Abstract
Purpose: :
It is reported that the P2Y2 receptor agonist, diquafosol tetrasodium, stimulated tear fluid secretion on Schirmer test. On the other hand, sodium hyaluronate is known to have a good water retention property, although its viscosity makes it difficult to measure tear fluid volume by Schirmer test. We have evaluated the combined effect of diquafosol tetrasodium and sodium hyaluronate ophthalmic solutions on the tear fluid volume of normal rabbits by measurements of the tear meniscus area.
Methods: :
The tear fluid volume on the rabbits was measured to obtain the Schirmer test value with topical anesthesia. To measure the tear meniscus area, digital photographs with a blue filter were taken to cover the whole area after instilling 3 µ L of 0.1% fluorescien dye without topical anesthesia. The tear meniscus area was then calculated by WinRoof, software for digital imaging analysis. The efficacy was shown as Δ tear meniscus area (Δ value), that is, the difference observed before and after instillation of each ophthalmic solution.
Results: :
The volume of external instillation to the ocular surface was accurately reflected in the Δ value. The efficacy of 0.1% sodium hyaluronate could not be confirmed by the Schirmer test, however, the Δ value of sodium hyaluronate was higher than that of artificial tears for 5 min after instillation. The efficacy of 3% diquafosol tetrasodium on the Δ values at 5-30 min after instillation was higher than that of sodium hyaluronate. The combined effect of diquafosol tetrasodium and sodium hyaluronate on the Δ value was higher than that of the single instillation of diquafosol tetrasodium or sodium hyaluronate at 5 and 30 min.
Conclusions: :
Measurement of the tear meniscus area was found to be a minimally invasive and useful method to evaluate the tear fluid volume. The combination of diquafosol tetrasodium and sodium hyaluronate seems to keep the tear fluid on the ocular surface more and longer than that of the single instillation of either drug. Thus, a combination of diquafosol tetrasodium and sodium hyaluronate may offer a more effective for dry eye than a single treatment.
Keywords: cornea: tears/tear film/dry eye