Abstract: A refractometric apparatus and method for monitoring the percentage of water in hydraulic and non-hydraulic fluids employ a temperature sensitive device allowing a user to obtain accurate and correct readings of various measured properties. In particular, the temperature sensitive member comprises a prism-wedge-mirror combination in conjunction with a bimetallic strip. The combination ensures the proper angular displacement of a light beam inside the refractometric apparatus and, therefore, the correct reading of a parameter to be measured.

Abstract: A subjective ophthalmic refractor of a type comprising a ring-shaped cylinder power scale having an internal gear actuated by a scale drive gear connected to a cylinder power adjustment knob of the refractor is improved by providing a bearing insert within the cylinder power scale. The bearing insert includes radially and axially facing annular bearing surfaces extending about a substantial portion of the scale, and a cut-out region allowing space necessary for the scale drive gear.

Abstract: A subjective ophthalmic refractor comprises a cylinder power adjustment knob for simultaneously actuating a cylinder power scale and an indexable lens carrier drive assembly. The drive assembly includes a gear phasing hub designed to allow a scale marking to be centered in a display window of the refractor and components of the drive assembly to be set in proper rotational orientation as independent operations.

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: An alignment system for an ophthalmic instrument comprises an optical axis along which an operator can directly view the patient's eye and the patient can fixate on a dark fixation target surrounded by a bright background that helps to illuminate the eye for operator viewing. A position detection system utilizing stored geometrical relationships determined by multiple regression during instrument calibration computes X-Y-Z alignment status of the instrument relative to a patient's eye based on local x-y position information from a pair of lateral detectors receiving corneally reflected light from a corresponding pair of lateral light sources. A heads-up display image is provided along an optical axis of the instrument for supplying instructive cues to an operator for moving the instrument to achieve alignment based on signal information from the position detection system, whereby the operator sees both a direct macro-image of the patient's eye and the display image.

Abstract: A subjective ophthalmic refractor is improved for operator visibility in a darkened examination room by forming a cylinder axis scale of the refractor as a light-transmitting component having opaque scale gradations and installing a polar array of illumination sources to project light through the cylinder axis scale, which preferably includes a translucent material for diffuse illumination. In an alternative embodiment, the cylinder axis scale includes a photoluminescent material to which the scale gradations are applied. The refractor is further improved by installing respective illumination sources near a cylinder power readout and a sphere power readout of the refractor. The disclosure additionally relates to a method for retrofitting an ophthalmic refractor to illuminate the cylinder axis scale, cylinder power readout, and sphere power readout.

Abstract: A hand-held non-contact tonometer comprises a housing having a handle portion for enclosing a rechargeable D.C. power source and an upper head portion for enclosing alignment and tonometric measurement systems of the tonometer. An operator can directly view the patient's eye along an optical axis extending through the head portion of the housing, and an instructional display image is superimposed with the directly viewed image of the eye to guide the operator in X-Y-Z alignment based on data supplied by an afocal position detection system. A transceiver for wireless data exchange and a recharging support stand are also provided.

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.