Accommodation and convergence: effects of lenses and prisms in ''closed-loop'' conditions

Experiments are described in which the steady-state accommodation response to binocularly viewed targets at various distances in the range 0.2-5 m was measured by laser optometry in normal, near-emmetropic subjects. Responses were determined with naked-eye viewing and when equal pairs of either spherical lenses or base-in or base-out prisms were placed before the eyes. Snellen acuity was also measured under the same range of conditions. The results show that, although the most accurate accommodation responses were found under natural viewing, the response accuracy was remarkably robust against both lenses and prisms. There was, however, always some change in response level to any increment in lens or prism power. The results are discussed in terms of earlier theories and data on the general relationship between accommodation and convergence.     

Objective measurements of the longitudinal chromatic aberration of the human eye

The optimum refraction at a series of wavelengths was determined by direct photoelectric measurement of the halfwidth of the double-pass, line-spread function. This was compared with the subjectively-estimated longitudinal chromatic aberration for the same eye. The agreement between the two sets of data is reasonable. The small observed discrepancies (~0.2 D.S.) may help to indicate the position of the reflecting retinal layers responsible for the double-pass image.     

Industrial hypertension program in a rural state. Efficacy and cost effectiveness.

A program was designed to evaluate the efficacy and cost of detecting and treating hypertension in an industrial population of a rural state. Original screening and evaluation was initiated by a trained blood-pressure technician team, but initiation of therapy was the responsibility of the private physician. Follow-up data were obtained at one year by rescreening in 83% and by telephone contact in 91% of the original hypertensive patients. Eighty-three percent of those patients with moderate or severe hypertension complied with physician visits. The condition of 60% of the treated patients was controlled, and the condition of 74% was improved. The total cost per patient treated for one year was 250 dollars; per patient with controlled hypertension, 446 dollars; and per patient with controlled or improved hypertension, $362.     

Humoral immune responses of cats to feline leukemia virus: comparison of responses to the major structural protein p30 and to a virus-specific cell membrane antigen (FOCMA).

Radioimmunoprecipitation was used to test cat sera for ability to bind to the purified major internal protein p30 of feline leukemia viurs (FeLV), to the endogenous cat virus (RD-114), and to murine leukemia virus (MuLV). The data were compared with results of tests for antibody to the feline oncornavirus-associated cell membrane antigen FOCMA and for the presence of viremia. In contrast to the general lack of free antibody to FeLV p30 in a random sample of healthy cats, high levels of antibody to FeLV p30 and FOCMA were found in normal animals from high-leukemia-cluster households. Titers of greater than or equal to 200 for p30 and greater than or equal to 32 for FOCMA were found in nonviremic animals; a percentage of animals with high FOCMA titers and lower or no p30 binding activity were viremic. Animals with neoplasms were low or negative for FOCMA antibody and did not have high titers of free p30 antibody. The p30 binding activity could be divided into three main categories: high binding with FeLV p30 and much lower activity with RD-114 and MuLV p30's, as seen with hyperimmune sera; high binding with FeLV and RD-114 p30's and low activity with MuLV p30, possibly indicative of specific antibody to both of the aforementioned proteins; and low level binding to all three p30's.     

Reaction and response times for accommodation

Using an infra-red dynamic optometer, a qualitative comparison of the accommodation responses of two observers to step changes in target position showed marked differences in their ability to accommodate correctly. Measurement of reaction time (or latency) gave results comparable with those of other workers and independent of target position. Measurements of response time showed for one observer that the response time was dependent on the extent of the accommodative change required; this was not true of the other observer. Possible reasons for the intersubject differences and the role of the instructions given to the observer are discussed.     

The opitcal system of the goldfish eye

Experiments are described in which the parameters of the various optical components of the eyes of both living and dead fish were measured. The results are used to construct a schematic eye for the goldfish; this then forms the basis of a discussion of various aspects of the goldfish visual system.