Introduction: Different polymers used in artificial tear formulations influence their physical properties, such as viscosity and pH, hence affecting their bioavailability. There is limited data available from manufacturers specifying the physical properties of artificial tears, even though these data can contribute to their efficacyand effectiveness. Purpose: The aim of this study was to evaluate 18 artificial tears available in the Malaysian market based on their physical properties. Methodology: Viscosity and pH of 18 artificial tears were evaluated using rheometer and compact pH-meter, respectively, at standard room temperature (25°C). The amount of fluid used for both tests of each artificial tear was standardised using micropipette. The Kruskal-Wallis test was employed to compare the viscosity median between the three groups (low, medium, and high viscosity) of artificial tears, while the independent t-test was used to compare the pH between preservative and non-preservative artificial tears. A p-value of 0.05 was set as the level of significance. Results: The mean viscosity for all 18 artificial tears was 12.05 cP ± 10.21 within a range of 0.55 cP to 34.49 cP. There was a significant difference observed in viscosity between low- (n = 7), median- (n = 8), and high- (n = 3) viscosity groups, χ2(2) = 14.474, p = 0.001. The mean pH for all 18 artificial tears was 7.21 ± 0.43, with a range of 6.19 to 7.85. pH for preservative artificial tears was slightly alkaline compared to non-preservative artificial tears (7.26 ± 0.47 vs 7.14 ± 0.38, respectively). Conclusion: Rheological findings indicated that different formulations of artificial tears have different viscosities, with most artificial tears falling within the recommended values. There was no difference in terms of pH between preservative and non-preservative artificial tears.

Introduction: This study aimed to evaluate the short-term efficacy of artificial tears (AT) instillation on tear film quality and quantity utilising two dual polymer artificial tears; Systane Hydration preservative (SH) and non-preservative (SHUD) in 60 minutes observation period compared to normal saline.  Materials and methods:  One hundred eyes of 50 participants involved in this prospective, double-masked randomised study. Viscosity and pH of both AT were evaluated using Rheometer and digital pH-meter respectively prior to tear film characteristics assessment. Tear break-up time (TBUT) and tear meniscus height (TMH) were measured at baseline, 5, 15 and 60 minutes after instillation. Tear ferning pattern (TFP) were compared between baseline and 60 minutes after instillation. One-way analysis of variance (ANOVA) was used to evaluate the effects of both AT instillation. Independent T-test was employed to compare between the two groups (SH vs SHUD) for each specific time-interval. P-value of 0.05 was set as the level of significance. Results: The viscosity of SH and SHUD was 0.0267Pa.s and 0.03273Pa.s respectively with pH of 7.85 for SH and 7.74 for SHUD. Both AT showed significant increment in TBUT between baseline and 15 minutes (SH: 5.82 ± 1.063,  p = 0.01; SHUD: 6.02 ± 0.979,  p<0.001), and 60 minutes (SH: 6.22 ± 0.616, p<0.001; SHUD: 6.34 ± 0.658, p<0.001). SHUD demonstrated significant increment in TMH at every measurement taken (0.1996 ± 0.02449,  p<0.001 at 5min, 0.2038 ± 0.02276,  p<0.001 at 15min and 0.2068 ± 0.02094, p<0.001 at 60min). Likewise, in SH group, significant increment in TMH at 15 minutes (0.1994 ± 0.02325,  p < 0.001) and 60 minutes (0.2012±0.02379,  p<0.001) were noted. With regards to TFP, both groups revealed improvement in TF grading (both,  p<0.001) at 60 minutes. No significant improvement was noted in control group. Conclusion:  Both SH and SHUD improved tear film characteristics at 60 minutes following instillation. However, SHUD is more effective as faster improvements were noted in all intended parameters.

Background: Artificial tears (ATs) are widely used in ophthalmic practice with various formulations, mainly as a treatment for dry eye, owing to their rapid ability to alleviate the signs and symptoms of this condition. We aimed to investigate drop comfort and subjective ocular symptoms after instillation of the following ATs with different physical properties: Optive® non-preservative (OUD) and Systane® Hydration non-preservative (SHUD). Methods: This was a prospective, double-blind, randomized, contralateral eye comparison study. A rheometer and a digital pH meter were used to evaluate the viscosity and pH of both ATs prior to instillation. We recruited 36 patients with dry eye disease. Single standardized AT volumes were set using a micropipette for all patients. Ocular discomfort was assessed using the Ora Calibra™ Ocular Discomfort and 4-Symptom Questionnaire (OOD4SQ; 0 – 5 scale) before and 60 min after instillation. Drop comfort was assessed using the Ora Calibra™ Drop Comfort Scale (0 – 10 scale) immediately after AT instillation. The difference in the drop comfort score (DCS) between the two ATs and ocular discomfort scores using OOD4SQ before and 60 min after instillation of each AT were recorded and compared. Results: The viscosities and pH of SHUD and OUD were 32.73 centipoise (cP) and 7.74 and 14.42 cP and 7.19, respectively. The mean (standard deviation) DCS was higher in the SHUD group than in the OUD group (1.83 [1.21] versus 1.67 [1.12]); however, the difference was not statistically significant (P > 0.05). There was a significant reduction in all parameters of OOD4SQ including overall discomfort, burning, dryness, grittiness, and stinging 60 min after OUD instillation (all P < 0.05), while a significant difference was only noted in dryness (P < 0.05) in the SHUD group. Conclusions: OUD, which has a lower viscosity and pH compared to SHUD, provides less subjective sensation and better ocular comfort 60 min after instillation. Further randomized clinical trials including patients with dry eye disease of different severities, larger sample sizes, and longer follow-up periods are required to verify our findings.