A 28-year-old female presents 3 days after a lime (calcium oxide) splash to her right eye. She reports initial severe pain that has now subsided, but vision remains poor. On examination, the cornea appears opaque with a white, ground-glass appearance. The conjunctiva shows blanching and ischemia in the interpalpebral zone. Intraocular pressure is 28 mmHg. What is the most important prognostic indicator in this alkali burn?