What layer of the cornea, if penetrated, will leave a scar?

The stroma is the main structural layer of the cornea, comprising about 90% of its thickness and consisting primarily of collagen fibers arranged in a highly organized manner. When the stroma is penetrated, which can occur due to trauma or surgical procedures, it is likely to result in scarring. This is because the stroma has the capacity to heal through the proliferation of fibroblasts, which can lead to the formation of scar tissue with a different composition and organization than the original corneal stroma, resulting in a permanent change in corneal clarity.

In contrast, the epithelium is the outermost layer of the cornea and has a remarkable ability to regenerate quickly after injury, often healing without leaving a noticeable scar. The wing cell layer is simply a transitional layer within the epithelium and does not have the capacity to leave a scar if damaged. The tear film, while important for corneal health and clarity, is not a structural layer of the cornea and does not play a role in scarring when penetrated. Therefore, penetration of the stroma is significant concerning the potential for scarring in the cornea.