Photobleaching method
The present disclosure provides an improved method for photobleaching an eye of a subject. The disclosed method may be used in a number of psychophysical test methods, including, but not limited to, measurement of dark adaptation. The improved 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 a tailored spectrum of wavelengths; (ii) restricting or otherwise spatially tailoring 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 intensity of ambient daylight. The present disclosure additionally provides a combination of a photobleaching light and an apparatus to administer a psychophysical test suitable for use in practicing the disclosed methods.
1. An apparatus for measuring an ability of an eye of a test subject to adapt to darkness using a series of responses, received from the test subject over a period of time, which indicate the test subject's observation of a stimulus light beam after exposure to a photobleaching light beam, the apparatus comprising:
a housing comprising:
a viewing opening;
a photobleaching light source configured to generate the photobleaching light beam, the photobleaching light beam having a tailored wavelength spectra spanning within a spectrum visible to human eye;
a stimulus light source configured to generate the stimulus light beam for stimulating the eye of the test subject; and
a display configured to:
a) display a bleach spot generated by the photobleaching light source and direct the photobleaching light beam to the eye of the test subject to photobleach one or more photoreceptors of the eye; and
b) display a stimulus spot generated by the stimulus light source and direct the stimulus light beam to the eye of the test subject.
2. The apparatus of claim 1 , wherein the tailored wavelength spectra comprises wavelengths in a green spectrum.
3. The apparatus of claim 2 , wherein the tailored wavelength spectra comprises a range of wavelengths from 490 nm to 510 nm.
4. The apparatus of claim 3 , wherein the bleach spot comprises a green flash.
5. The apparatus of claim 3 , wherein the photobleaching light source comprises an LED light source.
6. The apparatus of claim 3 , wherein the photobleaching light source comprises an OLED light source.
7. The apparatus of claim 3 , wherein the photobleaching light source comprises a photographic flash.
8. The apparatus of claim 3 , wherein the display comprises a plasma display.
9. The apparatus of claim 3 , wherein the display comprises a LED display.
10. The apparatus of claim 3 , wherein the bleaching spot is larger than the stimulus spot.
11. The apparatus of claim 10 , wherein the stimulus spot comprises a circular spot.
12. The apparatus of claim 11 , wherein the stimulus light source is configured to control intensity of the stimulus light.
13. The apparatus of claim 12 , wherein the display is configured to display the stimulus light at varying intensity levels.
14. The apparatus of claim 13 , wherein the display is configured to display the stimulus light at varying locations.
15. The apparatus of claim 14 , wherein the display is configured to display the stimulus light at a first intensity until a response indicating the subject's observation of the stimulus light beam is received.
16. The apparatus of claim 14 , wherein the display is configured to increase intensity level of the stimulus light until a response indicating the subject's observation of the stimulus light beam is received.
17. The apparatus of claim 15 , wherein the display is configured to display the stimulus light at a second intensity after the response indicating the subject's observation of the stimulus light beam is received, wherein the second intensity is lower than the first intensity.
18. The apparatus of claim 15 , wherein the display is configured to display the stimulus spot every 2 seconds.
19. The apparatus of claim 15 , wherein the display is configured to display the stimulus spot every 3 seconds.
20. The apparatus of claim 15 , wherein the display is configured to display the stimulus spot for a 200 millisecond duration.
21. The apparatus of claim 15 , wherein the display is further configured to display a fixation light.
22. The apparatus of claim 21 , wherein the display is configured to display the bleach spot while displaying the fixation light.
23. The apparatus of claim 22 , wherein the stimulus light comprises a range of wavelengths centered at 505 nm.
24. The apparatus of claim 22 , wherein the stimulus light comprises a range of wavelengths centered at 450 nm.
25. The apparatus of claim 1 , wherein the viewing opening is configured to receive a head of the test subject.