WO2016101204A1

WO2016101204A1 - Device for measuring phoria and method for measuring phoria using the device

Info

Publication number: WO2016101204A1
Application number: PCT/CN2014/094910
Authority: WO
Inventors: Jinhua BAO; Bjorn Drobe; Xinping YU; Binbin SU; Ge Wu; Hao Chen
Original assignee: SHANGHAI ESSILOR OPTICAL Co Ltd; Wenzhou Medical University; Essilor International Compagnie Generale dOptique SA
Current assignee: SHANGHAI ESSILOR OPTICAL Co Ltd; Wenzhou Medical University; EssilorLuxottica SA
Priority date: 2014-12-25
Filing date: 2014-12-25
Publication date: 2016-06-30
Anticipated expiration: 2017-06-25
Also published as: CN107106002A; CN107106002B

Abstract

A device for measuring phoria comprising: a front side (1), which comprises an opening (11) corresponding to the position of the eyes of the subject; a rear side (2), which is parallel to the front side (1) and presents a visual display pattern (21) disposed towards the front side (1) and configured to be utilized in the phoria measurement, and; optical means (5), which contain at least one set of lenses with different powers corresponding to different accommodation demands of the subject, wherein the optical means (5) are positioned corresponding to the opening (11) and in front of at least one eye of the subject, so that the visual display patterns (21) are adapted to be viewed by the subject through the optical means (5). The device provides cheap, simple, fast and precise way to measure phoria under different accommodation values.

Description

DEVICE FOR MEASURING PHORIA AND METHOD FOR MEASURING PHORIA USING THE DEVICE

TECHNICAL FIELD

The present invention relates generally to optometric tools， in particular it relates to a device for measuring phoria. In addition， this invention also relates to a method for measuring phoria using the device.

BACKGROUND TECHNOLOGY

General optometry usually refers to the measurement for single eye parameter， such as the degrees of myopia， hyperopia， astigmatism and presbyopia. However， in order to obtain a comprehensive prescription， it also needs to measure binocular vision value， especially phoria (heterophoria) ， which can be used for advanced and personalized eyeglass prescription， such as for determining near addition value for ophthalmic progressive lenses.

In particular， phoria is a type of eye condition in which the directions that the eyes are pointing at rest position， when not performing binocular fusion， are not consistent with each other. A person with two normal eyes has single vision (usually) because of the combined use of the sensory and motor fusional systems. The motor fusional system acts to point both eyes at the target of interest； any offset is detected visually (and the motor system corrects it) . Phoria only occurs during dissociation of the left eye and right eye， when fusion of the eyes is absent. If one covers one eye (e.g. with his/her hand) one removes the sensory information about the eye′s position in the orbit. Without this， there is no stimulus to binocular fusion， and the eye will move to a position of ″rest″ . The difference between this position， and where it would be were the eye uncovered， is the phoria.

Phoria can be found on almost each human being， and only the degree is different and dependent on different situations. Phoria is usually asymptomatic. This is when it is said to be ″compensated″ . When fusional reserve is used to compensate for heterophoria， it is known as compensating vergence. In severe cases， when the heterophoria is not overcome by fusional vergence， signs and symptoms appear. This is called decompensated phoria， which leads to eyestrain. In addition， phoria may result in squint or also known as strabismus.

In the art， there are many well known optometric measurements/tests， such as Von Graeffe， Modified Thorington test， Howell test， Maddox rod， and etc.， to measure the value of phoria. In general， these measurements/tests can be classified into the following two categories：

-with direct reading of the phoria value by a subject (the subject sees by himself the value of his phoria and reports it to the examiner， such as Modified Thorington) ； and

-with reading of the phoria by an examiner (the examiner determines the phoria value while the subject cannot see it， such as Von Graeffe) .

Phoria tests can be performed at any distance， but the phoria value varies with distance of measurement.

Furthermore， phoria can be measured for different accommodation values， either by shifting the plane of the target or by adding plus or minus lenses in front of the eyes of the subject. This requires either a phoropter or a trial lens set (which are both expensive) and need experienced examiner to be used. For near vision， the phoria test must be placed at the right distance manually. With trial frames， this will induce experimental errors as the test is usually held by the subject and cannot be placed at a precise distance.

In this regard， determination of near vision phoria under different accommodation conditions， needs sophisticated and expensive equipment (phoropter， trial frame) and a skilled person to use them. However， the measurements/tests in the art lack precision， because of the non-fixed distance to the near vision target (to be adjusted every time by the practitioner) . Moreover， because of changes in lenses， especially with trial frames， it is time-consuming to measure the phoria.

DESCRIPTION OF THE INVENTION

To this end， an object of the present invention consists in providing a device for measuring phoria， such as near phoria， with a fixed and precise distance as well as under different accommodation conditions， so as to overcome the abovementioned disadvantages mentioned.

The device for measuring phoria of a subject comprises：

-a front side， which comprises an opening corresponding to the position of the eyes of the subject；

-a rear side， which is parallel to the front side and presents a visual display pattern disposed towards the front side and configured to be utilized in the phoria measurement；

The device further comprises optical means， which contain at least one set of lenses with different powers corresponding to different accommodation demands of the subject， wherein the optical means are positioned corresponding to the opening and in front of at least one eye of the subject， so that the visual display patterns are adapted to be viewed by the subject through the optical means.

In various embodiments of the invention， one or more of the following arrangements may be used：

-the visual display pattern is adapted to be adjusted；

-the optical means contain two sets of the lenses respectively positioned in front of the eyes of the subject， and both sets contain the same lenses， wherein the order of the lens on both sets are configured to be reversed so as to ease binocular rotation. Preferably， the distance between the optical centers of the lenses in use of said two sets of the lenses are adjustable， corresponding to the pupillary distance of the subject， so as to be aligned with the visual axis of the subject；

-the optical means comprise a null position where no lens or lens with zero power (0.00D) is positioned and viewed by the subject；

-the number of the lenses of said at least one set of the lenses is limited， for example， limited in five lenses， the power values of which， for example， are+1.00D， +1.50D， +2.00D， +2,50D， +3.00D. Preferably， the power value of one lens of said at least one set of lenses is zero diopter；

-the device comprises variable prisms positioned corresponding to the opening and in front of at least one eye of the subject， and the visual display pattern is changed to be utilized in the Fusional Amplitude measurement；

-the device comprises at least one specific lens， for example a Maddox filter or a vertical prism， positioned corresponding to the opening to assist the phoria measurement；

-the device further comprises an indicator which is adapted to be adjusted by the subject to indicate a value of the phoria that subject obtains.

-the device further comprises a memory unit which records the value of the phoria for each lens， and recorded phoria values can be transmitted to a computer system which will send the values to a data base for further analysis；

-the device is mainly made of translucent plastic； and

-the device further comprises a padded forehead rest positioned on the front side for receiving the forehead of the subject.

Therefore， the device according to the present invention can facilitate the phoria measurement with accommodation conditions provided by the lens means as well as under fixed measuring distance owing to the configuration of the device， and provide more precise measurement results without expensive equipment in the art and experienced examiner using the same.

A second aspect of the invention provides a method for measuring phoria of a subject by using the device. The method comprises the following steps：

-a. Providing a visual display pattern on the rear side；

-b. Adjusting the distance between the front side and the rear side；

-c. Setting an initial power of said optical means；

-d. Presenting the visual display pattern for viewing by at least one eye of the subject through the optical means；

-e. Recording an identification of the parameter of the phoria measurement observed by the subject；

-f. Repeating steps c to e until a limited number of powers of the optical means are tested.

Alternatively， the step e further comprises a step of memorizing the identification by a memory unit.

Thanks to the abovementioned features， the present invention provides cheap， simple， fast and precise device and method to measure phoria (especially near vision phoria) with different accommodation values (different additions) . Meanwhile， the efficacy of measuring phoria is improved compared to the measurement devices and methods in the art.

BRIEF DESCRIPTION OF THE FIGURES

Further features and advantages of the invention will appear from the following description of embodiments of the invention， given as non-limiting examples， with reference to the accompanying drawings listed hereunder.

-Figure 1 is a perspective view of a device for measuring phoria according to a first embodiment；

-Figure 2 is a perspective view of the device in figure 1 without the optical means；

-Figure 3 is a front view of the optical means of the device in figure 1；

-Figure 4 is an enlarged front view of the visual display pattern for phoria test of the device in figure 1；

-Figure 5 is a perspective view of a device for measuring phoria according to a second embodiment；

-Figure 6 is a perspective view of the device in figure 5 without the optical means which shows a phoria test side；

-Figure 7 is a perspective view of the device in figure 5 without the optical means which shows a fusional amplitude test side；

-Figures 8 and 9 are front views of the optical means of the device in Figure 5；

-Figure 10 is an enlarged front view of the visual display pattern for fusional amplitude test of the device in figure 5.

MORE DETAILED DESCRIPTION

It should be understood that the appended drawings are not necessarily to scale， presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein， including， for example， specific dimensions， orientations， locations， and shapes will be determined in part by the particular intended application and use environment.

By referring to the embodiments and figures， the present invention is described. In the figures， the same references are used to denote identical or similar items.

Figures 1 to 4 show a first embodiment of the device according to the present invention. This embodiment is a simple version which contains a rectangular box and optical means 5 attached to the rectangular box for measuring horizontal phoria under different accommodative conditions.

In particular， the rectangular box comprises a front side 1 and a rear side 2 which is parallel to the front side 1.

The front side 1 comprises two

openings

11， 13， as shown in Figure 2， corresponding to the position of left and right eyes of a subject whose phoria value is intended to be tested. Preferably， on the bottom edge of the front side 1， there is a notch 16 for receiving nose of a subject.

Furthermore， the distance between the two

openings

11， 13 is adapted to be adjusted according different subjects， and in this embodiment the distance corresponds to the pupillary distance of the subject ranging from 55 mm to 65mm， preferably 60mm.

The rear side 2 is opposite to the front side 1 and is located on the other end of the box. A visual display pattern 21 is disposed on the rear side 2， towards the front side 1. The visual display pattern 21 is a phoria value indication for the phoria test， such as modified Thorington， which is printed on paper or plastic and can be changed and adjusted according to different phoria measurements， for example， Von Graeffe， Modified Thorington test， Howell test， Maddox rod， and etc.

The visual display pattern 21 further comprises a light source 23， such as LED light， for phoria measurement， as shown in Figure 4， as well as a battery and a switch， for turning on and off the light， fixed at the rear side of the device， not shown.

The front side 1 and the rear side 2 are connected by two

side connection components

3， 4 the length of which can be adjusted by adjustment means， for example expansion link， according to the measurement requirement， for example 33cm， and can be temporally fixed during the measurement.

The optical means， in the form of a wheel 5， comprise a set of lenses on the periphery of the wheel， as shown in Figure 3， and these lenses have a limited number， for example six， with different powers corresponding to different accommodation demands of the subject， such as +1.00D， +1.50D， +2.00D， +2,50D， +3.00D， 0,00D (or no lens， a null position) .

The wheel further comprises an open hole 51 in its central corresponding to a mounting point 15 on the left of the front side 1 for attaching to the latter by a screw， bolt or the like， so as to be rotatably mounted on the front side with at least one lens (or null position) covering the left opening 11.

Advantageously， the rectangular box is made of frosted polycarbonate to ensure light weight， the wheel 5 is made of same material， and the lenses are made of transparent polycarbonate.

In this embodiment， the accommodation variation is only produced monocularly on left eye when rotating the wheel 5， and the right eye uses a Maddox rod 131 which is positioned on the right opening 13 as shown in Figure 1.

According to this first embodiment， the device can be used to measure horizontal phoria under different accommodative conditions through the following steps：

1. The wheel 5 is set to no power lens or null position where no lens disposed for the left eye of the subject.

2. The subject is asked to look through the openings in the device and fixate the light at the center of the graduation. With his left eye， he will see the graduation and the light， with his right eye， due to the Maddox rod， he will see a vertical line.

3. The task is to read on which graduation is located the vertical line (value of his phoria without addition lens) and report it to the examiner.

4. The wheel 5 is turned to an addition lens， wherein one of the following three modes can be adapted： (1) increasing power： +1D， +1.5D， +2D， etc. (2) Decreasing power： +3D， +2.5D， etc. (3) random order.

5.

Steps

2， 3 and 4 are repeated and values written down until all lenses are tested (or a limited number， according to the judgment of the examiner) .

Alternatively， it is also possible to start step 1 with a different power. However， it is better to start the measurement with zero addition or null position.

Therefore， the values obtained with the device are the horizontal phoria values under different accommodative conditions， which can be used for example to determine a personalized addition value， to be prescribed for example for progressive addition lenses， bifocals or reading single vision lenses.

In addition， the device can further comprise an indicator (not shown) which is adapted to be adjusted by the subject to indicate a value of the phoria that subject obtains.

Moreover， the device can also comprise a memory unit which records the value of the phoria for each lens tested. Such recorded value can be transmitted to data base of a computer or cloud system which further analyzes the data for further process， such as determination of the personalized addition value for the subject， for example a child or a teenager.

Figures 5 to 10 show a second embodiment of the device according to the present invention. This is a more sophisticated version. It changes accommodation for phoria measurement binocularly (for both left and right eyes) and， preferably， can be reversed to measure fusional amplitudes without any change in accommodation.

This second embodiment contains a rectangular box， two

optical means

5L， 5R attached to the rectangular box for measuring phoria values binocularly under different accommodative conditions， and a Risley prism system for fusional amplitude test.

In particular， the rectangular box comprises a front side 1， a back side 6 which is parallel to the front side， and a rear side 2 which is positioned between the front side 1 and the back side 6 and is also parallel to the front side 1.

The front side 1 comprises two

openings

11， 13， as shown in Figure 6， corresponding to the position of left and right eyes of a subject whose phoria value is intended to be test. Preferably， on the bottom edge of the front side 1， there is a notch 16 for receiving nose of a subject.

Furthermore， the distance between the two

openings

The back side 6 is opposite to the front side and is located on the other end of the box. The back side 6 also comprises two

openings

61， 63， as shown in Figure 7， corresponding to the position of left and right eyes of a subject whose fusional amplitude value is intended to be tested. Preferably， on the bottom edge of the back side 6， there is another notch 66 for receiving nose of a subject

The rear side 2 is arranged between the front side 1 and the back side 6， and located in the box. A visual display means is disposed on the rear side 2， wherein a visual display pattern 21 for phoria value is facing the front side 1 and a visual display pattern 22 for fusional amplitude value is facing the back side 6.

The visual display means is， for example， a LCD or OLED display， which presents the visual display pattern 21 for phoria test， such as for Modified Thorington test， and the visual display pattern 22 for fusional amplitude， such as line of vertical letters.

The front side 1 and the back side 6 are connected by two

side connection components

3， 4 which have fixed length and the rear side 2 is attached to the two connection components and is adapted to slide thereon， so that the distance d1 between the front side 1 and the rear side 2 and the distance d2 between the back side 6 and the rear side 2 is adjustable according to the requirement， for example between 0cm and 40cm.

Furthermore， the visual display means can automatically adjust the display patterns depending on distances d1 and/or d2， so that the graduation of the phoria test corresponds always to 1 prismatic diopter and that the angular letter size of the Fusional amplitude test always equals 6/10. In this regard， advantageously， the distance d1 or d2 is measured electronically and used for the automatic display of right graduation and the angular size.

Referring to Figures 4 and 10， for example， for phoria measurement， the size of 1 graduation equals to 1 prismatic diopter： width (in mm) ＝Distance d1 (mm) /100， wherein the Distance d1 is provided through an electronic measurement and fed back to the display means. For fusional amplitude measurement， the size of letters as shown in Figure 10 is 1 letter angular size ＝6/10， i.e. 8.33 minutes of arc. Letter size (mm) ＝tan (8.33min of arc) x Distance d2 (mm) .

The optical means are in the form of two

wheels

5L， 5R， and each wheel comprises a set of lenses on the periphery of the wheel， as shown in Figures 8 and 9， and each set of lenses has a limited number， for example six， with different powers corresponding to different accommodation demands of the subject， such as +1.00D， +1.50D， +2.00D， +2,50D， +3.00D， 0,00D (or no lens， a null position) . Moreover， the orders of the lenses on both sets are configured to be reversed so as to ease binocular rotation.

The wheels respectively comprise an open hole 51L/51R in their center corresponding to two mounting

points

15L， 15R on the left and the right of the front side 1 for attaching to the latter by a screw， bolt or the like， so as to be rotatably mounted on the front side where at least one lens (or null position) of the wheel 51L covers the left opening 11 and at least one lens (or null position) of the wheel 51R covers the right opening 13. In addition， the wheels are adapted to move horizontally to adjust the distance therebetween according to the different pupillary distance of the subject， so as to be aligned with the visual axis of the subject

The risley prism system for fusional amplitude test is in the form of the horizontal Risley prisms positioned on the

openings

61， 63 for the two eyes of the subject. The distance between the two Risley prisms are adapted to be adjusted by adjustment means 68， such as adjustment wheels， so as to be aligned with the visual axis of the subject.

Similarly， the rectangular box is made of frosted polycarbonate to ensure light weight， the two wheels are made of same material， preferentially polycarbonate， and the lenses are made of transparent polycarbonate.

Therefore， the second embodiment comprises two working sides， the phroria side where the subject faces the front side and looks through the

openings

11， 13 for the phoria measurement， and the fusional amplitude side where the subject faces the back side and looks through the

openings

61， 63 for the fuional amplitude measurement.

Owing to the above arrangements， during the phoria measurement， the optical means can change the accommodation binocularly， whereas during the fusional amplitude measurement， there is no need to change the accommodation.

In this embodiment， the accommodation variation is produced binocularly on both left and right eyes when rotating the

wheels

5L， 5R， and the right eye also uses a Maddox rod 131 which is positioned on the right opening 13 as shown in Figure 7.

When the device is used for the phoria measurement， the subject faces the front side 1 and looks through the two

wheels

5L， 5R， and the phoria values of the subject are measured through the following steps：

1. Distance d1 of display means on the rear side is adjusted according to examiner’s decision (could be usual working distance at near， for example) . The device can automatically change the size of graduation on the display means accordingly to this distance， i.e. so that 1 graduation equals one prismatic diopter.

2. The wheels are set to no power lens or null position.

3. The subject is asked to look through the

openings

11， 13 in the device and fixate the light at the center of the graduation. With his left eye， he will see the graduation and the light， with his right eye， due to the Maddox rod， he will see a vertical line.

4. The task is to read on which graduation is located the vertical line (value of his phoria without addition lens) and report it to the examiner.

5. Both wheels are turned to an addition lens， wherein one of the following three modes can be adapted： (1) increasing power： +1D， +1.5D， +2D， etc. (2) Decreasing power： +3D， +2.5D， etc. (3) random order.

6.

Steps

3， 4 and 5 are repeated and values written down until all lenses are tested (or a limited number， according to the judgment of the examiner) .

Alternatively， it is also possible to start step 2 with a different power. However， it is better to start the measurement with zero addition.

Similarly， the device of the second embodiment can further comprise an indicator (not shown) which is adapted to be adjusted by the subject to indicate a value of the phoria that subject obtains.

Moreover， the device can also comprise a memory unit which records the value of the phoria for each lens test. Such recorded value can be transmitted to data base of a computer or cloud system which further analyzes the data for further process， such as determination a personalized addition value for the subject.

When the device is used for the fusional amplitudes test， the subject faces the back side 1， opposite side of the phoria measurement， and looks through the two Risley prims， and the fuional amplitudes of the subject are measured through the following steps：

1. The distance d2 of the display means is adjusted to the same distance as for the phoria measurement. The device automatically changes the size of the vertical letters on the display accordingly to this distance so that the letters have the same angular size whatever the distance.

2. The examiner sets both Risley prisms to zero.

3. The subject is asked to fixate the target on the display， usually a vertical line of letters.

4. The value of the prisms is increased slowly and constantly until the subject reports seeing blurred or double.

5. The combined value of the Risley prisms is written down as fusional amplitude.

Similarly， the values obtained with the second embodiment can be used for example to determine the personalized addition value.

According to a third embodiment of the present invention， not shown， it is similar to the second embodiment， whereas it can only be used in one direction (phoria side) on the second embodiment， wherein the Risley prisms are placed between the lens wheels and the eye opening on the front side to be able to measure fusional amplitudes with different accommodation values. The phoria measurement can be changed to a fusional amplitude measurement by rotating the wheels.

In this third embodiment， the phoria values are measured according to phoria measurement steps in the second embodiment. For all phoria measurements， the Risley prisms are set to zero.

As for the fusional amplitude measurement， the fusional amplitude can be determined in this embodiment for all addition lenses， including zero addition or no lens condition， similarly to the second embodiment.

Advantageously， in a variant， the device further comprises a padded forehead rest (not shown) positioned on the front side for positioning and receiving the forehead of the subject.

It should be noted that， the embodiments mentioned above are used as examples and cannot be construed as limiting the scope of the invention. On the basis of this， a man skilled in the art could expect other embodiments having the same function within the scope of protection of the application.

Various other embodiments and various changes and modifications to the disclosed embodiment (s) will become apparent to those skilled in the art. Particularly， otherwise explicitly mentioned， all above described features， alternatives and/or embodiments of the present invention can be combined with each other as far as they are not incompatible or mutually exclusive of others. All such other embodiments， changes， and modifications are intended to come within the scope of the appended claims.

Claims

A device for measuring phoria of a subject， which comprises ：

-a front side， which comprises an opening corresponding to the position of the eyes of the subject；

-a rear side， which is parallel to the front side and presents a visual display pattern disposed towards the front side and configured to be utilized in the phoria measurement；

the device further comprises optical means， which contain at least one set of lenses with different powers corresponding to different accommodation demands of the subject， wherein the optical means are positioned corresponding to the opening and in front of at least one eye of the subject， so that the visual display patterns are adapted to be viewed by the subject through the optical means.
The device according to claim 1， wherein the distance between the front side and the rear side is adjustable and is adapted to be fixed during the measurement at a near distance， for example 33 cm.
The device according to claim 1， wherein said visual display pattern is adapted to be adjusted.
The device according to claim 1， wherein the optical means contain two sets of the lenses respectively positioned in front of the eyes of the subject， and both sets contain the same lenses， wherein the order of the lens on both sets are configured to be reversed so as to ease binocular rotation.
The device according to claim 4， wherein the distance between the optical centers of the lenses in use of said two sets of the lenses are adjustable， corresponding to the pupillary distance ofthe subject，so as to be aligned with the visual axis of the subject.
The device according to claim 1， wherein said optical means comprise a null position where no lens is positioned and viewed by the subject.
The device according to claim 1， wherein the number of the lenses of said at least one set of the lenses is limited， for example， limited in five lenses， the power values of which， for example， are +1.00D， +1.50D， +2.00D， +2，50D， +3.00D.
The device according to claim 7， wherein the power value one lens of said at least one set of lenses is zero diopter.
The device according to claim 1， wherein the device comprises variable prisms positioned corresponding to the opening and in front of at least one eye of the subject， and the visual display pattern is changed to be utilized in the Fusional Amplitude measurement.
The device according to claim 1， wherein the device comprises at least one specific lens， for example a Maddox filter or a vertical prism， positioned corresponding to the opening to assist the phoria measurement.
The device according to claim 1， wherein the device further comprises an indicator which is adapted to be adjusted by the subject to indicate a value of the phoria that su bject obtains.
The device according to claim 10， wherein the indicator further comprises a memory unit which records the value of the phoria for each lens.
The device according to claim 1， wherein the device further comprises a padded forehead rest positioned on the front side for receiving the forehead of the subject.
A method for measuring phoria of a subject by using the device according to claim 1， comprising the steps of：

-a. Providing a visual display pattern on the rear side；

-b. Adjusting the distance between the front side and the rear side；

-c. Setting an initial power of said optical means；

-d. Presenting the visual display pattern for viewing by at least one eye of the subject through the optical means；

-e. Recording an identification of the parameter of the phoria measurement observed by the subject；

-f. Repeating steps c to e until a limited number of powers of the optical means are tested.
The method according to claim 14， wherein the step e further comprise a step of memorizing the identification by a memory unit.