Abstract: A non-contact tonometer changes a reference signal used for determining reliability of a signal indicating deformation of a cornea based on the reflectance of the cornea of an eye to be examined. Thus, the non-contact tonometer can perform stable measurement irrespective of the reflectance of the cornea of the eye to be examined.

Abstract: An air pulse discharging device for a noncontact type tonometer, which includes: a cylinder; a piston arranged reciprocatably in the cylinder and which compresses air in a compression space; a nozzle which discharges the compressed air to an examined eye; at least one opening provided on the piston and which communicates the compression space with a cylinder atmospheric-air releasing chamber; and a valve disk provided to the piston and which opens and closes the at least one opening, the valve disk closes the at least one opening based on a differential pressure between the compression space and the cylinder atmospheric-air releasing chamber when the piston is driven to a direction of compressing the air in the compression space, and opens the at least one opening based on the differential pressure when the piston is driven to a direction opposite to the direction of compressing the air in the compression space.

Abstract: A tonometer for quickly and efficiently remeasuring intraocular pressure when an intraocular pressure is higher or lower than a predetermined pressure. It is determined whether a predetermined number n of intraocular-pressure measurements have been completed, wherein when n intraocular pressures exist, the n intraocular pressures are compared with a predetermined upper limit and lower limit. When the n intraocular pressures are between the upper limit and the lower limit, it is then determined whether the measurements of left and right eyes have been completed. When the measurements have not been completed, a measuring section is moved to the other eye. When the lateral movement has been completed, the next intraocular-pressure measurement is performed. When, among the n intraocular pressures, at least one intraocular pressure outside the predetermined upper and lower limits exists, a warning is given.

Abstract: A noncontact tonometer is disclosed that stores, into a storage unit, the image of an anterior ocular segment immediately before an intraocular pressure value is measured, and that, if an anomaly is found in the measurement result, facilitates the specification of the reason of the anomaly by automatically displaying the image of the anterior ocular segment that was acquired in advance.

Abstract: A non-contact type tonometer includes a fluid blowing device which blows fluid against a cornea of an eye of an examinee; an intraocular pressure measurement part which detects a deformed state of the cornea caused by the blown fluid and determines intraocular pressure of the examinee's eye based on a result of detection of the deformed state; a pulsation detection part which detects pulsation of the examinee; a measurement timing determination part which can determine a measurement timing based on the detected pulsation to obtain a predetermined number of results of measurement on the intraocular pressure in synchronization with different phase points in the pulsation; a command signal input part which inputs a command signal for execution of the measurement; and a control part which outputs a control signal for controlling driving of the fluid blowing device based on the determined measurement timing and the input command signal.

Abstract: In a noncontact ophthalmotonometer: an image processing operation is performed on an image signal subjected to an imaging operation to extract a pupil, to compute location of the center of gravity thereof, and to move a measuring mechanism so that the center of gravity is located at the central axis of a nozzle. Locations of two alignment mark images from the signal are detected to compute distance from a nozzle end to a cornea from a gap between centers of gravity of the mark images. When the nozzle end approaches the cornea, the mechanism moves away therefrom. The mechanism moves toward an eye in the direction of the nozzle central to detect a second mark image. An aligning operation is performed using the second mark image. Eye pressure is then measured. The mechanism moves to a location farthest from the eye in the direction of the nozzle central axis.

Abstract: A puff tonometer includes two light sources located at diametrically opposite points, preferably equidistant from the optical axis of the objective lens assembly of the tonometer. The sources are arranged to direct light forwardly of the tonometer such that, in use, and when positioned close to a patient's eye under test, light from the two sources, after reflection by the anterior corneal surface of the eye under test, will be imaged by the objective lens assembly of the tonometer, to appear as two small areas of light in the field of view.

Abstract: A puff tonometer in which the eyepiece and objective lens form a simple telescope which is capable of presenting to the user an in-focus image of distant objects, as well as an image of light reflected by an eye under test at close quarters when viewed through the eyepiece. A Pechan-Schmidt prism inverts the image and presents to the user an image of the patient's eye which is correctly oriented and handed in a vertical and horizontal sense. The focal length of the eyepiece typically lies in the range 62-100 mm, preferably 80 mm.

Abstract: A puff tonometer which includes an object at a point in the optical path of light from a source of light in the tonometer, typically near to the source, such that an in-focus image of the object will be formed in the user's field of view when the tonometer is at the critical distance from an eye under test at which the automatic air pulse generating means will be triggered by light reflected from the eye forming an in focus image of a mask on a plurality of photoelectric sensors. A second object may be located in the same region of the tonometer as the first object, but in a plane which is spaced from the plane containing the first object, whereby its image will come into focus in the field of view just before the image of the first object comes into focus, as the unit is moved slowly towards the patient's eye.

Abstract: The invention concerns a combination of a microscope with a measurement device, in particular a diagnostic device, that is usable during an operation on or examination of a specimen performed with the microscope. During the operation or examination, specimen data that are ascertained or determined by the measurement device are directly displayable in the microscope as an optical signal. In the event the measured data of the specimen exceed or fall below threshold values and/or interval values, a warning signal is triggerable by way of which further actions, such as shutdown or switchover actions, can be automatically executed as applicable.

Abstract: A non-contact tonometer changes a reference signal used for determining reliability of a signal indicating deformation of a cornea based on the reflectance of the cornea of an eye to be examined. Thus, the non-contact tonometer can perform stable measurement irrespective of the reflectance of the cornea of the eye to be examined.

Abstract: A non-contact tonometer of a type having a cylinder, a piston received by the cylinder for axially directed movement relative to the cylinder, and a driven member for causing the piston to move relative to the cylinder in a compression stroke to generate a fluid pulse for transfiguring a cornea is improved by decoupling the piston from the driven member to eliminate the need for critical alignment between the driven member and piston and allow the piston to be self-aligning with respect to the cylinder.

Abstract: An apparatus for calibrating a non-contact tonometer comprises an electronic eye having a damped pressure sensor for receiving a tonometer air pulse and providing a pressure signal in response to the air pulse, and an applanation simulator connected to the pressure sensor for providing a pseudo-applanation event when the pressure signal reaches a predetermined level corresponding to a known IOP measurement standard. A method for calibrating a non-contact tonometer using the inventive calibration apparatus is also described.

Abstract: A non contact tonometer of a type having a fluid pump in flow communication with a fluid discharge tube for directing a fluid pulse at an eye of a patient to observably transfigure the cornea is improved by providing the fluid discharge tube with a flared inlet portion for reducing inlet losses. In a preferred embodiment, the flared inlet portion is defined by a circumferential internal radius.

Abstract: A fluid pump system of a non-contact tonometer is numerically simulated through its compression stroke by a simulation software program. System dynamic behavior is modeled for a variety of piston diameters, whereby an optimal piston diameter or range of piston diameters is selected in view of stoke length limitations and target applanation pressure requirements.

Abstract: A noncontact type tonometer monitors the rate of change X(t) in pressure between a standard curve and a measured curve. If X(t) exceeds a value of 1.3, the application of air pressure is stopped to prevent an abnormal rise in pressure. If X(t) is equal to 1, then the measured curve follows the standard curve and correction is not required. If X(t) is not equal to 1, an error condition exists and an amended time t′ is calculated based on the rate of change X(t). Instead of a calculated amended time, an approximated standard curve can also be determined based on either an equation stored in a memory or by matching the measured curve with one of a plurality of standard curves stored in memory.

Abstract: A method and apparatus for measuring the intraocular pressure of a cornea includes an interferometer directing a beam of a coherent light along a path to the cornea, a sensor for sensing the reflected light from the cornea, an air supply device for directing puffs of air to the cornea in alignment with the beam to cause the surface of the cornea to be artificially displaced and means for measuring variations of light intensity reaching the sensor.

Abstract: A noncontact ophthalmotonometer carries out the following first to sixth steps to measure eye pressure. The first step is to perform an image processing operation on an image signal that has been subjected to an imaging operation in order to extract a pupil, to compute the location of the center of gravity thereof, and to move a measuring mechanism so that the center of gravity is at the location of the central axis of a nozzle. The second step is to detect the locations of a pair of alignment mark images from the image signal in order to compute the distance from an end of the nozzle to a cornea from a gap between the centers of gravity of the first alignment mark images. When the end of the nozzle approaches the cornea, the measuring mechanism is moved away from the cornea. The third step is to move the measuring mechanism toward an eye to be examined in the direction of the central axis of the nozzle in order to detect a second mark image produced by a second alignment mark light source.

Abstract: A fluid pump system of a non-contact tonometer is numerically simulated through its compression stroke by a simulation software program. System dynamic behavior is modeled for a variety of piston diameters, whereby an optimal piston diameter or range of piston diameters is selected in view of stoke length limitations and target applanation pressure requirements.

Abstract: A metered fluid pump for a non-contact tonometer comprises a piston and a cylinder configured such that a plenum chamber defined thereby develops a massive leak through an exhaust port at a predetermined displacement position of the piston relative to the cylinder, thus reducing unnecessary impulse energy delivered to the eye that is a source of patient discomfort. A metering adjustment drive is provided for adjusting the piston and cylinder in a relative manner to meter the volume of fluid delivered before the leak develops, such that a suitable fluid pulse can be delivered to the eye.

Abstract: A non-contact tonometer comprises a fluid pump system configured and mounted to dissipate vibration energy to reduce the effect of vibrations on measurement components caused by the stroke of a piston with respect to a cylinder in the fuid pump system. In a preferred embodiment, a compression chamber receiving a piston and plenum chamber containing a pressure sensing device are spaced apart from one another and connected by a flow tube formed of a vibration damping material, and at least one vibration damping element is provided between the cylinder and a support frame of the non-contact tonometer.

Abstract: A method and apparatus for measuring the intraocular pressure of a cornea includes an interferometer directing a beam of a coherent light along a path to the cornea, a sensor for sensing the reflected light from the cornea, an air supply device for directing puffs of air to the cornea in alignment with the beam to cause the surface of the cornea to be artificially displaced and means for measuring variations of light intensity reaching the sensor.

Abstract: A non-contact type tonometer includes a fluid blowing device which blows fluid against a cornea of an eye of an examinee; an intraocular pressure measurement part which detects a deformed state of the cornea caused by the blown fluid and determines intraocular pressure of the examinee's eye based on a result of detection of the deformed state; a pulsation detection part which detects pulsation of the examinee; a measurement timing determination part which can determine a measurement timing based on the detected pulsation to obtain a predetermined number of results of measurement on the intraocular pressure in synchronization with different phase points in the pulsation; a command signal input part which inputs a command signal for execution of the measurement; and a control part which outputs a control signal for controlling driving of the fluid blowing device based on the determined measurement timing and the input command signal.

Abstract: During corneal deformation induced by a fluid pulse, observations associated with an inward first state of applanation and an outward second state of applanation are processed to provide a final reported intra-ocular pressure value that is substantially without error due to corneal thickness effects.

Abstract: A non-contact type tonometer includes a compressed air blowing unit which compresses air in a cylinder by means of a piston disposed within the cylinder and blows the compressed air to a cornea of an examinee's eye; a driving unit which drives the piston; a pressure sensor which detects pressure of the air in the cylinder; an optical system which projects light to the cornea; a photosensor which detects, of the light projected by the optical system, reflection light reflected from the cornea; and a controller which obtains a change in pressure for a predetermined time based on a detection result by the pressure sensor when the photosensor detects a predetermined change amount of the reflection light after the driving unit drives the piston to start blowing of the compressed air to the cornea from the compressed air blowing unit, and changes a timing of stopping supply of driving power to the driving unit based on the obtained change in pressure.

Abstract: A hand-held non contact tonometer includes a piston having a transparent plane parallel window normal to a measurement axis of the tonometer along which the piston travels to discharge a fluid pulse without interfering with optical alignment functions of the instrument. In a first embodiment intended for home use by a patient, an alignment guidance system utilizing a concave mirror and a target source in a plane containing the center of curvature of the concave mirror present an alignment image to the patient for guiding self-alignment. An infra-red light source at the focal point of the concave mirror irradiates the concave mirror so that a collimated beam is reflected along the measurement axis and focused by an objective lens.

Abstract: A noncontact type tonometer monitors the rate of change X(t) in pressure between a standard curve and a measured curve. If X(t) exceeds a value of 1.3, the application of air pressure is stopped to prevent an abnormal rise in pressure. If X(t) is equal to 1, then the measured curve follows the standard curve and correction is not required. If X(t) is not equal to 1, an error condition exists and an amended time t′ is calculated based on the rate of change X(t). Instead of a calculated amended time, an approximated standard curve can also be determined based on either an equation stored in a memory or by matching the measured curve with one of a plurality of standard curves stored in memory.

Abstract: A noncontact tonometer comprises an air current blowing means for blowing an air current against an eye, a cornea deformation measuring means for optically measuring a change in the shape of the cornea caused by the air current blowing means, and an arithmetic means capable of calculating the intraocular tension of the eye on the basis of the change in the shape of the cornea. Since the intraocular tension of the eye can be calculated on the basis of the change in the shape of the cornea by the arithmetic means, the pressure of the air current blown against the eye need not be high, which lightens load on the subject.

Abstract: A noncontact tonometer is provided which is capable of intercepting out-of-axis light of an index beam of light and performing precise alignment. The noncontact tonometer includes an index projecting optical system for projecting an index frontally onto a subject's eye (E) through a nozzle (12) through which gas is also is sprayed upon the eye (E). The index projecting optical system has a projection lens (27) and a diaphragm (23) disposed at a position conjugated to an end surface (F) of the nozzle (12) on the side of the projection lens (27). The diaphragm (23) intercepts rays of light traveling out of an optical axis, and enables precise alignment.

Abstract: In the non-contact intraocular pressure measuring apparatus for measuring the intraocular pressure of the eye to be examined for a suitable measurement time, after alignment of the apparatus main body with the eye to be examined is performed, the time required for charging the condenser is calculated based on current supply time for the rotary solenoid at the time of the previous intraocular pressure measurement. When the calculated charging time elapses, the desired quantity of current is supplied from the condenser to the rotary solenoid, allowing the air supply unit to spray air to the cornea of the eye to be examined. The cornea is transfigured and flattened by the sprayed air. At the same time, intraocular pressure measuring light is illuminated from the intraocular pressure measuring optical system to the flattened cornea. The reflected light therefrom is detected to calculate intraocular pressure value of the eye to be examined.

Abstract: A non-contact tonometer is improved by providing a non-telecentric applanation detection system enabling relaxation of instrument alignment requirements during testing. In a preferred embodiment, the applanation detection system comprises an emitter for directing an obliquely incident beam of light for reflection by the cornea, and a detector array having a plurality of photosensitive detector array elements located to receive corneally reflected light. The detector array generates a plurality of signal curves for light energy received at different locations on the array as a function of time, and the signal curves are evaluated to determine an optimal signal curve which best indicates the moment of applanation.

Abstract: A dynamic MRA study of a subject is performed using a 3D fast gradient-recalled echo pulse sequence. The frame rate of the resulting series of reconstructed images is increased by sampling a central region of k-space at a higher rate than the peripheral regions of k-space. A difference image is produced by subtracting a mask formed by central region k-space sampling from a selected image frame formed by central region and peripheral regions k-space sampling.

Abstract: A noncontact tonometer for measuring intraocular pressure is provided. When a rotary solenoid (7) is supplied with electric power, a piston (4) within a cylinder (2) is moved up, and thereby air is jetted through a nozzle (9) of a head (3) toward an eye (H) of a subject. At the same time, infrared rays are projected onto the eye (H) from a light source (11). Reflected light from a cornea of the eye (H) is received by a light receiving sensor (12). A signal generated by the light receiving sensor (12) is transmitted to a control circuit (16) via a flat-state detecting circuit (13). As a result, the intraocular pressure of the eye (H) is measured. The noncontact tonometer further includes two condensers (17, 18). A command from the control circuit (16) is input to a condenser switching portion (20) by operating a driving switch (21). Thereby, one of the condensers (17, 18) is selected to supply the rotary solenoid (7) with the electric power.

Abstract: An air pulse generator for a non-contact tonometer comprises a bi-directional linear motor drivably connected to a compression mechanism and responsive to an applanation signal for reducing unnecessary air pulse energy delivered to an eye. Upon receiving the applanation signal from an applanation detector, a motor controller reverses current flow in the coil of the motor to create a reverse electromagnetic force to stop generation of the air pulse. In a first embodiment, the linear motor includes a moving permanent magnet armature for reversibly driving the compression mechanism, while in a second embodiment, the linear motor includes a moving coil for reversibly driving the compression mechanism.

Abstract: A noncontact type of tonometer is provided which includes air injection device (70) for jetting a fluid from a nozzle (18) onto a cornea (C) of a subject's eye (E), an alignment light projecting optical system (30) for projecting a beam of light onto the cornea (C), and a corneal deformation detecting optical system (60) for detecting the deformation of the cornea (C). The number of times up to which the air injection device (70) has jetted the fluid is counted by a counter (82), and the count is displayed on a monitor (M).

Abstract: A non-contact tonometer includes a fixation axis intersecting the corneal vertex, and a fluid axis angularly displaced from the fixation axis to form a non-zero angle therewith. A nozzle is axially aligned along the fluid axis for discharging a fluid pulse along the fluid axis to the corneal surface of the eye. In a preferred embodiment, the fixation and fluid axes reside in the same vertical plane, with the fluid axis below the fixation axis approaching the eye. Alignment and applanation detection optics are arranged coplanar with the fluid axis.