Projection of defocused images on the peripheral retina to treat refractive error
An apparatus to treat refractive error of the eye comprises one or more optics configured to project stimuli comprising out of focus images onto the peripheral retina outside the macula. While the stimuli can be configured in many ways, in some embodiments the stimuli are arranged to decrease interference with central vison such as macular vision. The stimuli can be out of focus images may comprise an amount of defocus within a range from about 3 Diopters (“D”) to about 6 D. In some embodiments, the brightness of the stimuli is greater than a brightness of background illumination by an appropriate amount such as at least 3 times the background brightness. In some embodiments, each of a plurality of stimuli comprises a spatial frequency distribution with an amplitude profile having spatial frequencies within a range from about range of 1×10 −1 to 2.5×10 1 cycles per degree.
1. An apparatus for treating refractive error of an eye, the apparatus comprising:
a plurality of stimuli; and
one or more optics to image the plurality of stimuli anterior or posterior to a peripheral portion of a retina to form a plurality of defocused images on a peripheral portion of the retina;
wherein the plurality of stimuli and the one or more optics are arranged to reduce hindrance with a central vision of the eye and wherein said plurality of stimuli as imaged in the eye comprises a spatial frequency distribution providing a decrease in spatial frequency amplitude with an increase in spatial frequency for a range of spatial frequencies from about 1×10 −1 to about 2.5×10 1 cycles per degree.
2. The apparatus of claim 1 wherein a brightness of said plurality of defocused images is higher than a brightness of background illumination by a factor of at least 3.
3. The apparatus of claim 1 wherein each of said plurality of defocused images comprises an intensity profile distribution, the intensity profile distribution comprising one or more peaks distributed around an inner portion with a decreased intensity relative to the one or more peaks.
4. The apparatus of claim 3 , wherein the one or more peaks comprises a plurality of peaks and wherein the inner portion is located between the plurality of peaks.
5. The apparatus of claim 4 , wherein the plurality of peaks comprises four peaks and the inner portion is located between the four peaks.
6. The apparatus of claim 5 , wherein the inner portion comprises a cross extending between the four peaks.
7. The apparatus of claim 3 , wherein the one or more peaks comprises an annular peak and wherein the inner portion is located within the annular peak.
8. The apparatus of claim 1 wherein each of said plurality of defocused images comprises a polychromatic icon on a darker background to provide contrast.
9. The apparatus of claim 1 , wherein each of the plurality of stimuli comprises a length, edges, and an intensity profile distribution to generate spatial frequencies in a range of 1×10 −1 to 2.5×10 1 cycles per degree as imaged into the eye anterior or posterior to the retina.
10. The apparatus of claim 1 wherein said plurality of stimuli as imaged in the eye comprises a spatial frequency distribution providing a decrease in spatial frequency amplitude with an increase in spatial frequency for a range of spatial frequencies from 1×10 −1 to about 5×10 0 cycles per degree.
11. The apparatus of claim 10 , wherein the decrease in spatial frequency intensity is within a range from 1/(spatial frequency) 0.5 to 1/(spatial frequency) 2 for the spatial frequency amplitude in arbitrary units.
12. The apparatus of claim 10 , wherein the range of spatial frequencies is from about 3×10 −1 to about 1.0×10 1 cycles per degree.
13. The apparatus of claim 1 , wherein each of the plurality of stimuli as imaged in the eye is overlaid onto a substantially uniform grey background, said each of the plurality of stimuli comprising a white icon, such that said white icons have a total length of edges that generate features of spatial frequency predominantly in a range from 1×10 −1 cycles per degree to 2.5×10 1 cycles per degree.
14. The apparatus of claim 1 , wherein each of the plurality of stimuli as imaged in the eye comprises a polychromatic icon having an edge profile on a background that generates features of spatial frequency predominantly in a range from 1×10 −1 cycles per degree to 2.5×10 1 cycles per degree.
15. The apparatus of claim 1 wherein each of the plurality of stimuli comprises a global contrast factor greater than 0.7.
16. The apparatus of claim 1 , further comprising a sensor to measure a size of a pupil and further comprising a processor configured with instructions to direct the plurality of stimuli toward the eye in response to the size of the pupil.
17. The apparatus of claim 16 , wherein the processor is configured to adjust one or more of an intensity or a duration of the plurality of stimuli in response to the size of the pupil.
18. The apparatus of claim 16 , wherein the sensor comprises a sensor array.
19. The apparatus of claim 16 , wherein the plurality of stimuli is configured to allow dilation of a natural pupil when illuminated with the plurality of stimuli.
20. The apparatus of claim 1 , wherein the plurality of stimuli is configured to constrict the pupil by no more than one millimeter (mm) when the plurality of stimuli is provided as compared to a diameter of the pupil when the plurality of stimuli has not yet been provided.
21. The apparatus of claim 1 , wherein the pupil comprises a stimulation diameter when the eye is exposed to the plurality of stimuli and wherein the eye comprises a photopic diameter when the eye is exposed to photopic viewing conditions without the plurality of stimuli, and wherein the photopic diameter is at least one millimeter smaller than the stimulation diameter.
22. The apparatus of claim 1 , wherein the stimulus is configured to illuminate the peripheral portion of the retina with an eccentricity of greater than 35 degrees and configured to allow a pupil of the eye to be dilated by at least about 1 millimeter as compared to photopic illumination while the stimulus is provided to the peripheral portion of the retina with the eccentricity of greater than 35 degrees.
23. The apparatus of claim 1 , wherein no more than 10% of a total amount of energy of the plurality of stimuli is directed to a fovea of the eye in order to decrease constriction of the pupil in response to the plurality of stimuli.