The present disclosure provides an improved method for photobleaching an eyeof a subject. The disclosed method may be used in a number of psychophysical testmethods, including, but not limited to, measurement of dark adaptation. Theimproved method for photobleaching involves at least one of the following improvements:(i) the use of a bleaching light emitting a particular wavelength of light or atailored spectrum of wavelengths； (ii) restricting or otherwise spatiallytailoring the region of the retina that is subject to photobleaching； and (iii)utilizing a bleaching light having an intensity that is at or below the intensityof ambient daylight. The present disclosure additionally provides a combinationof a photobleaching light and an apparatus to administer a psychophysical testsuitable for use in practicing the disclosed methods.
