New aspects of contact lenses in ophthalmology.

The introduction of the hydrophilic contact lens has been a significant advance in ophthalmology for the correction of ametropia, as well as for the therapy of corneal disease. The number of potential contact lens candidates has been greatly expanded by the introduction of both spin-cast and lathe-cut lenses composed of a variety of individual hydrophilic polymers. Myopia, hyperopia, presbyopia, aphakia and moderate astigmatism can be corrected with a reasonable degree of success with the present lenses. Even in keratoconus hydrophilic lenses offer a nonsurgical alternative, especially when combined with spectacle overcorrection. The introduction of hydrophilic bandages in the treatment of corneal disease has been an important addition to the therapeutic armamentarium of the ophthalmologist. When properly applied, these lenses can provide subjective relief of pain while serving to protect the damaged cornea from the traumatic action of the lids and desiccating effects of the atmosphere. The hydrophilic material is permeable to many topically instilled medications and tends to prolong the contact time of the drugs with the corneal surface. Proper fitting of the bandage lenses can eliminate superficial corneal irregularities and, thus, improve the visual acuity while treatment progresses. Medical indications for the use of this therapy include bullous keratopathy, dry eye syndromes, chemical burns, exposure keratitis, and neurotropic keratitis. A number of recurrent erosions and ulcerations have also responded to this form of therapy. Surgical indications include lacerations, postoperative lamellar and penetrating keratoplasty, and keratectomies. One of the most promising applications concerns their use in the postoperative management of alkaline burns. Best results have been obtained by constant wear of the bandage lens, with topical administration of steroids, antibiotics, and saline solution (hypotonic or hypertonic) as indicated. The possible deleterious effects of standard ocular medication containing preservatives has been overstated. Patients receiving medications without preservatives must be placed on prophylactic antibiotics to avoid secondary infection. In many cases, the therapeutic efficacy is closely related to the diameter and curvature of the bandage lens as well as the inherent physical properties of the polymers. With meticulous fitting and close observation complications have been minimal. In many instances the results have been dramatic, but even if unsuccessful the method provides a safe and relatively simple nonsurgical alternative in the treatment of severe corneal disease. Just as with older modalities, the ultimate success or failure depends upon the intrinsic nature of the disease process as well as reasonable therapeutic application based on a knowledge of the mechanics involved.