Many ophthalmic lenses, for example, lenses which are of complex design like aspheric or multifocal lenses, require exact fitting of the lens in the frame of the spectacles, so that at least some key points on the lens will be in certain positions relative to the center of the eye's pupil of the wearer. For example, one specific point should be exactly in front of the center of the pupil when the wearer looks straight forward to the horizon. This point is usually called a fitting point. Additionally, since users of multifocal lenses usually have to lower their gaze in order to look at close objects, a specific spot on the lens should be in front of the pupil when the wearer lowers his gaze.
In order to ensure the correct positions of said key points, the standard practice in the industry is to mark these points with marking pen on demo lenses installed in the chosen spectacles frame. After taking geometric measurements of these markings relative to the frame, the manufactured lens is fitted in the frame accordingly.
Usually, lens that has specific fitting conditions may have markings which may be invisible to the wearer. Those markings may enable identification of the points of interest, for example, the fitting point. An optician may visually check that those points are in the right position relative to the person's pupil when the spectacles are worn by the person. This process is based on assessment of the right position by the optician, and although the optician may use advanced vision tools for the assessment, this process may introduce an undetected error in the fitting of the lens, which may cause un-adaptation and rejection of the lens.
For example, reference is made to
The two types of errors which are described above with reference to
Therefore, a method for verifying the correct adaptation of lenses to frame which provide better accuracy is needed.
The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.
Embodiments of the present invention may provide a method and device verifying the correct fitting of a lens in a frame, which may provide much better accuracy than the standard known methods. The better accuracy may be provided by reducing the number of variables in the optical system which may be source of errors. While in the known methods the light rays corresponding to the points of interest are blocked at the points of interest, for example, by opaque markings, in embodiments of the present invention the light rays corresponding to the points of interest are allowed to pass through the lens while other rays of light in an area around the points of interest are blocked. In a method according to embodiments of the present invention the wearer of the spectacles may determine by himself if the lens are installed properly in the frame. Therefore, the assessment of a third party, e.g., the optician, may not be required.
Reference is now made to
Transparent stain 24 may be located on mask 25 correspondingly to a test point on the lens, as shown and described in detail below with reference to
In order to perform the examination of the adaptation of the lenses to the spectacles frame, a patient wearing spectacles in which lens 22 is fitted may look through mask 25, while the person may hold his head in a natural position for looking at object of interest 26. In case the lens is fitted correctly, transparent stain 24 should be substantially in front of pupil 20, thus, for example, enabling the spectacles wearer to see object 26.
According to different embodiments of the present invention, transparent stain 24 may have a shape of a spot, line or any other shape of interest.
According to some embodiments of the present invention. Mask 25 may be placed on lens 22 by sticking mask 25 on lens 22. For example, mask 25 may be any suitable kind of a sticker. For example, in some embodiments mask 25 may be stick to lens 22 by electrostatic effect. Mask 25 and lens 22 may include corresponding markings (for example, as described below and shown in
Reference is now made to
According to different embodiments of the present invention, transparent stain 38 may have a shape of a spot, line or any other shape of interest.
According to some embodiments of the present invention. Mask 34 may be placed on lens 32 by adhering mask 34 on lens 32. For example, mask 34 may be any suitable kind of a sticker. For example, in some embodiments mask 34 may be adhered to lens 32 by electrostatic effect. Mask 34 may include markings 36 which may correspond to markings 33 on lens 32, for example, in order to verify accurate positioning of mask 34 on lens 32, e.g., so that transparent stain 38 may be located substantially on the test point on lens 32. For example, the markings 33 on lens 32 may substantially coincide with corresponding markings 36 on mask 34 when mask 34 is positioned accurately on lens 32. Markings 33 may be made on lens 32 in its production process and/or may be invisible to the wearer of lens 32. However, markings 33 may be recognized, for example, highlighted, in order that markings 36 of mask 34 may be positioned substantially on them.
When mask 34 is positioned accurately on lens 32, e.g., so that transparent stain 38 may be located substantially on the test point on lens 32, a patient may wear spectacles 30 and aim his gaze in the direction of an object of interest, for example, which corresponds to the test point on lens 32, while holding his/her head in a natural position for looking at the object. In case the patient is able to see the object, he may conclude that the test point and the corresponding transparent stain 38 are located substantially in the correct position in front of his pupil, and therefore, he may conclude that lens 32 is fitted correctly in spectacles frame 30. However, in the case the patient is not able to see the object, he may conclude that the test point and the corresponding transparent stain 38 are not located in the correct position in front of his pupil and therefore, he may conclude that lens 32 is not fitted correctly in spectacles frame 30.
According to different embodiments of the present invention, transparent stain 38 may have a shape of a spot, line or any other shape of interest.
Reference is now made to
When mask 44 is located positioned accurately on lens 42, e.g., so that transparent stain 48 may be located substantially on the convergence path of lens 42, a patient may wear spectacles 40 and aim his gaze in the directions of plurality of objects of interest through different points along the transparent stain 48; this corresponds to different points along the convergence path of lens 42, while holding the head in a natural position for looking at the objects. In case the patient is able to see the objects clearly, he may conclude that the convergence path and the corresponding transparent stain 48 are located substantially in the correct position in front of his pupil, and therefore, for example, he may conclude that lens 42 is fitted correctly in spectacles frame 40. However, in the case the patient is not able to see the objects clearly, he may conclude that the convergence path and the corresponding transparent stain 48 are not located in the correct position in front of his pupil and therefore, he may conclude that lens 42 is not fitted correctly in spectacles frame 40.
Reference is now made to
The mask and the method described above may be used also for measurement of the desirable position of points of interest on the lens relative to the frame. As described above in the background of the invention, the standard practice in the industry is to mark these points with marking pen on demo lenses installed in the chosen spectacles frame. However, by using embodiments of the present invention, the optician may apply mask 34 or 44, for example, on a demo lens. The patient may look through mask 34 or 44 and determine the correct position of stain 38 or 48 and therefore, for example, the correct position of the point of interest on the lens. The determination of the correct position of stain 38 or 48 may be done by looking through mask 34 or 44 at an object of interest corresponding to the examined points of interest. For example, for determination of a correct position of a fitting point, the patient may look at a far object through mask 34. If the patient sees the object in a satisfactory quality of vision, the patient may conclude that stain 38 is in the correct location on the lens, and therefore, that this is the correct location for the fitting point.
Some embodiments of the present invention may enable installation measurements and/or medical examinations. For example, a mask 34 according to some embodiments of the present invention may be used for measuring the distance between the lens and the eye, usually called back vertex distance. Additionally or alternatively, mask 34 may be used for measuring, for example, the eye length.
Reference is now made to
In other embodiments of the present invention, if the back vertex distance is known, the eye length may be calculated, which may be required, for example, for medical and/or optometrical examinations/diagnosis. Additionally or alternatively, it is possible to measure the eye length by bringing the mask as close as possible to the eye, so that the back vertex distance is close to zero and can be neglected in the calculation.
Additionally, it is possible to measure the difference between the back vertex distance for two different masks (which may correspond, for example, to two different lenses), by performing the calculation of the sum of the back vertex distance (bvd) and half of the eye length (el) in two different measurements with corresponding two different masks on the same person.
Alternatively, it is possible to measure the difference between the eye length of two different persons, by performing the calculation of the sum of the back vertex distance (bvd) and half of the eye length (el) in two different measurements with the same mask and same L, D, d and bvd values, wherein the mask is worn by a different person in each measurement.
Reference is now made to
While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.