WO2012032340A1

WO2012032340A1 - Apparatus and method for positioning a probe for observing microcirculation vessels

Info

Publication number: WO2012032340A1
Application number: PCT/GB2011/051664
Authority: WO
Inventors: Tarek Francis Antonios
Original assignee: St George's Hospital Medical School
Priority date: 2010-09-06
Filing date: 2011-09-06
Publication date: 2012-03-15
Also published as: GB201014783D0

Abstract

The invention relates to methods and apparatuses for positioning a probe for observing microcirculation vessels, in particular the microcirculation vessels in mucous membranes. In one aspect, the apparatus comprises a mechanical arm and a micropositioner for positioning the probe, thereby allowing fine control of the probe's position.

Description

APPARATUS AND METHOD FOR POSITIONING A PROBE FOR OBSERVING

MICROCIRCULATION VESSELS

The present invention relates to a method and apparatus for positioning a probe for observing microcirculation vessels, in particular the microcirculation vessels in mucous membranes.

There is an increase in interest in the role of microcirculation vessels (i.e. venules, arterioles and capillaries) in the pathogenesis of cardiovascular disease and in particular hypertension, pre-eclampsia, microvascular angina and the metabolic syndrome. For example, it has been shown that a significant reduction in microvascular density (or rarefaction) occurs in essential hypertension and that this rarefaction is likely to be a primary (i.e. antedates the onset of rising blood pressure) structural (i.e. anatomical) vascular abnormality.

Therefore, methods for testing the reactivity of micro vessels in humans have been developed. Conventional testing methods require obtaining subcutaneous fat biopsies and then mounting the vessels after dissection on a myograph.

Taking such biopsies suffers from the problem that the reactivity of the microvessels is not being observed in vivo. To this end, techniques such as video microscopy have been developed for observing microvessels located, for example, in the back of the hand or between the fingers or toes. Further, techniques such as orthogonal polarisation spectroscopy (OPS) and sidestream dark field (SDF) imaging have been developed. These methods produce high contrast microvascular images.

However, conventional microscopy techniques suffer from the problem that it can be difficult to obtain high quality video sequence images or still images, in vivo.

The present invention aims to at least partly overcome the above-mentioned problems. According to an aspect of the invention there is provided an apparatus for positioning a probe for observing microvessels, the apparatus comprising: a mechanical arm for supporting the probe for observing microvessels; and a micropositioner for making fine adjustments to the position of the mechanical arm; wherein the mechanical arm is connected, at a first end, to the micropositioner and wherein the mechanical arm is provided with connecting means at a second end for connecting to the probe for observing microvessels.

This apparatus has the advantage that the mechanical arm can be used for providing macro-scale positioning of the probe, whilst the micropositioner can be used to make micro-scale adjustments of the probe position. The micropositioner can change the position of the mechanical arm, which in turn changes the position of the probe that it supports. As such, it is possible to locate the probe in the desired location, and to make fine adjustments in order to allow proper focussing or to maintain the field of view of the probe.

The micropositioner may provide three-dimensional movement. As such, micro-scale adjustments can be made in all directions.

The micropositioner may be controllable remotely. Preferably, the apparatus further comprises a control unit responsive to the image obtained with the probe to control the micropositioner to maintain a substantially constant field of view with the probe. According to this embodiment, the apparatus is able to constantly maintain the same field of view, even if there are movements of the microvessels being observed (i.e. due to a subject moving, e.g. by breathing) relative to the probe. This ensures that any changes that are being monitored for can be observed.

Preferably, the apparatus further comprises a magnet attached to the first end of the mechanical arm, wherein the micropositioner comprises a ferromagnetic surface to which the magnet may attach. This arrangement allows for the arm to be detachable from the

micropositioner with ease. This makes it simple to attach the probe to the arm, before connecting the arm to the micropositioner. Further, this introduces an extra element of adjustability in the positioning of the probe itself.

The apparatus may further comprise means for supporting a person's head, wherein the mechanical arm and the means for supporting a person's head are in a fixed position with respect to each other.

According to another aspect, the invention provides an apparatus for positioning a probe for observing microvessels, the apparatus comprising: a mechanical arm for supporting the probe for observing microvessels; and a means for supporting a person's head, wherein the mechanical arm and the means for supporting a person's head are in a fixed position with respect to each other.

According to this aspect, the apparatus can support a person's head and the probe in a fixed position. By providing the arm and the means for supporting a person's head in a fixed position, the chance of relative motion between the person's head and the probe supported by the arm is reduced, thereby allowing for clearer images to be produced from the probe.

Preferably, the means for supporting a person's head comprises a chin rest. This allows a person to rest their chin on a surface, keeping the person's jaw stable in the same position. This is particularly useful when observing the mucous membranes in a person's mouth because the soft tissues in the person's mouth are kept as still as possible.

The apparatus may further comprise a dispenser for dispensing drugs into a person's mouth. According to another aspect of the invention there is provided an apparatus for positioning a probe for observing microvessels, the apparatus comprising: a mechanical arm for supporting the probe for observing microvessels; a means for supporting a person's head; and a dispenser for dispensing drugs into a person's mouth.

According to this aspect drugs may be dispensed into a person's mouth, and the probe may be used to observe the effect of the drugs on microvessels in the mucous membranes, for example, of the person's mouth. As such, the reactivity of the microvessels to the dispensed drugs can easily be observed. Further, by the provision of a dispenser, the person does not need to be disturbed once the probe is set up. As such, the same field of view can be maintained before and after the drugs are dispensed.

The dispenser can comprise a tube for supplying drugs from a reservoir, and the probe for observing microvessels can comprise the dispenser. This allows for the drugs to be delivered very locally to the field of view, and so the effect of the drugs on the area under examination can be observed immediately. Since no other instruments are required to supply the drugs, the risk of disturbing the probe is lowered and it is easier to provide the drugs to the area being observed. As a result, when the mechanical arm and head support are held in fixed relation ship to each other, it becomes easier to maintain a constant field of view with the probe because there are fewer requirements to move or adjust the probe to allow the use of other pieces of apparatus.

The probe can further comprise a duct for providing washing fluid or aspiration. The duct may be a further tube, or a space within a casing surrounding the probe, and may be connected to a source or suction or to reservoir of washing fluid. This enables the cleaning and clearing of the probe's field of view, without the need to move or disturb the probe.

The apparatus can further comprise a casing surrounding the probe. The casing can project from between 0.2 and 2.0 mm beyond an end of the probe, preferably between from 0.5 to 1.0 mm beyond the end of the probe. This produces a space at the end of the probe that, in use, can be used to retain drugs between the casing and the area under experimentation, allowing the more accurate dosing of a particular area.

The mechanical arm of any of the aspects may be flexible or have at least one adjustable joint. Preferably, the mechanical arm has at least three adjustable joints. This allows a great deal of freedom when positioning the probe.

The position of the mechanical arm may be controllable remotely. Automatic control of the arm allows for more accurate positioning.

Preferably, the mechanical arm may comprise means for locking the position of the mechanical arm. This helps reduce any relative motion between the probe and the microvessels being observed, by ensuring that the position of the arm is not accidentally changed. The apparatus may further comprise a camera for imaging microvessels in a person's eye. The microvessels in a person's eye may react differently to, for example, the microvessels in a person's mouth. Therefore, it may be desirable to monitor microvessels in a subject's mouth using the probe as well as a camera imaging the person's eye. For example, differences in speed of reaction could be determined using such an apparatus.

Preferably, the apparatus further comprises means for recording images produced by the probe. This enables the images to be analysed at a later point in time. Preferably, when the apparatus also includes means for dispensing drugs, the apparatus also has means for recording when the drugs are dispensed via the dispenser in conjunction with the images produced by the probe. This allows easier analysis of how the dispensing of drugs affects the microvessels.

The apparatus may further comprise the probe for observing microvessels. The probe may also emit light to be reflected from the microvessels. Examples of such probes include probes for orthogonal polarisation spectral imaging and probes for sidestream dark field imaging. These probes can produce high contrast images of microvessels.

Preferably, the probe is configured to detect, or to emit and detect, light at the isosbestic point of oxyhaemoglobin and deoxyhaemoglobin. That is, the probe is configured to detect, or to emit and detect, light having a wavelength in the range of from 500 to 600 nm, preferably of from 510 to 590 nm, more preferably of from 515 to 585 nm, and still more preferably of from 540 to 560 nm.

Operating at the isosbestic point allows for the microvessels to be observed by the probe with the maximum contrast, leading to the best possible images.

According to another aspect there is provided a method for positioning a probe for observing microvessels, the method comprising: connecting a micropositioner to a first end of a mechanical arm; attaching a probe for detecting light reflected from microvessels to a second end of the mechanical arm; adjusting the mechanical arm so as to position the probe for observing microvessels; adjusting the micropositioner to further position the probe; and producing images of the microvessels with the probe.

According to another aspect there is provided a method for positioning a probe for observing microvessels, the method comprising: supporting the probe for observing microvessels with a mechanical arm; and supporting a person's head with a head support, so that the head support and the mechanical arm are in a fixed position with respect to each other.

According to another aspect there is provided a method for positioning a probe for observing microvessels, the method comprising: supporting the probe for observing microvessels in a person's mouth with a mechanical arm; supporting a person's head with a head support; and dispensing drugs into the person's mouth. According to another aspect there is provided a method for determining the effect of a substance on microvessels, the method comprising: positioning a probe on the end of mechanical arm connected to a micropositioner to image microvessels in a subject's mouth; dispensing the substance into the subject's mouth; imaging the microvessels so as to observe the effect of the substance on the microvessels.

According to this method, the effectiveness of a new drug can be determined by observing the effect on microvessels in vivo. Preferably, the method further comprises imaging the microvessels in at least one of the subject's eyes so as to observe the effect of the substance on the microvessels. This enables a comparison to be drawn between the effects of the drug in different parts of the subject' s body.

The present invention is described below, by way of example only, with reference to the accompanying figures in which:

Fig. la is a drawing showing a front view of a drawing of an apparatus for positioning a probe for observing microvessels according to one aspect of the invention;

Fig. lb is a drawing showing a side view of the apparatus of Fig. la;

Fig. 2 is a drawing of an apparatus for positioning a probe for observing microvessels utilising automatic control of a micropositioner according to one aspect of the invention;

Fig. 3 is a drawing of an apparatus for positioning a probe for observing microvessels incorporating a means for dispensing drugs according to one aspect of the invention;

Fig. 4 is a drawing of an apparatus for positioning a probe for observing microvessels incorporating a camera for observing a subject's eye according to one aspect of the invention;

Fig. 5 shows an end view of a probe, and a projected view of the same probe;

Fig. 6a is projection view of another probe, whilst Fig. 6b shows the probe of Fig. 6a with a section of the casing removed.

Orthogonal polarisation spectroscopy (OPS) and sidestream dark field (SDF) imaging both produce high contrast pictures of microvessels.

OPS utilises a single light guide to illuminate microvessels with light at the isosbestic point of oxyhaemoglobin and deoxyhaemoglobin. That is, OPS typically uses green light having a wavelength in the range of from 500 to 600 nm, preferably of from 510 to 590 nm, more preferably of from 515 to 585 nm, and still more preferably of from 540 to 560 nm. The light is polarised, and the probe from which the light is emitted is placed against a subject's skin, for example. Light that is immediately reflected by the skin tends to remain polarised. Light that penetrates more deeply into the tissue experiences multiple scattering events. As such, any such light that returns to the probe is no longer polarised. Therefore, OPS imaging filters out any polarised light that is collected, and uses the depolarised light to create an image. The filtering out of the immediately reflected, polarised, light increases the contrast in the image finally produced.

SDF imaging also uses light at the isosbestic point for oxyhaemoglobin and

deoxyhaemoglobin.

However, in SDF imaging, the waveguide for collecting reflected light is not also used for providing the illumination. Instead, light sources are provided in a ring around the waveguide for receiving reflected light. As a consequence, when the probe is placed in contact with the skin, for example, any light that is immediately reflected from the skin is not received by the waveguide at all. As such, in SDF imaging, there is no need for polarisation of the light used for illumination. Simply, any light that penetrates deeply into the tissue and is subsequently reflected after scattering events is picked up by the probe and used to create an image. Once again, this technique prevents any reflected light from the skin being used to create the image, and therefore a high contrast image of the microvessels is created.

However, both of these techniques suffer from the problem that it can be difficult to obtain clear images in vivo. This is because imaging microvessels requires large magnifications, and subsequently the field of view is very small. As such, any small relative motion between the observed vessels and the imaging apparatus causes a substantial change in view with the imaging apparatus. Such relative motion occurs because a living subject is likely to move, simply due to natural processes such as breathing. In addition, apparatuses for OPS and SDF Imaging conventionally use hand-held probes, thereby introducing a further element of instability in the positioning of the probe itself.

It would be desirable to image microvessels in the mucous membranes of the mouth. This is because the microvessels in the mucous membranes will react quickly to any drugs supplied to the mouth. As such, the reaction of the microvessels to vasoconstrictors and vasodilators could be observed. Known vasodilators include: nitroglycerine (GTN), sodium nitroprusside, acetyl choline, nifedipine and other calcium channel blockers, potassium channel openers, endothelin antagonists, angiotensin receptor blockers and angiotensin converting enzyme inhibitors, direct rennin inhibitors, metformin and PPAR gamma agonists. Known vasoconstrictors include nitric oxide synthase inhibitors, potassium channel blockers, hydrocortisone, dexamethazone and sympathomimetics e.g. adrenaline, noradrenaline and isoprenaline. However, it is also desirable to observe the effects of new drugs, so that the response of the microvessels to the new drugs can be determined. To enable such observations, the present invention provides an apparatus for reducing the effects of any relative motion between an imaging apparatus and the subject. Fig. la shows a diagram of an apparatus according to the present invention, from a "front" view. Fig. lb shows a side view of the same apparatus.

The apparatus 1 may comprise a head support 10. The head support 10 may be of the sort used with an ophthalmic slit lamp table. The head support 10 helps keep a subject's head still. It has a chin rest 12 on which a subject rests their chin and a forehead rest 11 against which a subject leans their forehead.

The apparatus 1 may further comprise a micropositioner 20. The micropositioner 20 has control knobs 21 , which can be used to adjust the position of a surface 22 of the micropositioner 20. The control knobs 21 allow for fine control in three dimensions of the position of the surface 22. That is, the micropositioner allows for the surface 22 to be positioned on the scale of microns.

On the surface 22 of the micropositioner 20, may be positioned a mechanical arm 30. The arm 30 may be connected to the surface 22 with a releasable magnet 31 , the surface 22 being made of a ferromagnetic material. However, any alternative method of attachment could be used, such as a releasable suction cup. Indeed, permanent or semi-permanent attachments could also be used such as bolts or adhesives.

The mechanical arm 30 may comprise two rigid portions 32. The two rigid portions may be connected by a moveable joint 33, and one of the rigid portions may be connected by a further joint 33 to the magnetic connecting portion 31. At the other end of the arm 30 to the magnetic connecting portion 31 , the arm has a connector or holder 34 for an imaging probe 40. The holder 34 may also be attached to the arm 30 by a joint 33. The rigid portions 32 and the holder portion 34, may be manipulated by moving the joints 33, to position the holder 34 in the desired position on the macro-scale. When the arm 30 is suitably positioned, the joints 33 may be locked using control 35, for example.

The arm 30, may comprise several rigid portions 32 connected by several joints 33. That is, the arm 30 is not limited to having two rigid portions 32. Indeed, the arm may be entirely flexible, and may not have discrete rigid portions and joint portions.

The holder 34 of the arm 30, holds imaging probe 40, which is connected to a computer 50. Computer 50 is omitted from Fig. lb for clarity. Computer 50 may be used to control the probe (for example the light intensity or focus), and also to receive and store images from the probe. The computer 50 is connected to, and communicates with, the probe 40 via wire 36 in Figure la. Alternatively, wireless communication between the computer 50 and the probe 40 could be used, for example using infrared or radio communication. The holder 34 may hold the probe 40 by any suitable means, depending upon the configuration of the probe 40. For example, it may hold the probe 40 by a clamping mechanism, or may use a magnetic or hydraulic suction means for securing the probe 40.

When the arm 30 has been used to position the probe 40 on the macro-scale, (within a subject's mouth, for example) the position of the probe 40 may be further adjusted by using the micropositioner 20. Such positioning may be performed, for example, to select an appropriate field of view for the probe 40. Alternatively, whilst observing particular microvessels, if there is any relative motion (for example caused by the subject breathing) the micropositioner may be used to adjust the field of view of the probe 40 in order to restore the original field of view to that before the relative motion occurred.

In practice, the various aspects of the positioning and positioning control may be performed by automated means. Fig. 2 shows an example of such an automated apparatus. In Fig. 2 the position of the micropositioner 20 and arm 30 are controlled by computer 60. The position of the head support 10 may also be controlled by computer 60. For example, the position of the head support 10 may be adjustable, in order to provide a comfortable position for subjects of different heights. The position of the head support 10 may be adjustable, for example, by hydraulics, or an electronic motor. The chin rest 12 and the forehead support 11 may be separately adjustable. That is, the position of the chin rest 12 may be adjustable relative to the position of the forehead rest 11. Computer 60 may or may not be the same computer as computer 50, which receives and stores the images from the probe 40. However, it may be preferable, if the computers 50 and 60 are separate computers, that computers 50 and 60 are in communication.

As discussed above, the adjustable arm 30 and micropositioner 20 are used to position the probe 40. Computer 60 may be used to automate the positioning and locking of the arm 30, as well as the micro-control of the position of the probe 40 using the micropositioner 20.

In particular, the computer 60 may incorporate a feedback control mechanism, based on the images provided by the probe 40 to the computer 50. In this case, if the computer 60 is separate to the computer 50, the computers 50 and 60 are in communication. When a change in position of the field of view of the probe 40 is detected in the images received at computer 50, the feedback control in computer 60 may be used to automatically adjust the position of the probe 40, by controlling the micropositioner 20, in order to restore the original field of view. Such automatic control can lead to more accurate maintenance of the field of view, and therefore allow better measurements and comparisons to be obtained.

As previously mentioned, it may be desirable to introduce drugs to the mucous membranes in a subject's mouth at the same time as the microvessels are being observed, in order to observe and/or determine the effect of the drug on the microvessels in the mucous membranes. The apparatus of Fig. 3 shows how the apparatus 1 may be adapted for this purpose.

The head support 10 may be provided with a holder 13 for supporting a tube 71 that may be inserted into a subject's mouth and directed to the mucous membranes. Drugs may be supplied through tube 71, from a reservoir 72, such as a drip bag. Alternatively, the reservoir may simply be a syringe connected to tube 71. The flow from the reservoir 72 through the tube 71 may be controlled manually or automatically. In Fig. 3, the flow is regulated by pump 73. If the pump 73 is controlled automatically, the pump may also be connected to computer 50, so that a record of the flow through tube 71 as controlled by pump 73 may be kept alongside the results of the imaging. As such, this will allow direct comparison between the supply of any drug through the tube 71 with the reaction of the microvessels as recorded in the images.

In Fig. 4, a version of apparatus 1 that incorporates a camera 81 for viewing a subject's eye is depicted. The microvessels in the retina of a subject's eye will also be reactive to any drugs administered to the mucous membranes in the subject's mouth. As such, although there will be a delay in the reaction to drugs administered in the patient's mouth, it is desirable to monitor both the reaction of the microvessels in the mucous membranes in the mouth and also the reaction of the microvessels in the eye.

The camera 81 may be provided on an adjustable holder 82, which allows positioning of the camera 81 with respect to a subject's eye. The holder 82 may also be electronically controllable, and may also controlled in use with a feedback loop (based in images from the camera 81) to maintain a substantially constant field of view of the camera 81.

In a preferred embodiment, the apparatus of Fig. 2 uses computer 60 to also function as computer 50. That is, a single computer 50,60 is used to control the position of the

micropositioner/ mechanical arm and to communicate with the probe 40 and record images produced by the probe 40. The computer 50,60 also further controls the positions of the forehead rest 11 and chinrest 12. The apparatus is further adapted for dispensing drugs, as shown in Fig 3. That is, the apparatus is further provided with a holder 13, for supporting a tube 71 connected to a reservoir 72. Flow from the reservoir 72 is preferably controlled via computer 50, 60 via a pump or other flow control device 73. Additionally, the apparatus is provided with the camera 81 and camera holder 82 as shown in Fig. 4. Preferably, the camera 81 is also controlled via computer 50,60, as is the position of the camera 81 via the holder 82.

The probe 40 can be designed to ease the delivery of a drug or drugs, and the observation of the effects of any drug(s) delivered to field of view. Fig. 5 depicts a probe 40 that comprises two delivery tubes 41, 42 in addition to the probe sensing/illuminating apparatus 43. The delivery tube 41 is for providing one or more drugs, whilst the delivery tube 42 can be used to supply water or another fluid to wash the field of view, or can operate in suction to aspirate the site under observation.

The tubes 41,42 can be any suitable tubes, such as tubing for intravenous lines, for providing the required drug(s)/molecule(s). The tubes 41,42 may be directly attached to the main probe apparatus 43 by chemical means such as an adhesive. However, it may be preferable for the tubes 41, 42 to be detachable from the probe 40, to allow easy cleaning of the probe 40 or to allow replacement of the tubes 41, 42 for example. It may be preferable to incorcoborate the tubes 41, and 42 to the main cover of the main probe so that the new cover can be for example sterilized prior to use and then disposed off after testing. Alterantively, the tubes 41,42 may be attached to the main probe apparatus by another mechanical means, such as adhesive tape.

In use, the presence of tubes 41 ,42 allows for improved observation of the effects of a drug or drugs on microvessels. The probe 40 can be positioned (for example, within a patient's mouth) to observe a particular field of view of interest. The drug(s) can then be delivered very locally to the microvessels in the field of view, via the tube 41 from a reservoir. That is, the drugs supplied through tube 41 will be supplied next to or within the field of view of the probe 40. This allows for the effect of the drug(s) to be observed from the moment they are supplied. In contrast, conventional means of supplying drugs will not be able to reliably provide drugs so locally to the field of view, or would risk disturbing the probe as the apparatus for supplying the drug(s) is introduced to the field of view.

In addition, the provision of the tube 42 allows for the field of view to be washed and/or aspirated to help provide a clear picture and also, for example, to remove excess drug that has been supplied. Once again, this enables the experiment to proceed without disturbing the probe and changing the field of view.

Figs. 6a and 6b depict an alternative probe design. In this design, an outer casing 44 is provided around the main probe apparatus 43 and a drug delivery tube 41. However, the tube 42 is replaced by a space 46 between the probe apparatus 43 and the casing, which can act as a duct for supplying washing fluid or for aspirating the field of view. As such, tube 42 and space 46 are both fluid flow-ducts (whether liquid or gas), and may be connected to a fluid supply and/or a suction device.

Optionally, the outer casing 44 protrudes slightly further than the main probe apparatus 43, leave a small space 45 between the sensing end of the main probe apparatus 43 and the area of examination. This gap can be between from 0.2 to 2.0 mm, preferably between from 0.5 to 1.0 mm. The creation of small gap 45 reduces the pressure being applied onto the examination area, and so reduces any blood flow restriction introduced by observing the microvessels with the probe 40. That is, only the outer casing 44 will rest on the area of examination, preferably with little or no pressure, and not the entire end surface of the main probe apparatus 43.

As the outer casing 44 rests on the area of examination, for example the sublingual mucosa, a seal is formed preventing any pharmacological agent leaving the confines of the outer casing 44. This enables the pharmacological agent to remain in a local area rather than it being distributed over a larger area (e.g. throughout the mouth).

Although Figs 5 -6b show a single drug delivery tube 41 and a single tube or space 42,46, the probe may be supplied with multiple tubes/ducts of each type. For example, it may be desired to supply two drugs each through a separate tube, and/or provide separate ducts for washing and aspirating.

Claims

An apparatus for positioning a probe for observing microvessels, the apparatus comprising:

a mechanical arm for supporting the probe for observing microvessels;

a means for supporting a person's head; and

a dispenser for dispensing drugs into a person's mouth.

An apparatus according to claim 1 , wherein the dispenser comprises a tube for supplying drugs from a reservoir.

An apparatus according to claim 1 or claim 2, further comprising the probe for observing microvessels, and wherein the probe comprises the dispenser.

An apparatus according to claim 3, wherein the probe further comprises a duct for providing washing fluid or aspiration.

An apparatus according to claim 3 or claim 4, further comprising a casing surrounding the probe.

An apparatus according to claim 5, wherein the casing projects from between 0.2 and 2.0 mm beyond an end of the probe, preferably between from 0.5 to 1.0 mm beyond the end of the probe.

An apparatus according to any one of the preceding claims, wherein the mechanical arm is flexible or has at least one adjustable joint.

An apparatus according to any one of the preceding claims, wherein the position of the mechanical arm is controllable remotely.

An apparatus according to claim 8, wherein the mechanical arm has at least three adjustable joints.

An apparatus for positioning a probe for observing microvessels, the apparatus comprising: a mechanical arm for supporting the probe for observing microvessels; and a micropositioner for making fine adjustments to the position of the mechanical arm;

wherein the mechanical arm is connected, at a first end, to the micropositioner and wherein the mechanical arm is provided with connecting means at a second end for connecting to the probe for observing microvessels.

11. An apparatus according to claim 10, wherein the micropositioner provides three- dimensional movement.

12. An apparatus according to any one of the preceding claims, wherein the micropositioner is controllable remotely.

13. An apparatus according to claim 12, further comprising a control unit responsive to the image obtained with the probe to control the micropositioner to maintain a substantially constant field of view with the probe.

14. An apparatus according to any one of the preceding claims, further comprising:

a magnet attached to the first end of the mechanical arm; and

wherein the micropositioner comprises a ferromagnetic surface to which the magnet may attach.

15. An apparatus according to any one of the preceding claims, further comprising means for supporting a person's head, wherein the mechanical arm and the means for supporting a person's head are in a fixed position with respect to each other.

16. An apparatus for positioning a probe for observing microvessels, the apparatus

comprising:

a mechanical arm for supporting the probe for observing microvessels; and a means for supporting a person's head;

wherein the mechanical arm and the means for supporting a person's head are in a fixed position with respect to each other.

17. An apparatus according to claim 15 or 16, wherein the means for supporting a person's head comprises a chin rest.

An apparatus according to any one of claims 10 to 17, further comprising a dispenser for dispensing drugs into a person's mouth.

An apparatus according to any one of the preceding claims, wherein the mechanical arm comprises means for locking the position of the mechanical arm.

An apparatus according to any one of the preceding claims, further comprising a camera for imaging microvessels in a person's eye.

An apparatus according to any one of the preceding claims, further comprising means for recording images produced by the probe.

An apparatus according to claim 21 when appendant to claim 1 or 18, further comprising means for recording when drugs are dispensed via the dispenser in conjunction with the images produced by the probe.

An apparatus according to any one of the preceding claims, further comprising the probe for observing microvessels.

An apparatus according to claim 23, wherein the probe is also for emitting light to be reflected from microvessels.

An apparatus according to claim 3, claim 23 or claim 24, wherein the probe is configured to detect, or to emit and detect, light having a wavelength in the range of from 500 to 600 nm, preferably of from 510 to 590 nm, more preferably of from 515 to 585 nm, and still more preferably of from 540 to 560 nm.

An apparatus according to claim 3, claim 23 or claim 24, wherein the probe is configured to detect, or to emit and detect, light at the isosbestic point of oxyhaemoglobin and deoxyhaemoglobin.

An apparatus according to any one of claims 3 or 23 to 26, wherein the probe is a probe for orthogonal polarization spectral imaging.

28. An apparatus according to any one of claims 3 or23 to 26, wherein the probe is a probe for sidestream dark field imaging.

29. A method for positioning a probe for observing microvessels, the method comprising:

supporting the probe for observing microvessels in a person's mouth with a mechanical arm;

supporting a person's head with a head support; and

dispensing drugs into the person's mouth.

30. A method according to claim 29, wherein the dispensing comprises dispensing drugs through a tube from a reservoir.

31. A method according to claim 29 or claim 30, wherein the probe comprises the dispenser used in the step of dispensing.

32. A method according to claim 31 , wherein the probe further comprises a duct for

providing washing fluid or aspiration.

33. A method according to claim 31 or claim 32, wherein the probe further comprises a casing surrounding the probe.

34. A method according to claim 33, wherein the end of the casing projects from between 0.2 and 2.0 mm beyond an end of the probe, preferably between from 0.5 to 1.0 mm beyond the end of the probe.

35. A method according to claim 33 or 34, further comprising positioning the end of the casing on the sublingual mucosa.

36. A method according to claim 35, wherein the dispensed drugs are held confined between the sublingual mucosa and the casing.

37. A method for positioning a probe for observing microvessels, the method comprising:

connecting a micropositioner to a first end of a mechanical arm; attaching a probe for detecting light reflected from microvessels to a second end of the mechanical arm;

adjusting the mechanical arm so as to position the probe for observing microvessels;

adjusting the micropositioner to further position the probe; and

producing images of the microvessels with the probe.

A method according to claim 37, wherein the micropositioner provides three-dimensional movement.

39. A method according to claim 37 or 38, wherein the positioning of the micropositioner is performed remotely.

40. A method according to claim 39, further comprising controlling the micropositioner to maintain a substantially constant field of view with the probe, in response to images obtained with the probe.

41. A method according to any one of claims 37 to 40, wherein the

micropositioner comprises a ferromagnetic surface and the method further comprising connecting the micropositioner to the mechanical arm via a magnet, the magnet being attached to the first end of the mechanical arm.

42. A method according to any one of claims 37 to 41 , further comprising supporting a

person's head with a head support, so that the mechanical arm and head support are in a fixed position with respect to each other.

A method for positioning a probe for observing microvessels, the method comprising: supporting the probe for observing microvessels with a mechanical arm; and supporting a person's head with a head support, so that the head support and the mechanical arm are in a fixed position with respect to each other.

A method according to claim 42 or 43, wherein the head support comprises a chin rest.

A method according to any one of claims 37 to 44, further comprising dispensing drugs into a person's mouth.

46. A method according to any one of claims 29 to 45, wherein the mechanical arm is flexible or has at least one adjustable joint.

47. A method according to claim 46, wherein the position of the mechanical arm is controlled remotely.

48. A method according to claim 46 or claim 47, wherein the mechanical arm has at least three adjustable joints.

49. A method according to any one of claims 29 to 48, further comprising locking the

position of the mechanical arm.

50. A method according to any one of claims 29 to 49, further comprising imaging

microvessels in a person's eye with a camera.

51. A method according to any one of claims 29 to 50, further comprising recording images produced by the probe.

52. A method according to claim 51 when appendant to claim 37or 38, further comprising recording when drugs are dispensed via the dispenser in conjunction with the images produced by the probe.

53. A method according to any one of claims 29 to 52, further comprising emitting light from the probe to be reflected from microvessels.

54. A method according to claim 53, further comprising detecting, or emitting and detecting, light having a wavelength in the range of from 500 to 600 nm, preferably of from 510 to 590 nm, more preferably of from 515 to 585 nm, and still more preferably of from 540 to 560 nm.

55. A method according to claim 54 further comprising detecting, or emitting and detecting, light at the isosbestic point of oxyhaemoglobin and deoxyhaemoglobin. A method according to any one of the claims 29 to 55, wherein the probe is a probe for orthogonal polarization spectral imaging.

A method according to any one of claims 29 to 56, wherein the probe is a probe for sidestream dark field imaging.

A method of determining the effect of a substance on microvessels, the method comprising:

positioning a probe on the end of a mechanical arm connected to a micropositioner to image microvessels in a subject's mouth;

dispensing the substance into the subject's mouth;

imaging the microvessels so as to observe the effect of the substance on the microvessels.

A method according to claim 58, further comprising imaging the microvessels in at least one of the subject's eyes so as to observed the effect of the substance on the

microvessels.

An apparatus for observing microvessels in mucous membranes constructed and arranged substantially as hereinbefore described or as illustrated in any one of Figures 1 to 4 of the accompanying drawings.

A method for observing microvessels in mucous membranes substantially as hereinbefore described or as illustrated in any one of Figures 1 to 4 of the accompanying drawings.

A method of determining the effect of a substance on microvessels substantially as hereinbefore described or as illustrated in any one of Figures 1 to 4 of the accompanying drawings.