David W. Lamberts

Donor to host transmission of disease via corneal transplantation

A literature search was conducted to report all cases of documented transmission of infectious diseases from donors to recipients of corneal transplants. Fourteen such cases have been reported. There is no experimental or clinical evidence to suggest the transmissions of either hepatitis or syphilis via corneal grafting. Available evidence regarding a number of neurologic and other disorders in which a slow virus etiology has been implicated were reviewed. On the basis of this review, we are able to draw certain conclusions and guidelines for selection or rejection of donor material for transplant surgery.

Systemic Tetracycline Hydrochloride as Adjunctive Therapy in the Treatment of Persistent Epithelial Defects

Recent evidence shows tetracyclines have anticollagenolytic activity that may be clinically effective in disease treatment. This led us to use systemic tetracycline (oral tetracycline hydrochloride 1 g daily divided into 4 doses) as adjunctive therapy in treating 18 patients with persistent corneal epithelial defects. Fourteen of 18 patients healed their defects; within 48 hours (9 patients) and within two weeks (the other 5 responding patients). Two patients showed no effect and two showed disease progression.

Clinical Evaluation of Trimethoprim-Containing Ophthalmic Solutions in Humans

We studied trimethoprim in combination with sulfacetamide and polymyxin B and also in combination with polymyxin B alone (without the sulfacetamide) to determine the efficacy and safety of these new antibiotic combinations in the eyes of patients with bacterial conjunctivitis or blepharitis. Patients were selected for the study if they showed at least three of the following criteria: (1) symptoms of a surface ocular infection; (2) a purulent discharge; (3) a polymorphonuclear neutrophilic response on Giemsa stain; (4) a history of recent exposure to an infected individual; (5) a history of an inadequately treated surface bacterial infection. Trimethoprim-sulfacetamide-polymyxin B and polymyxin B-neomycin-gramicidin (Neosporin, the control) eliminated bacteria from the eyes of patients with conjunctivitis or blepharitis with equal effectiveness. There was no loss of effectiveness when trimethoprim-polymyxin B was compared with trimethoprim-sulfacetamide-polymyxin B, suggesting that the sulfacetamide was not a necessary component. The combination antibiotic containing trimethoprim and polymyxin B appears to be an effective topical antibiotic solution for the treatment of ocular surface infections.

Kinetics of capillary tear flow in the Schirmer strip

The popular Schirmer test of tearing ability heretofore has never been analyzed kinetically and the interpretation of the results is usually based on implicit, often erroneous assumptions. We have analyzed the capillary flow of fluids in filter paper strips in vitro systems for the cases of unlimited supply and limited supply at constant rates, and in vivo using human subjects, who kinetically corresponded to limited supply having variable rates. The effects of evaporation, surface tension, viscosity, paper pore-size, and the wettability of the cellulose fibers in the paper were also studied. The results show that in the case of unlimited supply, the fluid absorption is kinetically identical to fluid uptake by a horizontal capillary. This implies that the paper strip can absorb fluids only at a certain maximum rate which decreases with time. At lower secretion rates, the rate of wetting length increase is linearly proportional to the secretion rate provided that evaporation is prevented. Evaporation increases with increased wetting length until a steady state is reached where the length of wetting remains constant in time. As long as the secretion rate remains below the maximum uptake rate of the paper strip, the paper and fluid characteristics have a negligible influence on the wetting rate thus the rate of wetting can provide quantitative information on the secretion rate. Wetting length versus time curves obtained in vivo can be best described mathematically by assuming that the initially high secretion rate exponentially decays to a lower, final value. From the data, the magnitude of the initial and final tear secretion rates as well as the secretion rate decay coefficient can be calculated. These physiologically relevant values quantitatively characterize the functioning of the lacrimal system and may have diagnostic value in detecting marginal lacrimal deficiencies and predicting poor contact lens tolerance.

Chronic Unilateral External Ocular Inflammation

To diagnose the cause of chronic unilateral external ocular inflammation, the physician must take into account many factors usually not considered in bilateral cases. We report on the diagnosis and treatment of ten unilateral cases encompassing a variety of ocular and systemic problems. The purpose of this report is to emphasize the importance of systematic consideration of all diagnostic possibilities and to suggest a diagnostic protocol to aid in the study of patients with chronic unilateral external ocular inflammation.