A Comparison of Corneal Stromal Edema Induced From the Anterior or the Posterior Surface*

Abstract

BACKGROUND: Many differences between the anterior and posterior corneal stroma have been reported. The physiological and mechanical properties of the cornea are a summation of these properties across each of the corneal regions. This article investigates corneal stromal swelling that is experimentally induced through each surface. METHODS: Corneal stromal swelling was induced in human and rabbit corneas through either the anterior or posterior surface. The rate of stromal swelling was analyzed with a linear regression model. RESULTS: Swelling in the rabbit stroma was 3.65 x faster when induced through the posterior surface than through the anterior surface (p less than .0001), while the human stroma swelled 13.1 x faster through the posterior surface (p less than .0001). The hydration of the stroma increased during swelling through the posterior surface, but paradoxically decreased during swelling through the anterior surface. CONCLUSIONS: These experiments showed that stromal swelling occurs more rapidly through the posterior corneal surface than through the anterior surface. These results may have implications for the refractive surgeon performing laser ablative procedures on the anterior surface of the cornea.