Device and method for optical imaging of retinal function
An Optical Imaging Device of Retinal Function has been developed to detect changes in reflectance of near infrared light from the retina of human subjects in response to visual activation of the retina by a pattern stimulus. The measured changes in reflectance correspond in time to the onset and offset of the visual stimulus in the portion of the retina being stimulated. Any changes in reflectance can be measured by interrogating the retina with a light source. The light source may be presented to the retina via the cornea and pupil or through other tissues in and around the eye. Different wavelengths of interrogating light may be used to interrogate various layers of the retina. Additionally, various novel patterns and methods of stimulation have been developed for use with the imaging device and methods.
1. An apparatus for the functional imaging of a retina comprising:
a. a stimulation source positioned with respect to the retina;
b. a retinal interrogator constructed and arranged to emit light in the direction of the retina and along an optical path;
c. a detector constructed and arranged to detect the light emitted from the retinal interrogator and reflected from the retina;
d. wherein the retinal interrogator is constructed and arranged to emit light in a plurality of wavelengths and positioned to transmit light through a and sclera; and
e. a computer for analyzing the light detected by the detector, the light comprising a retinal image frame, and extracting a signal that corresponds to stimulus-evoked activity of a specific class of retinal cells thereby determining a relationship of a baseline response to the stimulation source.
2. The apparatus of claim 1 , wherein the stimulation source is constructed and arranged to be selectively disabled.
3. The apparatus of claim 2 , wherein the retinal interrogator is mounted on a contact lens.
4. The apparatus of claim 1 , wherein the retinal interrogator is constructed and arranged to transmit light through a lower eyelid.
5. The apparatus of claim 1 , wherein the retinal interrogator is constructed and arranged to transmit light through an inferior orbital area.
6. The apparatus of claim 1 , wherein the retinal interrogator is constructed and arranged to emit light in a range of near infrared wavelengths.
7. The apparatus of claim 1 , wherein the retinal interrogator is constructed and arranged to emit light in a range of infrared wavelengths.
8. The apparatus of claim 1 , wherein the retinal interrogator comprises at least one light emitting diode.
9. The apparatus of claim 1 , wherein the detector comprises at least one CCD sensor.
10. The apparatus of claim 1 , further comprising an Allen dot placed in the optical path wherein the Allen dot masks optic nerve head reflection.
11. The apparatus of claim 1 , wherein the stimulation source activates a specific class of retinal cells wherein differences in stimulus wavelength, spatial pattern, spatial frequency, temporal pattern, temporal frequency, eccentricity, contrast, intensity, motion, and properties of adaptation facilitate activation.
12. The apparatus of claim 11 , wherein the retinal cells activated are selected based an attribute selected from the group consisting of:
functional type;
layer;
location;
functional type and layer;
functional type and location; and
layer and location.
13. The apparatus of claim 1 , wherein the stimulation source selectively stimulates a layer of the retina.
14. The apparatus of claim 1 , wherein the stimulation source differentially stimulates two different sets of retinal layers wherein activity of one of the sets of retinal layers is isolated.
15. A method for stimulating a functional signal in a retina comprising the steps of:
a. recording a baseline retinal response wherein the recording comprises transmitting light through a sclera;
b. applying a stimulus to the retina during a stimulus phase;
c. recording a retinal response during the stimulus phase wherein the recording comprises transmitting light through a sclera; and
d. computing a relationship of the baseline response to the stimulus response by analyzing a captured retinal image frame, the captured retinal image frame comprising the recorded stimulus response, and extracting a signal that corresponds to stimulus-evoked activity of a specific class of retinal cells.
16. The method of claim 15 , further including the step of applying a stimulus to the retina while recording the baseline retinal response.
17. The method of claim 16 , wherein the step of recording the baseline retinal response comprises the application of a diffuse luminant stimulus to the retina.
18. The method of claim 15 , wherein the applied stimulus comprises a selectable spatial frequency.
19. The method of claim 15 , wherein the applied stimulus comprises a visually perceptible pattern.
20. The method of claim 15 , wherein the applied stimulus is applied with at least one LCD.
21. The method of claim 20 , wherein the at least one LCD is positioned with respect to the retina along an optical path of a fundus camera.
22. The method of claim 15 , wherein the stimulus applied activates a specific class of retinal cells wherein differences in stimulus wavelength, spatial pattern and frequency, temporal pattern and frequency, eccentricity, contrast, intensity, motion, and properties of adaptation facilitate activation.
23. The method of claim 22 , wherein the retinal cells activated are selected based on an attribute selected from the group consisting of:
functional type;
layer;
location;
functional type and layer;
functional type and location; and
layer and location.
24. The method of claim 15 , wherein the stimulus applied selectively stimulates a layer of the retina.
25. The method of claim 15 , wherein the stimulus applied differentially stimulates two different sets of retinal layers wherein activity of one of the sets of retinal layers is isolated.
26. The method of claim 15 wherein the step of analyzing further comprises:
registering the retinal image frames.
27. The method of claim 15 wherein the step of analyzing further comprises:
grouping and averaging the retinal image frames.
28. The method of claim 15 wherein the step of analyzing further comprises:
removing variations in illumination in the retinal image frames.
29. The method of claim 15 wherein the step of analyzing further comprises:
correcting for a baseline frame in the retinal image frames.
30. The method of claim 15 wherein the step of extracting a stimulus response provides immediate feedback of data quality at the time of collection.
31. A system for the functional imaging of a retina, comprising:
a. a means for stimulating the retina;
b. a means for interrogating a retinal response to the stimulation means wherein the means for interrogating the retina comprises a means for illuminating the retina via transcleral illumination;
c. a means for detecting a reflection of light from the retina resultant from the interrogating means; and
d. a means for analyzing the light detected by the detector, the light comprising a retinal image frame, and extracting a signal that corresponds to stimulus-evoked activity of a specific class of retinal cells thereby determining a relationship of a baseline response to the stimulation source.
32. The system of claim 31 , wherein the means for stimulating the retina comprises a means for emitting light.
33. The system of claim 32 , wherein the means for emitting light comprises at least one LCD.
34. The system of claim 31 , wherein the means for interrogating the retina comprises a means for emitting light in at least one near infrared wavelength.
35. The system of claim 31 , wherein the means for interrogating the retina comprises a means for emitting light in at least one infrared wavelength.
36. The system of claim 31 , wherein the means for interrogating the retina comprises an emitter constructed and arranged to emit light at a wavelength in the range of 700 nm to 900 nm.
37. The system of claim 31 , wherein the means for interrogating the retina comprises at least one LED.
38. The system of claim 31 , wherein the means for interrogating the retina comprises a halogen light source.
39. The system of claim 31 , wherein the means for interrogating the retina comprises a tungsten light source.
40. The system of claim 31 , wherein the means for detecting the reflection comprises a CCD.
41. The system of claim 31 , wherein the means for stimulating activates a specific class of retinal cells wherein differences in stimulus wavelength, spatial pattern and frequency, temporal pattern and frequency, eccentricity, contrast, intensity, motion, and properties of adaptation facilitate activation.
42. The system of claim 41 , wherein the retinal cells activated are selected based on an attribute selected from the group consisting of:
functional type;
layer;
location;
functional type and layer;
functional type and location; and
layer and location.
43. The system of claim 31 , wherein the means for stimulating selectively stimulates a layer of the retina.
44. The system of claim 31 , wherein the means for stimulating differentially stimulates two different sets of retinal layers wherein activity of one of the sets of retinal layers is isolated.