# US 10,502,979 B2 · Impedance sensing circuits for ophthalmic devices

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- Number: US 10,502,979 B2
- Document ID: US10502979B2
- Status: Granted
- Kind: B2
- Application number: 15/386,028
- Filed: 2016-12-21
- Published: 2018-06-21
- Granted: 2019-12-10
- Earliest claimed: 2016-12-21
- Assignees: Johnson & Johnson Vision Care, Inc.
- Applicants: Johnson & Johnson Vision Care, Inc.
- Inventors: Corey Kenneth Barrows; Steven Philip Hoggarth; Scott Robert Humphreys; John Rocco Robillotto; Adam Toner; George A. Zikos
- Web page: https://patentgrep.com/patent/US10502979B2

## CPC

- G02C 7/083: {Electrooptic lenses}
- A61B 5/053: Measuring electrical impedance or conductance of a portion of the body
- A61B 5/398: Electrooculography [EOG], e.g. detecting nystagmus; Electroretinography [ERG]
- A61B 5/6821: {Eye}
- A61B 5/7225: {Details of analogue processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation (input circuits for detecting, measuring, or recording bioelectric or biomagnetic signals A61B5/30; specific diagnostic methods using bioelectric or biomagnetic signals A61B5/316)}
- A61F 2/145: {Corneal inlays, onlays, or lenses for refractive correction}
- A61F 2/1624: {having adjustable focus; power activated variable focus means, e.g. mechanically or electrically by the ciliary muscle or from the outside}
- A61F 2/1635: {for changing shape}
- G02C 7/049: {Contact lenses having special fitting or structural features achieved by special materials or material structures}
- A61B 5/7246: {using correlation, e.g. template matching or determination of similarity}
- A61B 2560/0204: of power management
- G02C: SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES (trial frames for testing the eyes A61B3/04; goggles or eyeshields not having the same features as spectacles A61F9/00)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)

## Abstract

The present disclosure relates to sensor systems for electronic ophthalmic devices. In certain embodiments, the sensor systems may comprise a sensor such as an adjustable resistor configured in series with an eye of a user of the electronic ophthalmic device. The sensor systems may comprise a gain stage configured to amplify a signal indicative of a difference between a voltage drop across the eye and the adjustable resistor. The sensor systems may comprise an integrator configured to integrate the amplified signal. A resistance value of the adjustable resistor is configured to cancel a DC component of a resistance of the eye when an electrical current is caused to flow through the eye and the adjustable resistor. As such, the configured resistance value of the adjustable resistor is indicative of an impedance of the eye.

## Claims

### Claim 1

A sensor system for an electronic ophthalmic device, the sensor system comprising:
an adjustable resistor configured in series with an eye of a user of the electronic ophthalmic device;
a gain stage configured to amplify an error signal comprising a difference between a voltage drop across the eye and a voltage drop across the adjustable resistor; and
an integrator configured to integrate the amplified signal, wherein a resistance value of the adjustable resistor is configured to cancel a DC component of a resistance of the eye when an electrical current is caused to flow through the eye and the adjustable resistor, and wherein the resistance value of the adjustable resistor is adjusted to decrease the error signal.

### Claim 2 (depends on 1)

The sensor system according to claim 1, wherein the resistance value of the adjustable resistor is configured to minimize the error signal.

### Claim 3 (depends on 1)

The sensor system according to claim 1, wherein the integrator comprises a Nagaraj integrator.

### Claim 4 (depends on 1)

The sensor system according to claim 1, further comprising an out-of-bounds circuit configured to detect an output of the integrator that exceeds a predetermined threshold.

### Claim 5 (depends on 4)

The sensor system according to claim 4, wherein the out-of-bounds circuit comprises an operational amplifier with systematic offset.

### Claim 6 (depends on 4)

The sensor system according to claim 4, wherein the gain stage is configured to autozero in response to the output of the integrator exceeding a predetermined threshold.

### Claim 7 (depends on 1)

The sensor system according to claim 1, further comprising an H-bridge configured to transmit an electrical current to the eye and/or receive an electrical current from the eye.

### Claim 8 (depends on 1)

An ophthalmic device comprising the sensor system of claim 1.

### Claim 9 (depends on 8)

The ophthalmic device of claim 8, wherein the ophthalmic device comprises a contact lens, an intraocular lens, an overlay lens, an ocular insert, or an optical insert, or a combination thereof.

### Claim 10 (depends on 1)

An electronic ophthalmic device comprising the sensor system of claim 1, the electronic ophthalmic device comprising:
an ophthalmic lens having an optic zone and a peripheral zone;
a variable optic element incorporated into the optic zone of the ophthalmic lens, the variable optic being configured to change the refractive power of the ophthalmic lens; and
an electronic component incorporated into the peripheral zone of the ophthalmic lens, the electronic component including the sensor system for detecting ciliary muscle movement associated with the process of accommodation, the sensor system configured to generate an action for controlling the variable-optic element.

### Claim 11 (depends on 10)

The electronic ophthalmic lens according to claim 10, wherein the ophthalmic lens comprises a contact lens.

### Claim 12 (depends on 11)

The electronic ophthalmic lens according to claim 11, wherein the contact lens is a soft or hybrid contact lens.

### Claim 13 (depends on 10)

The electronic ophthalmic lens according to claim 10, wherein the sensing system comprises a power source, a signal processor, a controller, and an actuator.

### Claim 14 (depends on 13)

The electronic ophthalmic lens according to claim 13, wherein the power source comprises a battery.

### Claim 15 (depends on 13)

The electronic ophthalmic lens according to claim 13, wherein the signal processor comprises a digital signal processor.

### Claim 16 (depends on 13)

The electronic ophthalmic lens according to claim 13, wherein the controller comprises a microprocessor.

### Claim 17 (depends on 13)

The electronic ophthalmic lens according to claim 13, wherein the actuator is operatively associated with the variable-optic element.

### Claim 18

A method for sensing a characteristic of a ciliary muscle in a user of an ophthalmic device, the method comprising:
causing an electrical current to flow through an eye of the user and an adjustable resistor configured in series with the eye of the user of the ophthalmic device;
amplifying an error signal comprising a difference between a voltage drop across the eye and a voltage drop across the adjustable resistor; and
integrating the amplified signal, wherein a resistance value of the adjustable resistor is configured to cancel a DC component of a resistance of the eye when an electrical current is caused to flow through the eye and the adjustable resistor, and wherein the resistance value of the adjustable resistor is adjusted to decrease the error signal.

### Claim 19 (depends on 18)

The method according to claim 18, wherein the resistance value of the adjustable resistor is configured to minimize the error signal.

### Claim 20 (depends on 18)

The method according to claim 18, wherein the integrator comprises a Nagaraj integrator.

### Claim 21 (depends on 18)

The method according to claim 18, further comprising an out-of-bounds circuit configured to detect an output of the integrator that exceeds a predetermined threshold.

### Claim 22 (depends on 21)

The method according to claim 21, wherein the out-of-bounds circuit comprises an operational amplifier with systematic offset.

### Claim 23 (depends on 18)

The method according to claim 18, wherein the gain stage is configured to autozero in response to the output of the integrator exceeding a predetermined threshold.

### Claim 24 (depends on 18)

The method according to claim 18, wherein causing the electrical current to flow through an eye of the user and the adjustable resistor is implemented via an H-bridge.