John Nathan

Recognition of Colored Road Traffic Light Signals by Normal and Color-Vision-Defective Observers*

Normal and color defective observers were asked to identify 13 signal light colors as either red, green, or yellow under laboratory conditions simulating road traffic signals but with only chromaticity and brightness differences as cues for identification. Choice reaction times and errors were measured. A high correlation between these yields was found and each was analyzed separately. Special statistical techniques were necessary for analysis of the errors. Reaction times provided a sensitive measure and proved simpler to analyze than errors. It was concluded that the chromaticity boundaries similar to those specified by ASA D10-1 (1958) were more reliable for all classes of observers than those more liberal boundaries established by the CIE (1955) and BS:1376 (1953). None of the yellow filters proved satisfactory for color defectives. Reaction times and errors suggest that the extension of the yellow limit of the red signals in the new U. S. standard (1964) may be undesirable.

Phenotypical variations of tritanopia

Abstract The colorimetric investigation of six tritans is reported. The tritans are all members of the one family and three have been shown to be tritanopes. The other three tritans are trichromatic and have a defect which could be diagnosed as tritanomaly. It is postulated on the basis of this result and an examination of the tritanomals reported in the literature that tritanomaly is not the result of a separate allelomorph and the term incomplete tritanopia may be preferable. Spectral mixture data, purity thresholds and extended Rayleigh matches are also reported for some of the tritans. Two incomplete tritanopes exhibit evidence of an alteration system raising doubts as to the adequacy of the simple loss theory of tritanopia.

Hippocrates to Duke-Elder: an overview of the history of glaucoma.

Objective: To briefly trace the history of the diagnosis, understanding and treatment of glaucoma.

Geoffrey Herbert Henry DSc MAppSc BSc LOSc. Noted optometrist and eminent neuroscientist. 17 November 1929--21 February 2010.

Geoff Henry died peacefully at the end of a long and productive life. If one can measure worthiness by the sum of life’s contributions and the respect and love engendered on the journey, then by all counts Geoff was a very worthy man. He came from a happy scholarly home; his father was a school principal and sometime Deputy State Director of Secondary Education. Geoff’s early education was in rural Victoria and later at Melbourne Boys High School, The University of Melbourne and the Australian College of Optometry, gaining honours along the way. His bent was towards the biological sciences but also he excelled in geology and chemistry. Throughout these years, he read widely in diverse subjects such as Greek mythology, philosophy, Australian and European history and later the creative arts. He was proud of his AngloAustralian heritage and his links with rural Australia, often speaking of one of his forebears, who was reputably Melbourne’s first commercial brewer. Geoff was a gregarious and hospitable man, happy with a glass of red and lively conversation. Age was no barrier but pretentiousness was not tolerated. Geoff completed his undergraduate studies in 1951 and immediately established a private optometric practice in a suburb of Melbourne, Victoria. Shortly after graduation he became a teaching clinician, part-time lecturer, physiology demonstrator and member of the Council of the Australian College of Optometry. In 1955, he was appointed Chairman of the College Council and held that position for 12 years. This was a period of extraordinary development for Victorian optometric education and not the least due to Geoff Henry. It was a time when the first fulltime lectureship was established, land was acquired for the college and a new building erected; the college was affiliated with the University and the optometry course of the college was incorporated within the newly formed Faculty of Applied Science of The University of Melbourne. Having achieved university status for optometry in Victoria, the next step was to develop a research school. Henry, along with Barry Cole and me, commenced several co-operative research projects on colour vision and through opportunistic circumstance concentrated on tritan colour vision defects and the recognition of coloured road signal lights by people with abnormal colour vision. This led to three significant papers published in international journals and earned senior degrees for all three of us but perhaps more importantly the discipline and spirit of enquiry required in the process convinced Geoff that his future lay in full-time research. After 15 years of private practice and now with a wife and four young children, he applied for and was awarded a Churchill Fellowship in the very first round of those scholarships. This enabled him to work as a Research Fellow on primate colour vision with Russell Devalois at Indiana University and to spend several valuable months with William Rushton at Cambridge University. On returning to Australia in 1968, he joined Dr Peter Bishop at the John Curtin School of Medical Research, Australian National University, an ideal environment in which to develop his career as a neuroscientist. Over the ensuing 30 years, he was principally concerned with furthering our understanding of the visual cortex using the striate cortex of the cat as a model. In C L I N I C A L A N D E X P E R I M E N T A L