BACKGROUND

Myopia, or near-sightedness, is a refractive error in which far objects are focused anterior to the retina. This can be related to the axial length of the eye. In general, a 1.0 mm increase in axial length of the eye corresponds to an increase in myopia of 2.5 Diopters (“D”).

Spectacle lenses, contact lenses and refractive surgery can be used to treat refractive errors of the eye such as myopia. Although these approaches can be effective in treating myopia, the eye may continue to grow axially, such that the amount of myopia continues to increase. The relatively high prevalence of myopia has prompted studies to understand the underlying mechanisms of axial growth and the development of possible treatment directed to axial growth.

While myopia is known to have genetic causes, the dramatic increase in the incidence of myopia cannot be explained by genetic factors alone; rather, they must be interpreted simply as the remarkable ability of the visual system to adapt to altered environmental conditions, specifically a shift in visual habits from long to short distances and from open to enclosed spaces.

It is known that the retina of many species, including human beings responds to defocused images and grows in order to minimize the blur caused by the defocus. The mechanism of the generation of the growth signal is still under study, but the one of the observable phenomena of the response of retinal tissue to the growth signal is the change in thickness of the choroid. A myopically defocused image can cause the choroid to grow thicker, thus effectively shortening the axial length of the eye, while a hyperopically defocused image can cause the choroid to grow thinner, leading to an increase in axial length. Work in relation to the present disclosure suggests that the change in axial length caused by retinal response to a hyperopic blur or defocus can contribute to myopia development.

While the defocus of images can play a role in choroidal thickness and changes in the axial length of the eye, the prior methods and apparatus are less than ideally suited to address changes in retinal thickness and axial length of the eye. For example, pharmaceutical treatments have been proposed to treat myopia associated with axial length growth, these treatments can have less than ideal results in at least some instances. While atropine and other muscarinic agents can slow myopia progression, possible concerns about post treatment rebound effects and the short and long-term side effects associated with prolonged treatment may have discouraged the widespread use of these drugs.

Although animal studies have demonstrated that refractive development and axial growth can be regulated by visual feedback associated with the eye's effective refractive status, the methods and apparatus used in these animal studies are less than ideally suited for the treatment of myopia in humans.

Work in relation to the present disclosure suggests that the retinal shell becomes more aspheric as the eye becomes more myopic. Examples of image shells on the retina with myopic eyes and traditional correction are described in Cooper, J, “A Review of Current Concepts of the Etiology and Treatment of Myopia” in Eye & Contact Lens, 2018; 44: pp 231. With traditional spherical lenses, the peripheral aspheric retina of the myopic eye receives light focused behind the retina while light is focused at the center of the retina, which can trigger a growth signal because the peripheral light is focused behind the retina, similarly to an eye with insufficient axial length. A conventional spherical or toric lens (e.g. a contact lens or a spectacle lens) generally cannot generate an image shell that matches the optimum shape required for refractive correction that would stop the growth signal to the retina to become even more myopic. One approach has been to provide an aspheric lens that focuses light onto the peripheral regions of the aspheric retina.

Previous refractive correction devices to prevent myopia progression may produce less than ideal results in at least some instances. The refractive correction to provide appropriate focus at the peripheral retina can require a highly aspheric image shell, that can be created by a highly aspheric optic. Unfortunately, such an aspheric optic can generate a central image with a substantial aberration, compromising far vision and reducing quality of vision of the wearer in at least some instances. One approach has been to limit the amount of asphericity to about 2 D or less in order to provide distance vision without significant aberrations to central vision, but this limitation on the amount of asphericity can also limit the amount of correction to peripheral portions of the retina, which can lead to a less than ideal treatment in some instances.

A second approach adopted by some prior art devices is to provide a bifocal or multifocal optic, comprising a central optical zone dedicated to correction of refractive error only, while the peripheral zones generally have more plus power to form a myopically defocused image on the peripheral retina. Ray tracing analyses show that these bifocal optics can create one or more foci at the fovea, compromising the image quality at the fovea.

Studies in animal models as well as clinical studies have suggested that the retina can distinguish a “plus blur” from a “minus blur”, or image blur caused by a myopic defocus from a hyperopic defocus, possibly by utilizing longitudinal chromatic aberration as a guide, since the sign of the longitudinal chromatic aberration will be opposite, depending on whether the image blur is hyperopic or myopic. However, prior clinical approaches may not have adequately addressed chromatic aberration to decrease myopia progression in at least some instances.

Therefore, new approaches are needed to treat refractive error of the eye and promote changes to axial length of the eye and choroidal thickness that ameliorate at least some of the limitations of the prior approaches.

SUMMARY

In some embodiments, a device to stimulate to the retina is configured to project one or more images on the retina that falls outside the fovea. The stimulation can be configured to promote a change in the axial length and/or choroidal thickness of the eye. The projected image may comprise a still image or a dynamic image, for example with a refresh rate in the range from 1 Hz to 500 Hz. The light may comprise monochromatic or polychromatic light within a range from 400 nm to 800 nm. The one or more images can be configured in many ways with an image structure corresponding to information or content of the image associated with spatial frequencies. In some embodiments, the one or more images comprises a spatial frequency within a range from 1 cycle per degree to 180 cycles per degree or from 1 cycle per degree to 30 cycles per degree or from 1 cycle per degree to 10 cycles per degree, and a contrast within a range 99.9% to 2.5%, for example. The projected image can be projected on to the retina with an eccentricity in relation to the fovea, and the eccentricity can be within a range from 5 degrees to 40 degrees. The projected image may cover the whole retina within the specified range of eccentricity, for example with an annular pattern, or the projected image may cover a portion of the retina within the range of eccentricity. The stimulation may be continuous or periodic or aperiodic. When periodic, the stimulation may persist for a duration within a range 1 sec to 24 hours. The stimulation may be applied in many ways, for example when the subject is awake or asleep and combinations thereof. The retinal stimulation may be applied using a light projection system. The light projection system can be configured in many ways and is suitable for combination with one or more of many devices. The projection optics as described herein can be integrated into one or more of a projector, an ophthalmic equipment, a TV screen, a computer screen, a handheld device such as a smart phone, a wearable device such as a spectacle lens, a near eye display, a head-mounted display, a goggle, a contact lens, a corneal onlay, a corneal inlay, a corneal prosthesis, or an intraocular lens. For example, the projection optics can be combined with a combination of these devices.

In some embodiments, a device to simulate the retina comprises a light source and optics to form an image in front of the retina, behind the retina or on the retina with one or more of an appropriate resolution, depth of focus or diffraction. The image formed on a region of the retina may comprise a resolution finer than the resolution of the retina at the region, such as the highest resolution of the retina at the region. The light beam can be directed to the region of the retina at an angle relative to the optical axis of the eye, so as to illuminate an outer portion of the retina away from the fovea with a resolution finer than the corresponding location of the retina. The depth of focus can be configured to illuminate the retina with an appropriate amount of blurring of the image on the retina, and the diffraction of the spot can be appropriately sized to provide resolution of the image formed in front of the retina finer than the resolution of the retina.

In accordance with some embodiments, a device to stimulate the retina comprises micro-displays located away from a center of a lens and toward a periphery of the lens, in which each of the micro-displays is coupled to a micro-lens array located posteriorly to the micro-display. The micro-displays may comprise an OLED (organic light emitting diode) or an array of micro-LEDs. The micro-lens arrays can be optically coupled with the displays to efficiently collect light from the micro-displays, and substantially collimate the light and/or converge the light before projecting the light into the entrance pupil. The images created by these displays can be myopically or hyperopically defocused and placed symmetrically in a plurality of regions on the retina, such as four sectors (nasal-inferior, nasal-superior, temporal-inferior and temporal-superior). The micro displays can be located away from the optical center of the lens by a distance within a range from 1.5 mm to 4.0 mm, such as 2.5 mm to 3.5 mm. The central optical zone14of the lens can be configured to provide emmetropic vision for the wearer, and may have a diameter within a range 3.0 to 5.0 mm. Each micro-display can generate a retinal image with an appropriate shape, such as circular or arcuate and at an angle of about 20 to 60 degrees with respect to the fovea. In some embodiments, the retinal images are formed at the peripheral retina at an eccentricity in the range of 7.5 degrees to about 45 degrees or 15 degrees to about 45 degrees or 15 degrees to 40 degrees, for example within a range from 15 to 30 degrees, 20 to 30 degrees, or 25 to 30 degrees. The lens may comprise an electronic control system mounted with the micro-displays on a flexible transparent sheet of material such as plastic and other components.

In some embodiments, the micro displays comprise OLEDs with pixel sizes within a range from 2.0 micrometers (microns) to 5.0 microns, with a pitch within the range of 3.0 microns to 10.0 microns. In some embodiments, the micro displays comprise OLEDs with pixel sizes within a range from 5.0 micrometers (microns) to 50.0 microns, with a pitch within the range of 10.0 microns to 100.0 microns. In some embodiments, the micro-displays embedded in the lens comprise micro-LEDS illuminating an object, such as a thin film placed in front of it and toward the eye. The film may be transparent or translucent comprising a printed pattern that may be a Fourier transform of the image designed to be projected on the retina. The micro-displays may comprise polychromatic or monochromatic micro-displays. The polychromatic images can be formed by RGB pixels in the OLED or micro-LEDS of different colors, organized in arrays so as to form an RGB display. In some embodiments, the wavelength for stimulation of the retain is within a range from about 450 nm to about 560 nm (in some embodiments, from about 410 nm to about 560 nm), and can be near 500 nm, the peak wavelength of stimulation of rods in the eye, although other wavelengths may be used. In some embodiments, the chromaticity of the light sources includes violet light comprising a wavelength within the range from 400 to 450 nm.

In some embodiments, an optical configuration comprises one or more light sources coupled to one or more projection optics that comprise one or more of a collimating lens, a compound lens such as a Gabor lens, a prism, an array of prisms, a mirror, a lightguide, a waveguide, a plurality of mirrors, or holographic mirrors. In some embodiments, the waveguide is configured to preserve a phase of the wavefront transmitted therethrough. The one or more projection optics can be configured to image the one or more light sources so as to a project an image of the light source in front of, behind, or on the peripheral retina. In some embodiments, the optic configuration is placed at or near the anterior surface of the lens, and rays from the micro-displays are focused by the lens. In some embodiments, the lens is configured to provide refractive correction to the wearer, and the display optics configured to provide additional focus to provide the defocused image of the micro-display on the retina. In some embodiments, the amount defocus is in within a range from about 2.00 Diopter (D) to 6.00 D, and can be within a range from about 2.0 D to 4.0 D.

In some embodiments, a spectacle lens is configured with a near eye display that projects a 2.0 to 5.0 D or 2.0 to 7.0 D myopically defocused image at the outer retina toward the retinal periphery, while maintaining central vision. In some embodiments, a device comprises pair of spectacle lenses is configured with near eye displays that project a pair of 2.0 to 5.0 D or 2.0 to 7.0 D myopically defocused images at the retinal periphery, while maintaining central vision. Each optic of the device may be coupled to a near eye display to project the one or more myopically defocused images at the retinal periphery while the optical center of the spectacle lens optic provides the required refractive correction to the wearer for far vision. The optic can be configured to provide the refractive correction in order to allow comfortable and clear viewing of the real world at all object distances, while the display projects the 2.0 to 5.0 D or 2.0 to 7.0 D myopically defocused images toward an outer portion of the retina.

In some embodiments, a spectacle lens is configured to project myopically defocused images at the retinal periphery while maintaining good focus at the central retina. In some embodiments, a spectacle lens is configured to provide a light field, in which the refractive power of the lens varies with the gaze direction and object distance across the body of the spectacle lens optic. In some embodiments, the spectacle lens is configured to provide a match between vergence, image magnification and refractive correction. In some embodiments, near vision is usually associated with a lower gaze angle (inferior gaze), and the refractive power of a multifocal or progressive addition spectacle lens optic increases downwards. In some embodiments, the spectacle is configured for a wearer who can accommodate the spectacle provides less plus power. Additionally, the optical design of a binocular optic may be adjusted to promote binocular summation while executing conjugate eye movements. In some embodiments, the area of the spectacle lens optic that is left unmodified is an area approximately 8 to 15 mm, preferably 10 to 12 mm in diameter disposed around the optical center of the spectacle lens optic. In some embodiments, the area of the spectacle lens optic that is left unmodified is an area preferably 10 to 15 mm in diameter disposed around the optical center of the spectacle lens optic.

In some embodiments, the near eye display comprises a microminiature light source, such as an organic light emitting diode (“OLED”), a transparent organic LED (“TOLED”) or an i-LED, and a micro-lens array to substantially collimate the light emanating from the light source and direct it to the pupil of the eye. Alternatively or in combination, a micro-mirror array can be used to collimate the light emanating from the light source and direct it to the pupil of the eye. In some embodiments, the light source is mounted on a transparent substrate (e.g., a TOLED), while in some embodiments, it may be mounted on an opaque substrate, such as silicon. The light source may comprise an active matrix or a passive matrix. The components can be held together in a transparent hermetically sealed package. In some embodiments, the hermetic sealing package may be conformal, comprising a multilayer film of total thickness within a range from 5 microns to 25 microns, for example from 10 microns to 15 microns. The device can also include a component that can monitor eye movements such as a gaze tracker. In some embodiments, a gaze tracker is configured to locate the point on the spectacle lens optic corresponding to the point of regard, at which the optic axis of the eye intersects the optic for a particular position of the eye as the eye executes pursuit eye movement such as tracking of a moving object. In some embodiments, eye movement may be monitored and followed by an eye tracker which may comprise a coil embedded in the eyeglass frame that senses movement of the eye through the development of a transient magnetic field during eye movement, for example from movement of a coil such as a coil within a contact lens worn on the eye. In some embodiments, retinal images formed by the light rays from the display are myopically defocused by 2.0 D to 5.0 D or 2.0 to 7.0 D anteriorly to the retina and are incident on the outer portions of the retina so as to form images anteriorly to the retina. While the images can be formed anteriorly to the retina in many ways, in some embodiments the images are formed about 15 degrees to 40 degrees eccentric to the fovea. In some embodiments the images are formed about 5 degrees to 40 degrees eccentric to the fovea.

