Protective effects of citric acid-disodium hydrogen phosphate rinsing solution on ocular surface of mice with acute chemically induced corneal burns

Background

Immediately ocular rinsing is a key step for the prevention of eye tissue damage after acute chemical burns.A good ophthalmic rinsing solution can neutralize chemical substance and improve the prognosis of patients.

Objective

This study attempted to evaluate the therapeutic effect of self-made citric acid-disodium hydrogen phosphate buffer and citric acid-disodium hydrogen phosphate-potassium chloride buffer on corneal chemical burns in mice.

Methods

Citric acid-disodium hydrogen phosphate buffer solution (solution 1) and citric acid-disodium hydrogen phosphate-potassium chloride buffer solution (solution2) with the pH 7.4 were prepared.One hundred and twenty clean male C57 mice aged 6-8 weeks were randomized to two groups, and filter papers containing 1 mol/L H₂SO₄ or 0.15 mol/L NaOH were attached to the central corneas of the right eyes to create the acid or alkali burning models.Then the eyes were immediately rinsed by 40 ml solution 1, tap water or solution 2 according to the grouping and the model eyes without rinsing served as the control group.The corneal opacity was examined by slit lamp microscope and scored in 3, 7 and 14 days after modeling.The percentages of corneal fluorescein staining, corneal neovascularization and corneal ulcer were analyzed.The study protocol was approved by Experimental Animal Ethic Commission of Second Military Medical University.

Results

In the corneal acid burning models, the number of eye with corneal opacity scored 1 in the solution 1 group, tap water group and solution 2 group was significantly more than that in the non-rinsing group in 3, 7 and 14 days after modeling (all at P<0.01); In 3 days after modeling, the numbers of eye scored 1 were more in the solution 1 group than those in the tap water group and solution 2 group (χ²=11.000, P=0.001; χ²=4.000, P=0.046). There were no differences in the eye number of different corneal opacity scores in 14 days after acid burning (all at P>0.05). In 3, 7 and 14 days after corneal alkali burning, the number of eyes with corneal opacity scored 1-2 was significantly increased in the solution 1 group, tap water group and solution 2 group compared with non-rinsing group (all at P<0.01). The percentage of corneal ulcer in the solution 1 group, tap water group and solution 2 group was 7%, 27% and 13%, respectively, which was significantly lower than 73% in the non-rinsing group(P=0.000, 0.027, 0.003), and no significant differences were seen in various time points after corneal alkali burning (all at P>0.05). Corneal neovascularization occurred in 50% mice in non-rinsing group in 14 days after acid burning.However, no neovascularization was seen in the mice of the solution 1 group, tap water group and solution 2 group in both acid and alkali burning mice.

Conclusions

Citric acid-disodium hydrogen phosphate buffer (pH 7.4) appears to be an effective emergency rinsing solution for corneal chemical burns and the rinsing solution with or without potassium chloride is not obviously affected to the prognosis of corneal chemical burns in the mice.

Eye burns/chemically induced; Burns, chemical/drug therapy; Cornea; Buffer solution; Emergency treatment/methods; Citric acid and disodium hydrogen; Potassium chloride; Mice, inbred C57