Abstract
Purpose: To quantitatively assess the effects of pH on the corneal stroma under an applied hydrostatic pressure. Methods: Sclera-stroma preparations from adult sheep eyes were perfused with isotonic mixed salts solutions at 37°C for 9 hr under an applied hydrostatic pressure and then fixed for electron microscopy.Results: Exposure to pH 7.25 solutions resulted in slight swelling, retention of lamellae, and the keratocytes were intact. The collagen fibril diameter was 40.0 ± 3.5 nm, which was the same as non-perfused samples (40.9 ± 3.7 nm). Perfusion at pH 5.75 resulted in slight compaction, some disorganization of the lamellae, and almost total destruction of the keratocytes. The collagen fibril profiles in cross section were irregular and reduced to a mean of 30.2 ± 3.5 nm (p < 0.001). Conclusions: Exposure of the corneal stroma to slightly acid pH at the so-called critical electrolyte concentration pH for proteoglycan-ionic interactions can cause substantial structural changes.