These Proceedings of the Fourth International Congress on the Cornea continue a tradition of summarizing the state-of-the art basic and clinical research in cornea and ex ternal diseases since the first Congress was held in 1964. Reflecting the emerging impor tance of refractive surgery, two of the twelve sessions of the Congress were devoted to refractive surgery; this is reflected in an emphasis in these Proceedings. In addition, an en tire session was devoted to the molecular and cellular biology of the cornea with impor tant new information on the role of growth factors and cytokine modulation of corneal wound healing. Within these Proceedings an international group of expert researchers and practitioners provide the latest insights into the tear film and ocular surface, corneal trans plantation and eyebanking, the corneal stroma and endothelium, contact lenses, microbial and nonmicrobial keratitis, keratoconus, and world corneal health. Notable subjects covered include the latest understanding of the barrier function of the ocular surface epithelium, corneal hydration control, the molecular mechanisms con trolling gene expression in corneal wound healing, stromal~pithelial interactions in the cornea, the immunology of blepharitis, the effect of contact lenses on the conjunctiva, morphologic and functional evaluation of the human corneal endothelium, long-term fol low-up of penetrating keratoplasty in keratoconus, the Tampa trephine penetrating kerato plasty, and the refractive results of the Nidek EC-5000 excimer laser.