Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
  • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
  • A61B3/12—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for looking at the eye fundus, e.g. ophthalmoscopes
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
  • A61B3/0008—Apparatus for testing the eyes; Instruments for examining the eyes provided with illuminating means
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
  • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
  • A61B3/12—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for looking at the eye fundus, e.g. ophthalmoscopes
  • A61B3/125—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for looking at the eye fundus, e.g. ophthalmoscopes with contact lenses
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
  • A61B5/316—Modalities, i.e. specific diagnostic methods
  • A61B5/398—Electrooculography [EOG], e.g. detecting nystagmus; Electroretinography [ERG]
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
  • A61B90/36—Image-producing devices or illumination devices not otherwise provided for
  • A61B2090/364—Correlation of different images or relation of image positions in respect to the body
  • A61B2090/366—Correlation of different images or relation of image positions in respect to the body using projection of images directly onto the body

Definitions

• the invention relates generally to ophthalmic instruments, and more particularly to a retinal-projection system and method for projecting an image onto a selected 5 area of the retina, which can be significantly anterior to the posterior retina.
• the invention relates to such a system and method used as a pattern electroretinogra (PERG) projector capable of projecting ERG patterns that can be segmented to probe 0 selected areas of the retina (posterior, medial and/or anterior out to the far periphery) for evaluating retinal degeneration caused by glaucoma and other diseases.
• PEG pattern electroretinogra
• ERG electroretinogram
• the specific problem to which the invention can be applied is a pattern electroretinogram (PERG) system capable of assessing the function of the retinal ganglion cell layer and nerve fiber layer, and evaluating retinal degeneration, significantly anterior to the posterior retina, such as for glaucoma diagnosis and management.
• the test should have the following features: (1) Sensitivity and specificity; (2) Reproducibility; (3) Ease of use in very young, elderly and disabled patients; (4) Brevity of performance; (5) Easy interpretation; (6) Minimal requirement for patient response and/or attention; (7) Reliability in spite of ocular media opacities; and (8) Freedom from refractive correction.
• IOP Elevated Intraocular Pressure
• Pattern ERG has significant advantages over these current approaches to diagnosing and evaluating retinal degeneration from glaucoma.
• the patient views a pattern image (such as light and dark squares shown on a CRT) , and the retina is stimulated by alternating the pattern (such as by light/dark pattern reversal) , generating an ERG amplitude response.
• Many studies have confirmed that the PERG amplitude is significantly reduced in patients with glaucoma (References 3-7,13).
• PERG is particularly advantageous because research indicates that the PERG response signal is generated only by the proximal (inner) layers, which are precisely the layers selectively damaged by glaucoma.
• PERG has great potential for diagnosing and monitoring retinal degeneration caused by glaucoma (References 3-7,13,14) .
• Brevity i.e., one pattern alternation generates a corresponding PERG response
• Specificity i.e., PERG response is generated by the ganglion cells (the retinal component damaged in glaucoma) .
• the current technique for performing PERG measurements based on viewing a CRT pattern has at least two important limitations: (1) It requires an accurate refractive correction to obtain sharp pattern contrast; and
• the entire retina can be stimulated by a flash ERG
• FERG flash ERG
• a flash of light generates a dynamic ERG amplitude response caused by the stimulation of both the distal (photoreceptor) and proximal (ganglion) layers of the retina in all retinal regions (posterior, middle and anterior) .
• This mass retinal response is of no advantage in monitoring glaucomatous retinal degeneration, which selectively affects only the nerve fibers and their parent ganglion cells.
• the invention is a retinal-projection system and method for projecting an image onto a selected area of the retina with a field-of-view that can be significantly anterior to the posterior retina.
• the system can be used to project an ERG pattern for evaluating degeneration in any area of the retina (posterior, medial and/or anterior out to the far periphery) .
• the retinal-projection system includes a light source, at least partially coherent, for generating a projection beam.
• Modulation optics modulates the projection beam with a desired image
• wide-angle imaging optics adjacent the eye focuses the modulated projection beam, such that the projection beam passes through the pupil and diverges to provide a field- of-view significantly anterior to the posterior retina.
• the field-of-view can be adjusted to include the anterior retina out to the far periphery.
• the retinal- projection system is used as a pattern ERG (PERG) projector for evaluating retinal degeneration caused by glaucoma or other disease.
• the PERG projector includes imaging optics to project an ERG pattern into any selected area of the retina — posterior, medial and/or anterior out to the far periphery.
• an exemplary PERG projector includes imaging optics that provide wide-angle projection of an alternating, selectively segmented ERG interference pattern, enabling the entire retina (posterior, medial and/or anterior out to the far periphery) to be probed.
• Interferometry modulation optics modulates the projection beam with an ERG interference pattern characterized by a selected fringe line spacing, and selectively alternates the interference pattern to create the ERG pattern shift that stimulates an ERG response. Segmentation optics allows the ERG pattern to be selectively segmented for stimulating a selected area of the retina.
• the interferometry optics comprises a shearing interferometer.
• a pair of prisms are separated by a gap defined by opposing non-parallel surfaces that define a shearing angle.
• One of the prisms is pivotally mounted for selectively changing the shearing angle to provide precision angle tuning of the interference pattern.
• the incident projection beam partially reflects from one opposing prism surface, and after transiting the prism gap, partially reflects from the opposing prism surface.
• the two reflected projection beams interferometrically combine to form an interference pattern.
• the prism gap is filled with a Kerr fluid and the opposing prism surfaces are coated with transparent conductive electrode layers, such that an adjustable time-varying electric field can be used to change the refractive index in the prism gap, and alternate (reverse) the interference pattern.
• the interferometry optics includes a piano convex lens and a reflective optical flat.
• the lens is coated antireflective on a flat side so that it partially reflects and partially transmits the incident projection beam.
• the reflective optical flat reflects the transmitted portion of the incident projection beam back through the piano convex lens, thereby creating an interference pattern with the two reflected projection beams.
• the optical flat can be selectively translated to shift the interference pattern.
• the wide-an:le imaging optics can be formed by an aspheric parabolic lens, followed by a positive meniscus lens.
• the lenses are configured to allow the projection beam to be brought to a sufficiently sharp focus in the area of the eye lens to transmit through even a constricted pupil, and then diverge to fill substantially the entire field-of-view of the retina (posterior and anterior out to the far periphery) .
• the retinal-projection system can be used to project video or printed information directly into the eye.
• the modulation optics can be formed by a LCD video panel.
• the technical advantages of the invention include the following.
• the retinal-projection system can be used to project selected images, including video, text and other information, onto the retina with a field-of-view significantly anterior to the posterior retina.
• Laser light can be used for projection to bypass potential ocular media opacities, and to obviate the need for any refractive correction.
• an ERG pattern (such as an alternating interference pattern) can be projected into any selected area of the retina — posterior, medial and/or anterior out to the far periphery — providing the ability to test the retinal elements damaged by glaucoma in the areas where they are most likely to be affected first (i.e., the ganglion cells in the anterior retina and especially in the periphery) .
• the ERG pattern can be selectively segmented to probe selected areas of the retina, allowing a retinal map to be developed for the entire retinal field, and allowing the different retinal regions to be compared to each other.
• the ERG interference pattern can be modulated both spatially (spatial frequency or fringe line spacing) and temporally (alternation frequency) .
• FIGURE 1 is a functional block diagram of the retinal- projection system of the invention
• FIGURE 2a illustrates an application of the retinal- projection system as a PERG projector capable of projecting an ERG pattern onto the entire field-of-view of the retina, including a shearing interferometer for generating an ERG interference pattern;
• FIGURE 2b illustrates an exemplary segmentation of the ERG pattern from the PERG projector, to allow selected segments of the entire retina to be probed;
• FIGURE 3 is a functional block diagram of a PERG system for performing under computer control PERG testing using a PERG projector according to the invention
• FIGURE 4 illustrates an alternative embodiment using a Newton's ring interferometer to generate an ERG interference pattern.
• FIGURE 5 illustrates an alternative embodiment of the interferometry optics using a Michaelson interferometer
• FIGURE 6 illustrates an alternative embodiment of the interferometry optics using a pressure driven interferometer.
• the invention has general applicability to projecting images (modulated light) onto the retina with a field-of-view that can be significantly anterior to the posterior retina.
• FIGURE 1 illustrates the retinal-projection technique of the invention.
• a projection beam 11 is generated by a light source 12 that is at least partially coherent.
• the light is modulated by modulation optics 14 to form a modulated projection beam 15 with the desired pattern or ima-e.
• the modulated projection beam 15 is input to wide- angle imaging optics 16, adjacent to the eye 20.
• the wide- angle imaging optics brings the modulated projection beam to a sharp focus in the area of the eye lens 22, enabling the beam to pass through a constricted pupil. After passing through the pupil, the beam diverges rapidly within the eye, and is projected onto the entire retina 24. That is, the retinal-projection technique enables a pattern or other image to be projected with a field-of- view that is significantly anterior to the posterior retina, including out to the far periphery 25.
• the exemplary PERG projection system provides wide-angle ERG pattern projection onto the entire retina — posterior, medial and anterior out to the far periphery. Then ERG pattern can be selectively segmented to probe selected areas of the retina for degeneration caused by glaucoma or other diseases.
• FIGURE 2a illustrates an exemplary embodiment of the PERG projector 30, including a laser light source 32 for providing a coherent projection beam 33, modulation optics 34 for generating a PERG interference pattern, segmentation optics 35 for selectively segmenting the PERG pattern, and wide-angle imaging optics 36 for imaging the PERG pattern onto the retina.
• the ERG response is detected by an ERG detection system 37 that includes an ERG electrode 37a.
• a PERG processor 38 controls modulation optics 34 and segmentation optics 35 to produce the desired interference pattern and the desired segmentation, and receives the resulting ERG responses from the ERG detection system 37.
• FIGURE 2b illustrates an exemplary segmentation of the retina.
• the entire field-of-view for the retina is represented by a circle 40 divided into seventeen representative segments.
• the retinal field-of-view is separated into concentric posterior 41 and anterior 42 regions, separated by a medial region 43.
• the field-of-view in the anterior and medial regions is sectored by radial sector lines 45, defining segments such as 47.
• the PERG processor executes a PERG program to appropriately control the modulation optics 34 and the segmentation optics 35, controlling the retinal segments (regions and sectors) stimulated by the PERG, and the spatial and temporal frequencies for the projected ERG pattern.
• the retinal segments can be selectively probed to develop an accurate map of the entire retinal field. Using this retinal map, the retina can be evaluated for degeneration caused by glaucoma (or other disease) .
• light source 32 includes a laser 51 (such as helium neon or argon) that generates a projection beam 52 of coherent light.
• a point source of light could be used to provide partially coherent light.
• the projection beam is directed through a polarizer 53 and an analyzer 54, which are polarized sheets.
• the projection beam 52 is adjusted in intensity by rotating the polarizer relative to the plane of polarization established by the analyzer to be perpendicular to the drawing sheet.
• the projection beam is expanded by a lens 55, recollimated by a lens 56, and directed toward modulation optics 34.
• the intensity of the laser light can be controlled to maintain a comfortable and safe level, but sufficient to induce an ERG response.
• Modulation optics 34 comprises a shearing interferometer. Alternate interferometer configurations are described in Section 2.5. Other suitable interferometers include the Michaelson and Twyman-Green interferometers (see Section 2.6) .
• the exemplary shearing interferometer includes two prisms 61 and 62 with respective opposing partially reflecting surfaces 61a and 62a, separated by a gap 63. The prisms are mounted such that the reflecting prism surfaces are non-parallel, and define a shearing angle Theta.
• the incident projection beam 33 enters prism 61, partially reflecting from prism surface 61a to provide a first-reflection beam 67, and partially transmitting across gap 63.
• the partially transmitted projection beam partially reflects from prism surface 62a, back across gap 63 to provide a second-reflection beam 68.
• the first- and second-reflection beams combine interferometrically into a PERG interference beam 69, producing an ERG interference pattern of light and dark fringe lines.
• the PERG pattern is controlled in spatial frequency (i.e., the fringe line spacing) by the shearing angle Theta.
• Prism 61 is stationary, while prism 62 is spring- loaded and pivotally mounted at a pivot point 62b. Prism 62 can be selectively pivoted by a motor-driven micrometer 64. Pivoting micrometer 64 is responsive to control signals from PERG processor 38 to control the shearing angle Theta between non-parallel prism surfaces 61a and 62a, providing precision angle-tuning of the spatial frequency for the interference pattern.
• the PERG interference pattern is alternated through a light-dark cycle with a selected frequency of alternation.
• Interferometer prisms 61 and 62 are at least partially immersed in a Kerr cell 72 filled with a Kerr fluid (such as carbon disulfide) , such that the Kerr fluid fills the gap 63 between the prisms.
• a Kerr fluid such as carbon disulfide
• the opposing prism surfaces 61a and 62a that define the gap 63 are coated with a transparent conductive material such as indium-tin-oxide.
• the conductive coatings are coupled to a high voltage amplifier 74.
• the high voltage amplifier receives a low frequency 1- 20 Hz signal from PERG processor 38.
• PERG processor 38 receives a low frequency 1- 20 Hz signal from PERG processor 38.
• an electric field is established in the gap 63, and applied to the Kerr fluid, which changes refractive index in response to changes in the electric field.
• the effective path length through the gap for the second- reflected beam 68 can be changed. This path modulation results in a selective shift in the light/dark ares of the interference pattern.
• the PERG interference beam 69 modulated with an interference pattern characterized by a selected angle- tuned spatial frequency, and a selected alternation frequency, is directed to segmentation optics 35.
• Segmentation optics 35 provides the desired segmentation for the projected ERG pattern.
• the time-varying PERG interference beam 69 is first expanded by lenses 82 and 84, and directed through a spatial light modulator 86.
• the exemplary spatial light modulator 86 is conventionally formed by liquid crystal films sandwiched between transparent electrode plates.
• the modulator is configured to provide the segmentation of the retinal field-of-view illustrated in FIGURE 2b.
• spatial light modulator 86 selectively passes the entire time-varying PERG interference beam 69 (i.e., the entire ERG interference pattern) , or any selected segment.
• the modulator could be controlled to pass the ERG interference pattern only in the anterior region (42 in FIGURE 2b) , or only in one sector of that region (47 in FIGURE 2b) .
• the time-varying PERG interference beam is directed to the wide-angle imaging optics 36.
• wide-angle imaging optics 36 injects the PERG interference beam into the eye, projecting the segmented ERG pattern into the entire field-of-view of the retina.
• wide-angle imaging optics includes two lenses located adjacent, but not in contact with, the eye — a parabolic aspheric lens 92 with a back focal length of about 30mm, followed by a positive meniscus lens 94 with a focal length of about 60mm.
• Parabolic lens 92 is made aspheric to correct for spherical aberration.
• a contact lens could be used for at least a portion of the imaging optics.
• the incident PERG interference beam is brought to a sharp focus at the eye lens, such that the beam can pass through a constricted pupil.
• the beam then diverges rapidly to project onto the entire retina, filling the field-of-view out to the far periphery.
• the projected PERG beam Since the projected PERG beam is collimated, it does not depend on the accommodation of the subject eye. Also, if any lens opacity exists, it can be circumvented to some extent by focal point adjustment.
• a suitable fixation beam 102 may be steered into the eye along the optical axis by a micro-miniature mirror 104. During the PERG test, the patient fixates on the fixation spot while the PERG processor executes a PERG program.
• zoom optics such as described in Section 2.6 can be included in the optical path to control the diameter of the projected PERG pattern.
• imaging optics that do not provide for wide-angle projection can be used.
• the resulting electrophysiological signal from the eye is detected by ERG detection system 37, and a corresponding ERG response is provided to the PERG processor 38.
• the ERG detection system 37 converts the electrophysiological ERG response from the eye to a corresponding digital ERG response for input to the PERG processor.
• the electrophysiological ERG response is detected by an electrode 37a, such as a fine gold leaf placed beneath the lower eye lid.
• the electrode may be placed on a part of a contact lens.
• the electrophysiological ERG response is input to ERG detection system 37.
• the ERG detection system operates conventionally in providing signal amplification and analog-to-digital conversion, outputting a corresponding digital ERG response signal.
• FIGURE 3 is a functional diagram illustrating a PERG system 100 for implementing a processor-controlled PERG program. This PERG program is a routine extension of the conventional approach to acquiring
• a PERG projector 101 is coordinated with a PERG processor 102.
• the PERG projector receives pattern-control signals from the PERG processor, creating a desired ERG interference pattern that is projected onto the retina.
• the PERG processor provides pattern modulation signals that control spatial frequency (pattern fringe line spacing) and alternation frequency (pattern phase shifting) .
• pattern fringe line spacing control spatial frequency
• alternation frequency pattern phase shifting
• the resulting ERG electrophysiological response is acquired by an ERG detection system 103.
• the ERG detection system is controlled by the PERG processor, which receives the ERG response data.
• a PERG program 104 executed by the PERG processor, carries out a series of PERG pattern tests using segmented patterns to probe the retina, and develop an ERG response map of the entire retinal field. Using the retinal map, an ERG analysis is performed by the PERG processor, and reported in an output device 106.
• FIGURES 4, 5 and 6 illustrate alternate embodiments of the interferometry optics used to modulate the projection beam with an alternating interference pattern.
• FIGURE 4 illustrates a PERG projector in which the interferometry optics is based on a Newton's ring interferometer design.
• a laser projection beam 111 is expanded and collimated as in the embodiment described in Sections 2.1-2.4, and polarized normal to the plane of the FIGURE.
• the projection beam is reflected from a mirror 112 to a polarizing beam splitter cube 114.
• the projection beam is completely reflected by the beam splitter cube through a quarter-wave rotating plate 116, toward a Newton's ring interferometer 120 for modulating the beam with a Newton's ring interference pattern.
• the interferometer is formed by a piano convex lens 122 and an optical flat 124.
• the piano convex lens is antireflective (AR) coated on the flat side 122a.
• the projection beam propagates to the left of the beam splitter cube, it is imparted with a circular polarization of one-quarter wave rotation by the quarter- wave rotating plate 116.
• the quarter-rotated projection beam is partially reflected from the piano convex lens 122, and then reflected partially from the optical flat 124.
• the two reflected beams combine interferometrically to create a PERG interference beam 126 with the Newton's ring interference pattern.
• the interference pattern can be alternated (periodically reversing light-dark interference rings) by translating optical flat 124 in a back-and-forth motion along the optical axis.
• Such translation may be imparted by a conventional electromagnetic mechanism 128, such as a speaker coil diaphragm operating at the desired alternation frequency.
• the PERG interference beam now propagating to the right, is again quarter-rotated by the quarter-wave rotating plate 116.
• the resulting 90° polarization rotation allows the PERG interference beam (i.e., the interference pattern) to pass through the beam splitter cube 114.
• the PERG interference beam is directed to segmentation optics formed by a ring aperture 132 and a sectoring aperture 134.
• the ring aperture allows the ERG pattern to be segmented into, for example, posterior, medial and anterior regions (41, 43 and 42 in FIGURE 2b) .
• the sectoring aperture allows the interference pattern to be further sectored, for example, along radial lines (45 in FIGURE 2B) .
• the selectively segmented PERG interference beam is directed to wide-angle imaging optics 140, which includes a zoom lens 142, and focusing lenses 144 and 146.
• the zoom lens adjusts (variably) beam diameter.
• the pair of focusing lenses (which do not necessarily contact the cornea) have aspheric surfaces which produce extremely short focusing of the beam to a point within eye 150, near the surface of the eye lens 151.
• the light pattern After transmitting through the pupil, the light pattern rapidly diverges, and is projected onto the retina.
• the diameter of the PERG interference beam, and hence the area of the retina onto which the beam is projected, can be controlled location on the retina, of the ring pattern is controlled by the zoom lens 142.
• the beam can be projected onto the entire retina (out to the far periphery) , and the ring aperture used to control the region of the retina (posterior, medial and/or anterior) receiving the ERG pattern.
• various components of the PERG projector can be controlled by a PERG processor (not shown) executing a PERG program.
• the PERG processor can control the rate and amplitude of the translation of the optical flat 124, the setting of the sectoring aperture 134, and the magnification of zoom lens 142.
• FIGURE 5 illustrates an embodiment of the interferometry optics (34 in FIGURE 2a) based on a Michaelson interferometer design. Interferometry optics
• 160 includes two mirrors 161 and 162, and a beam splitter
• the optical path for the mirror 161 includes a Kerr cell 164, to which are attached electric field plates 165.
• the electric field plates are coupled to a high voltage amplifier 166 controlled by the PERG processor in a manner analogous to the HVA 74 in FIGURE 2a (see Section 2.2).
• Mirror 161 is stationary, while mirror 162 is spring- loaded and pivotally mounted at pivot point 168. Mirror 162 can be selectively pivoted by a motor-driven micrometer 168.
• MDM 168 is controlled by the PERG processor in a manner analogous to the MDM 64 in FIGURE 2a (see Section 2.2), providing precision angle-tuning of the spatial frequency (fringe line spacing) for the interference pattern.
• a collimated projection beam 170 (33 in FIGURE 2a) is split by splitter 163 into separate beams 171 and 172.
• Beam 171 passes through the Kerr cell and reflects from mirror 161 passing back through the Kerr cell.
• Beam 172 reflects from tuning mirror 173, but with a slight angular displacement Theta.
• FIGURE 6 illustrates an embodiment of the interferometry optics (34 in FIGURE 2a) based on a pressure controlled interferometer design. Interference pattern modulation is accomplished by selectively varying the index of refraction of a gas media by varying its pressure.
• a gas cell 180 replaces the Kerr cell 164 in FIGURE 5.
• the gas cell contains a suitable gas media (such as a fluorocarbon) .
• the pressure of the gas in the cell is controlled by a flexible diaphragm 181, and is modulated by a ferromagnetic plunger 182 moved by an electromagnetic coil 183. Pattern phase modulation is accomplished by controlling the coil current such as with a driver amplifier 185 that responds to control signals from the PERG processor.
• the retinal-projection technique of the invention can be used in any application in which images (modulated light) need to be projected into the eye with a field-of-view that is significantly anterior to the posterior retina (including out to the far periphery) .
• the retinal-projection technique can be used to project video or printed information directly into the eye.
• the interferometry modulation optics could be eliminated, and the LCD spatial light modulator 86 could be used to modulate the projection beam with video or printed information. This information could be imaged by the wide- angle imaging optics 36 onto the entire field-of-view of the retina.

Landscapes

• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Medical Informatics (AREA)
• Biophysics (AREA)
• Ophthalmology & Optometry (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Physics & Mathematics (AREA)
• Molecular Biology (AREA)
• Surgery (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Pathology (AREA)
• Eye Examination Apparatus (AREA)
• Prostheses (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=24278337

Family Applications (1)

Country Status (7)

Families Citing this family (3)

Family Cites Families (7)

• 1991
  • 1991-07-29 EP EP91914231A patent/EP0544709A1/en not_active Ceased
  • 1991-07-29 AU AU83184/91A patent/AU657918B2/en not_active Ceased
  • 1991-07-29 KR KR1019930700441A patent/KR930701131A/ko not_active Withdrawn
  • 1991-07-29 CA CA002086746A patent/CA2086746A1/en not_active Abandoned
  • 1991-07-29 JP JP3513395A patent/JPH06501171A/ja active Pending
  • 1991-07-29 WO PCT/US1991/005359 patent/WO1992003088A1/en not_active Application Discontinuation
  • 1991-08-08 TW TW080106269A patent/TW203551B/zh active

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events