Patent Application
20130321774
This invention relates to instruments for determining a person's dominant eye. This invention relates particularly to a hand-held laser device for determining a person's dominant eye.
Most people have a dominant eye, or one eye that looks directly at the object of regard. The non-dominant eye sees the object at a slight angle. Thus, when a person uses both eyes, the non-dominant eye is seeing a slightly different view. The difference between views gives humans depth perception.
It is important to know which eye is dominant for certain activities that require the person to judge the relative position of objects, such as sports that require accurate aim or making an accurate drawing of an object. It is also important to know which is eye is dominant for prescribing corrective eyeglasses and for corrective eye surgery. In surgical cases, where monovision (one eye for distance and one eye for close-up vision) is required, the dominant eye is usually set for distance vision and the non-dominant eye for close-up vision.
A common method for determining the dominant eye involves cutting a hole about one inch square in a piece of paper, holding it at arm's length, and focusing on an object through the hole with both eyes. The person then closes his right eye. If the object disappears from view, the person is right-eye dominant. If the person closes his left eye instead and the object disappears from view, the person is left-eye dominant. This method is simple, but is disadvantageous because it isn't standardized; for example the hole size, the object focused on, and the distance of the object focused on differs from person to person. It would be desirable to have a device that enables the eye dominance test to be standardized.
This is a device for determining the dominant eye of a person. The device is a hand-held device, having a cone with a small hole at its apex which serves as a view port. The cone is attached to a handle, which contains a battery-powered, low-level laser light source that emits light through a light port in the handle. The cone and handle are designed to be made from a single sheet of material.
To determine a person's dominant eye, the person holds the device at arm's length by the handle, preferably by both hands at the person's nose level. The laser is turned on and the person aims the light at a distant wall. The person looks through the base of the cone through the view port with both eyes open, and locates the laser light spot on the distant wall through the view port. The person then closes his right eye. If the laser spot disappears from view, the person is right-eye dominant. Conversely, if the person closes his left eye and the laser spot disappears from view, the person is left-eye dominant.
Preferably the base of the cone 11 is larger than the person's interpupillary distance, so that the person looks through, not past, the cone when focusing on the light spot. Thus, because the average adult human interpupillary distance is considered to be between 60-70 mm, typically the base of the cone will be at least 7 cm in diameter. The view port 18 is preferably at least 12.5 mm and in the preferred embodiment is about 25 mm. A larger view port may suffice.
In a preferred embodiment, the light source is a battery-powered semiconductor laser diode 50, available commercially. A low-level laser diode is used to produce a tightly focused spot of laser light at a distance of about 5 m. The spot will preferably be about 2-3 mm in diameter. Preferably the laser diode emits red light. Also preferably the laser diode is small enough to fit inside the handle and emit light out the light port 19 without need for light-bending optical elements. That is, preferably laser diode is chosen that is short enough to be positioned along a diameter of the handle so that the axis of the light it emits is substantially parallel to a diameter of the handle. In a specific example, if the handle is perpendicular to the axis of the cone a, the diode is positioned so that the light it emits b is substantially perpendicular to the handle. Other light sources, such as incandescent lamps or LEDs may be suitable, although the heat and lack of focus at distance are disadvantageous relative to a laser light source.
To determine a person's dominant eye, the person holds the device 10 at arm's length by the handle 12. See
At arm's length, view port 18 is held, on average, at about 84 cm from the person's eyes. The light source is turned on and the person shines the emitted light on a far wall. Preferably the distance from the person's eyes to the light spot on the far wall is about 4.6 m, which is easily attained in ophthalmologists' examination rooms, which are customarily at least that long. The person then looks through the view port 18 to locate the light spot on the distant wall. The person then closes his right eye. If the laser spot disappears from view, the person is right-eye dominant. Of course, if the person instead closes his left eye and the laser spot disappears from view, the person is left-eye dominant.
In the preferred embodiment, the patient holds the device 10 at arm's length while standing about 4.5 m from the wall. The patient looks through the 25 mm diameter opening at the apex of the conical section and locates the red laser spot on the wall with both eyes open. When the patient closes one eye, and the red dot disappears, the closed eye is the dominant eye.
The cone 11 and handle 12 are preferably designed to be made from a single sheet of material.
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The single sheet manufacture enables lower-cost manufacturing than other methods. Alternatively, instead of a single sheet to manufacture the device, the device can be formed of a handle component attached to a cone component, such as a modified plastic funnel. The handle may be attached to a cone using a fastening means such as a weld, adhesive, or snap-fit plastic. Alternatively, the handle may be integral with the cone, for example as achieved by injection-mold manufacturing.
While there has been illustrated and described what is at present considered to be the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made and equivalents may be substituted for elements thereof without departing from the true scope of the invention. Therefore, it is intended that this invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
