Long term treatment with sodium hyaluronate-containing artificial tears reduces ocular surface damage in patients with dry eye

Abstract

Background/aims: Several studies have reported that sodium hyaluronate is able to improve both symptoms and signs in patients with dry eye but none have demonstrated an improvement of conjunctival epithelial cell abnormalities of the ocular surface. The aim of this study was to explore the effect of sodium hyaluronate-containing eye drops on the ocular surface of patients with dry eye during long term treatment.

Methods: A randomised double blind study was undertaken in 86 patients with medium to severe dry eye (that is, rose bengal and/or fluorescein test score of at least 3, tear film break up time <10 seconds, or Schirmer's test <5.5 mm). Patients were treated with either preservative-free sodium hyaluronate or saline for 3 months at a dose of one drop 4-8 times a day. Bulbar impression cytology, slit lamp examinations, and subjective symptoms were evaluated after 1, 2, and 3 months. Impression cytology was considered the primary efficacy parameter of the study.

Results: The efficacy analysis was performed on a total of 44 patients who were able to fully adhere to the protocol. After 3 months of treatment sodium hyaluronate improved impression cytology score (p = 0.024 v baseline). At the same time also the difference with respect to placebo was statistically significant (p = 0.036). Study medication was well tolerated and no treatment related adverse events occurred during the study.

Conclusions: Sodium hyaluronate may effectively improve ocular surface damage associated with dry eye syndrome.

Figure 1

Impression cytology scores after treatment with sodium hyaluronate (Na-Ha) or saline (placebo). Data are expressed as mean values (SEM) of left and right eye scores obtained at each day visit (V1 = baseline; V2 = 1 month; V3 =2 months; V4 =3 months). Between groups comparison (Na-Ha v saline): V1: p = 0.115; V2: p = 0.720; V3: p = 0.479; V4: *p =0.036. Within groups comparison: saline: V2 v V1: p = 0.776; V3 v V1: p = 0.752; V4 v V1: p = 0.259. Na-Ha: V2 v V1: p = 0.083; V3 v V1: p = 0.158; V4 v V1: *p = 0.024.

Figure 2

Cell characteristics after treatment with either sodium hyaluronate or saline. (A) Cytological characteristics before treatment (visit 1): presence of large epithelial cells, showing a polygonal shape and a variable staining cytoplasm and a nucleus/cytoplasm ratio of 1:3 – 1:4; goblet cells are absent. (B). Sodium hyaluronate group after 3 months of treatment (visit 4): presence of both smaller cells with polygonal and round shape and of goblet cells. (C and D) Saline group after 3 months of treatment (visit 4): presence of polygonal cells with keratinised, basophilic cytoplasm with markedly reduced nucleus/cytoplasm; goblet cells are absent.