Vascularization of the cornea caused by wearing contact lenses has been observed clinically and in experimental animals. Several million Americans are wearing these lenses. The prevention of this type of corneal vascularization requires an understanding of the conditions producing it. Clinical Observations Lauber1 in 1929 and Strebel2 in 1937 reported corneal vascularization due to wearing scleral lenses. Strebel stated that vascularization of the cornea in keratoconus developed after wearing the lenses in the presence of central erosions but that it was beneficial in flattening the corneal curvature. Delgado,3 Paton,4 and Baird5 have contributed clinical cases to this report. Delgado's case was a brush-like vascularization of the deep corneal stroma extending to within 2½ mm. of the corneal apex. The patient was a 50-year-old man with aphakia who used the lenses for 6 months, frequently sleeping with them on the corneas. After the lenses were discontinued,