DEVICE FOR ALLEVIATING COMPUTER VISION SYNDROME
BACKGROUND OF THE INVENTION
The invention relates to a vision-improving device worn over one's eyes, similar to a pair of spectacles or a device that is attached to spectacles, for alleviating the condition known as "computer-vision syndrome (CVS)" which is the collective term for the conditions of eye fatigue, eye strain, and eye irritation that occur when viewing video- display terminals (VDTs) , particularly computer screens, for extended periods of time.
According to a news release of the American Optometric Association, the most common symptoms of CVS are tired, burning, itching and watering eyes, headaches, flickering sensations and double vision. The first of these complaints, known as eye fatigue, eye strain, or "tired eyes", is often attributed to fatigue of the ciliary muscle, i.e., the ring muscle that surrounds the crystalline lens of the eye and, by contracting or relaxing, controls the degree of convexity, and thus the focal length, of the lens. A relaxed state of the ciliary muscle corresponds to a greater focal length, which allows distant objects to be seen sharply, while contraction of the ciliary muscle has the result of shortening the focal
length for viewing close objects. The process whereby the ciliary muscle adjusts the crystalline lens to the distance of an object to be viewed is called accommodation.
In addition, prolonged activity at a computer can cause problems in other areas of the body. While the reader of printed material remains comfortable by shifting body position as well as by varying ways of holding a book or paper, computer users tend to maintain a rigidly fixed posture that can cause musculoskeletal difficulties like neck aches, shoulder pains and backaches. In part the fixed and in some cases unnatural posture is dictated by the spatially fixed arrangement of the video display and keyboard. Also, wearers of bifocals, trifocals and progressive lenses have a special problem in that their glasses will cause them to tilt their head back in order to view the screen through the lower part of the lenses.
The condition of "tired eyes" can be explained as muscle fatigue or, in severe cases, as a muscle cramp of the ciliary muscle, which is caused by keeping a fixed gaze at a close object over an extended period of time, as is particularly the case when working at a video display terminal. One could argue that the prolonged and unnaturally fixed contraction of the ciliary muscle also occurs when reading a book. While this may be true, however, printed material is free from the further aggravating factors of computer screens, i.e., reflective glare, flicker and fuzziness. These factors are essentially rooted in the
physics of the computer image as an array of dynamically illuminated pixels, which is fundamentally different from the static and passive (not self-illuminated) nature of a printed page .
Starting from the premise that the condition of "tired eyes" is in part related to the process of accommodating the optics of the eye to the distance of an object, there are, in principle, two ways in which to attempt a solution of the problem. With the first solution, commonly known as "computer glasses", individuals who have difficulty in accommodating to the specific distance at which video terminals are viewed are fitted with corrective lenses so that the combined focal length of the crystalline lens of each eye together with the respective spectacle lens is optimized for the distance of the VDT . However, this solution goes only as far as restoring the "computer vision" of the patient to the normal level, so that his or her eye fatigue will be no worse than for an individual with normal eyesight. Also, as a consequence of optimizing the focal length of the spectacle glasses specifically for the distance of the video display, the wearer' s vision at normal reading distance (which includes looking at the keyboard and at reference documents) will be under-corrected. Furthermore, the additional problems of the reflective glare of the screen and the flicker and fuzziness of the image are not being addressed at all by computer glasses.
As a second, less well-known possibility, one might consider the concept of so-called stenopaeic spectacles or
"pinhole glasses". These are best described as a kind of spectacles in which the lenses are replaced by opaque (i.e., light-impervious) shields with multiple pinhole-shaped openings. The principle of stenopaeic spectacles is easily understood by considering the diaphragm aperture of a camera: The smaller the aperture (i.e., the greater the f-stop setting) the greater the depth of field, i.e., the range of distances where objects will produce sharp images on the film. When looking through one of the holes of stenopaeic spectacles, the hole takes the place of the diaphragm opening; the crystalline lens in the eye of the viewer corresponds to the camera lens; and the retina of the viewer's eye corresponds to the camera film. Because of the smallness of the holes (corresponding to a large f-stop setting) the viewer' s depth of field will be greatly expanded, enabling him or her to see close as well as more distant objects sharply in a relaxed state of the ciliary muscle. Specifically in regard to working at a computer, the first benefit of stenopaeic spectacles is the reduction in eye strain, because the pin- hole effect removes or at least reduces the need to accommodate to the relatively close distance of the screen as well as the frequent change in accommodation between screen, mouse, keyboard, working documents, and other objects.
At the same time as the pin-hole effect extends the depth of field, the width and height of the field of vision are generally restricted when looking through a narrow opening. In other words, the peripheral areas of the field of vision are cut off. Although the loss in peripheral vision is
generally undesirable, it does have a significant benefit in the specific context of working at a computer. While the unprotected eyes of a worker take in useful information only from the small screen portion being focussed on, they are at the same time exposed to the irritation of the glare and flicker from the entire screen. By cutting off the peripheral field of vision, stenopaeic spectacles, therefore, provide a second kind of relief from eye strain in that they remove unnecessary "visual noise".
As an additional benefit, stenopaeic glasses can help to alleviate the problems experienced by computer users in other areas of the body. The restricted field of vision encourages the wearer to frequently shift his head position and thereby prevent the aforementioned stiffness of the neck. Most particularly, individuals normally wearing bifocals, trifocals or progressive lenses will be able to maintain a natural head posture when wearing stenopaeic spectacles for their computer work. This is in contrast to the upward-tilted head position that is necessary for viewing the video screen through the lower part of bifocals, trifocals or progressive lenses.
In conclusion, the concept of stenopaeic spectacles has great potential to solve the problems of Computer Vision Syndrome by addressing the two major root causes, i.e., fatigue of the ciliary muscle and irritation from "visual noise". However, there is a severe drawback in that, by cutting off peripheral vision, stenopaeic spectacles may feel
unacceptably awkward to the wearer. An acceptable solution would have to combine the aforementioned benefits with a satisfactory degree of peripheral vision of the surroundings.
OBJECT OF THE INVENTION
In view of the foregoing analysis of the problem of Computer Vison Syndrome caused by prolonged viewing of a video-display screen and the available options for. a solution, the objective of the present invention is to provide a device worn over one' s eyes for viewing a video display terminal based on the principle of stenopaeic spectacles, but without the handicap of restricting the wearer' s peripheral vision to an unacceptable degree.
SUMMARY OF THE INVENTION
The invention solves the problem just stated by providing a device that comprises a transparent, light- reducing shield worn over both eyes, or two separate shields - one for each eye - (i.e., essentially sun glasses), with at least one narrow aperture allowing light of non-reduced brightness to enter the pupil and reach the retina of each eye. The inventive device has a significant advantage in that it uses transparent shields or lenses rather than the light- impervious shields of state-of-the-art stenopaeic spectacles. Thus, the device will feel to the wearer about the same as sun glasses, i.e., the problems of restricted peripheral vision
and the associated awkwardness have been successfully eliminated.
In a simple but entirely functional embodiment, the narrow apertures - at least one for each eye - are perforations in the form of small holes or narrow slits.
The following, further developed embodiments will add specific features and enhancements to the principal concept of the invention.
As a first enhancement, the perforations of the foregoing basic embodiment can be replaced by clear (i.e., non-darkened) "windows" within the otherwise dark transparent shield. As an obvious advantage, a smooth shield is easier to keep clean than a perforated shield. In addition, the non- perforated shields provide a cosmetically more pleasing appearance, particularly in combination with a further enhancement where the shield is made to reflect light (as in reflective sun glasses), whereby the "windows" become invisible from the outside.
It goes without saying that the light-reducing property of the shield "can be achieved in any of the ways known from sun glasses or other light-protective eyewear devices such as welder's goggles. Instead of or in addition to being reflective, the shields can also reduce the passage of light by absorption and/or polarization.
Certain configurations and dimensions are preferred (without excluding other possibilities) for the narrow apertures. Typically, they are of a compact shape, about 1/16 inch to 1/4 inch across as measured in any direction, the most preferred size being about 1/8".
As an alternative to the compact-shaped apertures, the invention provides for at least one narrow horizontal slit (in relation to an upright position of the wearer of the spectacles) . Narrow slits, to a certain extent, exhibit the same field-depth enhancing properties as compact-shaped openings. The preferred width of the narrow slit or slits is about 1/8 inch (again without excluding other possibilities).
A further preferred embodiment has two parallel horizontal slits spaced about 3/10" to 8/10" apart. This arrangement is advantageous as it allows the wearer to shift his gaze between the screen and the keyboard without having to tilt his head to a major degree.
Another advantageous embodiment of the transparent shield has a plurality of apertures (i.e., perforations or windows) arranged in a single-line pattern or in a horizontal band extending horizontally (in relation to an upright position of the wearer) over at least a part of the shield.
The so arranged apertures can be separate from each other, or they can also be overlapping each other to any degree, including the singular case where they form a smooth-bordered horizontal slit. It has been found that even if the apertures
are somewhat spaced apart, the viewer will be able to combine the images received through the different apertures while retaining the benefits of the stenopaeic phenomenon as explained above for the case of a single aperture. The arrangement of the apertures along a single horizontal line or within a horizontal band has a particular advantage in that it provides a horizontal band of enhanced vision, which helps the wearer in focussing on selected lines of a text or rows of a spreadsheet displayed on a video screen. Also, shifting between lines or rows on the screen requires frequent small movements of the head, which helps to lessen the aforementioned possibility of neck cramps.
It is possible to produce embodiments of the inventive device that are fully integrated into the field of corrective, protective, and cosmetic eyewear of the conventional state of the art. The transparent shields can be made of the same materials and in the same shapes and sizes as conventional spectacle lenses, so that they can be cut and ground to size on the same machines, fitted into the same frames, and thus commercialized through the same channels, as conventional spectacle lenses. Furthermore, it is possible to add the element of stenopaeic apertures to corrective spectacle lenses of a light-reducing kind (such as in corrective sun glasses) to combine the benefits of a refractive optical lens with the field-depth enhancing effect of narrow apertures.
A further advantageous embodiment of the invention incorporates a hinge whereby the shield can be swiveled away from the wearer's eyes.
Finally, it goes without saying, that the concept of the invention can also be incorporated into devices that are attachable accessories, e.g., clip-on' s, to conventional spectacles .
The novel features that are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both in its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
The invention is explained below with details referenced against the attached drawing, where
Fig. 1 represents a general example of an embodiment of the invention;
Figures 2-5 represent portions of cross-sections of shields as used in the device of Fig. 1; and
Figures 6-9 represent frontal views of shields as used in the device of Fig. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Fig. 1 illustrates a general embodiment of the invention in the form of a pair of spectacles 1 with transparent, light-reducing shields or lenses 2 (essentially sun-glass lenses) containing one or more narrow apertures 3. It goes without saying that the spectacles 1 can be of the most varied configurations such as goggles with one shield covering both eyes, or a device that clips onto or otherwise attaches to normally worn eye glasses, to name only two examples .
Each of the Figures 2 to 5 shows a portion of a transparent, light-reducing shield in a cross-section containing one of the narrow apertures of Fig. 1. In the example of Fig. 2, the narrow aperture is a material-free perforation 203, e.g., a hole or a slit through a transparent, light-reducing shield 202. Fig. 3 illustrates as an alternative solution a solid (i.e., non-perforated) shield 302 consisting entirely of a transparent, light-reducing material except for one or more "windows" 303 where the shield material
is clear (i.e., fully transparent and not darkened). Shield 402 in Fig. 4, on the other hand, consists of clear material throughout and carries a transparent, light-reducing coating 404. In this case, the aperture is a narrow area 403 that is free of coating 404. Finally, the shield 502 of Fig. 5 has a reflective coating 505 covering the entire outer surface of the shield, e.g, for the cosmetic purpose of hiding the apertures (not shown here) . The apertures of shield 502 may be formed, e.g., in the manner of the windows 303 in shield 302 (Fig. 3) or the coating-free areas 403 of shield 402 (Fig. 4) .
Stenopaeic apertures in transparent, light-reducing shields are preferably compact-shaped, typically round, as in the example of aperture 603 in shield 602 of Fig. 6, with a width w of about 1/16 to 1/4 inch, the preferred size being about 1/8 inch.
As another preferred shape, Fig. 7 shows a shield 702 with an aperture in the form of a narrow horizontal slit 703 approximately across the middle of the shield 702. Optionally, there may be a second parallel slit 704 below the slit 703. The preferred width w of the slits is again about 1/8 inch. The preferred distance d between the slit 703 and the second, optional slit 704 is about 3/8" to 8/10".
In the case where a shield 802 has a plurality of compact-shaped, typically round, apertures 803, the latter are preferably arranged in a single horizontal line (Fig. 8) . The
compact-shaped apertures can have different degrees of separation, or they can overlap as in the case of the apertures 903 in Fig. 9. Analogous to the second, optional slit in the embodiment of Fig. 7, there can also be a second, optional line of compact-shaped apertures running parallel at a distance d (about 3/8" to 8/10") from the line of apertures 803 or 903, respectively.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of the aforedescribed contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the appended claims.