One of the most common causes of corneal neovascularization is iatrogenic pathology from extended contact lens wear. This is especially likely with lenses made with older hydrogel materials such as HEMA (2-hydroxyethyl methacrylate) for both daily and extended wear. Such older hydrogel materials have a relatively low oxygen transmissibility so the cornea becomes starved of oxygen; this leads to the ingress of blood capillaries into the clear cornea, in an attempt to provide more oxygen to the affected area. Older estimates cite 128,000 to 470,000 cases of lens-induced CNV each year, but this may be decreasing due to the increasing popularity of daily disposable lenses.