What is Corneal Neovascularization?

Picture from JS Andersen, et al. "A Handbook of Contact Lens Management." Vistakon, Johnson & Johnson Vision Products, May 1996.

This is a picture of a condition called corneal neovascularization. The cornea is the clear part that covers the colored part of the eye. Contact lenses sit on the cornea. The cornea is normally avascular, or has no blood vessels growing within it. Contact lenses, particularly soft contact lenses or PMMA lenses (the older hard contact lenses) can put stress on the cornea by limiting the amount of oxygen that the cornea receives. If this lack of oxygen is severe or occurs over a long period of time, some corneal swelling can occur which allows spaces to form for blood vessels to grow into the edge of the cornea. This is more of a problem with extended wear contact lenses (lenses you sleep in). Corneal neovascularization is also seen to some degree in patients who have been long-term soft contact lens patients. Corneal neovascularization is managed by implementing strategies to increase the oxygen to the corneas. This can be done by discontinuing extended wear, being re-fit into a different lens type or material, or by decreasing your contact lens wear time. The blood vessels that grow into the cornea never go away, but they can regress into what are referred to as ghost vessels.