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Three instruments developed by David M. Maurice, i.e., pachometer, fluorophotometer and specular microscope, helped clinicians develop improved clinical practice. It covered wide areas, such as contact lens practice, cataract surgery, medical therapy of intraocular inflammation and glaucoma.

This paper explores the seminal contributions of David Maurice to the field of ophthalmic instrumentation. His development of the specular microscope, the scanning slit optical confocal microscope, and the corneal microfluorometer resulted in advances in our understanding of corneal morphology, physiology, and pathology. The development of the scanning slit, clinical confocal microscope is not a new paradigm or a paradigm shift, but a continuous series of interlinked technical advances from the early work of Vogt to Thaer's development of a clinical confocal microscope. For each instrument both the connection to the prior work of others and the unique advances are discussed and contrasted. This paper develops the connections and parallel developments in the instrument developments of Goldmann, Maurice, Svishchev, Baer, Koester, Masters, and Thaer. The evidence in support of the thesis consists of published papers, patents, personal communication, and study of Goldmann's book collection in Bern. A second theme is that knowledge of physics is a prerequisite for optical instrument development in ophthalmology. David Maurice had a university degree in physics and Hans Goldmann learned physics from his books. The contributions of David Maurice to optical instrumentation follow the major contributions of Goldmann and facilitated and stimulated other scientists who acknowledged their important intellectual debt to David Maurice.

The author has done pretty much what he wanted to do throughout his professional life. Little harm resulted. A few findings may survive., (Copyright 1998 Academic Press Limited.)

Fluoresceinated dextran was injected into the vitreous cavity of rabbits and its concentration was followed in the vitreous and aqueous humors for a period of weeks by slip-lamp fluorometry. The concentrations in both fluids fell in parallel and in an exponential manner where the time constant was determined by the molecular weight of the dextran. The rate of movement of the dextran from the vitreous into the anterior chamber is controlled by passive diffusion and may be assumed to be relatively steady; accordingly, the faster the rate of flow in the aqueous humor the lower will be the concentration of dextran in it. Circadian variations in the aqueous flow were observed, a drop at night time being noted. These were small enough for changes due to systemic influences to be determined; in particular, it was found that general anesthesia with ketamine had no significant effect. The ratio of the concentration in the anterior chambers of the two eyes of one animal normally remains constant with time. Changes in the ratio can be used to determine the influence of unilateral interventions. This was illustrated by the use of adrenergic drops which led to a brief rise in flow rate and then a longer-lasting fall, and by X-ray irradiation with 1000 rads, which caused an immediate fall in flow rate interrupted for a time by a phase of increased flow. An absolute estimate of the aqueous flow can be derived from measurements of the total amount of dextran in the eye and its concentration in the anterior chamber. A definite value has not yet been established owing to ambiguities in determining the former quantity.

The time taken to cross the rabbit corneal epithelium and stroma was estimated for fluorescein (F), carboxyfluorescein (CF), rhodamine B (RB), and sulforhodamine B (SRB). Paired corneas were mounted in vitro; one was intact and the dye solution was kept in continuous contact with its epithelial surface; the epithelium was scraped from the other and the dye was applied as a pulse to the bare stroma. The time course of the dye appearing in a solution rapidly passing over the endothelial surface was determined by fluorometry. This rate of appearance was compared in the two cases and used to estimate the diffusional lag time introduced by the epithelium. For the very hydrophilic CF and SRB, the delay was too short to measure; this is compatible with the passage of these dyes taking place through the paracellular spaces. For the very lipophilic RB, the delay was about 2 min; this was rather too slow for it to be explained as being controlled entirely by diffusion in the cytosol. For the intermediate F, the delay was 5 min; it is suggested that this is a result of it partitioning between the spaces and the cytosol during its passage. The experiments also led to determinations of the permeability of the epithelial and endothelial layers to the dyes. In both cases lipophilicity was a strong determinant of penetration, but not the only one. The permeability of the endothelium to F was unchanged from its in vivo value in these experiments, but that of the epithelium was increased four-fold. The diffusion rate of the dyes across the stroma could also be determined. There was no clear relationship with molecular size or partition coefficient. The rate of diffusion of F across the tissue was about half that in its plane, as determined in previous experiments. This is possibly a result of the anisotropic structure of the tissue.