Connective tissue remodeling in corneal and scleral wounds

The fluorescent dye dichlorotriazinyl aminofluorescein will bind to amino groups of proteins covalently under physiological conditions. It has been used to dye the connective tissue around an ulcer or nonpenetrating, linear incision in the rabbit cornea and sclera, and the healing of the tissue has been examined up to 1 yr later. Sagittal sections were stained for light microscopy, and adjacent unstained sections were examined in the fluorescence microscope. The stained sections showed the reestablishment of the lamellar organization of the stromal collagen across the site of the incision; the fluorescence showed where the connective tissue that was present when the wound was made persisted, and thereby defined the limits of remodeling in the healing process. In Bowman's layer and the adjacent stroma, there was often an abrupt transition from fluorescent to new, undyed connective tissue. Deeper in the scar, and particularly around the ulcer, dark streaks were observed between the fluorescent lamellae, showing apparently new (non-fluorescent) tissue interdigitating with the old. These observations are discussed in relation to the mechanism of healing and the residual mechanical weakness that persists across scars in the cornea and sclera.