Polyvinylpyrrolidone iodine: corneal toxicology and epithelial healing in a rabbit model.

Polyvinylpyrrolidone-iodine (PVP-I) is a biocompatible broad spectrum antimicrobial that is widely used as an ophthalmic pre-operative prepping agent. In order to determine if PVP-I is safe for treating corneal ulcers and conjunctivitis, we evaluated the ocular toxicity of frequent dosing in a rabbit model. We evaluated ocular irritation in 18 rabbits according to the McDonald-Shadduck method. Concentrations of 0.5% PVP-I or less were practically non-irritating when administered six times per day. We evaluated corneal epithelial wound healing in 16 rabbits with standardized abrasions. Concentrations of 0.33% PVP-I showed epithelial healing comparable to gentamicin treated eyes and untreated controls. Concentrations of 0.5% PVP-I delayed epithelial healing by one day. Because of its broad spectrum and apparently low toxicity, PVP-I may be a useful treatment for corneal ulcers, keratitis and conjunctivitis.

An update of the indications for penetrating keratoplasty. 1979 through 1983.

We performed a retrospective analysis of the clinical and pathologic diagnoses of 497 corneal buttons that had been submitted to the Estelle Doheny Eye Pathology Laboratory, Los Angeles, during the five-year period 1979 through 1983. The leading indications, in order of decreasing frequency, were pseudophakic bullous keratopathy (17.5%), regrafts (15.1%), aphakic bullous keratopathy (10.9%), corneal trauma (9.3%), and Fuchs' endothelial dystrophy (9.1%). The emergence of pseudophakic bullous keratopathy as the most common cause for penetrating keratoplasty correlates well with the dramatic increase in the number of cataract extractions with intraocular lens implantations performed since the mid-1970s. Less frequent indications for penetrating keratoplasty included the following: corneal scars (6%); active ulcerative keratitis (7%); keratoconus (6%); keratitis secondary to virus (5%); non-Fuchs' corneal dystrophies (3%); congenital corneal opacities (3%); interstitial keratitis (2%); and chemical burns (1%).

Temperature variations in eyebank containers: comparative study of corneal transport containers and packing methods.

Two containers ("Iowa" and "Virginia") commonly used for transporting donor corneas, and various packing methods were evaluated for constancy of temperature maintenance. The larger Iowa container was found to be superior for extended storage. Packing methods that allowed the vials (containing McCarey-Kaufman medium) to be in direct contact with wet ice or with ice water resulted in the best cooling. Direct contact with supercooled ice may cause freezing of the medium. Separating the vials from the ice water slush by dry foam rubber or Styrofoam did not allow adequate cooling. Heat sealing the vials in a plastic bag containing minimal air permitted proper cooling and may reduce the risk of contamination from the ice water.

Suppressor cell decrease in alopecia areata.

There is considerable evidence to suggest that autoimmunity plays a role in the pathogenesis of alopecia areata. Since it is known that T cells regulate the immune system, a study was undertaken to measure T helper (OKT-4) and T suppressor (OKT-8) cells in the peripheral blood of patients with alopecia areata (both active and stable) and in controls. Total T cells, B cells, immunoglobulins, and autoantibodies were also measured. There was a highly significant decrease in the T-suppressor cell population of patients with alopecia areata (P less than 0.001). Two of ten patients had microsomal antibodies and three of ten had elevated IgE levels. Other parameters were not significantly different. The decrease in suppressor cells suggest an impairment of the prime negative regulator of the immune system, with loss of tolerance and resultant autoimmunity.