An optical stimulator is described to meet the special requirements of retinal neurophysiology. It is compact and convenient to use, and modular construction confers flexibility of problems to which it may be applied. The maximum stimulus intensity from a Zeiss tungsten light source gives 4.19 log m–c of illuminance at the cat retina. An electromagnetic shutter provides light pulses which rise or fall to within 1/e of the final value in 0.3–0.4 msec. Controls are included for stimulus intensity, color, duration, and frequency. Both spot and annular stimuli of variable size are provided. The stimulus may be positioned anywhere on the retina by a combination of coarse and micrometer controls. Interchangeable stimulus light sources are used for special problems, and a simple attachment permits studying the Stiles-Crawford effect. A background beam is also provided with controls for intensity and color. A direct ophthalmoscopic view of the fundus gives high resolution of retinal details.
A modified eye holder provides three needle channels into the fundus of the eye. An improved hydraulic advancer controls microelectrode depth in the retina. A simple head holder is used to position the cat or monkey eye in the stimulator.
© 1964 Optical Society of AmericaFull Article | PDF Article
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