EP1384462B1

EP1384462B1 - Prism based dynamic vision training device and method thereof

Info

Publication number: EP1384462B1
Application number: EP03013071A
Authority: EP
Inventors: Chao-Chyun Lin
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-07-22
Filing date: 2003-06-10
Publication date: 2006-04-19
Anticipated expiration: 2023-06-10
Also published as: ATE323460T1; EP1384462A3; RU2003119855A; DE60304631D1; MXPA03006059A; DE60304631T2; MY134992A; EP1384462A2

Abstract

A vision training device includes a fixed frame positionable in front of a wearer's face. The fixed frame defines two windows corresponding in position to the eyes of the wearer, through which light passes. An optic system includes a prism lens, which may have fixed power or variable power by changing shapes thereof. The prism lens is mounted to the fixed frame and is movable between first and second positions, wherein in the first position, light is allowed to pass in a first state with which the eyes are adducted, and in the second position, light is allowed to pass in a second state with which the eyes are abducted. A transmission system is coupled to and selectively drives the prism lens between the first and second positions. Thus, by repeatedly and cyclically moving the prism lens between the first and second positions, the eyes are forced to change between adduction and abduction thereby realizing training of vision. <IMAGE>

Description

BACKROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a method for training and thus improving vision of human beings, especially the nearsighted, and in particular to repeatedly and cyclically moving prisms in front of and away from eyes to forcibly abduct eyeballs in order to exercise and relax eyeball movement muscles thereby slowing down potential myopic progress and decreasing severity of myopia.

2. The Related Art

The structure of a human eye is similar to a camera. Generally, a human eye has ciliary muscles controlling the thickness of the lens, and thus causing accommodation of the lens to form a clear image when the eye looks at an object located at either a short distance or a far distance. Six extraocular muscles act on the eyeball and control the movement of the eye. The extraocular muscles of the two eyeballs of an individual coordinate together to look towards the same direction and focus on the same object. When looking at a near distance, the two eyeballs adduct to focus on the same object. When the object is at a far distance, on the contrary, the two eyeballs abduct.
It is a known fact of ophthalmology that the adduction and abduction of the eyeballs, which cause convergence and divergence of the eyeballs respectively, work synergistically with accommodation of the lenses to enhance the process of focusing. When focusing at a close-distanced object, the eyeballs adduct, aiding the contraction of the ciliary muscles, which thickens the lenses to form a clear image. This is referred to as "accommodation". On the other hand, when focusing at a far-distanced object, the abduction of the two eyeballs helps in relaxing the ciliary muscles to slim up the lenses, hence forming a clear image for the far-distanced object. This is referred to as "relaxation of accommodation".
In the past decades, due to modernization and changes in lifestyle, there has been a dramatic increase in the need for individuals to sustain constant short-range viewing. Long durations of short-range work, such as writing, reading, operating computers and watching television, require prolonged contraction of the ciliary muscles and the internal rectus muscles, making the muscles stiffened. This is especially likely in young people, whose eyes are still in development. Due to the stiffened ciliary muscles, the thickened lenses are difficult or even unable to become thin again when viewing distant objects. The image of the distant object thus falls in front of the retina and becomes unclear, thus causing myopia.
There are two types of myopia: "functional myopia" (refractive myopia) and "structural myopia" (axial myopia), differentiated by their mechanism of formation. Functional myopia is formed by over-contraction of the ciliary muscles, which causes over-thickening of the lenses, making image of a distant object fall in front of the retina. In "structural myopia", the lenses are normal, but the oculi axes are too long to make the image fall in front of the retina.
All myopias begin with functional myopia, including the so called "pseudo-myopia". In the functional myopia, if the eye movement muscles (extraocular and intraocular muscles) are unable to relax due to prolonged hours of constant short-range viewing, the eyeballs start to adapt to the situation by increasing the length of the oculi axis so that the image of close objects fall on the retina, inducing formation of structural myopia. This acquired myopia can be found in most modernized countries.
The progression of myopia is the result of a vicious circle of the functional myopia and the structural myopia. Therefore, if the functional myopia can be controlled and over-lengthening of the oculi axes can be prevented, the progression of the structural myopia can be stopped or at least slowed down.
Humanoid has their eyes side by side in front of the head and is, by default, accustomed to convergence rather than divergence. Due to the arrangement of the eyes, the most abducted eye position is usually that of a parallel vision occurring when viewing a far-distanced object. Theoretically, increasing abduction of the eyeballs to an eye position that is more abducted than that of a parallel vision will balance out over-adduction that comes along with the modern life-style.
The ophthalmological facts are as follows. With increased adduction, accommodation of eye increases. On the other hand, when the eyes abduct, accommodation decreases, namely relaxation of accommodation. Therefore, it can be said that, prolonged duration of adduction and accommodation is the cause of myopia and its progression.
Long hours of viewing with the eyes, compounded by a fixed focal length, especially a short fixed focal length, is the most common cause of myopia. People with normal vision (namely, a person having no myopia) is able to have clear images of both close and far distanced objects because their eye movement muscles (extraocular and intraocular muscles) remain agile and not stiffened due to less time of short-distance fixed focal length.
Muscles, such as those of legs, arms and the rest of human body, start aching and get stiffened when the muscles fixed in one position for long while. However, periodical exercise maintains the muscles agile and prevent the muscles from getting aching. The eye movement muscles (extraocular and intraocular muscles) are of no exception. Constant change of focal length by movement of the eyeballs effectively prevents the eye muscles from stiffening, thus preventing myopia. Therefore, by maintaining constant movement of the eye muscles, especially within short durations of time, during short-range viewing, myopia can be prevented and giving up short-range viewing in an effort to prevent myopia is unnecessary. That is, the eyeballs must change positions among adduction, abduction, accommodation, and relax of accommodation, in a short time for protection purposes. The focal length is altered constantly to prevent myopia from occurring, as myopia is caused by long hours of looking with a short fixed focal length.
A number of vision training devices are available in the market. These known vision training device all emphasize on exercising eyeballs. Some of these devices train the extraocular muscles by having eyes follow a series of lights, while the others train the intraocular muscles by having eyes look at one object that constantly moves toward and away from the viewer. These known devices are only good in simultaneously moving the two eyeballs as a whole and are not able to affect abduction of the eyeballs. The training result of these known devices is in general not very good, because the "optimal relaxation of accommodation" can only be achieved by the abduction of the two eyeballs and the use of convex lenses that substitute for the contraction of the ciliary muscles.
Clinically, the lengthening speed of the oculi axes in structural myopia is far greater than that of the normal growth lengthening. Hence, with an ophthalmoscope, a bluish crescent can be found at the temporal side of the optic disk on the retina, which is called the temporal choroidal crescent or more commonly, the myopic crescent. A possible explanation of this phenomenon is that the eyeballs are, by functional requirement, constantly held in adduction for long durations. The optic nerve is situated at the posterior of the eyeball closer to the nasal side. When the eyeballs adduct, the corneal section turns towards the nasal side, while the posterior section of the eye turns towards the temporal side, causing the temporal side of the junction of the optic nerve and the eyeball to be stretched, forming the myopic crescent, and lengthening the posterior wall. Therefore, adduction of the eyeballs could be the reason for lengthening of the oculi axes and the formation of the myopic crescent.
Further, the conventional vision training devices require a predetermined and devoted period of time every day for using the device and training the eyes. People often find that it is troublesome and boring to take the training by using the device everyday. Thus, most people are not able to continue with the training sessions day after day, let alone for months or years. Training is thus often abandoned shortly after commencement. As a result, these conventional devices are considered ineffective.
The device disclosed in US Patent No. 3,875,934, which is in accordance with the preamble of claim 1 comprises eye and object means so mounted that they may be moved between the nearest and farthest positions by a driving means to reciprocally change the distance between them and prism means rotatably mounted in front of the object lens. Such a conventional device, although providing a movable image in front of the viewer's eye, has a complicated structure and occupies a great amount of space, which makes it impossible for such a conventional device to be worn as a regular eyeglass and has to be supported in front of the face of the viewer by a particularly design supporting device. Daily living of the viewer is certainly affected by the device when the viewer wears the device.
Thus, the present invention is aimed to provide a dynamic vision training device that overcomes the deficiencies of the prior art and effectively improve human vision by slowing down the speed of myopic progression and alleviating myopia.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a vision training device that can be used during normal "working" time. The device can be worn when a wearer is writing, operating computers, and even watching television to relax eye movement muscles of the wearer unwittingly. The daily life of the wearer is in general not affected and the wearer does not feel the training process troublesome or boring.
A further object of the present invention is to provide a vision training device that is designed to wear on the head, or positioned over the eyes as glasses or eyeshade, or a tabletop type device.
A further object of the present invention is to provide a vision training device in which a combination of convex, concave and prism lenses is selected to coordinate with the different viewing distances of different users and to substitute the glasses of the myopic users.
To achieve the above objects, in accordance with the present invention as defined by claim 1, there is provided a vision training device comprising a fixed frame positionable in front of a wearer's face. The fixed frame defines two windows corresponding in position to the eyes of the wearer, through which light passes. An optic system comprises a prism lens, which may have fixed power or variable power by changing shapes thereof. The prism lens is mounted to the fixed frame and is movable between first and second positions, wherein in the first position, light is allowed to pass in a first state with which the eyes are adducted, and in the second position, light is allowed to pass in a second state with which the eyes are abducted. A transmission system is coupled to and selectively drives the prism lens between the first and second positions. Thus, by repeatedly and cyclically moving the prism lens between the first and second positions, the eyes are forced to change between adduction and abduction thereby realizing training of vision.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be apparent to those skilled in the art by reading the following description of preferred embodiments thereof, with reference to the attached drawings, in which:

Fig. 1: is a schematic view showing the eyesight of a person looking at a short distance object whereby the eyeballs are adducted;
Fig. 2: is a schematic view showing the principle of the present invention wherein prism lens are placed in front of the eyes of a person to make the eyeball abducted when the person is looking at a short distance object;
Fig. 3: is a schematic view showing a conventional convex lens;
Fig. 4: is a schematic view showing a convex-prism lens to be incorporated in a vision training device constructed in accordance with the present invention;
Fig. 5: is a side elevational view showing the vision training device of the present invention worn on the head of a wearer;
Fig. 6: is a cross-sectional view of a vision training device in accordance with a third embodiment of the present invention observed from a top side thereof, some components being removed for simplicity;
Fig. 7: is a front view of the vision training device of the third embodiment of the present invention and
Fig. 8: is a front view similar to Figure 12 but showing prism lens of the vision training device in non-operating positions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings and in particular to Figures 1-4, a description of the principle of vision training in accordance with the present invention will be given first before details of the constructions of preferred embodiment are illustrated. Figure 1 shows a general condition when a person has his or her eyeballs A looking at an object B, which is located nearby. Due to the image fusion mechanism of human brain, the eyeballs A are adducted to form a single image. In order to realize abduction of the eyeballs A, in accordance with the present invention, a prism lens C is placed in front of each eyeball A whereby the eyeballs A are abducted, again, to avoid formation of double images.
In accordance with the present invention, a prism lens may be separately used or used in combination with a convex lens. Figure 3 shows a conventional convex lens D. A prism lens C can be integrated with the convex lens D to form a convex-prism lens E in accordance with the present invention. The convex-prism E provides vision training in accordance with the present invention while at the same time allows for a nearsighted wearer to perform his or her daily job without being subject to undesired constraints that are commonly observed in the conventional vision training devices. One way to make the convex-prism lens E is to grind a prism lens C to form a convex configuration on one or two sides thereof. This is a well-known technique in the field of lens-making and thus no further details will be given herein. It is noted that in the following description, the term "prism lens" may sometimes include the "convex-prism lens".
Referring to Figure 5, a vision training device constructed in accordance with the present invention is broadly designated with reference numeral 900 is positioned in front of a wearer's head 902. The vision training device 900 comprises prism lens C or convex-prism lens E aligned with the eyeballs A of the wear 902 for changing the eyesight from a non-abducted condition to an abducted condition as respectively illustrated in Figures 1 and 2. With this, the eyeballs A are forced to abduct and thus achieving vision training in accordance with the present invention.
In the following description, for purpose of simplification, the prism lens C or the convex-prism lens E has a thicker side which will be referred to as "base" of the lens and is used as a benchmark. The lens C (or E) are referred to as "base in" when two lens C (E) are positioned in front of the eyeballs A of the wearer 902 with the bases thereof close to each other wherein the eyeballs A abduct as illustrated in Figure 2. In other words, the bases of the lens are facing each other. On the other hand, when the bases of the two lenses are oriented away from each other in opposite directions, it is referred to as "base out". When the bases point downwards at the time when the vision training device 900 is worn, it is referred to as "base down" wherein the eyeballs A turn upwards.
As human life becomes more and more civilized in recent years when compared to that of the old time when there have been fewer cases of myopia, there is an increase in short-range viewing, where the eyeball movement is generally inward and downward, but rarely upward. To correct the undesired consequence of the short-range viewing, the prism lens C or the convex-prism lens E are placed at the base-down and base-in positions to increase the upward-turning action and abduction of the eyeballs A, thus training the extraocular muscles to move smoothly in every direction and hence slowing down the speed of myopic progression.
When the wearer 902 looks at a distant object, the base-in and base-out positions of the prism lenses C (or the convex-prism E) interchange for the eyeballs A to repeatedly and cyclically abduct and adduct. Alternatively, the base-out condition of the prism lens C (or convex-prism lens E) can be replaced by no prism lens C and the operation of the vision training device 900 of the present invention becomes repeated and cyclical base-in and "no prism lenses".
The length of time that the wearer has to see through the prism lenses for vision training purposes is dependent on whether the wearer is doing short-range or long-range viewing. For example, in a short-range viewing (writing, reading or operating computers), the time period with the prism lens C or the convex prism lens E (that is base-in) is about 20 seconds and the time period without the prism lens C or the convex-prism lens E (that is base-out) is about 6 seconds. In a long-range viewing, such as watching TV, the time period with the prism lens C or the convex-prism lens E (that is base-in) is about 10 seconds and the time period without the prism lens C or the convex-prism lenses E (that is base-out) is about 6 seconds.
In general, the time period with the prism lens C or the convex-prism lens E on is approximately between 10-30 seconds. If the time period is less than 10 seconds, dizziness can result, due to the rapid change. If the time period is greater than 30 seconds, the training result is reduced.
The time period with the lens C or E off or at the base-out position is approximately between 5-20 seconds. During this time, the eye movement muscles, such as the extraocular and intraocular muscles, return to their contracted and tense state. Thus the time period for base-out or "no prism lens" should not be too long, so as to reach the intended purpose of this invention for exercising and relaxing the eyeballs.
The change of the prism lens or the convex-prism lens includes change of degree of power and change of position. In the description, it is assumed same degree of power for the prism lens and/or the convex power for both eyes. The "degree of power" mentioned hereafter is for that of one single eye. During short-range viewing, the degree of power used should be greater than the degree used at long-range viewing. This is because the degree of adduction at short-range viewing is more than the degree of adduction at long-range viewing. Hence a greater prism power is needed for the eyeballs to abduct.
Thus, the degree of prism power and convex power for short-range viewing is:

Prism power: 4 ΔDiopter -10 ΔDiopter (for single eye)
Convex power: +1.0 Diopter - +3.0 Diopter (for single eye)

During long-range viewing, the degree of power used should be less than the degree used at short-range viewing. The degree of adduction is already small during long-range viewing, so if a too powerful prism degree is used, double vision will occur due to the brain being unable to perform the image fusion mechanism. If the prism power is less than 3 ΔDiopter, the degree of eyeball abduction caused is too small, and the training result is limited. However, if the prism power is too great, double vision will occur and it is not possible to perform the image fusion mechanism.
Thus the degree of prism power and convex power for long-range viewing is:

Prism power: 3 ΔDiopter - 8 ΔDiopter (for single eye)
Convex power: +0.25 Diopter - +0.75 Diopter (for single eye)

Clinical trials show that the degree of prism power used should differ from person to person. People with exophoria have a more abducted eye position normally and thus a greater degree of prism power can be used. People with esophoria, on the other hand, should use prism lenses that are less powerful. This person-to-person differences of the prism power needed can be overcome by changing the prism lens.
The degree of the convex lens power is approximately between +0.25 Diopter - +3.0 Diopter. This includes the total convex power used. In the present invention, the described degree of convex power is only for the single eye and if the prism lenses are superimposed, the degree of power described should then be the total of all lenses used for one single eye.
During short-range viewing, the degree of convex lens power should be more than the degree used during long-range viewing. The degree of convex power should be inversely proportionate to the "distance to the object" viewing, that is, the further the object is, the lesser the power should be used. The actual use of convex power in this invention should be +0.25 Diopter - +0.75 Diopter more than the convex power calculated optically, so as to produce a fogged vision, which facilitates the total relax of accommodation.
For example if a person is using the vision training device 900 of the present invention with a viewing distance of 50cm: 100cm ÷ 50cm = 2.0 Diopter. Then, the convex power used should be approximately +2.25 Diopter - +2.75 Diopter.
If a person is using the vision training device 900 of the present invention with a viewing distance of 33cm: 100cm ÷ 33cm = 3.0 Diopter. Then, the convex power used should be approximately +3.25 Diopter - +3.75 Diopter.
In the present invention, the vision training device 900 can be made in a plurality of configurations. For example, it can also be designed to wear on the head 902 as shown in Figure 5, wear over the eyes as glasses or eyeshade, or as a tabletop type device.
Referring to Figures 6-8, the vision training device constructed in accordance with the present invention is illustrated and designated with reference numeral 900C. The vision training device 900C comprises a fixed frame 10 defining two viewing windows corresponding to which two prism lenses C that are retained in two first rings 11 are arranged. Each first ring 11 defines a circumferential groove along an outer circumference thereof for engaging rollers 12 that support the rotation of the first ring so as to move the prism lenses C between base-in and base-out positions. A first motor 15 controlled by a control circuit (not shown) is coupled to a gear 14 by a pair of bevel gears 151, 141 and the gear 14 mates external teeth (not labeled) formed on the circumference of the first ring 11.
A swing arm 112 is rotatably mounted to the fixed frame 10 by a pivot shaft 112A and carries a second ring 11A in which a convex-prism lens E is mounted. A pinion 171 is mounted to the swing arm 112 and is coaxial with the pivot shaft 112A. The pinion 171 is coupled to a second motor 15A controlled by a control circuit (not shown), by means of a gear train comprised of at least one idle gear 17. By means of the operation of the step motor 15A, the swing arms 112 is rotated about the pivot shaft 112A and the lens E is moved between the base-in position in front of the viewing window as shown in Figure 7 and the base-out position offset from the viewing window as shown in Figure 8.

Claims

A vision training device (900C) comprising: a fixed frame (10) adapted to position in front of a wearer's face, the fixed frame (10) defining at least a window corresponding in position to an eye of the wearer, through which light passes; an optic system comprising a prism lens (E) movably mounted to the fixed frame (10) to be movable between first and second positions, wherein in the first position, light is allowed to pass in a first state and in the second position, light is allowed to pass in a second state that is different from the first state; and a transmission system coupled to and selectively driving the prism lens between the first and second positions, the transmission system comprising a rotatable ring (11A) carrying the prism lens (E), characterized by the rotatable ring (11A) being rotatable about a pivot (112A) to move the prism lens (E) between the first position where the prism lens (E) does not overlap the window and the second position where the prism lens (E) overlaps the window.
The vision training device as claimed in Claim 1, wherein the optic system comprising a convex-prism lens (E) comprising a convex configuration formed on a prism lens, the convex-prism lens having a base that has a great thickness.
The vision training device as claimed in Claim 1, wherein the pivot (112A) extends in a direction substantially normal to the wearer's face.
The vision training device as claimed in Claim 3, wherein the transmission system comprises a gear system (17, 171) coupled between a driving device (15A) and the pivot (112A) for rotating the pivot (112A).