MX2012009385A - Device for ophthalmic diagnostic. - Google Patents

Abstract

The present invention refers to an ophthalmic diagnostic device, of the type that allows visual fields to be evaluated in an objective manner in the macular area of subjects to be studied, which comprises a perimeter structure from which a chromatic luminous stimulus is provided, the position, color and luminescence being programmable, the stimulus being provided by a plurality of LEDs, and a back illumination programmed in luminance and provided by a white luminous source; a circuitry for supplying the back and chromatic luminous stimuli; a video camera for acquiring images at a minimum speed of thirty squares per second; a system for converting analogic images into digital images; a user interface for programming the color, luminance, position and duration of the stimuli; a first block that enables the automatic processing of images for obtaining the pupillary area per square; a second block enables the automatic obtention of the positioning of the pupil centroid for determining los s of fixation of focal point, both the first and second blocks being operated by a PC; the third block is intended to display the results of the evaluation of the obtained images, qualifying as positive or negative in case of being seen or not by the subject under study; and an ophthalmologic support for the initial fixation of position of the studied subject.

Description

Device for ophthalmic diagnosis TECHNICAL FIELD OF THE INVENTION The present invention relates generally to the field of video-acquisition, and in particular refers to a device that allows to evaluate in an objective and quantitative way the visual fields in the macular area.

BACKGROUND OF THE INVENTION The evaluation of visual fields is a widely used resource in ophthalmology and neurology, both as a focal diagnostic method or as a method of monitoring eye diseases or visual pathways. The standard visual field perimetry is the clinical tool used to evaluate the visual fields, despite the inherent limitations of this method. Among these limitations are the subjectivity of the patient's responses, the patient's learning effect, the inability of some patients to maintain central fixation during the evaluation time, etc.

Objective perimetry is in great demand; since it eliminates the possibility of cheating during the test and allows evaluating patients who have difficulties cooperating in conventional perimetry.

The pupil plays two important roles in their normal working conditions: it controls the retinal illumination and determines the quality of the retinal image. The size of the pupil decreases with age and certain levels of luminance. The diameter of the pupil can vary between 2 mm and 8 mm depending on the level of luminance. This reaction is known as the pupillary reflex to light.

The pupiloperimetry (PLP) represents an objective method to evaluate the visual fields by examining the pupillary response to a focal light stimulus projected on the retina. Defects in the visual field determined by means of PLP are recognized by the absence or diminution of the pupillary response to light in said areas. In PLP, the amplitude of the pupillary reflex to light due to a small luminous stimulus is measured thanks to the acquisition of images of the pupil by means of a video camera, and then a computerized analysis to obtain the parameters to be evaluated. Since the central visual field (30 °) in man possesses a high motor ward sensitivity it does not represent problems to be quantified by PLP.

The threshold chromatic perimetry is the determination of the differential threshold along the retina by means of color stimuli, that is, it allows the study of the central and peripheral chromatic vision of the visual field by means of colored stimuli on a base luminance of different color.

The chromatic perimetry has interesting clinical applications, since it is possible to evaluate the variations in chromatic thresholds that produce some pathologies such as macular degeneration or optic nerve affections. This makes the chromatic perimetry more sensitive than conventional for the diagnosis and detection of certain ocular conditions.

From the revealed results of a conducted search to know the current proposals that exist in the state of the art to evaluate visual fields from the chromatic perimetry, the following are presented for a better understanding of the technical field to which the present invention belongs: The patent US5805271 granted on September 8, 1998, for the invention entitled "Transparent selective wavelength occluder, refractively corrected for an unproven eye for visual field tests", where Alan R. Kirschbaum and Christopher L. Petersen, disclosed an apparatus for visual tests that uses a stimulus that produces light in a first spectral range of color and a backlight that produces light in a second spectral range of color; the visual field test occluder comprises: (a) one base; (b) a fastener configured to hold the base over the eyes of the subject; (c) a mounting glued to the base configured to contain a filter and a refractive lens; and (d) a filter fastened in the assembly; wherein the filter substantially prevents the transmission of light in the first spectral range of color and substantially transmits light in the second spectral range of color.

On the other hand, in patent application US2006 / 0189886 by Warren Jones and Ami Klin., Protection is sought for a system for quantifying and assigning visual salience to a visual stimulus, which includes a processor, software to receive data indicative of a group of eye responses of the individual to a visual stimulus, software to determine a distribution of visual resources in each of at least two times for each of at least a portion of the individuals. The system also includes a software to determine and quantify a distribution of the group of visual resources in each one of at least two times and the software to generate a distribution screen of the group of visual resources to visual stimulation.

Another document is the patent EP1790281 of Hideo Fukunaga et al., Where the invention entitled "Diopsimetro" was disclosed, wherein the perimeter comprises a screen device, infrared light-emitting diodes, a CCD camera, a medium mirror , an image processing device, a computer, and an operating switch.

Finally the international patent application PCT / IL / 2010/000624 published on February 10, 2011 under the number WO2011 / 016029, where Rotenstreich Ygal, discloses a system, a device and a method for objective visual field test, and in particular, a system of this type and method in which an objective test of chromatic perimetry or color vision test is provided using a pupillometer. By virtue of the current teachings of the state of the art, the purpose of the invention which, as a device for ophthalmic diagnosis, is presented in this patent application, is to provide a completely new and innovative device in the field of perimetry. chromatic, with which the following are intended: Objectives of the invention.

An objective of the present invention is to provide an ophthalmic diagnostic device.

Another objective of the present invention is to provide a device for ophthalmic diagnosis, which allows the evaluation of the visual field in chromatic form.

Another objective of the present invention is to provide an ophthalmic diagnostic device, which allows the visual field to be examined at a wide variety of luminances in the stimuli.

Another objective of the present invention is to provide a device for ophthalmic diagnosis, which allows the objective fields to be evaluated objectively and quantitatively.

Another objective of the present invention is to provide a device for ophthalmic diagnosis, which allows the evaluation of the macular area of a subject under study.

Another objective of the present invention is to provide a device for ophthalmic diagnosis, wherein the pupillary response of a subject under study is quantified by means of a computerized analysis.

Still another object of the present invention is to provide a diagnostic device ophthalmic, where the perimeter is automated to obtain images, generate stimuli, detect loss of fixation and analyze the images obtained by generating an evaluation of the stimulus, qualifying it as positive or negative depending on the computerized analysis of the images obtained from the pupil.

The objects of the present invention referred to above and even others not mentioned, will be evident from the description of the invention and the figures that illustrate and not restrictive accompany it, and that are presented below.

Brief description of the figures.

Figure 1. A block diagram is shown from which an ophthalmic diagnostic device, made in accordance with the present invention, is illustrated. Figure 2. A schematic representation of the elements that make up the device of Figure 1 is shown.

Figure 3. A front elevational view of a perimeter structure that is an integral part of the device of Figure 1 is shown.

Figure 4. A detailed view of section "A" of figure 3 is shown.

Figure 5. A front elevation view of a light emitting diode (LED) is shown, which is implemented in the perimeter structure that is an integral part of the device of Figure 1.

Figure 6. A view in right lateral elevation of a light-emitting diode is shown (LED) with its respective light guide, which is implemented in the perimeter structure that is an integral part of the device of Figure 1.

Detailed description of the invention.

According to what is illustrated in FIGS. 1 to 6, the present invention consists of an ophthalmic diagnostic device 100, hereinafter referred to as device 100, which allows to evaluate the macular area of a subject in study 99 and which is comprised of : a perimeter structure 10 from which a chromatic light stimulus 1 1 programmable in position, color and luminance is provided, provided by a plurality of LEDs 21, and a backlight 12 programmable in luminance, provided by a light source white 13; circuitry 30 suitable for feeding the chromatic light stimuli 1 1 and background 12; a camcorder 50 capable of acquiring images at a minimum speed of thirty frames per second; a system for converting images from analog to digital; a user interface 70 operated through a PC 80 that allows to program the color, luminance, position, duration of the stimuli and presentation of results; a first block 81 that allows automatic processing of images to obtain the pupillary area per frame; a second block 82 that allows to automatically obtain the positioning of the centroid of the pupil to determine loss of central point fixation, a third block 83 that evaluated the pupillary changes; said first 81, second 82 and third 83 blocks operated through a PC 80; and an ophthalmological support 90 that helps the initial fixation of the position of the subject under study 99. The structure of the perimeter 10 is integrated from a hemispherical hollow body of expanded polystyrene of 58 cm in diameter, in whose central part and in accordance with As illustrated in Figures 3 and 4, a plurality of holes 14 have been made in a pattern of four concentric circles (15, 16, 17, and 18) wherein the internal circumference 15 is 3.8 cm in diameter and the circumference external 18 of 15.2 cm in diameter, while at the center of the circumferences was placed a central hole 19, each of these holes 14 serving to house, inside the perimeter structure 10, a plurality of emitting diode guides 20 light (LEDs) 21, through which chromatic light stimuli 11 are provided in the device 100.

In the same structure of the perimeter 10 and above the plurality of holes 14, an orifice (not shown) has been configured which allows the lens 51 of the chamber 50 to be partially disposed towards the interior of said structure 10.

In the device 100, given the characteristics required for the chromatic light stimulus 11, it was decided to use three-color light emitting diodes Red-Green-Blue (RGB LEDs) 21. Thus, with a minimum of 56 LEDs 21, the central 30 ° of the field is covered. visual in man. In order to decrease the opening angle of the LEDs 21, a light guide 20 was implemented. Said guide 20 is defined from a clear acrylic tube of 0.5 cm in diameter, adhered to the LED 21 by means of glue with base acrylic, as shown in figure 6.

The LEDs 21 and their respective light guides 20 are placed in the perimeter structure 10 according to the pattern of the four concentric hole circumferences described above.

In the device 100, to achieve the backlight 12, an LED was selected white 13 of 3 W with 120 ° of opening, which requires a regulated power source as a power supply.

The video camera 50 used to acquire images of the pupil, has an optical zoom of at least 40X and composite video output with minimum sampling of thirty frames per second, as well as the function for taking pictures in night mode.

In turn, the analog to digital image converter system consists of an external video acquisition card with minimum output image resolution of 320 x 240 pixels at a minimum speed of 30 frames per second.

In relation to the circuitry 30 of the device 100, which is implemented to feed and control the chromatic light stimuli 11 and background 12, a printed circuit is designed, by means of which the instructions that light the light stimulus to be evaluated with the user-defined characteristics through the user interface 70, as well as the circuitry implemented as power supply to all circuits.

The luminance control of the LEDs 21 is implemented by means of a microcontroller, where the firmware is responsible for communicating a personal computer 80 via the USB protocol with the luminance control circuit of the stimuli.

It is important to note that in the device 100, the luminance control of the four LEDs 21 (red 12, green 12, blue 12, white 13) can be selected from 0 to 254 levels, corresponding to a percentage of the working cycle of a square signal with an approximate frequency of 1 KHz, where 0 corresponds to 0% of the work cycle and 254 to 100% of the work cycle. The controls were designed to light one stimulus at a time, allowing to select the tonality, luminance and desired position as well as the stimulation time.

Finally, the first block 81 that allows the automatic processing of images to obtain the pupillary area per frame and the second block 82 that allows to automatically obtain the positioning of the centroid of the pupil to determine loss of fixation of central point, both operated through the PC 80, acquire the corresponding information through a USB port in which the image digitizer card 60 is connected, in such a way that both blocks convert the images to gray levels, equalize them and based on the level introduced by the user binarizes them to leave them blank or black, where the black area represents the pupillary area per frame. In the user interface 70, a graph is presented showing the change in the pupillary area with time. From these data the software assesses whether the stimulus was seen or not by the subject of study 99. Quantifying the response based on the percentage of pupillary contraction Thus, from the configuration described above of the device for ophthalmic diagnosis, it is possible to determine that all the objectives of the invention originally defined and still others not specified are met, obtaining an invention completely different from those hitherto known in the field of devices that allow to evaluate in an objective and quantitative way the visual fields in the macular area.

Claims (11)

Claims

1. 1.A device for ophthalmic diagnosis, of the type that allows to evaluate in an objective and quantitative way the visual fields in the macular area, which is characterized in that it is comprised of a perimeter structure from which a light stimulus is provided chromatic programmable in position, color and luminance, provided by a plurality of LEDs, and a programmable luminance backlight, provided by a white light source; a circuitry to feed the chromatic and background light stimuli; a video camera capable of acquiring images at a minimum speed of thirty frames or per second; an analog to digital image converter system; a user interface that allows to program the color, luminance, position and duration of the stimuli; a first block that allows the automatic processing of images to obtain the pupillary area by frame; a second block that allows the positioning of the centroid of the pupil to be automatically obtained to determine 5 loss of fixation of central point, both first and second blocks operated through a PC; a third block that allows the visualization of the assessment obtained through the analysis of images, advising whether the stimulus was or was not seen by the subject under study; and an ophthalmological support that helps the initial fixation of the subject's position in the study.

2. The device for ophthalmic diagnosis, as claimed in claim 1, characterized in that the perimeter structure is integrated from a hollow hemispherical body, in whose central part a plurality of holes have been made in a pattern of four concentric circles, where a central hole is placed at the center of the circumferences.

3. The device for ophthalmic diagnosis, as claimed in claim 2, characterized in that the hollow hemispherical body is constructed of expanded polystyrene and is 58 cm in diameter.

4. The device for ophthalmic diagnosis, as claimed in claim 2, characterized in that the internal circumference is 3.8 cm in diameter, and the outer circumference is 15.2 cm in diameter.

5. The device for ophthalmic diagnosis, as claimed in claim 2, characterized in that, above the plurality of holes, an orifice has been configured which allows the camera lens to be partially disposed towards the inside of the perimeter structure.

6. The device for ophthalmic diagnosis, as claimed in claim 1, characterized in that the light-emitting diodes (LEDs) used to generate the chromatic light stimulus are three-color LEDs Red-Green-Blue (RGB) of high efficiency controllable in luminance by means of pulse width modulation (PWM).

7. The device for ophthalmic diagnosis, as claimed in claim 6, characterized in that the LEDs are incorporated in the perimeter structure according to the pattern of the four concentric circles of holes by means of a light guide that is defined from a transparent acrylic tube of 0.5 cm in diameter.

8. The device for ophthalmic diagnosis, as claimed in claim 1, which is characterized in that to achieve background illumination, a 3W white LED with 120 ° opening was selected, which requires a regulated source as a power supply. current.

9. The device for ophthalmic diagnosis, as claimed in claim 1, characterized in that the video camera used to acquire images of the pupil, has an optical zoom of at least 40X and composite video output with minimum sampling of thirty frames per second.

10. The ophthalmic diagnostic device, as claimed in claim 1, characterized in that the analog to digital image converter system consists of an external video acquisition card, with minimum output image resolution of 320 x 240 pixels at a minimum speed of 30 frames per second.

11. The device for ophthalmic diagnosis, as claimed in claim 1, characterized in that in the circuitry that is implemented to feed and control the chromatic light stimuli for luminance control for the LEDs, a printed circuit is implemented, which by means of a microcontroller it executes the instructions that light up the luminous stimulus to be evaluated, with the characteristics previously defined by the user.