[Sustained effects of sodium hyaluronate solution on tear film stability evaluated by Tear Stability Analysis System]

To investigate the sustained effects of sodium hyaluronate solution (HA) on tear film stability using a Tear Stability Analysis System (TSAS), a method enabling quantitative evaluation of tear film stability.

Eighteen eyes of 18 normal subjects (N group) and 21 eyes of 21 dry eye patients (D group) were examined. Dry eye was diagnosed by the 2006 diagnostic criteria. In each subject, artificial tears (AT), 0.1% sodium hyaluronate solution (H 01) or 0.3% sodium hyaluronate solution (H 03) were instilled into both eyes, and tear film stability in the right eye before and 1, 5, 15, 30, 60 and 120 minutes after instillation was compared using a break up index (BUI: 0-100), the TSAS's index of tear film stability.

N group: In both the AT and H 01 subgroups, no significant change was found in the BUI ratios (BUI after instillation/before instillation) at any point during the 120 minute period after instillation. However, in the H 03 subgroup, the BUI ratio temporarily decreased to 0.650 one minute after H 03 instillation (p = 0.0038). D group: In the AT subgroup, the BUI ratio significantly increased to 1.568 five minutes after AT instillation (p = 0.0259), but began to decrease 15 minutes after instillation and returned to the initial value 30 minutes after instillation. In the H 01 subgroup, the BUI ratio significantly increased to 1.531 five minutes after H 01 instillation (p = 0.0087), and was maintained at 1.347 120 minutes after instillation (p = 0.0088). In the H 03 subgroup, the BUI ratio rose to 1.544 15 minutes after H 03 instillation (p = 0.0009), and was maintained at high levels of 1.413 30 minutes after (p = 0.0122), 1.629 60 minutes after (p = 0.0008), and 1.407 120 minutes after instillation (p = 0.0008).

The current study confirms that both 0.1 and 0.3% sodium hyaluronate solution effectively improve tear film stability in dry eyes for up to two hours after instillation.