The Effect of Sodium Hyaluronate on the Migration of Rabbit Corneal Epithelium. II. The Effect of Topical Administration

Abstract

ABSTRACT

The effect of topically administered sodium hyaluronate (Na-HA) on the healing of corneal epithelial defect was investigated using rabbit eyes. The corneal epithelium was removed surgically or with iodine vapor or n-heptanol, and saline was administered to one eye as the control, and 0.1% or 0.25% Na-HA with a molecular weight of 87.3 × 10⁴ to the other eye once daily. The area of epithelial defect was measured once daily before a topical administration, and the healing rate of epithelial defect was calculated.

When the corneal epithelium was removed with iodine vapor, a topical administration of 0.1% or 0.25% Na-HA did not significantly accelerate the epithelial healing. But when removed surgically or with n-heptanol, the healing rates of the corneas treated with 0.25% Na-HA significantly exceeded those of the control eyes. When the epithelium was removed surgically, treatment with 0.1% Na-HA also significantly accelerated the healing.

To determine why the effect of Na-HA differed in these three models with the epithelial defect, the amount of fibronectin (FN) produced by the cornea with epithelial defect and that of Na-HA retained on the cornea were investigated. The amount of FN produced was determined from the concentration of FN in the medium obtained after incubation of the corneo-scleral section with corneal epithelial defect, and the amount of Na-HA retained on that cornea was estimated from radioactivity detected in tears and cornea after a topical administration of ¹⁴C-labeled Na-HA (¹⁴C-Na-HA). The corneo-scleral section whose corneal epithelium had been removed surgically, or with n-heptanol, produced a significantly larger amount of FN than that whose corneal epithelium had been removed with iodine vapor. In addition, the amount of ¹⁴C-Na-HA retained on the cornea of the first or second model also significantly exceeded that on the cornea of the third model.

The topical administration of Na-HA would thus appear to accelerate the healing of the epithelial defect producing a larger amount of FN or retaining a larger amount of Na-HA.