WO2020039203A1

WO2020039203A1 - Optometry device

Info

Publication number: WO2020039203A1
Application number: PCT/GB2019/052368
Authority: WO
Inventors: Phillip BUCKHURST
Original assignee: University Of Plymouth
Priority date: 2018-08-24
Filing date: 2019-08-23
Publication date: 2020-02-27
Also published as: GB2576561A; GB201813816D0

Abstract

An optometry device is described comprising a projection device (12a, 12b) whereby a target image can be projected onto a tear film on a patient's eye, the projection device (12a, 12b) being of hollow tubular form and so defining a passage through which a patient can view a viewing location (28) and through which imaging of the patient's eye can be undertaken, a recording device (22a, 22b) operable to record an image of the patient's eye onto which the target image has been projected, and a partially reflective beam splitter (26a, 26b) located optically between the patient's eye and the recording device (22a, 22b), and between the patient's eye and the viewing location (28).

Description

OPTOMETRY DEVICE

This invention relates to an optometry device, and in particular to a device for use in the analysis of tear films on a patient's eye.

Dry eye disease is a common condition which is characterized by a loss of homeostasis of the tear film on the surface of the eye. This causes inflammation and damage to the surface of the eye, leading to symptoms including itching, foreign body sensation, ocular discomfort, tearing and photophobia. The prevalence of dry eye is difficult to estimate given the multifactorial nature of the syndrome. Reports have suggested a prevalence levels of as low as 5% in Australia and as high as 34% in Taiwan. The condition can affect people of any age but it is more commonly found amongst women and elderly individuals.

Non-invasive tear break up time (NIBUT) is a common technique for evaluating the quality of the tear film. NIBUT is assessed using a method that involves projecting an illuminated grid pattern onto the tear film on a patient's eye and evaluating the quality of the reflection over time. All devices currently marketed for measuring NIBUT have two common shortcomings:

Firstly, all commercially available devices for measuring NIBUT are closed field, meaning that while a patient's NIBUT is being measured they have to look at a specific target within the device. A closed field device restricts the ability to assess the real-time tear film characteristics whilst a patient is engaged in a particular activity. For example, if a patient experienced dry eye syndrome whilst using a computer it is not possible to assess their tear film whilst they are engaged in the task and it can only be assessed before or after computer usage. Consequently, the measured NIBUT may not provide an accurate reflection of a patient's actual tear break up time under real life conditions.

Secondly, all available devices are only able to assess one eye at a time. However, dry eye affects both eyes. It is an object of the present invention to provide an optometry device which allows measurement of NIBUT and in which at least some of the disadvantages associated with known devices are overcome or are of reduced impact.

According to the present invention there is provided an optometry device comprising a projection device whereby a target image can be projected onto a tear film on a patient's eye, the projection device being of hollow tubular form and so defining a passage through which a patient can view a viewing location and through which imaging of the patient's eye can be undertaken, a recording device operable to record an image of the patient's eye onto which the target image has been projected, and a partially reflective beam splitter located optically between the patient's eye and the recording device, and between the patient's eye and the viewing location.

In use, the recording device is operable to record an image of the patient's eye onto which the target image has been projected, and consequently, a NIBUT reading for that one of the patient's eyes can be derived. As the partially reflective beam splitter is located optically between the patient's eye and the recording device, it will be appreciated that these readings may be taken whilst the patient is undertaking tasks such as reading, using a computer, mobile telephone device or tablet computer device located at the viewing location. Consequently, the NIBUT reading obtained through the use of the device may be more representative of the patient's tear break up time than is the case where traditional NIBUT recording devices or equipment is used. As the patient is able to undertake visual tasks whilst the NIBUT measurements are being taken, the patient's view only being partially obstructed by the presence of the device, it will be appreciated that the device is of the type sometimes referred to as an open field device. In addition to allowing NIBUT measurements to be made, it will be appreciated that other information such as blink rate may also be recorded for both eyes, simultaneously, whilst real, day-to-day tasks are being undertaken. Preferably, the device is further arranged to project a target image onto the patient's other eye, and to record an image of the patient's other eye. In this manner, NIBUT measurements for both eyes may be taken simultaneously. This may be achieved through the use of a second projection device and a second recording device. A second partially reflective beam splitter may be provided located optically between the patient's other eye and the second recording device, or the aforementioned beam splitter device may further be located between the patient's other eye and the second recording device. By enabling NIBUT measurements to be taken for both of the patient's eyes simultaneously, it will be appreciated that the device may be a binocular device.

Lenses may be provided to focus the reflected images of the patient's eyes onto the recording devices.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic view of an optometry device in accordance with an embodiment of the invention; and

Figure 2 is a view illustrating part of the device of Figure 1.

Referring to the accompanying drawings, an optometry device 10 is illustrated for use in taking NIBUT measurements, the device 10 being of an open field form and of a binocular nature so that NIBUT measurements for both of a patient's eyes may be recorded simultaneously whilst the patient is undertaking normal tasks such as reading or using a computer, looking as a television screen or the like. The device 10 comprises a projection device 12a operable to project a target image onto a tear film on one of a patient's eye. The projection device 12a comprises a member 14 of hollow, generally frustoconically shaped form in which a series of slits are formed such that the member 14 takes the form of a series of annular rings 16 interconnected by struts 18. Around the outside of the member 14 is wound a light emitting tape 20. In use, the device 12a transmits an image which, when viewed on the patient's eye, has the appearance of a series of concentric rings and a series of radially extending lines.

Whilst the use of a light emitting tape is convenient in that it allows the device 12a to be of relatively small and convenient form, it will be appreciated that the invention is not restricted in this regard and other light sources may be employed without departing from the scope of the invention. Likewise, although a target image of the form outlined hereinbefore is convenient, the invention is not restricted in this regard.

The projecting device 12a, being of hollow form, defines a passage 13 through which the patient has a substantially unobstructed forward view.

A second, similar projection device 12b is operable to project a similar image onto the tear film of the other of the patient's eyes.

If desired, the first and second projections devices 12a, 12b could be built into a single housing which, in use, is located immediately in front of the patient's eyes.

The nature of the projection devices 12a, 12b is such that the patient is able to see directly ahead through the device 12a, 12b, along the passage 13, and so whilst the presence of the devices 12a, 12b in front of the patient's eyes may interfere with or obstruct his peripheral vision, forward vision is unimpeded. The optometry device 10 further comprises first and second recording devices 22a, 22b, and associated focussing lenses 24a, 24b, and first and second beam splitter devices 26a, 26b. The first and second beam splitter devices 26a, 26b are located optically in front of the patient's eyes, between the patient and a viewing location 28 at which a book, computer or television screen, or other device or item that the patient is viewing is located whilst the NIBUT measurements are being undertaken. The recording devices 22a, 22b conveniently comprise respective high definition video recording devices, conveniently including image stabilisation systems to allow the recording of a good, high quality image of the patient's eyes. The partially reflective nature of the beam splitter devices 26a, 26b is such that the patient is able to see through the beam splitter devices 26a, 26b to the location 28, and hence his view of the book, computer screen, etc, at the location 28 is substantially unimpeded by their presence.

The recording devices 22a, 22b are positioned such that they are each able to record an image of a respective one of the patient's eyes as reflected by the respective beam splitter devices 26a, 26b, the lenses 24a, 24b serving to focus the reflected images onto the recording devices

22a, 22b. The recorded images record how the target images projected onto the tear films of the patient's eyes change over time, and so give an indication of how the tear films themselves change over time. Other characteristics such as each occasion on which the patient blinks will also be recorded.

In use, therefore, the patient is positioned relative to the device 10 so that each of his eyes is positioned immediately in front of a respective one of the projection devices 12a, 12b. In this position, he is able to see straight ahead looking through the projection devices 12a, 12b and the beam splitter devices 26a, 26b to a book, screen or other item located at a location 28. He is thus able to undertake reading, normal use of a computer device, or a range of other normal activities.

With the patient in this position, the projection devices 12a, 12b are operated to project the target images onto tear films on the patient's eyes, and the recording devices 22a, 22b are operated to record images of the projected target images to build up a record of how the images change over time. By analysis of the recorded images and how they change over time, NIBUT measurements indicative of the time taken for the tear film to break up can be derived. Measurements indicative of the patient's blink rate and other characteristics can be acquired through appropriate analysis of the recorded images. All of this information can be derived for both of the patient's eyes using images acquired for both eyes at the same time, and the information can be derived under 'normal' conditions in which a patient is undertaking a normal, day-to-day task. Consequently, the measurements are more likely to be representative of the patient's actual tear film break up condition, and others of the patient's characteristics such as blink rate, than is the case where this information is derived using conventional equipment.

Although in the arrangement described hereinbefore two separate beam splitter devices are provided, if desired, by appropriate positioning of the recording devices 22a, 22b and lenses 24a, 24b, just a single beam splitter device may be required. Although it is thought to be especially beneficial to be able to record images for both of a patient's eyes simultaneously, it will be appreciated that by appropriate modification, the invention may be applied to monocular arrangements, if desired.

Whilst a specific embodiment of the invention is described hereinbefore with reference to the accompanying drawings, it will be appreciated that a wide range of modifications and alterations may be made thereto without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS:

1. An optometry device comprising a projection device whereby a target image can be projected onto a tear film on a patient's eye, the projection device being of hollow tubular form and so defining a passage through which a patient can view a viewing location and through which imaging of the patient's eye can be undertaken, a recording device operable to record an image of the patient's eye onto which the target image has been projected, and a partially reflective beam splitter located optically between the patient's eye and the recording device, and between the patient's eye and the viewing location.

2. A device according to Claim 1, wherein the device is further arranged to project a target image onto the patient's other eye, and to record an image of the patient's other eye.

3. A device according to Claim 2 and further comprising a second projection device and a second recording device.

4. A device according to Claim 3 and further comprising a second partially reflective beam splitter located optically between the patient's other eye and the second recording device.

5. A device according to Claim 3, wherein the beam splitter device is further be located between the patient's other eye and the second recording device.

6. A device according to any of the preceding claims and further comprising lenses to focus the reflected images of the patient's eyes onto the recording device(s).