WO2025186666A1

WO2025186666A1 - A corneal topographer incorporating an opacifying disc to detect the tear film lipid layer of the eye

Info

Publication number: WO2025186666A1
Application number: PCT/IB2025/052111
Authority: WO
Inventors: Marco ARRIGUCCI
Original assignee: Visia Imaging SRL
Current assignee: Visia Imaging SRL
Priority date: 2024-03-05
Filing date: 2025-02-27
Publication date: 2025-09-12
Anticipated expiration: 2026-09-05
Also published as: WO2025186666A8

Abstract

The present invention relates to a machinery for corneal topography wherein there is an electrically controllable light diffusing screen for switching from the diffusing condition to the transparent condition and vice versa, and arranged along the path of the light beam which is then projected into the eye, so as to be able to perform either a corneal topography or an ocular Lipid Layer Thickness analysis depending on the condition in which the screen is placed.

Description

A CORNEAL TOPOGRAPHER INCORPORATING AN OPACIFYING DISC TO

DETECT THE TEAR FILM LIPID LAYER OF THE EYE

Scope of the Invention

[001] The present invention relates to the technical field of eye analysis/measurement machineries.

[002] In particular, the invention relates to an innovative integrated machinery for general ophthalmic analyses, which allows at least one corneal topography and/or at least one analysis of the lipid layer of the eye (also called Lipid Layer Thickness) to be performed.

A brief outline of the prior art

[003] Corneal topography of an eye has long been well known. This type of examination is performed with a special machinery called a corneal topographer.

[004] The examination is non-invasive and allows a map of the corneal curvature to be reconstructed.

[005] Figure 1A depicts a corneal topographer of the prior art .

[006] The refore a support frame (102' , 60) is provided, which supports a light-projecting device 100.

[007] A camera 300 is placed to the rear of said lightprojecting device. There is also a support, placed directly in front of the light-projecting device 100, which allows the patient to rest his/her chin and head stably in such a way that it is firmly in position allowing the machinery to perform its function.

[008] For purely descriptive purposes, the eye 200 in front of said light-projecting device 100 is represented schematically, while, for the sake of descriptive simplicity, the additional support for the chin and forehead is not shown.

[009] The light-projecting device 100, in a well-known configuration, may include a so-called Placido disc 100, which is nothing more than a disc that is flat or made from a conical body (Figure 1A shows the conical body) and backlit by a plurality of light sources 101.

[0010] The Placido disc provides a plurality of concentric circles formed in the conical body that appear, generally, as white circles alternating with black circles. The white circles allow light to pass through while the black ones shield the light. In this way, backlighting 101 is projected precisely in the form of these concentric circles in the eye placed opposite as light will only pass through the white circles and be shielded by the black circles .

[0011] Figure 1A schematically shows the light rays 102 passing through the white circles and also shows, with arrows 103, the image acquired by the camera 300 through an axial hole in the Placido disc 100.

[0012] The eye will therefore reflect a plurality of concentric circles, or rings or discs as you like, which represent the lighting 101 alternating with black circles that are circles without illumination or dark so to speak (i.e. an unlit area of the eye) as they are, as mentioned, generated precisely by the non-passage of light.

[0013] In a well-known variant, the Placido disc can be replaced directly with a specific distribution of light sources arranged to project a pattern onto the eye that performs a similar function to the rings of the Placido disc .

[0014] The patient therefore stands in front of the machinery, resting his/her chin on the support so that the light-projecting device is, in essence, in front of the patient's eye. [0015] In this way, the concentric discs are reflected on the eye (or the Placido disc or the pattern in any case related to the case of light distribution) which are then projected onto the surface of the anterior cornea .

[0016] The acquisition of images of the eye through the camera 300, specially processed using well-known software, allows a corneal topograph to be reconstructed.

[0017] Figure 1A therefore shows the case of a backlit Placido disc, with the camera 300 placed at the rear and the eye 200. The same applies, of course, in the case where the Placido disc is replaced with the solution that directly sees, on a surface, a distribution of light sources .

[0018] The image in Figure IB shows the concentric circles projected into the patient's eye during this examination, an image taken by the camera 300 placed on axis.

[0019] Obviously, in addition to corneal topography, other examinations may be necessary, but these are in contrast to corneal topography and therefore require specific machineries.

[0020] One such case is, for example, the analysis of the lipid layer of the tear film of the eye, known in technical jargon as the "Lipid Layer Thickness".

[0021] This examination allows the physician to clearly view in the eye the actual presence of the lipid layer on the surface of the eye.

[0022] This type of examination, in an eye in which concentric circles are projected as shown in Figure IB, is inaccurate and complex because the dark circles represent a non-illuminated area that therefore makes it impossible to detect the lipid layer present.

[0023] More specifically, circle (or pattern) illumination makes the lipid layer visible in a discontinuous manner precisely because this can only be seen where there is more light intensity, i.e. where the rings (or circles or discs as the case may be) are reflected, while it cannot be seen where there is no ring image. Thus, the rings make it difficult to view the lipid film because they illuminate it discontinuously.

[0024] Sp ecial machineries are therefore required to measure the Lipid Layer Thickness.

[0025] In particular, it is complicated to make multifunction machineries that can perform corneal mapping operations in conjunction with the measurement of the Lipid Layer Thickness, as the lighting obtained interferes with the correct detection of the liquid layer.

[0026] Having said that, there are various solutions on the market that have tried to solve the aforementioned technical problem, i.e. in an attempt to integrate both the presence of the Placido disc for corneal analysis and the possibility of being able to detect the so-called Lipid Layer Thickness.

[0027] For example, the known and marketed solution depicted in Figure 2, features a classic topographer 100 comprising the Placido disc 101 which, as already described, is supported by a load-bearing column 102' forming part of the support frame. The images of the eye acquired (see the screen on which the images are sent) are processed using special software in order to be able to determine, as far as possible, the Lipid Layer Thickness despite the presence of the Placido discs reflected in the eye and thus present in the image of the eye. The solution is therefore imprecise and in any case complex.

[0028] In a further known solution, the Placido disc is formed in a cone 500 (see Figure 3) that has a small ring- free area. In essence, the rings are interrupted and thus are not continuous, resulting in a ring-free area 501. This ring-free area 501 is projected into the eye (see zone 502) and therefore allows the presence of the lipid layer to be assessed in this area as it would be in a well-lit zone. However, it is clear that even this solution has the limitation of allowing a very limited view of the eye area. In particular, both the detection of the lipid layer and the corneal topography are inaccurate. [0029] Finally, a solution is known and already marketed in which a removable opaque screen is applied, which then acts as a light diffuser. As is well known, the light diffuser lets the light beam pass through it but deflects it in several different directions, thus generating uniform lighting that causes the real image to be lost. If, for example, a light beam representing a ring passes through a transparent screen, this beam passes the screen undisturbed while maintaining its direction and is projected into the eye. If, on the other hand, the ring of light passes through a diffuser screen, which is opaque, the rays are deflected in several directions and the resulting light projected onto the eye will be a homogeneous light that illuminates an entire area, thus losing the ring conformation.

[0030] That being said, the solution of the prior art introduced here uses a diffuser screen (thus opaque) that is removably applied in front of the Placido disc.

[0031] In particular, the concentric circle pattern lighting, which thus highlights the lipid film in a discontinuous manner, is transformed into uniform lighting by placing such a diffuser in front of the Placido disc.

[0032] Thus, when the machinery is to function no longer as a corneal topographer but as a machinery to detect the lipid layer of the ocular surface, it is then sufficient to apply such a diffuser screen in front of the Placido disc . [0033] However, although functional, this solution has the technical drawback of presenting the diffuser screen as an accessory that must be applied to cover the Placido disc when necessary.

[0034] In particular, when an evaluation of the Lipid Layer is to be carried out, the screen covering the Placido disc is applied, and when corneal mapping is to be carried out, the screen is removed and classic topography is performed.

[0035] Cl early, this is not a versatile solution, also because the accessory, precisely by virtue of being a separate component, can get lost or its quick-connect system to the Placido disc can fail.

[0036] In addition, assembly/disassembly takes time.

[0037 ] Additionally, the following publications are known: US2014 / 104574 , US2019/227327 , US2008 /204659 , US6447119.

Summary of the invention

[0038] It is thus the purpose of the present invention to provide a machinery that solves at least part of the aforementioned technical drawbacks.

[0039] In particular, it is the purpose of the present invention to provide a machinery which, in a versatile and functional manner, as well as being accurate and fast, makes it possible to carry out both a corneal topographic measurement and a measurement of the lipid layer of the tear film of the eye, without necessarily having to disassemble or reassemble accessories, thus conferring versatility to the machinery itself.

[0040] These and other purposes are achieved with the present machinery for allowing execution of at least one corneal topography and/or Lipid Layer Thickness analysis to be performed in accordance with claim 1.

[0041] This machinery comprises: At least one light- projecting device (100) ;

And wherein a screen (20) is comprised covering at least part of said light-pro ecting device (100) .

[0042] Therefore, in other words, the screen 20 is placed in such a way as to intercept the path of at least part of the light pattern emitted by the device 100, e.g. by placing the screen 20 in front of the device 100 and thus as also mentioned by placing the screen 20 covering at least part of said light-projecting device.

[0043] In all of the aforementioned cases, according to the invention, said screen (20) is electrically controllable so as to be selectively changeable from a transparent state to an opaque state and/or vice versa.

[0044] In this way, all the aforementioned technical drawbacks are solved.

[0045] The solution of a controllable screen, i.e. one whose state can be controlled and thus switched from opaque to transparent and/or vice versa, makes it possible, for example, to attach the screen permanently to the light-projecting device, e.g. a Placido disc. For example, the fastening can be fixed and irremovable, thus making the machinery compact, versatile and quick to use.

[0046] All the operator has to do is to check the state of the screen, thus putting it in the opaque or transparent condition depending on the examination to be performed.

[0047 ] Alternatively, the machinery via a special control can automatically switch the functionality of screen 20 according to the type of examination that is selected on the machinery in question (e.g. via a special control panel) .

[0048] When the screen is placed in a transparent condition, the light beam is not deflected and therefore it is as if the screen were not present. When the screen is switched to opaque, it acts as a diffuser, illuminating the relevant area with even, diffused light.

[0049] Depending on the examination that needs to be carried out, the screen can be placed in the transparent state or in the diffuser state. In the diffuser state, the Lipid Layer Thickness can be examined as the screen 20 uniformly diffuses the lighting from the projection of concentric discs, for example, relative to a Placido disc. In this way, the discs are not visible as they are transformed into diffused and homogeneous light. In the same way, normal corneal topography can be carried out in a transparent state, allowing for the reflection of concentric discs as they project faithfully.

[0050] Even in the case of a removable screen, i.e. applied in such a way that it can be removed if necessary, the screen can still be kept fixed to cover the lightprojecting device, e.g. the Placido disc, for a long time and while the machinery is in use, so that it can then be removed if necessary, e.g. for maintenance or other reasons .

[0051] Whether the screen is therefore permanently fixed or removable, in any case once fixed it does not interfere with the operation of the machinery when carrying out corneal topography and can therefore remain in place without any problems and can be switched to allow examination of the Lipid Layer Thickness.

[0052] An object of the invention is also the use in an ophthalmic instrument comprising at least one lightprojecting device (100) projecting a light pattern in use, of a screen (20) positioned so as to intercept the path of at least part of said light pattern emitted by said lightprojecting device (100) .

[0053] According to the invention, the screen (20) is now electrically controllable to switch from an opaque condition, in which it acts as a diffuser of the light emitted by said light- projecting device (100) passing through it, to a transparent condition in which it allows, without any deviation, the light emitted by said light-pro ecting device (100) passing through it and/or vice versa.

[0054] Advantageously, in this way, the same ophthalmic instrument can have several functions at the same time.

[0055] For example, said ophthalmic instrument could perform the function of a corneal topographer when said screen (20) is placed in said transparent condition and be suitable for a Lipid Layer Thickness measurement when said screen (20) is placed in said opaque condition.

[0056] More specifically, for example, the said ophthalmic instrument could perform the function of corneal topographer when the light-projecting device 100 is a device adapted to project a luminous pattern suitable for a corneal topography measurement, e.g. it could be a Placido disc or similar.

[0057] In this case, when said screen (20) is placed in such a transparent condition that it does not deflect the light pattern emitted by the light-projecting device 100, a corneal topography measurement is then possible.

[0058] Using the same ophthalmic instrument, it is now possible to take a Lipid Layer Thickness measurement when said screen (20) is placed in the opaque condition such that, in said opaque condition, the light pattern emitted by said light-projecting device is now diffused.

[0059] Advantageously, said screen (20) comprises at least one layer of transparent material coated with an electrically switchable film in such a way as to permit, by means of electrical excitation, the transition from the transparent to the opaque state and/or vice versa.

[0060] Advantageously, said film may be polymeric of the PDLC or PNLC type. [0061 ] Advantageously, a controller configured to automatically control said screen by controlling its transition from the opaque to transparent state and/or vice versa may be comprised.

[0062] Advantageously, a manual switch (70) can be included as an alternative or in combination with the controller .

[0063] Advantageously, said screen (20) can be fixed irremovably .

[0064] More specifically, preferably, the screen can be irremovably fixed to said light-projecting device (100) .

[0065] Advantageously, alternatively, said screen (20) can be fixed in a removable manner.

[0066] In this case, it can preferably be fixed for example to the light-pro ecting device in a removable manner (100) .

[0067 ] Advantageously, said light-projecting device (100) can be a Placido disc comprising a plurality of backlit concentric discs.

[0068] Alternatively, advantageously, it may be a surface with a plurality of light sources arranged in a certain pattern .

[0069] Advantageously, said machinery may comprise a camera (300) arranged behind the light-projecting device (100) in such a way that said device (100) is comprised between the camera and said screen.

[0070] Advantageously, said device (100) and the screen have a hole on axis with the camera.

[0071 ] Advantageously, in all configurations, the machinery object of the invention comprises a support frame (102' , 60 ) .

[0072 ] Advantageously, in all configurations, the support frame supports the screen (20) .

[0073] An object of the present invention is also the use in an ophthalmic instrument comprising at least one light-projecting device (100) projecting a light pattern in use, of a screen (20) positioned so as to intercept the path of at least part of said light pattern emitted by said light-projecting device (100) .

[0074] According to the invention, the screen (20) is electrically controllable to switch from an opaque condition, in which it acts as a diffuser of the light emitted by said light-projecting device (100) passing through it, to a transparent condition in which it allows, without any deviation, the light emitted by said lightprojecting device (100) passing through it and/or vice versa .

[0075] Thus, advantageously, said ophthalmic instrument can perform the function of corneal topographer when said screen (20) is placed in said transparent condition and be suitable for a Lipid Layer Thickness measurement when said screen (20) is placed in said opaque condition.

[0076] The refore, advantageously, it is an object of the invention to use a machinery in accordance with one or more of the preceding features, in order to enable at least one corneal topography and/or at least one analysis of Lipid Layer Thickness to be performed with the same machinery .

[0077] It is also a purpose of the present invention to provide a method for performing at least one corneal topography and/or a Lipid Layer Thickness analysis, the method comprising the following steps:

Providing a light-projecting device (100) so that a light pattern can be projected in use;

Arranging at least one screen (20) so as to intercept, in use, at least part of the pattern of light emitted by said light-projecting device, said screen being an electrically controllable screen capable of switching from a transparent to an opaque state and/or vice versa by means of an electrical control .

Brief description of the drawings

[ 0078 ] Further features and advantages of the present machinery, in accordance with the invention, will become clearer with the following description of certain embodiments , made by way of example and not limitation, with reference to the accompanying drawings , wherein : [ 0079 ] Figure 1A schematically shows a corneal topographer according to the prior art ;

[ 0080 ] Figure IB shows the concentric circles reflected in the eye and used precisely for corneal topography;

[ 0081 ] Figure 2 shows a corneal topographer of the prior art that allows images of the eye within which the concentric Placido discs are reflected to be obtained, which are then analysed using special software also to assess the Lipid Layer Thickness in addition, of course , to the corneal topography;

[ 0082 ] Figure 3 shows a further solution of the prior art in which the concentric circles of the Placido disc are interrupted, creating a small area 501 without circles to allow for correct detection of the Lipid Layer Thickness ;

[ 0083 ] Figure 4 and Figure 5 represent the solution in accordance with the invention of applying a screen that is controllable between the light-di f fusing and the transparent condition, e . g . using the well-known smart film technology;

[ 0084 ] Figure 6 is a diagram of the machinery;

[ 0085 ] Figures 7 and 8 are further diagrams of the machinery in which the same reference numbering has been retained for the parts the same as the prior art ; in particular, the screen 20 in accordance with the invention is highlighted according to its two functions , namely : Transparent in which it does not deflect rays and opaque (i.e. with a diffuser function) in which it deflects the rays creating uniform lighting;

[0086] Finally, Figure 9 shows an image of an eye as viewed in accordance with the machinery according to the invention .

Description of some preferred embodiments

[0087] It is an object of the present invention a machinery for allowing execution of at least a corneal topography and/or a Lipid Layer Thickness analysis to be carried out, said machinery comprising;

[0088] At 1 east one light-pro ecting device (100) adapted to project a pattern of light along a path;

[0089] And wherein a screen (20) is comprised, placed to intercept the path of at least a part of said light pattern emitted by said light-projecting device (100)

[0090] And wherein said screen (20) is electrically controllable in such a manner as to be selectively changeable from a transparent to an opaque state and/or vice versa.

[0091] Figures 6-8 show a solution in accordance with the invention. Parts the same as the prior art are numbered with the same numerical references.

[0092] The support frame ( 102 ’ , 60) is thus provided.

[0093] It consists of a base 60 from which the upright (102' ) rises .

[0094] The projecting device of the light 100 is fixed to the upright (102' ) .

[0095] This can, for example, as mentioned, be in the form of a conical body forming the Placido disc or in alternative forms, such as a flat backlit surface or a surface with a distribution of lights placed in front.

[0096] Even in the case of the conical body forming the Placido disc, there are light distributions 101, which are, however, placed to the rear of the disc and are therefore forced to pass through the concentric discs, which alternately allow the passage of light and its shielding, as already discussed in the prior art.

[0097] Also as described in the prior art is the camera 300 located to the rear of the light-projecting device 100 on axis with it. The device therefore has a hole on axis with the camera to enable the image of the eye 200 to be captured .

[0098] In accordance with the invention, a screen 20 is now provided which, as explained below, is electrically controllable so as to be able to switch from a transparent to a light-diffusing, hence opaque, state.

[0099] Figure 7 shows the rays of light projected by the light sources 101 and passing through the cone and indicated as rays 102. These are non-def lected rays because, as schematically shown in Figure 7, the screen 20 is controlled in such a way that it is in a transparent condition .

[00100] Figure 8, on the other hand, shows the condition in which the screen 20 is controlled to switch to a diffuser condition, i.e. opaque.

[00101] In the transparent condition of Figure 7, the screen is as if it were not there and the rings (in the case of the Placido disc) are projected into the eye exactly as shown in Figure IB;

[00102] In the case of Figure 8, the screen 20 is electrically switched to a diffuser, thus creating a homogeneous scattering of light, which results in a large area in the eye being homogeneously illuminated, i.e. in which concentric rings are no longer seen in the reflected eye and thus allowing a good measurement of the lipid layer . [00103] Figure 4 shows an enlarged detail of the Placido disc.

[00104] In accordance with the invention, as indicated in Figure 4, the screen 20 is now present, which is shown in an opaque condition in Figure 4.

[00105] In the image in Figure 4, the part of the concentric discs covered by the screen is somewhat masked by the screen, which is in an opaque condition and thus acts as a diffuser, as described above.

[00106] Figure 4 also shows a bar (30' ) that is part of the machinery and well known which serves as a support for the patient's forehead, which is placed in front of the Placido disc with an additional support 30 for the chin.

[00107] Figure 5 shows the condition in which the screen 20 is practically transparent.

[00108] Bas ically, when the patient has to perform an eye examination, he/she stands in front of the machinery resting his/her forehead on the bar 30' and his/her chin on the support 30, thus, in effect, having his/her eyes facing the backlit Placido disc.

[00109] When the Placido disc (or luminous device in general) is illuminated, the light pattern of the device is projected onto the eye, e.g. concentric circles as shown for example in Figure IB, and the camera captures the image and allows it to be viewed on the screen.

[00110] In accordance with the invention and as indicated above, the operator (e.g. the doctor) can now control the screen 20 by being able to switch it from an opaque condition (Figure 4 or Figure 8) to a transparent condition (Figure 5 or Figure 7) and vice versa.

[00111] In the opaque condition (see Figure 4 or 8) , the screen acts as a light diffuser, thus projecting uniform light into the eye.

[00112] In this condition, the operator (e.g. the physician) can accurately assess the Lipid Layer Thickness as there are no concentric discs in the eye but, on the contrary, a large homogeneously illuminated area. [00113] In the condition of the screen made transparent as in Figure 5 or 7, it is as though the screen were not present and therefore the image is, in fact, that of Figure IB because the rays are not deflected and therefore reflect exactly the pattern emerging from the lightprojecting device 100.

[00114] Thanks to this solution, the screen that is applied to the light-pro ecting device 100, e.g. a Placido disc, can also be a permanent screen, i.e. irremovably fixed .

[00115] By means of a control, such as a button, the operator can easily switch between the opaque screen condition and the transparent screen condition as required .

[00116] Of course, the removable screen solution is not ruled out.

[00117] For example, it could be applied in a removable manner with screws or magnets and thus left in place for as long as necessary and then, for example, be easily removed for maintenance, replacement or other reasons.

[00118] That said, in a preferred solution of the invention, the screen is made according to the technology known as Polymer Dispersed Liquid Crystal and known by the acronym PDLC or also as "smart film".

[00119] This technology is well known in itself and is, for example, widely used in the furniture industry where windows in homes are made of glass incorporating this technology so that it can become opaque or transparent depending on the needs of the homeowner and according to his/her times and preferences.

[00120] It is an electro-optical liquid crystal film. [00121] PDLC technology confines the liquid crystal molecules in micro-droplets that are in turn distributed in a polymer compound deposited between two surface- conductive polyester films. With the application of an electric field, the molecules change the optical properties of the film to incident light.

[00122] The application of the electric field arranges the molecules of the liquid crystal in an ordered arrangement. Light can thus pass through the film undisturbed (without light deflection by molecules) , showing the transparent film to our eyes. In this respect, the PDLC film acts as a filter capable of creating an electrically controllable mist .

[00123] By removing the electric field, the molecules of the liquid crystal return to a disordered/random state. The light will then be deflected (scattered) by the molecules over and over again, preventing our eyes from reconstructing images of objects beyond the film (translucent state) .

[00124] Then it is sufficient to apply such a film to a glass and apply electrical contacts to generate an electric field and control the opaque or transparent condition with a simple on/off switch.

[00125] Activating the electric field, i.e. setting the switch to "On", creates a transparent condition, while deactivating the electric field, i.e. setting the switch to "Off", creates an opaque or translucent condition such that the screen covers the image by partially blurring it. [00126] In a variant of the invention, the machinery could automatically control the transition of the screen from transparent to opaque depending on the examination to be performed, for example by entering the examination to be performed from the machinery' s control panel or otherwise selecting the machinery's operating mode. A manually activated control is therefore not necessary.

[00127] In a variant, said polymer film can be of the PNLC type where PNLC stands for "Polymer Network Liquid Crystal". These are the reverse of the previously described PDLCs and are also called reverse PDLCs .

[00128] More specifically, the PNLC is in a transparent state when there is no electrical excitation and becomes opaque when there is electrical excitation.

[00129] Figure 6 thus depicts a cone 100 representing the Placido disc and supported by a frame. The frame may comprise a vertical support 102' resting on a base 60, as is well known in the prior art.

[00130] As depicted in Figure 6, the screen 20 is thus placed in such a way as to cover at least part of the concentric discs. Therefore, screen is preferably circular, so that it can fit around the circular perimeter of the cone. As shown in Figure 6, the diameter of the screen 20 is such that it fits within the cone so that it covers a number of concentric discs.

[00131] This also applies in the case of a light-diffusing device that is not in the form of a cone but of a flat surface, with the screen still covering part of the lightdiffusing device 100, even placed at some distance from it .

[00132] It is clear that the diameter can be selected as desired, so that, for example, the screen 20 may have a diameter equal to or slightly smaller than the diameter of the largest base of the cone (in the case of the cone example) . Clearly, the greater the diameter of the screen, the greater the number of concentric discs that can be masked or generally made opaque.

[00133] Figure 6 thus depicts the switch 70 which is connected to the screen 20 in such a way that the electric field can be activated as well as deactivated thereby changing the conditions to opaque or transparent as required .

[00134] As mentioned, the switching can also be automatic.

[00135] In all the configurations, the screen 20 is of course perforated with a through-hole on axis with the camera to obviously allow the camera to take the image of the eye 200.

[00136] As mentioned, in a preferred solution of the invention, the screen 20 can be fixed irremovably.

[00137] Alternatively, it can still be removable and re- applicable, e.g. through the use of quick means such as magnets or snap-lock elements, screws and the like.

[00138] The machinery thus created is thus capable of performing at least corneal topography and the Lipid Layer Thickness assessment.

[00139] Obviously, the same machinery can be further equipped to be able to perform at least one or more of the further operations in addition to the above:

[00140] Pupillography ;

[00141 ] Meibomian gland analysis;

[00142] Tear meniscus;

[00143] Tear break up time;

[00144] Bloodshot eyes;

[00145] Fluo rescein/ staining;

Claims

1 . A machinery for allowing execution of at least a corneal topography and/or a Lipid Layer Thickness analysis to be carried out , said machinery comprising :

At least one light-proj ecting device ( 100 ) adapted to proj ect a pattern of light along a path;

And wherein a screen ( 20 ) is comprised, placed to intercept the path of at least a part of said light pattern emitted by said light-proj ecting device ( 100 ) ;

Characterised in that said screen ( 20 ) is electrically controllable in such a manner as to be selectively changeable from a transparent to an opaque state and/or vice versa, and wherein said screen ( 20 ) comprises at least one layer of transparent material coated with an electrically switchable film in such a manner as to permit , by means of electrical excitation, the transition from a transparent to an opaque state and/or vice versa .

2 . The machinery, according to claim 1 , wherein said film is polymeric of the PDLC or PNLC type .

3. The machinery according to one or more of the preceding claims , wherein a controller is comprised, configured to automatically control said screen by controlling its transition from the opaque state to the transparent state and/or vice versa or, alternatively or in combination with the controller, a manual switch ( 70 ) is included .

4 . The machinery, according to one or more of the preceding claims, wherein said screen (20) is irremovably fixed; preferably irremovably fixed to said light-projecting device (100) .

5. The machinery according to one or more of the preceding claims 1 to 3, wherein said screen (20) is movably fixed; preferably movably fixed to said light-projecting device (100) .

6. The machinery according to one or more of the preceding claims, wherein said light-projecting device (100) is a Placido disc comprising a plurality of backlit concentric discs or a surface having a plurality of light sources arranged according to a certain pattern.

7. The machinery, according to one or more of the preceding claims, comprising a camera (300) arranged rearwardly with respect to the light-pro ecting device (100) in such a manner that said device (100) is comprised between the camera and said screen, preferably said device (100) and the screen having a hole on axis with the camera.

8. The machinery, according to one or more of the preceding claims, said machinery comprising;

A support frame (50, 60) ;

And wherein said light-projecting device (100) is fixed to at least a part of said frame ( 102 ’ , 60) in such a manner that it can project said predetermined light pattern.

9. The use, in an ophthalmic instrument comprising at least one light-projecting device (100) projecting a light pattern in use, of a screen (20) positioned so as to intercept the path of at least a part of said light pattern emitted by said light-projecting device (100) , and said screen (20) being electrically controllable to switch from an opaque condition, in which it acts as a diffuser of the light emitted by said light-pro ecting device (100) and passing through it to a transparent condition, in which it allows, without deflection, the passage of said light emitted by said light-projecting device (100) passing through it and/or vice versa, and wherein said screen (20) comprises at least one layer of transparent material coated with an electrically switchable film so as to allow, by means of electrical excitation, the transition from a transparent state to an opaque state and/or vice versa.

10. The use, according to claim 9, wherein said film is polymeric of the PDLC or PNLC type.

11. The use of a machinery in accordance with one or more of the preceding claims 1 to 8 to enable at least one corneal topography and/or at least one Lipid Layer Thickness analysis to be performed with the same machinery .

12. A method for making a machinery adapted to perform at least a corneal topography and/or a Lipid Layer Thickness analysis, the method comprising the following steps:

Providing a light-projecting device (100) so that a light pattern can be projected in use; Providing at least one screen ( 20 ) so as to intercept , in use , at least part of the pattern of light emitted by said light-proj ecting device , said screen being an electrically controllable screen capable of switching from a transparent state to an opaque state and/or vice versa by means of an electrical control , and wherein said screen ( 20 ) comprises at least one layer of transparent material coated with an electrically switchable film so as to allow, by means of electrical excitation, the transition from a transparent state to an opaque state and/or vice versa .

13. The method, according to claim 12 , wherein said film is polymeric of the PDLC or PNLC type .