Fluorophotometric measurement of pH of human tears in vivo

The new preservative-free ophthalmic formulation of bilastine 0.6% preserves the ocular surface epithelial integrity in a comparative in vitro study

Allergic conjunctivitis (AC) is the most common form of allergic eye disease and an increasingly prevalent condition. Topical eye drop treatments are the usual approach for managing AC, although their impact on the ocular surface is not frequently investigated. The aim of this study was to perform a comparative physicochemical characterization, and in vitro biological evaluations in primary conjunctival and corneal epithelial cells of the new multidose preservative-free bilastine 0.6% and main commercially available eye drops. MTT assay was used to measure cell viability; oxidative stress was analyzed with a ROS-sensitive probe; and apoptosis was evaluated monitoring caspase 3/7 activation. Differences in pH value, osmolarity, viscosity and phosphate levels were identified. Among all formulations, bilastine exhibited pH, osmolarity and viscosity values closer to tear film (7.4, 300 mOsm/l and ~ 1.5-10 mPa·s, respectively), and was the only phosphates-free solution. Single-dose ketotifen did not induce ROS production, and single-dose azelastine and bilastine only induced a mild increase. Bilastine and single-dose ketotifen and azelastine showed high survival rates attributable to the absence of preservative in its formulation, not inducing caspase-3/7-mediated apoptosis after 24 h. Our findings support the use of the new bilastine 0.6% for treating patients with AC to preserve and maintain the integrity of the ocular surface.

Biophysical properties of tear film lipid layer I. Surface tension and surface rheology

Tear film lipid layer (TFLL) is the outmost layer of the tear film. It plays a crucial role in stabilizing the tear film by reducing surface tension and retarding evaporation of the aqueous layer. Dysfunction of the TFLL leads to dysfunctional tear syndrome, with dry eye disease (DED) being the most prevalent eye disease, affecting 10%-30% of the world population. To date, except for treatments alleviating dry eye symptoms, effective therapeutic interventions in treating DED are still lacking. Therefore, there is an urgent need to understand the biophysical properties of the TFLL with the long-term goal to develop translational solutions in effectively managing DED. Here, we studied the composition-function correlations of an artificial TFLL, under physiologically relevant conditions, using a novel experimental methodology called constrained drop surfactometry. This artificial TFLL was composed of 40% behenyl oleate and 40% cholesteryl oleate, representing the most abundant wax ester and cholesteryl ester in the natural TFLL, respectively, and 15% phosphatidylcholine and 5% palmitic-acid-9-hydroxy-stearic-acid (PAHSA), which represent the two predominant polar lipid classes in the natural TFLL. Our study suggests that the major biophysical function of phospholipids in the TFLL is to reduce the surface tension, whereas the primary function of PAHSA is to optimize the rheological properties of the TFLL. These findings have novel implications in better understanding the physiological and biophysical functions of the TFLL and may offer new translational insight to the treatment of DED.

Physicochemical Stability of a Novel Tacrolimus Ophthalmic Formulation for the Treatment of Ophthalmic Inflammatory Diseases

Tacrolimus is an immunosuppressant used to treat a large variety of inflammatory or immunity-mediated ophthalmic diseases. However, there are currently no commercial industrial forms available that can provide relief to patients. Various ophthalmic formulations have been reported in the literature, but their stability has only been tested over short periods. The objective of this study was to evaluate the physicochemical stability of a preservative-free tacrolimus formulation (0.2 and 1 mg/mL) at three storage temperatures (5 °C, 25 °C and 35 °C) for up to nine months in a multidose eyedropper. Analyses performed were the following: visual inspection and chromaticity, turbidity, viscosity, size of micelles, osmolality and pH measurements, tacrolimus quantification by a stability-indicating liquid chromatography method, breakdown product research, and sterility assay. In an in-use study, tacrolimus quantification was also performed on the drops emitted from the eyedroppers. All tested parameters remained stable during the nine month period when the eyedrops were stored at 5 °C. However, during storage at 25 °C and 35 °C, several signs of chemical instability were detected. Furthermore, a leachable compound originating from a silicone part of the eyedropper was detected during the in-use assay. Overall, the 0.2 mg/mL and 1 mg/mL tacrolimus ophthalmic solutions were physicochemically stable for up to nine months when stored at 5 °C.

Assessment of the Efficiency of HP-Guar and hyaluronic Acid Tear Supplements to Control Tear Film Evaporation Rate in Dry Eye Subjects

Background:

The most common factor that could lead to dryness is the accelerated tear evaporation rate. Controlling the tear evaporation rate is increasingly used as a method to control dry eye complications. The present study explores the effects of different tear supplements formulations on tear film evaporation rate.

Objective:

This study aimed to evaluate the short-term effects of Systane ULTRA and Artelac Advanced eye drops on the tear film evaporation rate.

Methods:

Fifteen male dry eye subjects were enrolled in the current study. Tear film parameters were observed at several time points post installation (10, 20, 30, and 60 min). The tear film parameters observed in the current study were tear evaporation rate, noninvasive breakup time (NITBUT) and tear meniscus height (TMH). Two visits were required to conduct this study. One visit was conducted to assess the physiological tear film parameters with the use of Systane® ULTRA eye drop. The other visit was conducted to assess tear film parameters with the use of Artelac Advanced eye drop.

Results:

The mean tear evaporation rate at baseline was 52.58 ± 23.24 g/m2 h. A box plot of tear evaporation showed a reduction in tear film evaporation rate after instillation of Systane eye drop. A drop in tear film evaporation rate of 14% was observed at 20 and 60 min time point after instillation of Systane ULTRA eye drop. A significant increase in NITBUT was found after instillation of Systane ULTRA (P = 0.01) and Artelac Advanced (P = 0.02).

Conclusion:

The current study indicates a significant improvement in the tear film parameters using both HP-Guar and hyaluronic acid formulations. However, it was apparent that the use of HP-Guar was superior to hyaluronic acid in controlling the tear evaporation rate in dry eye subjects.

Topical Administration of SLN-Based Gene Therapy for the Treatment of Corneal Inflammation by De Novo IL-10 Production

One of the main challenges in gene therapy is the issue of delivery, and it is especially relevant for the success of gene therapy in the cornea. In the present work, eye drops containing biocompatible non-viral vectors based on solid lipid nanoparticles (SLNs) as gene delivery systems to induce the expression of interleukin 10 (IL-10) were designed to address the treatment of corneal inflammation. Two kinds of SLNs combined with different ligands (protamine, dextran, or hyaluronic acid (HA)) and formulated with polyvinyl alcohol (PVA) were prepared. SLN-based vectors were characterized in terms of size, adhesiveness, viscosity, and pH, before topical administration to wild type and IL-10 knock out (KO) mice. The formulations showed a homogenous particle size below 400 nm and a positive surface charge to favor bioadhesion; the incorporation of PVA improved the corneal penetration. After three days of treatment by topical instillation, SLN-based vectors mainly transfected corneal epithelial cells, HA-formulations being the most effective ones. IL-10 was capable of reaching even the endothelial layer. Corneal sections showed no histological change and formulations seemed to be well tolerated after repeated topical administration. These promising results highlight the possible contribution of non-viral gene augmentation therapy to the future clinical approach of corneal gene therapy.

Zeta potential of tear samples: A tool to explore the effects of wear of contact lenses

PURPOSE

The aim was to develop a method to assess the electrostatic properties of human tear samples, and to evaluate their modifications induced by the wear of contact lenses (CLs).

METHOD

The barrier method was developed for the measurement of the isoelectric point (IEP) on relatively small quantities. The method was applied to compare three groups: tears (T_NW) of non-wearers, tears (T_{W_etaf}) of regular wearers of etafilcon A CLs, and tears (T_{W_omaf}) of regular wearers of omafilcon A CLs. Zeta potential (ζ) as a function of pH was measured by a Zetasizer Nano ZS90 (Malvern Instruments) on 40%-diluted samples, obtained by mixing 57 μL of tears of different subjects of the same group with 85 μL of HCl aqueous solution. IEP was deduced as the pH at which ζ is zero, i.e. the net electric charge on tear constituents being neutralized.

RESULTS

Within an error of about 0.05, IEPs were found to be 2.90 (T_NW), 2.80 (T_{W_omaf}), and 3.16 (T_{W_etaf}). On average, a lower H⁺ concentration is needed to neutralize the surface charge of the tear components of etafilcon A wearers, compared to both T_NW and T_{W_omaf}.

CONCLUSION

IEP measurements on tear samples of wearers of different types of CLs are proposed in order to enhance the knowledge on the modifications of the profile of charged species in tears. The T_{W_etaf} results, compared to those of the other groups, are compatible with an increase, due to the wear of etafilcon A CLs, of the relative concentration of high-IEP proteins.

Novel liposome-based and in situ gelling artificial tear formulation for dry eye disease treatment

PURPOSE

Artificial tears are widely used in the treatment of dry eye disease, although current formulations do not closely resemble natural tears. The purpose of this study was the design and characterization of a novel in situ gelling artificial tear formulation, containing both lipid and aqueous components, in order to resemble natural tears and replenish the tear film.

METHODS

Liposomes, containing phosphatidylcholine, cholesterol, vitamins A and E, were prepared by the thin-film hydration method. The aqueous phase of the formulation was comprised of gellan gum, hydroxypropyl methylcellulose, levocarnitine, electrolytes (sodium chloride and potassium chloride), trehalose, and borates. The artificial tear was characterized in terms of liposome size, pH, surface tension, and viscosity. In vitro tolerance studies were performed in a human epithelial carcinoma cell line (HeLa) and a murine macrophage cell line (J774). In vivo tolerance was assessed in rabbits.

RESULTS

Liposomes presented a unimodal distribution with a mean size of 200.1 ± 4.4 nm. The resulting surface tension was 53.4 ± 1.1 mN/m (at 33 °C) and the pH was 7.6 ± 0.1. The viscosity of the formulation presented a mean value of 4.0 ± 0.1 mPa s within the shear rate interval of 200-1000 s^-1 at 33 °C. Cell viability remained higher than 90% in both cell lines. No discomfort or clinical signs were observed in rabbits.

CONCLUSIONS

The liposome-based and in situ gelling artificial tear formulation presented good tolerance and suitable properties for topical ophthalmic administration. It may be beneficial in the treatment of dry eye disease.

Photon correlation spectroscopy applied to tear analysis

This study aims to deepen the knowledge on tear film properties by the development of a protocol for analyses of Photon Correlation Spectroscopy (PCS) on human tears and by the comparison between PCS results obtained on tears of contact lens wearers and non-wearers. Tears (5μL) were collected by a glass capillary. The analyses provide the hydrodynamic diameter of tear components by analyzing intensity fluctuations in time of scattered light. PCS appears a promising technique for studying tear features and for shedding light on specific eye conditions, such as on the clinical effects of CL wear. In fact, statistical difference (p<0.001) was found between the measured mean hydrodynamic diameter of tear components of wearers and non-wearers, the resulting value significantly higher for CL wearers. The scenario does not substantially change after (25±5)min from the CL removal. The difference is attributed to changes in the interactions between tear constituents due to CL wear. In order to get deeper insights on the influence of CL wear on aggregation and structure of tear components, a preliminary Electron Spin Resonance (ESR) investigation was performed, monitoring Fe³⁺ species. ESR spectra on tears of both CL wearers and non-wearers showed the presence of intense signals, probably associated to iron (III) centers in proteins such as lactoferrin, and a weaker resonance attributable to Fe³⁺ species interacting with S-S bridges of lysozyme. Differences in ESR spectra between CL wearers and non-wearers were detected and tentatively ascribed to changes in coordination or in local environment of Fe³⁺ centers connected to aggregation phenomena induced by CL wear, which promote their interaction with other neighboring iron species.

TFOS DEWS II Tear Film Report

The members of the Tear Film Subcommittee reviewed the role of the tear film in dry eye disease (DED). The Subcommittee reviewed biophysical and biochemical aspects of tears and how these change in DED. Clinically, DED is characterized by loss of tear volume, more rapid breakup of the tear film and increased evaporation of tears from the ocular surface. The tear film is composed of many substances including lipids, proteins, mucins and electrolytes. All of these contribute to the integrity of the tear film but exactly how they interact is still an area of active research. Tear film osmolarity increases in DED. Changes to other components such as proteins and mucins can be used as biomarkers for DED. The Subcommittee recommended areas for future research to advance our understanding of the tear film and how this changes with DED. The final report was written after review by all Subcommittee members and the entire TFOS DEWS II membership.

[Potential for use of hydroxypropyl guar in tear substitute therapy]

Of the large number of polymers used in artificial tear formulations, natural polysaccharides - hydroxypropyl guar, sodium hyaluronate, chondroitin sulfate, dextran, etc., are gaining more and more popularity. Hydroxypropyl guar stands out through its ability to form a long-lasting structured matrix adhered to the damaged ocular surface and ensuring good wettability of the latter and regeneration of epithelial cells. At that, the viscosity of hydroxypropyl guar increases with increasing tear pH (which, in turn, correlates with the severity of xerosis) and further prolongs the moisturizing effect. According to experimental studies, the in vitro protective activity of hydroxypropyl guar surpasses that of sodium hyaluronate, which is widely used. Thus, corneal epithelial cell cultures were more tolerant to drying and pericardial leaflets showed lower friction coefficient, if pretreated with hydroxypropyl guar and not hyaluronic acid. Subsequent clinical studies showed that Systane Ultra was more effective in patients with dry eye syndrome than a carboxymethylcellulose and glycerol-containing drug. It has been also proved that Systane Balance provides a greater increase in thickness of the tear film lipid layer and in overall stability of the tear film as compared to SootheXP, which has a similar lipid composition. The present review also covers potential utility of other artificial tear formulations that, besides the moisturizing effect, are able to reduce the tear film osmolarity, prevent further oxidative stress, and abate the inflammatory process.

Assessment and Management of Dry Eye Patients for Non-Ophthalmic Healthcare Practitioners

Dry eye is a very common condition in many parts of the world. Both ophthalmologists and other healthcare professionals, such as optometrists and general practitioners, are often involved in the care of these patients. The main thrust of dry eye management is over-the-counter tear lubricants. There is a wide range of tear lubricants available today. These lubricants vary in viscosity, duration of action, type of preservatives, osmolarity/osmolality and pH. This article aims to educate healthcare professionals on 1) how to assess and manage patients with mild to moderate dry eyes and 2) how to identify patients who may need a referral to an ophthalmologist. Strategies on the use of available treatments and their limitations, as well as factors that may affect patient compliance will be discussed.

A randomized clinical evaluation of the safety of Systane Lubricant Eye Drops for the relief of dry eye symptoms following LASIK refractive surgery

Purpose

To evaluate the safety of Systane^® Lubricant Eye Drops in relieving the symptoms of dry eye following laser-assisted in situ keratomileusis (LASIK) surgery.

Methods

This was a randomized, double-masked, single-center, placebo-controlled, contralateral eye study of 30 patients undergoing LASIK surgery. The mean age of patients was 42.4 ± 10.7 years, and the mean spherical equivalent was −3.29 (range, +1.75 to −7.38). Patients’ right and left eyes were randomized to receive either Systane^® or placebo – a preserved, thimerosal-free saline solution – beginning from the day of surgery and ending 30 days following surgery. Outcome measures included tear film break up time (TFBUT), visual acuity, degree of corneal and conjunctival staining, and treatment-related adverse events.

Results

Preoperatively, placebo-treated eyes had statistically significantly higher sum corneal staining score than Systane^®-treated eyes (p = 0.0464); however, the difference was clinically insignificant (p = 0.27). Two weeks post operatively, the average TFBUT in the Systane^®-treated eyes was 1.23 seconds longer than that of the placebo-treated eyes (p = 0.028). All other evaluated variables were comparable between the two treatments. No adverse events were reported in the study.

Conclusion

Systane^® Lubricant Eye Drops are safe for use following LASIK surgery to relieve the discomfort symptoms of dry eye associated with the procedure.

One month use of Systane improves ocular surface parameters in subjects with moderate symptoms of ocular dryness

OBJECTIVE

To evaluate the efficacy of Systane((R)) Lubricating Eye Drops in improving the symptoms of moderate ocular dryness.

METHODS

Fifty subjects with moderate symptoms of ocular dryness were enrolled in this open label study. The mean age of subjects was 57.6 +/- 15.4 years. To be eligible, subjects' tear film break-up time (TFBUT) had to be <10 seconds, and subjects had to have at least one ocular discomfort symptom in addition to dryness. Saline was used for a washout period of 3-5 days. Subjects were re-examined, and those continuing to meet the inclusion criteria were dispensed Systane((R)) and re-examined again after 28 days. At each visit, slitlamp examination was conducted, and ocular discomfort symptoms and TFBUT were evaluated. Subjects rated their overall satisfaction at baseline and on the last visit.

RESULTS

No significant changes in TFBUT or ocular discomfort symptoms were observed after saline use, compared with screening visit. After 28 days of Systane((R)) use there was statistically significant improvement of TFBUT (p = 0.0001) compared with baseline. Subjects experienced significant symptomatic relief for all 6 ocular discomfort symptoms at the endpoint visit.

CONCLUSION

Systane((R)) effectively relieved the symptoms associated with moderate ocular dryness, with measurable improvement in objective TFBUT, subjective symptoms, and overall satisfaction.

The impact of artificial tears containing hydroxypropyl guar on mucous layer

PURPOSE

The aim of this study was to investigate the effect of lubricant eyedrops containing propylene glycol 400 (PEG) and polyethylene glycol (PG) with hydroxypropyl guar (HP-guar) as a gelling agent on the precorneal mucous layer in vivo.

METHODS

Sixteen New Zealand white rabbits were randomly assigned to 1 of 4 groups. All rabbits received PEG/PG/HP-guar tear products in the right eye. PEG/PG/HP-guar with Polyquad, 0.1% hyaluronate sodium, 0.5% carboxymethylcellulose, or phosphate-buffered saline was placed in the left eyes of animals in each group. All eyedrops were used 4 times a day for 7 days. An additional 8 rabbits were randomly assigned to 1 of 2 groups. One group received PEG/PG/HP-guar products 4 times a day for 7 days (long-term exposure group), and the other group received PEG/PG/HP-guar products 3 times at 5-minute intervals (short-term exposure group). Fifteen minutes after the last drop was administered, each cornea was immediately excised and mucous layer thickness measured by transmission electron microscopy.

RESULTS

Mucous layer thickness was significantly greater in eyes treated with PEG/PG/HP-guar products compared with those treated with 0.1% hyaluronate sodium, 0.5% carboxymethylcellulose, or phosphate-buffered saline (all P values < 0.001). There were no significant differences in mucous layer thickness between PEG/PG/HP-guar products and PEG/PG/HP-guar with Polyquad or in the long- and short-term exposure animals.

CONCLUSIONS

This study demonstrates that even a short exposure to PEG/PG/HP-guar tear product increased precorneal mucous layer thickness.

The RIM101 signal transduction pathway regulates Candida albicans virulence during experimental keratomycosis

PURPOSE

To examine the role of the fungal RIM101 signal transduction pathway in the pathogenesis of Candida albicans keratitis.

METHODS

C. albicans wild-type strain SC5314, prototrophic mutant control DAY185, and homozygous fungal mutants for the rim8, rim13, rim20, rim101, and phr1 genes were evaluated in vitro using proliferation and filamentation assays. Scarified corneas of BALB/c and C57BL/6J mice were topically inoculated and observed daily for keratitis severity. Corneal adaptation and pathogenicity were assessed ex vivo by maintaining infected porcine corneas for 3 days in an explantation culture system for histologic evaluation of hyphal penetration.

RESULTS

All C. albicans strains had similar growth kinetics, and SC5314 and DAY185 demonstrated pH-induced filamentation. Fungal mutants had reduced hyphal formation at alkaline and neutral pH, but normal acidic assays ascertained that mutant strains did not have a generalized filamentation defect. SC5314 and DAY185 caused moderate to severe keratitis in mice, whereas fungal strains lacking constituents of the RIM101 pathway had significantly (P<0.05) attenuated severity in vivo. Three days after inoculation of porcine corneas, SC5314 and DAY185 produced hyphae that penetrated 28% and 25%, respectively, of the corneal thickness, and all five mutant strains showed significantly (P<0.05) less stromal penetration.

CONCLUSIONS

The RIM101 signal transduction pathway plays an important role in the development of C. albicans keratitis. The fungal pathway intermediates Rim8p, Rim13p, Rim20p, and Rim101p and the downstream cell-wall protein Phr1p are pivotal in the process of corneal invasion by C. albicans.

A fungal pH-responsive signaling pathway regulating Aspergillus adaptation and invasion into the cornea

PURPOSE

To investigate the role of PalB and PacC, two components of a pH-responsive signal-transduction pathway of Aspergillus nidulans, during the pathogenesis of fungal infection of the cornea.

METHODS

Fungal strains included an A. nidulans wild-type isolate (A83), loss-of-function A. nidulans mutants of the palB (B7) or pacC (C6309) genes, and reconstituted genotypic strains (B7R and C6309R). Doubling times and radial growth rates were examined under neutral and acidic conditions. Corneal virulence was assessed ex vivo by topical inoculation of scarified porcine or human corneas with A. nidulans strains maintained in buffered medium until histologic examination after days 1, 3, and 5.

RESULTS

In vitro growth kinetics were similar for A. nidulans strains in liquid medium at pH 6.0 (P = 0.24) and 7.3 (P = 0.75). The pacC mutant C6309 grew more slowly (P < 0.001) on solid medium, whereas palB and pacC rescuants had growth kinetics comparable to those of the wild-type. Wild-type A. nidulans germinated on porcine corneas and produced hyphae that progressively invaded the stroma, reaching an average maximum penetration of 56% +/- 9% at 5 days after exposure. In contrast, hyphal invasion was significantly less by mutant strains B7 (P = 0.005) and C6309 (P = 0.003). Fungal penetration by C6309 was also significantly less than the wild-type (P = 0.0005) on explanted human corneas. Both fungal rescuants showed stromal invasion similar to the wild-type.

CONCLUSIONS

Corneal invasion by filamentous hyphae is attenuated by palB and pacC mutant strains of A. nidulans. The PacC pathway is involved in regulating fungal filamentation during ex vivo Aspergillus infection of the cornea.

In situ fluorescence measurement of tear film [Na+], [K+], [Cl-], and pH in mice shows marked hypertonicity in aquaporin-5 deficiency

PURPOSE

Tear film composition depends on water and ion transport across ocular surface epithelia and on fluid secretion by lacrimal glands. The purpose of this study was to establish in situ fluorescence methods to measure tear film ionic concentrations and pH in mice and to determine whether tear film composition is sensitive to deficiency of the major ocular surface aquaporin water channels.

METHODS

Tear film ionic concentrations and pH were measured in anesthetized mice by ratio imaging fluorescence microscopy after topical application of ion/pH-sensing, dual-wavelength fluorescent indicators. [Na(+)], [K(+)], and [Cl(-)] were measured with membrane-impermeant indicators developed by our laboratory, and pH was measured with bis(carboxyethyl)-carboxyfluorescein fluorescence-conjugated dextran. Measurements were performed on wild-type mice and on knockout mice lacking aquaporins AQP1, AQP3, and AQP5.

RESULTS

In wild-type mice, tear film [Na(+)] was 139 +/- 8 mM, [K(+)] was 48 +/- 1 mM, [Cl(-)] was 127 +/- 4 mM, and pH was 7.59 +/- 0.2 (SE; n = 5-8). pH did not differ significantly in the AQP knockout mice. [Na(+)] was increased by approximately twofold in AQP5 null mice (230 +/- 20 mM) and was greatly reduced after exposure of the ocular surface to a humidified atmosphere. [K(+)] was mildly reduced in AQP1 null mice.

CONCLUSIONS

These results establish an in situ optical methodology to measure tear film [Na(+)], [K(+)], [Cl(-)], and pH in living mice, without the need for fluid sampling. Tear film hypertonicity in AQP5 deficiency is likely caused by reduced transcorneal water secretion in response to evaporative water loss.

An evaluation of tear film breakup time extension and ocular protection index scores among three marketed lubricant eye drops

PURPOSE

To report the performance of an artificial tear containing propylene glycol and polyethylene glycol as active demulcents with hydroxypropyl-guar as a gelling agent (Systane Lubricant Eye Drops; Alcon, Fort Worth, TX) and compare it with that of 2 artificial tears containing carboxymethylcellulose (Refresh Tears and Refresh Endura Lubricant Eye Drops; Allergan, Irvine, CA).

METHODS

This was a single-center, 3-visit, randomized, double-masked crossover study that evaluated the effect of Systane versus Refresh Tears and Refresh Endura using tear film breakup time (TFBUT) and ocular protection index (OPI) in subjects with dry eye (n = 50). TFBUT values (5, 10, 15, 20, 30, 45, and 60 minutes after instillation) divided by interblink interval (IBI) yielded OPI scores.

RESULTS

Systane significantly improved TFBUT at 5, 10, 15, 20, and 60 minutes versus Refresh Tears and at 5, 10, 15, 20, and 30 minutes versus Refresh Endura. Systane OPI scores were significantly higher than Refresh Tears at 15 and 30 minutes and than Refresh Endura at 5 minutes.

CONCLUSIONS

This study suggests that Systane Lubricant Eye Drops was more effective than Refresh Tears at prolonging TFBUT up to 20 minutes after instillation and more effective than Refresh Endura at prolonging TFBUT up to 30 minutes after instillation. These data show that Systane is an effective first-line dry eye therapy and a superior ocular surface protector compared with Refresh Endura and Refresh Tears in the sample test population.

A clinical evaluation of Systane

BACKGROUND

Systane is a new artificial tear solution containing the pH dependent gelling polymer hydroxypropyl-Guar (HP-Guar). We evaluated Systane in an open trial.

METHODS

Patients complaining of dry feeling eyes were eligible to enroll, with inclusion criteria based on the presence of corneal staining with sodium fluorescein (NaFl) and participants' desire to use ocular lubricants. Six symptoms of ocular irritation were rated on a four-point scale. Conjunctival injection, conjunctival and corneal fluorescein staining were graded and tear break-up time (TBUT) and tear meniscus height were measured. Subjects were instructed to instill one drop of Systane into each eye four times a day for approximately four weeks. Ocular symptoms and signs were then reassessed and subjects were asked to rate eight statements concerning their satisfaction with the product.

RESULTS

A total of 38 subjects were enrolled with 32 completing the follow-up visit. The following variables improved significantly at follow-up: all ocular irritation symptom scores, conjunctival injection, total conjunctival and total corneal staining scores, and TBUT. Tear meniscus height showed no significant change. Systane proved effective in reducing the symptoms of dry eye; however induced blur appeared to be a complication for many participants.

CONCLUSIONS

The study represents a community based evaluation of the benefits of a novel ocular lubricant in optometric practice. The results suggest that the gelling properties of HP-Guar may be influential in promoting ocular surface recovery through improved ocular surface retention, however further randomised controlled trials are needed to confirm this. The extent and significance of induced blur also needs further investigation.

Aqueous humor levels of topically applied levofloxacin, norfloxacin, and lomefloxacin in the same human eyes

PURPOSE

To assess the relative penetration of topical eyedrops of 3 fluoroquinolones into the aqueous humor in human eyes.

SETTING

Department of Ophthalmology, Sano-Kosei Hospital, Sano, Japan.

METHODS

Fifty-nine cataract patients (36 women, 23 men) received 3 drops each of levofloxacin 0.5%, norfloxacin 0.3%, and lomefloxacin 0.3% in the same eye at 15-minute intervals beginning 90 minutes before cataract surgery. At the beginning of surgery, 50 microL of aqueous humor was aspirated from the anterior chamber and stored at -80 degrees C until analyzed. The drug concentrations in the samples were analyzed using high-performance liquid chromatography.

RESULTS

Five patients were excluded from the study because their sample volumes were insufficient. Norfloxacin was detected in 3 patients; the mean aqueous humor level was 0.10 microg/mL +/- 0.02 (SD). Levofloxacin was detected in all cases; the mean aqueous humor level was 0.60 +/- 0.28 microg/mL (n = 54). Lomefloxacin was not detected in 10 patients; the mean aqueous humor level was 0.23 +/- 0.11 microg/mL (n = 44).

CONCLUSION

Topically applied levofloxacin had better penetration into the aqueous humor than lomefloxacin and norfloxacin.

Corneal ciprofloxacin precipitation during bacterial keratitis

PURPOSE

To examine how age affects the risk of developing a white corneal precipitate during ciprofloxacin therapy for bacterial keratitis and to explore the effect of a white precipitate on rates of clinical improvement and cure.

DESIGN

Prospective, multicenter, observational cohort study.

METHODS

Occurrence of a white precipitate of the corneal surface was recorded among 624 patients with presumed bacterial keratitis who were treated with topical ciprofloxacin 0.3% solution or ointment. Relative risks of corneal precipitation were estimated from logistic regression for age categories and other clinical characteristics. The time-dependent effects of precipitate on rates of infection resolution and corneal reepithelialization were estimated by proportional hazards regression.

RESULTS

Ninety-five (15.2%) patients developed a white corneal precipitate during ciprofloxacin therapy; 72 (75.8%) began within the first 3 days of treatment. Compared with those younger than 40 years old, patients aged 60 to 69 years had 2.8 (95% confidence limits [CL], 1.9, 3.9) times the risk of ciprofloxacin precipitation; patients 70 years and older had 3.7 (95% CL, 2.6, 5.0) times the risk. Median duration of the visible corneal precipitate was 8.5 days (90% decile, 32 days). Presence of ciprofloxacin precipitation did not significantly affect the time until therapeutic improvement (P =.09) but slowed the time until reepithelialization by 55% (95% CL 32%, 70%).

CONCLUSIONS

Older patients treated with topical ciprofloxacin for bacterial keratitis have a higher risk of corneal deposition. A white precipitate apparently does not interfere with antibacterial therapeutic response but may delay epithelial healing of ulcerative keratitis.

Demonstration of increasing standard pH value of lacrimal fluid with increase of flow rate

PURPOSE

To test the hypothesis that pH value of human tears is affected by flow rate.

METHODS

After stimulation with a drop of 70% alcohol into the ipsilateral nasal cavity tears from the left eyes of 30 healthy volunteers were collected with glass capillaries while flow rate of tear secretion was registered. The pCO(2), actual and standard pH were determined in the collected samples with the Astrup method: Standard pH is defined as the pH of the sample that has been equilibrated at 37 degrees C with a gas mixture having pCO(2)=40 mmHg.

RESULTS

The flow rate correlated positively and significantly with both the standard pH value (r=0.503, p<0.01) and the pCO(2) (r=0.517, p<0.01) while there was no correlation between the actual pH and the flow rate.

CONCLUSION

Loss of CO(2) from the sample is a cause of serious uncertainty in tear pH determination. A positive flow rate-pH relationship was found for human tears when the uncertainty was removed by determination of the standard pH.

Contact lens-associated chemical burn

We present the case of a young man who presented as an ophthalmic casualty after inserting a pair of bizarre-effect cosmetic hydrogel contact lenses while in a night-club. He failed to follow the manufacturer's guidelines and inserted the lenses before neutralising the storage solution. On presentation he was found to have bilateral corneal epithelial defects which required hospital treatment for 4 days. He appears to have suffered no long-term sequelae.