Vascular response of the cornea to contact lens wear

The subject of contact lens-induced corneal vascularization has attracted considerable interest in recent times in view of the relatively high prevalence of this condition with the use of extended wear soft lenses. This paper reviews clinical features and underlying mechanisms of the vascular response to lens wear. The concept of a "normal" vascular response to contact lens wear is proposed; the limits of this response are defined and incorporated into a simple grading system. The clinical presentation of vessel growth in the cornea is described together with appropriate methods of slit lamp evaluation. Current theories of the pathology and etiology of lens-induced vascularization are reviewed, and a dual-etiology model of stromal vessel formation is described. It is concluded that the prognosis for halting the progression of vascularization is excellent; however, little information is available concerning the long-term regression of "ghost" vessels.