears prevent Acanthamoeba keratitis? An in vitro approach.

BACKGROUND: The use of contact lenses has increased in recent years as has the incidence of Dry Eye Syndrome, partly due to their use. Artificial tears are the most common treatment option. Since these changes can facilitate Acanthamoeba infection, the present study has been designed to evaluate the effect of three artificial tears treatments in the viability of Acanthamoeba genotype T4 trophozoites. Optava Fusion™, Oculotect®, and Artelac® Splash were selected due to their formulation. METHODS: Viability was assessed using two staining methods, Trypan Blue stain and CTC stain at different time intervals (2, 4, 6, 8 and 24 h). Trypan Blue viability was obtained by manual count with light microscopy while the CTC stain was determined using flow cytometry. RESULTS: Trypan Blue staining results demonstrated a decrease in viability for Optava Fusion™ and Artelac® Splash during the first 4 h of incubation. After, this effect seems to lose strength. In the case of Oculotect®, complete cell death was observed after 2 h. Using flow cytometry analysis, Optava Fusion™ and Oculotect® exhibited the same effect observed with Trypan Blue staining. However, Artelac® Splash revealed decreasing cell respiratory activity after four hours, with no damage to the cell membrane. CONCLUSIONS: The present study uses, for the first time, CTC stain analyzed by flow cytometry to establish Acanthamoeba viability demonstrating its usefulness and complementarity with the traditional stain, Trypan Blue. Artelac® Splash, with no preservatives, and Optava Fusion TM, with Purite®, have not shown any useful amoebicidal activity. On the contrary, promising results presented by Ocultect®, with BAK, open up a new possibility for Acanthamoeba keratitis prophylaxis and treatment although in vivo studies should be carried out.