In 1961, after several years of experimentation, I presented a self-illuminated stimulus for tangent screen perimetry1 utilizing a white electroluminescent panel lamp which maintains a constant and standardized level of brightness at all times, under all conditions of room and background illumination.
The need for such a stimulus of constant and measured luminance has been recognized for years. It was one of Goldmann's2,3 prime considerations in designing his perimeter and it prompted me4 to develop fluorescent sulfide tangent screen stimuli activated by ultraviolet (black) light which thus become their own source of light.
It has been almost impossible to maintain a constant incandescent illumination on all areas of a 1 or 2 meter tangent screen without resorting to complicated and expensive installations of lights and reflectors. Projection methods for use with tangent screens have not been satisfactory and are also difficult to maintain at a constant level
HARRINGTON DO. Tangent Screen Stimuli of Variable Luminance. Arch Ophthalmol. 1964;72(1):23-28. doi:10.1001/archopht.1964.00970020025006