Comparison of Ocular Lubricant Osmolalities

Safe and Effective Management of Dry Eye Symptoms with Hydroxypropyl Guar and Hyaluronic Acid Dual-Polymer Lubricating Eye Drops: A Review of Preclinical and Clinical Studies

Dry eye disease (DED) is a chronic ocular surface disorder often characterized by decreased tear production and rapid tear evaporation that affect tear film stability and homeostasis. The common symptoms of DED include ocular discomfort, visual disturbances, dryness, and itching. Artificial tears are the mainstay of DED management and supplement one or more layers of the tear film. Artificial tear drops are available as a combination of viscosity-enhancing agents (demulcents/lubricants), humectants, and buffers either with or without preservatives. Artificial tears, as a combination of components (polymers/demulcents/viscosity-enhancing agents), can provide synergistic action compared with a single component for the management of multifactorial signs and symptoms of DED. This review describes the formulation components, physicochemical properties, mechanism of action, and summary of preclinical and clinical evidence on the hydroxypropyl guar-hyaluronic acid (HPG-HA) dual-polymer lubricant eye drops (SYSTANE™ HYDRATION). The dual-polymer eye drops consist of dual demulcents (propylene glycol and polyethylene glycol 400) and the polymers hydroxypropyl guar (HPG) and hyaluronic acid (HA). When instilled on the ocular surface, HPG forms a cross-linked gel matrix with borate ions that prolongs the retention of demulcents, thus providing long-lasting lubrication and ocular surface protection. Additionally, HA stabilizes the tear film, increases corneal wettability, and reduces friction during blinks due to its hygroscopic and viscoelastic properties. Preclinical evidence demonstrates that HPG HA dual-polymer lubricant eye drops provide protection against desiccation by cell hydration and surface retention, cell barrier protection, prolonged lubrication, and promotion of corneal re-epithelialization. Clinical scientific evidence demonstrates that HPG HA dual-polymer lubricant eye drops are safe and effective in the management of DED. Specifically, they reduce the signs and symptoms of DED, reduce dry eye symptoms post-cataract surgery, and improve tear film quality in healthy eyes.

Effect of artificial tears on dynamic optical quality in patients with dry eye disease

BACKGROUND

In clinical practice, fluctuating vision or decreased quality of vision is a common complaint in DED patients. Our study was designed to investigate the change in dynamic optical quality in dry eye patients after the use of artificial tears.

METHODS

Fifty-nine patients with dry eye disease (DED) and 31 control subjects were included in this prospective case-control study. There was no significant difference in age and sex between these two groups (P = 0.342, P = 0.847, respectively). Clinical evaluation of the ocular surface included Ocular Surface Disease Index (OSDI), tear film break-up time (TBUT), lipid layer thickness (LLT), and Schirmer I test. DED patients were divided into two groups, mild (31 patients) and severe (28 patients). The optical quality of the tear film was measured with the Optical Quality Analysis System (OQAS) using the mean objective scatter index (mean OSI), standard deviation of objective scatter index (SD-OSI) and modulation transfer function cut-off (MTF cut-off). After baseline examinations, one drop of artificial tears (ATs, carboxymethylcellulose ophthalmic solution, 0.5%) was instilled in both eyes, and optical quality parameters were measured again at 5 and 30 min following application of ATs.

RESULTS

At baseline, the mean OSI was higher in the DED group (0.95 ± 0.54) than in controls (0.54 ± 0.23, P < 0.001). The SD-OSI was also significantly increased in DED patients (0.44 ± 0.71) compared to control subjects (0.12 ± 0.06, P = 0.003). Five minutes after AT instillation, mean OSI and SD-OSI decreased significantly in severe DED patients (P = 0.044; P = 0.018), remained unchanged in mild DED patients, and increased in the control group (P = 0.019; P < 0.001). Thirty minutes after AT instillation, no significant difference in optical quality parameters was observed among the three groups.

CONCLUSION

The effect of ATs on optical quality in patients with DED may differ according to the severity of the disease. Measurement of optical quality might be a promising tool to evaluate the effects of various ATs and possibly individualize treatment in DED patients.

Osmolality and pH of commercially available contact lens care solutions and eye drops

PURPOSE

The physical properties of contact lens care solutions and Eye Drops (ED) may affect initial comfort and dry eye symptomatology in contact lens wearers, although these properties are not always provided by manufacturers. The present study aimed to measure and compare the osmolality and pH of commercially available contact lens care solutions and ED.

METHODS

Forty-four solutions were tested (17 lens care solutions and 27 ED) and classified by the presence and/or combination of the viscosity/lubrication-enhancing ingredients. Solution osmolality was obtained with the Fiske 110 osmometer and pH was measured with a micro-pH 2000. Each measurement was taken ten times, following the manufacturer's instructions, while controlling for room temperature and humidity. Differences between the values of the physical properties of the solutions were analysed by type and viscosity/lubrication-enhancing agent subclassification.

RESULTS

Osmolality ranged from 192.6 ± 2.17 to 364.6 ± 2.88 mOsm/Kg, while pH ranged from 6.35 [6.35-6.26] to 7.99 [7.99-8.00]. A significant difference in the osmolality and pH values of contact lens care solutions and ED was found when classified by type or viscosity/lubrication-enhancing agent (ANOVA and Kruskal-Wallis respectively, both p < 0.001).

CONCLUSIONS

The physical properties of some contact lens care solutions and ED are not readily available. The osmolality and pH values of various commercially available lens care solutions and ED vary significantly both by type and viscosity/lubrication-enhancing ingredients.