Abstract:
A multilayer electrode sensor assembly for electroretinography and pattern electroretinography formed as a thin strip to fit under a lower eyelid and contain an electrode in line with the pupil of an eye with signals detected carried through an integrally formed thin conductive strip to a terminal to be connected to an electrical conductor for carrying such signals to an analyzer.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an electrode sensor assembly for electroretinography and pattern electroretinography. 
     Determining the functioning of the retina is significant in diagnosing, assessing and monitoring the progression of dysfunction due to disease or trauma. Electroretinography (ERG) and Pattern Electroretinography (pERG) are systems which use different visual stimuli including patterns to stimulate the eye and causes the retina to generate responses, and resulting signals are analyzed. An analysis of signal amplitude and latency leads to monitoring and diagnosis of retinal health. 
     Microelectrical signals are generated in the retina during ERG and pERG testing and are analyzed by standard diagnostic equipment and techniques. pERG vision testing is a well established technology with a broad foundation of scientific support. This invention permits significantly improved test administration. 
     A significant aspect of such systems is the ability to detect the electrical signals generated in the retina for analysis. A variety of approaches have been tried to locate electrodes close enough to the retina which allow for detection of electrical signals without materially interfering with the test itself. These prior art systems generally are clumsy and cumbersome and detract from patient comfort and cooperation. 
     There are contact lens electrode systems which require placing a contact lens on the eye and suitable electrodes within or attached thereto which then are attached to leads carrying electrical signals from the retina. There are other systems in which individual circular electrodes are adhesively attached around the eye, close to the eyelid, with leads hanging therefrom. The individual electrode placements around the eye is unwieldy, somewhat inefficient and not very secure. Additionally, some of these prior art systems are sensitive to eye movement, thereby creating noise which interferes with the accuracy of the pERG or ERG test. The plurality of leads dangling from the eye interferes with appropriate utilization of these electrodes for reliable collection of data during a pERG or ERG procedure or otherwise interferes with patient comfort sufficient so that the retinal analysis becomes impaired. 
     An object of this invention is to provide an improved electrode sensor assembly for ERG, pERG and other retina exam procedures in order to monitor the biopotential on tissue. 
     Another object of this invention is to provide such an electrode sensor assembly which is easy to place on the patient, located close enough to receive electrical signals and easy to remove after a test is complete. 
     Another object of this invention is to provide such an assembly which minimizes interference with the testing, minimizes discomfort of the patient and reduces undesirable noise. 
     Yet another object of this invention is to provide such an assembly which does not directly touch the eye but is capable of suitably receiving electrical signals and thereby minimizes discomfort of the patient as well as interference with the efficacy of the test. 
     Yet another object of this invention is to provide such an assembly which is disposable to reduce the possibility of contamination and cross-contamination, is easily placed and located where desired and easily and quickly removable after a test is complete. 
     Another object of this invention is to improve the collection of data during a pERG or ERG procedure utilizing standard equipment to analyze the collected data so that the present invention can be used by personnel already trained in the field. 
     Still another object of this invention is to facilitate greater widespread use of pERG or ERG vision testing. 
     Other objects, advantages and features of this invention will become more apparent from the following description. 
     SUMMARY OF THE INVENTION 
     In accordance with the principles of this invention, the above objects and features are provided for an electrode sensor which has a multilayer assembly. The multilayer assembly has an adhesive backed electrode and thin conductor strip shaped and sized to fit on the skin below the lower eyelid, tucked under the lower eyelashes, to be easily attached and removed. 
     An electrode is formed within the strip and located below the eye. A conductor is integrally formed within the strip and connects to the electrode to carry electrical signals generated in the retina to a miniature connector or terminal. The conductive strip of this invention is suitable for ERG and pERG, as well as other electroretinographic procedures which generate electrical pulses and signals within the retina responsive to triggering events. 
     The conductive strip, preferably, is disposable, further ensuring cleanliness and minimizing potential cross contamination and infection. Many prior art electrodes are used and reused, which is undesirable. 
     The electrode sensor assembly serves as a lid sensor and works cooperatively with reference sensors placed on the patient&#39;s face to collect electrical signal information for processing and diagnostic analysis. The shape of the lid sensors are narrow, elongated, easily placed on the skin below the lower eyelid, tucked under the lower eye lashes conforming to the skin below the lower eyelid and comprise an electrode surrounded by adhesive material to attach the lid sensor to the skin. 
     The conductive strip may have a thin middle section, a micro-connector on one end and an encapsulated electrode contained therein which detects and senses signals from the retina. 
     The lid sensor is formed of a plurality of layers comprising a bottom plastic or white vinyl layer covered with a conductive material forming the electrode. An insulating layer covers the electrode and an adhesive layer is formed on either side of the electrode with a removable medical tape liner covering the adhesive layer. 
     In use, the medical tape liner is removed from the adhesive layer, and the conductive strip is positioned on the skin below the lower eyelid. The strip has a visible indication to locate the electrode in line with the pupil. The conductive strip or sensor is placed close to the eyelid margin below the eyelashes so that the electrical signals collected in the retina are collected by the sensor. 
     It will be understood that the data collected is analyzed in the standard manner, but the collection of such data as well as patient comfort and cooperation is improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front plan view of a face showing placement of the lid sensors of this invention as well as reference sensors used in pERG. 
         FIG. 2  is a front plan view of the left eye of a patient with the lid sensor of this invention in place. 
         FIGS. 3   a - 3   g  are top perspective views of the lid sensor of this invention showing the multilayer formation of the lid sensor assembly. 
         FIG. 4  is an exploded sectional view showing the layers of the lid sensor. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  is a front plan view of the front of a face  10  showing sensors  12  and  14 , which are the sensors used for pERG or ERG set up and testing. The present invention is directed to the right and left lower lid sensors  12  and  14 , respectively, which are elongated and thin, placed on the skin (no number) on the lower eyelid  16 , with lower eyelashes  17  covering the sensors to pick up retinal signals. The signals from the lid sensors  12  and  14  are utilized in conjunction with signals in OD Reference, Ground and OS Reference sensors,  20 ,  22  and  24 , respectively, with sensors  20  and either side of the temple and sensor  22  located centrally above the eyebrows. 
     With suitable pERG testing, signals are generated at the lid sensors  12  and  14 . Reference sensors are placed in an area that is distant from any response generated by the retina. The references serve as controls for the pERG test. The generated signals from the procedure are carried on conductors  26  for OD lid sensor  12 ,  28  for OD reference sensor  20 ,  30  for ground sensor  22 ,  31  for OS reference sensor  24 , and  32  for OS lid sensor  14 . Conductors  26 - 32  are connected to suitable terminals in analyzing equipment. A visible indication of where the electrode on the lid sensor  14  is located may be designated, for instance, with a dot  33  to assist to properly locate the electrode in line and below the pupil of the eye. 
       FIG. 2  is a close up front plan view of the left eye  34  of a patient, showing the lid sensor  14  placed on the skin just below the lower eyelid  35  and tucked under lower eyelashes  17 . The lid sensor  14  comprises an embedded electrode (see  FIG. 3 ) connected to an embedded electrical conductor with the conductor carried through to a micro-connector  38  at the end of lid sensor  14 . 
     The lid sensor comprises a first section  40  having the electrode and a portion of the conductor (see  FIGS. 3   a - 3   g ) as a second section  42  and an intermediate section  44 . The sensors  12  and  14  are elongated and thin and are sized and shaped to extend from the inner corner  46  of the eye to the outer corner  48  edge of the eye as shown. 
     The lid sensor  14  is attached to the skin below the eyelid with an adhesive material revealed when a tape liner is removed from covering the adhesive layer. The lid sensor  14  is placed as indicated in  FIG. 2  with the electrode directly below and in line with the pupil and signals are generated and carried through to the conductor  38 . An indication of where the electrode in the lid sensor  14  is located may be designated, for instance, where the dot  33  is located to assist in properly locating the electrode in line and below the pupil of the eye. 
       FIGS. 3   a - 3   g  shows a lid sensor ( 12  or  14 ) which comprises a vinyl or other plastic soft thin base layer  50  having an enlarged left or first section  40 , a thinner middle section or intermediate section  44  and a right or second section  42 . The silhouette of the lid sensor is shown in  FIG. 3   a  and the plastic or vinyl layer forms the base layer  50 . 
       FIG. 3   b  shows the application and formation of the electrodes and conductors within the lid sensor  12  or  14 . A conductor material such as silver ink is used to form electrode  52  located in section  40 , being substantially square in shape and connected to a conductor  54  extending from electrode  52  through the intermediate section  44  to the right or second section  42 . The conductor  54  is formed of a thin extended length of conductive material which connects to a terminal  56  in the right section  42 . 
     The location of electrode  52  is designated on the visible side of the lid sensors  12  and  14  so as to locate the electrode  52  directly in line with the pupil of the eye. The larger the electrode  52  the more signal it can pick up and carry through conductor  54  to terminal  56 . 
       FIG. 3   c  shows the application of a conductive gel  58  substantially square in shape and slightly larger than electrode  52  which further assists the carrying of electrical signals from electrode  52  to conductor  54 . 
       FIG. 3   d  is a view of the silhouette of the lid sensors similar to  FIGS. 3   a - 3   c , in which an insulating dielectric layer  60  is placed on top of the prior layers deposited on base layer  50  ( FIG. 3   a ). This insulating or dielectric layer may be formed of a blue dielectric ink and prevents stray noise from being picked up in the conductor  54 . The dielectric layer is shown on top of conductor  54  but it could also be deposited on top of electrode  52 . 
       FIG. 3   e  shows the application and location of adhesive material  62  on either side of electrode  52  in first section  40 . The adhesive material enables the electrode to remain in place with the adhesive material securing the lid sensor of this invention to the skin just below the lower eyelid. 
     It is intended that only the left end  40  be attached to the skin with the balance of the lid sensor near but not being attached to the skin because additional adhesive material may be difficult to remove. On the other hand, it is within the ordinary skill of one in the art to select the type of adhesive material so that greater adhesion could be obtained with lesser material and the electrode size could be larger and adhesive material could be carried in the middle section  44 , if desired. Terminal or connector  56  may be a microconnector and may comprise female contacts Nicomatic 14106-12. 
       FIG. 3   f  shows the placement of a tape liner  64  on top of the left section  40  of the lid sensor which, when removed, exposes the adhesive material  62  to enable the lid sensor to be attached to the skin under the lower lid as shown in  FIGS. 1 and 2 . 
       FIG. 3   g  shows a contact  66  connected to connector  54  which carries the electrical signals picked up by electrode  52  to electrical wires  26  and  32 . 
     Adhesive material  62  surrounds electrode  52 . 
     The height of sections  40  and  42  is greater than the height of section  44 . Electrode  52  is substantially equal in height to first section  40 . 
       FIG. 4  is an exploded sectional view through the lid sensor showing the multilayer assembly to form the skin sensor. The first base layer  50  is the polyester or plastic layer upon which is then deposited the electrode material  52  of a silver ink which is then covered by a conductive gel of silver chloride. The electrode material forms electrode  52  and conductor  54 . Any suitable conductive material may be utilized. Thereafter, an insulating or dielectric material  60  is deposited on top of the lower layers and an adhesive layer  62  is then placed on the dielectric layer, which is then (with the electrode  52 ) covered by a removable medical tape  64 . 
     It should be understood that the preferred embodiment was described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly legally and equitably entitled.