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.

The corneal endothelium and central corneal thickness in pigmentary dispersion syndrome.

The corneal endothelial cell count and central corneal thickness of 20 eyes of patients with pigmentary dispersion syndrome and 20 age-, sex-, and refractive error-matched control eyes were investigated in a masked fashion with a specular microscope and a pachometer. Despite the existence of glaucoma and different degrees of pigment dispersion with Krukenberg's spindles, there was no significant difference in the central corneal endothelial cell density and central corneal thickness between these two groups.

Timolol inhibits corneal epithelial wound healing in rabbits and monkeys.

To determine the effect of timolol maleate on corneal epithelial wound closure, 6.4-mm (diameter) epithelial defects were created chemically in five experiments. In rabbits, wound closure was not significantly altered by the administration of 0.5% Timoptic (a commercially prepared timolol maleate solution) every eight hours, but it was inhibited during the first 15 hours of healing when a 4% solution was applied every two hours. Monkeys received a 5% solution every 12 hours and were divided into treated and control groups. Two phases of wound healing were apparent: a rapid initial phase and a slower final phase. Wound closure was inhibited in treated eyes during the initial rapid phase. This experiment repeated on the same monkeys, but with the control and treated animals switched, yielded the same result. Another experiment, with the fellow eye of the monkey used as a control, showed no significant difference in wound closure.

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.

Investigation of the accuracy of tear lysozyme determination by the Quantiplate method.

The accuracy of lysozyme concentration determination by the method of measuring lysis diameter in agarose gel slabs containing Micrococcus lysodeikticus bacteria uniformly suspended throughout the gel was determined for various methods of tear sample collection. The effects of storage of lysozyme solution samples at subzero temperatures for several days was also examined. It was found that a power rather than the suggested exponential dependence between the lysozyme concentration and lysis diameter provides the most accurate fit and thus should be used for interpolation. Storing samples frozen in glass capillaries lowered the lysozyme concentration in a predictable manner. When Weck-Cel sponges were used to collect the samples the lysozyme concentration was greatly diminished in a nonlinear manner because of internal adsorption. The relative loss (cause by adsorption) depended on the actual lysozyme concentration as well as on the sample volume/sponge weight ratio. Storing samples absorbed by such sponges in a frozen state further altered the results in an unpredictable way. The observation that smaller tear samples for a given sponge size yielded lower apparent values for lysozyme concentration casts doubt on findings that have reported lower lysozyme concentration in the tears of keratoconjunctivitis sicca patients, where either cellulose sponges or filter paper discs were used for tear collection.

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.

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.

Effect of nonisotonic solutions on tear film osmolality.

We found that the original osmolality of the tear film is regained rapidly subsequent to the installation of hypotonic artificial tears or other nonisotonic solutions. The minor irritation due to nonisotonicity and the increased tear volume both contribute to the increased turnover rate which in turn results in the short half-life (measured in seconds) of these solutions in the eye. Despite the expected fluctuation in tear volume and probably in tear secretion rate during the experiment, the osmolality of the tears followed an exponential decay with relatively good correlation.