Design Team Partners

Bio-rad Laboratories, Inc.

Keratometer Research and Development

David A Wallace

Steven E Feldon

Thor R Halseth

Barry G Broome

Douglas L Whiting

James E Grove

Robert A Monsour

Scott A Karns

William J Dally

Disclosed is a completely portable, hand-held digital ultrasonic instrument about the size and shape of an ordinary pen. The housing is contoured such that it can be easily grasped in the manner of a writing pen. An activation button is located on the interior dorsal surface in close approximation to the index fingertip of the user. A liquid crystal display provides a digital readout of a thickness measurement on the barrel of the instrument housing. The instrument incorporates a 10 MHz or 20 MHz solid phase piezoelectric transducer, a microprocessor, a gate array, a hybrid analog circuit, a liquid crystal display, batteries and a removable battery cover. The 20 MHz transducer is used to measure corneal thickness and is attached to a swan neck connector which is attached to the instrument housing. The 10 MHz transducer is used for measuring axial length and it is attached to a truncated conical connector which is also attached to the instrument housing. In addition, a pinjack connector is available to link the unit to other electronic media such as a microcomputer, personal computer, or printer.

Self contained hand held ultrasonic instrument for ophthalmic use

Disclosed is a digital ultrasonic instrument for measuring the corneal thickness (often referred to as a pachymeter) and for measuring the axial length of the eye (often referred to as a biometric ruler). A number representing corneal thickness or axial length is displayed digitally on a liquid crystal display. The pachymeter incorporates a 20 MHz solid phase piezoelectric transducer, a microprocessor, a gate array, a hybrid analog receiver circuit, a liquid crystal display and four batteries. When axial length is measured, the instrument operates as a biometric ruler, a 10 MHz transducer is used and the software in the microprocessor is modified. Ultrasonic echoes generated by the transducer and various interfaces in the eye are sampled at the rate of 40 MHz which results in equal or greater sensitivity, resolution and accuracy as compared to other pachymeters and biometric rulers currently available. The 40 MHz sample rate is accomplished by use of a grey code counter and a binary counter, each of which is sampled twice after an ultrasonic echo is detected. The two grey code samples are compared to determine a valid sample period. A counter value obtained during a valid sample period is recorded in a shift register and compared to subsequent counter values corresponding to subsequent ultrasonic echoes. The apparatus for correlating ultrasonic echoes with particular counter values assures that the counter will be sampled at a point in time when the counter is stable as opposed to being in a state of transition. The apparatus allows for a counter accuracy of 25 ns.

Digital ultrasonic instrument for ophthalmic use

Ophthalmic instrument

Disclosed is a battery powered, hand-held self-contained electronic tonometer with a digital readout for displaying pressure in millimeters of mercury. The tonometer includes a transducer which is a solid state pressure sensitive element and which produces a voltage proportional to intraocular pressure. An electrical waveform is produced by gently bringing the transducer in contact with the cornea. The waveform is converted to a digital signal and processed by a single chip microprocessor. The baseline of a reference signal is nulled by equalizing the charges on two capacitors on the inputs of two differential amplifiers. Equalizing the differential inputs of the two amplifier stages results in a gain of zero and removes any carrier signal. Microprocessor software detects the baseline condition established by equalizing the differential inputs. The microprocessor then looks for a series of valid measurements and calculates the average intraocular pressure along with an estimate of reliability. This average value and the reliability indicator are displayed on a liquid crystal display.

Electronic tonometer with baseline nulling system

An improved keratometer instrument capable of measuring keratometric values of an eye is provided. An optical reference of a predetermined dimensional value is directed at the cornea of the eye and an optical sensor measures the same at different meridians. A computer circuit can determine whether the instrument is de-centered or de-focused relative to the eye and can derive measurements of keratometric values. The axis of astigmatism can be visually displayed to the surgeon during an operation.

Keratometer

Growing community of inventors

Beverly Hills, CA, United States of America

David A Wallace