An apparatus and method for the self-measurement of intraocular pressure utilize a tonometer disposed within a housing and having a tonometer tip. The apparatus further includes an adjustment mechanism in communication with the tonometer for positioning the tonometer tip in contact with a test eye of the user, and an illuminator mounted within the housing adjacent the tonometer tip. A receiver is aligned with the tonometer tip for receiving an applanation pattern created by contact of the tonome...

A device using light emitting diodes directed at the patient as a light source for evaluating the appropriate color and density of filters or sunglasses for a patient is disclosed. The device may be used with additional filters or sunglasses to determine what filter or sunglass color and density will provide optimal vision for targets of varying spatial frequency. The device may also be used with additional filters of varying color and density to determine the health of the patient's ocular medi...

A spectacle lens is disclosed. The disclosed lens provides a vision correcting area for the correction of a wearer's refractive error. The viewing correction area provides correction for non-conventional refractive error to provide at least a part of the wearer's vision correction. The lens has a prescription based on a wave front analysis of the wearer's eye and the lens can further be modified to fit within an eyeglass frame.

In a frequency modulation type switching regulator for producing an output voltage to a load, an error amplifier produces an error voltage indicative of a difference between the output voltage and a reference voltage. A switching device is turned on and off at a switching frequency corresponding to the error voltage. A voltage-frequency modulation circuit monitors an operation condition of the load. The modulation circuit generates a varying voltage, which varies around the error voltage, when t...

Apparatus for self-examination of the human eye comprising a pen light for generating a beam of light, a reflecting sphere for orthogonally reflecting the beam through an opaque disc having a pin hole and a cylindrical head enclosing the reflecting sphere and opaque disc. The reflecting sphere is adjustable along its axis, and functions to reflect a uniformly diffuse beam of light through the pin hole. When the pin hole is at the anterior focus of the human eye and along its pupilary axis, a vie...

A system for assessing subjects for inadequate visual attention capabilities presents a sequence of display screens to the subject on a conventional computer monitor. The display screens include a foveal target and a peripheral target, and may additionally include distractor elements around the peripheral target. The display time for the displays is varied either as a function of the responses of the subject or in a preprogrammed manner. The responses are evaluated for accuracy, and are then use...

An SMPS converter with an inductor connected in series to the standard inductor present in the output filter to form an inductive divider supplying an intermediate voltage having an amplitude greater than the output voltage. The intermediate voltage is supplied to a capacitor that stores the voltage during the conduction phase of the integrated circuit that forms the switch of the converter and transfers the voltage during opening of the integrated circuit to a capacitor connected between the ou...

A visual function test apparatus for testing a visual function by presenting an optotype to an examinee's eye is disclosed. This apparatus includes a first half mirror disposed on a projection optical axis of light of the optotype; an illumination light source having a projection optical axis which is made substantially coaxial with the projection optical axis of the optotype light by the first half mirror; a concave mirror which reflects an illumination light from the illumination light source ...

A DC power converter is disclosed for converting an input voltage to a final output voltage that is higher than the input voltage. The power converter includes an input terminal for receiving the input voltage and a final output terminal. A boost converter generates an intermediate voltage that is higher than the input voltage and lower than the final output voltage. The boost converter includes an inductor having a primary winding that has a first end connected to the input terminal, a switch f...

A circuit to generate a bias voltage, the circuit including an inductor, a first capacitor associated with the second inductor node, a diode, and a second capacitor being associated with ground, the second capacitor including a second capacitor node, a switch configured to connect the inductor current to ground when closed. The first capacitor and the second capacitor become charged via the trigger resistor by the inductor current until the trigger node reaches the trigger threshold and the trig...