Immediate effects of artificial tears with and without preservatives containing hyaluronic acid and carboxymethyl cellulose
Authors: Arif Fatin Amalina Che , Hilmi Mohd Radzi , Rejab Noor Shazana Md , Wolffsohn James S 
Published: October 2023

Background: Currently, hyaluronic acid (HA) and carboxymethyl cellulose sodium (CMC) are common polymers incorporated in artificial tears (ATs). The aim of the present study was to evaluate the immediate effect of preservative- and preservative-free HA- and CMC-containing ATs on tear-film parameters and determine patient preference after AT instillation.

Methods: In this prospective, double-blind, randomized, comparative study, we assessed fluorescein tear break-up time (TBUT), bulbar redness, and tear ferning pattern (TFP) up to 60 min after the instillation of ATs with and without preservatives containing HA and CMC in the recruited participants. To test patient preference, each patient was administered with the Ora Calibra™ Ocular Discomfort and 4-Symptom Questionnaire (OOD4SQ; scale of 0–5) before and 60 min after the instillation of ATs. The selection of 14 descriptive words based the 11-point Ora Calibra™ Drop Comfort Scale (ODCS; scale of 0–10) was administered immediately after instillation of each AT to test the drop comfort score.

Results: We enrolled 200 eyes of 200 patients, including 163 (81.5%) women and 37 (18.5%) men, with a mean (standard deviation) age of 28.38 (5.42) years. Immediately or 5, 15, or 60 min after the instillation, the mean TBUT did not differ by presence of preservatives, HA, or CMC (all P > 0.05). However, it was significantly higher 5-min post-instillation compared to baseline and significantly lower 15- and 60-min post-instillation (all P < 0.05). The mean grade of bulbar redness immediately or 3, 5, 15, or 60 min after instillation did not differ by presence of preservatives for HA or CMC containing ATs (all P < 0.05). It did not differ significantly 3-, 5-, 15-, or 60-min post-instillation compared to baseline (all P > 0.05). The mean drop comfort scale after the instillation of ATs did not differ significantly by presence of preservatives, HA, or CMC (all P < 0.05). Positive descriptive words were selected by a higher proportion of participants in both groups. According to OOD4SQ, the overall discomfort and mean dryness scores improved significantly after instillation of HA-containing ATs (both P < 0.05), while the mean burning sensation, grittiness, and stinging scores remained unchanged (all P > 0.05). The overall discomfort and mean scores for each ocular symptom (P < 0.05), except for stinting (P > 0.05), improved significantly after instillation of CMC-containing ATs. The TFP did not change significantly from baseline to 60 min after the instillation of any AT (P > 0.05).

Conclusions: Both ATs with and without preservatives containing HA and CMC produced positive short-term objective and subjective effects. However, TBUT, TFP, bulbar redness, and patient feedback were comparable for both HA- and CMC-containing ATs. Further trials with longer observation periods or the recruitment of patients with different severities of dry eye could provide more robust and clinically applicable conclusions.