WO2000040141A1 - Determination of the correction for far-sightedness - Google Patents
Determination of the correction for far-sightedness Download PDFInfo
- Publication number
- WO2000040141A1 WO2000040141A1 PCT/NL1999/000811 NL9900811W WO0040141A1 WO 2000040141 A1 WO2000040141 A1 WO 2000040141A1 NL 9900811 W NL9900811 W NL 9900811W WO 0040141 A1 WO0040141 A1 WO 0040141A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- pernickety
- performance
- signs
- distance
- testing device
- Prior art date
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/02—Subjective types, i.e. testing apparatus requiring the active assistance of the patient
- A61B3/028—Subjective types, i.e. testing apparatus requiring the active assistance of the patient for testing visual acuity; for determination of refraction, e.g. phoropters
- A61B3/032—Devices for presenting test symbols or characters, e.g. test chart projectors
Definitions
- the present invention relates to a method for determining a reading correction, in particular for possible measurements for reading glasses, using a pernickety test for determining the pernickety performance.
- the pernickety performance is the inverse value of the smallest detail size that can just be observed at a specific distance.
- the pernickety performance is therefore an indication of the just discernible detail size of a sign or a series of signs as a function of the reading distance and is expressed in m "1 .
- the just discernible detail size as a function of the distance shows a minimum value at a specific distance from the eye. This minimum distance value will often depend on the degree of presbyopia; according as a person grows older, accommodation will be more difficult for him/her, and the distance at which this minimum occurs will come to be more and more remote from the person.
- the object of the invention is therefore to provide an efficient and reliable determination of a reading correction, in particular for possible measurements for reading glasses, which reading correction determination is possible without the use of a set of trial frames and without the necessary assistance of other persons. According to the invention, this object is achieved by establishing the accommodation of an eye and determining the above reading correction from this accommodation in combination with the pernickety performance.
- the invention is therefore based on the insight that only two parameters are necessary for determining a reading correction, namely the accommodation D 0 , this is the inverse value of the smallest distance at which focusing is possible without glasses, and the pernickety performance P 0 .
- the reading correction can be established for each eye separately or for both eyes together. In the first case, always one eye has to be covered, and the method according to the invention has to be carried out for each eye separately. In the second case, accommodation and pernickety performance are determined for both eyes simultaneously and equally.
- the needed reading correction D b is substantially determined by the relation ob
- A, E> -1 P 0 in which D 0 is the accommodation of an eye, P 0 is the pernickety performance and P ob is the target value of the pernickety level obtained by means of reading glasses. If the requirement is imposed that every person with reading glasses has to show the same value for the pernickety performance, then P ob is to be regarded as a constant applicable to all persons. In practice, it has been found that not everyone needs the same reading power. According to a further aspect of the invention, it is favorable if the target value of the pernickety level can be selected differently for a limited number of categories of persons. These may, for instance, be persons supposed to read either only extra large signs or also signs of average size or, additionally, extra small signs.
- the invention not only relates to a method for determining a reading correction but also to a device for using this method.
- this device is characterized in that a pernickety testing device is present as well as distance measuring means for determining the distance at which a pernickety test is carried out, while furthermore memory means are present to enable the determination of the above reading correction from the pernickety performance determined by means of the pernickety test and the above distance.
- the memory means may consist of a table on paper, on the basis of which the needed reading correction can be read by means of the pernickety performance and accommodation determined by the pernickety testing device and the distance measuring means.
- the pernickety testing device comprises a visual acuity chart having series of signs depicted thereon, the sizes of which are shown smaller and smaller, and may be slidably provided on a measuring rule, which during the determination of the pernickety performance is kept in a fixed position with respect to the eye of a test person, in particular pressed against the chin of the test person.
- the pernickety testing device can easily be moved to the nearest position at which the visual acuity chart can just be observed sharply. By means of the measuring rule, the corresponding distance can be read.
- the testing device which of course also comprises a visual acuity chart, is fixedly arranged, and the distance measuring means are formed by a likewise fixedly arranged electronic sensor for determining the shortest distance to the testing device at which a test person still sharply sees specific details of the visual acuity chart.
- the pernickety testing device is not moved, but the test person moves, namely until such a distance from the testing device that the person can still sharply observe specific details of the visual acuity chart.
- the pernickety testing device comprises a visual acuity chart, which can, taken into the hand, be controlled by a test person himself/herself , while the distance measuring means are formed by an electronic sensor provided on the pernickety testing device for determining the shortest distance to the testing device at which a test person still sharply sees specific details of the visual acuity chart.
- the pernickety testing device can be rather simple. Possible is a visual acuity chart behind glass, which can be illuminated by a lamp placed behind. In the position in which the test person can just sharply see details of the visible or visualized signs, he/she will have to be able to read the signs. For a verification whether the test person has properly read the signs, he/she can either memorize the signs read or read them out while another person is verifying the signs; then this person, too, can read the adjusted distance. A more elegant solution, however, is obtained if the whole device according to the invention is electronic.
- the pernickety testing device comprises a display unit on which signs read from a memory can be depicted, which display unit comprises means for identifying a depicted sign, while furthermore checking or verification means are present to establish whether the depicted signs have been identified correctly, in which case this process is repeated with other and/or smaller signs, and in case, optionally after repeated times, the signs are not identified correctly, to provide an electric signal indicating the pernickety performance.
- the pernickety performance may be depicted on the display unit.
- the means for identifying a depicted sign may simply be formed by knobs on the display unit, which are actuated by the test person, and via which he/she indicates which signs he/she has believed to identify.
- the device contains a further memory to which the signal indicating the pernickety performance is applied, as well as a distance measuring signal of an electronic distance sensor, on the basis of which signals from the last -mentioned further memory a signal indicating a reading correction is provided.
- a further memory is present, in which this table is included.
- This further memory may therefore be a PROM, in which for a number of values of the accommodation D 0 of an eye a number of values of the pernickety performance P 0 and a number of values of the corrected pernickety performance P ob the reading correction D b according to the relation
- the electronic distance sensor is preferably formed by an ultrasonic sensor or an infrared laser sensor.
- FIG. 1 is a diagrammatic view of a simple arrangement of the device according to the invention
- Fig. 2 is a visual acuity chart which can be fitted in the pernickety testing device
- Fig. 3 is a table in which the reading correction is expressed as a function of the pernickety performance and the accommodation;
- Fig. 4 is a diagram in explanation of the table of Fig. 3;
- Fig. 5 is a block diagram of an exemplary embodiment of a device according to the invention realized by means of electronics, and
- Fig. 6 is an exemplary embodiment of a device according to the invention.
- the arrangement of the device according to the invention in its simplest form comprises a measuring rule 1 and a pernickety testing device 2 slidable thereon.
- the measuring rule By placing the measuring rule against the chin, the measuring rule is kept in a fixed position with respect to the eyes of the person whose eyes have to be tested. Although for determining a reading correction the person in question will possibly wear no glasses, this is absolutely no requirement. By keeping his own reading glasses on, the person can establish which extra reading correction or reading addition he/she needs.
- the pernickety testing device 2 is formed by a box having at the front a display on which are provided, for instance, the Landolt C signs shown in Fig. 2.
- the box comprises a lamp for illuminating these signs, if desired.
- the test person first slides the pernickety testing device over the measuring rule until the shortest distance has been reached at which he/she still sees details of the signs sharply. It should be noted that, for the sake of convenience, it will hereinafter be assumed that one eye is covered, so that the eyes are tested separately.
- Fig. 2 shows to the left of the rows with Landolt C's the corresponding pernickety performance and to the right the size of the gap in the Landolt C's.
- the test person after this focusing at the shortest possible distance, has just been able to read from the signs shown in the pernickety testing device the fourth row of Landolt C's correctly, that is to say can just identify a gap size of 0.05 mm, then the pernickety performance P 0 has the value of 20 mm "1 .
- the corresponding distance from the pernickety testing device to the eyes can then be read from the measuring rule 1.
- the inverse value of this distance is the accommodation D 0 of the eye.
- the size D b of the needed reading correction or reading addition will be determined on the basis of the measured values for P 0 and D 0 .
- This chart shows a matrix of D b -values, to the left of which is indicated the pernickety performance (pernickety score) P 0 , while above it, in the uppermost line, the minimum distance in meters at which the signs can still be seen sharply is indicated with the inverse values thereof below, that is to say the accommodation D 0 expressed in dioptries.
- FIG. 5 is a block diagram of an electronic device according to the invention.
- This block diagram shows a memory 3, in which, for instance, the codes of the four different types of Landolt C's are stored in different sizes.
- the diverse codes can be read out by means of an addressing circuit 4, and the corresponding Landolt C's are depicted on a display 5 in rows or columns arranged to size.
- the test person brings the device at a specific distance at which he/she believes to be able to see a specific series of Landolt C's just sharply.
- an actuating knob 6 belonging to each type of Landolt C these can be identified in sequence in a comparator circuit 7.
- the Landolt C's are depicted on the display once again, and the identification process can be repeated. It is also possible that on a part of the display it is indicated that not all the Landolt C's have been identified correctly and that the identification process has to be repeated. To increase the accuracy and reliability, it could also be prescribed that the identification process must be repeated a fixed number of times, for instance three times. If the identification has eventually proceeded correctly, then a signal indicating the corresponding pernickety performance is applied via a line 8 to and recorded in a register 9.
- the block diagram further shows a memory 10 in the form of a PROM, in which memory for a number of values of the accommodation D 0 , the pernickety performance P 0 and the corrected pernickety performance P ob the reading correction is stored in accordance with the above-mentioned relation.
- the address part indicating the corrected pernickety performance and contained in the addressing circuit 12 is controlled from a selector switch on the display case via a line 11.
- the address part indicating the pernickety performance is controlled from the register 9 by the addressing circuit 13.
- the address part indicating the accommodation of the eye is controlled from a distance sensor 14 by the addressing circuit 15.
- the distance sensor 14 can be formed by an ultrasonic or an infrared laser sensor arranged at the top of the display case, so that the distance at which the test person keeps the display case can be determined constantly.
- the memory 10 gives the desired power for the reading glasses . This can be depicted on the display and/or printed.
- Fig. 6 is a possible embodiment of the device according to the invention.
- the device is formed by a hand- operated electronic device to be held in the hand, at the top of which the distance sensor 14 is arranged.
- the case of the device is also the case of the display 5. On this case the required knobs and switches may be arranged.
- the invention is not limited to the exemplary embodiments described herein with reference to the figures but comprises all kinds of modifications, of course as far as falling within the scope of protection of the appended claims.
- All kinds of instructions facilitating the operation of the device to obtain a reliable result and to make the device more customer-friendly may be depicted on the display.
- the device is not limited to the testing by means of Landolt C's either; all kinds of words or different signs decreasing in size can be used.
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- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Medical Informatics (AREA)
- Biophysics (AREA)
- Ophthalmology & Optometry (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Heart & Thoracic Surgery (AREA)
- Physics & Mathematics (AREA)
- Molecular Biology (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Eye Examination Apparatus (AREA)
- Eyeglasses (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU30814/00A AU3081400A (en) | 1998-12-31 | 1999-12-28 | Determination of the correction for far-sightedness |
JP2000591906A JP2002534145A (en) | 1998-12-31 | 1999-12-28 | Measuring method for correction of presbyopia |
EP99964775A EP1139856A1 (en) | 1998-12-31 | 1999-12-28 | Determination of the correction for far-sightedness |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL1010939A NL1010939C2 (en) | 1998-12-31 | 1998-12-31 | Method and device for determining a reading correction. |
NL1010939 | 1998-12-31 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2000040141A1 true WO2000040141A1 (en) | 2000-07-13 |
Family
ID=19768404
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/NL1999/000811 WO2000040141A1 (en) | 1998-12-31 | 1999-12-28 | Determination of the correction for far-sightedness |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP1139856A1 (en) |
JP (1) | JP2002534145A (en) |
AU (1) | AU3081400A (en) |
NL (1) | NL1010939C2 (en) |
WO (1) | WO2000040141A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2016523132A (en) * | 2013-06-06 | 2016-08-08 | 6 オーバー 6 ビジョン リミテッド | System and method for measurement of refractive error of the eye based on subjective distance measurement |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3067647A (en) * | 1958-10-28 | 1962-12-11 | Sato Kichiro | Subjective optometer |
US5596379A (en) * | 1995-10-24 | 1997-01-21 | Kawesch; Gary M. | Portable visual acuity testing system and method |
-
1998
- 1998-12-31 NL NL1010939A patent/NL1010939C2/en not_active IP Right Cessation
-
1999
- 1999-12-28 AU AU30814/00A patent/AU3081400A/en not_active Abandoned
- 1999-12-28 WO PCT/NL1999/000811 patent/WO2000040141A1/en not_active Application Discontinuation
- 1999-12-28 EP EP99964775A patent/EP1139856A1/en not_active Withdrawn
- 1999-12-28 JP JP2000591906A patent/JP2002534145A/en active Pending
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3067647A (en) * | 1958-10-28 | 1962-12-11 | Sato Kichiro | Subjective optometer |
US5596379A (en) * | 1995-10-24 | 1997-01-21 | Kawesch; Gary M. | Portable visual acuity testing system and method |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2016523132A (en) * | 2013-06-06 | 2016-08-08 | 6 オーバー 6 ビジョン リミテッド | System and method for measurement of refractive error of the eye based on subjective distance measurement |
JP2019069180A (en) * | 2013-06-06 | 2019-05-09 | 6 オーバー 6 ビジョン リミテッド | System and method for measurement of refractive error of eye based on subjective distance metering |
US10702143B2 (en) | 2013-06-06 | 2020-07-07 | 6 Over 6 Vision Ltd. | System and method for measurement of refractive error of an eye based on subjective distance metering |
US10898071B2 (en) | 2013-06-06 | 2021-01-26 | 6 Over 6 Vision Ltd. | System and method for measurement of refractive error of an eye based on subjective distance metering |
Also Published As
Publication number | Publication date |
---|---|
NL1010939C2 (en) | 2000-07-03 |
EP1139856A1 (en) | 2001-10-10 |
AU3081400A (en) | 2000-07-24 |
JP2002534145A (en) | 2002-10-15 |
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