Humphrey Instruments Incorporated

Optical Research and Development Corporation

Other

William E Humphrey

Charles E Campbell

Donald E Lehmer

James E Sheedy

A computer indicated lens movement direction protocol is utilized in combination with a lensmeter to designate required movement of lenses with respect to a lensmeter to insure sequential measurement of progressive addition lenses. Lens measurement occurs at four sample points closely spaced on the lens surface. The system uses power variations (PV.sub.1 and PV.sub.2) at each of the spaced apart lens sampling points to indicate when sampling of the lens occurs in a region of constant spherical power, when sampling of the lens occurs in a region of changing spherical power, and finally when sampling again occurs in a region of constant and increased spherical power. When sampling of the lens occurs in a region of changing power, lens movement is guided along a path of constantly changing sphere utilizing changes in astigmatism measured in the 45.degree.-135.degree. directions (C.sub.X). A lens examination protocol is set forth with vector indicators setting forth the vertical direction required for movement as well as both desired left and right movement to maintain the shortest possible path between the respective lens portions.

Lensometer with guided lens movement for progressive addition lens

An objective refractor having no moving parts is disclosed. The refractor, which can be either a hand held or table mounted instrument, includes a reference array and an interrogating array projected onto the eye fundus. The reference array is projected from light sources and the interrogating array is projected to light detectors. Both the reference array and the interrogating array are projected onto the fundus of the eye through preselected spaced apart regions of the eye lens. The movement of the reference array with respect to the interrogating array is observed. By the expedient of making at least two sequential observations utilizing at least three separate regions of the eye lens, the amount of relative pattern displacements can be reduced to a requisite optical prescription for the eye.

Objective refractor

In an eye field tester, a vidicon camera observes the eye being tested and relays the resultant low light level image to the periphery of a digital display. The digital display contains both an image of the eye on the periphery and the plot of the visual field of the eye under test in the center. The vidicon observing the position of the eye has its horizontal and vertical sync pulses software generated to presettable counters. These counters generate corresponding delayed horizontal sync and vertical sync pulses for the vidicon. As a result of the delayed sync pulses, the central eye image of the vidicon is offset to the periphery of the digital screen (typically to the upper left-hand portion thereof). The offset image is gated into character spaces on the digital screen utilizing software generated character attribute.

Superimposed analog video image on plotted digital field tester display

An optical system for forming an image of the retina of the human eye. The system includes a rotating drum having transmission/receiving slit pairs formed thereon. The rotation of the drum scans an illumination region and viewing beam across the retina. Embodiments for forming stereo images, for synchronizing the formation of the image of the retina with the sweep of a vidicon tube, for automatically focusing the system, for providing flare control, for providing displaced slit functions, and for providing multiple functions are included.

Fundus camera

A wide angle lens system of at least two, and preferably four, similar powered symmetrical component lenses is disclosed; these lenses are from object to image, at least two paired concavo-convex lenses, and preferably two lenses of a concavo-convex or convexo-convex type. The first and last lenses are displaced and rotated usually by rotation about the object (taken as a defining aperture of the optical system, such as a portion of the cornea) or its conjugate, in a first direction to use lens portions between the lens center and one edge; the intermediate lens (preferably the second and third lenses) are displaced and rotated (again usually by rotation about the image conjugate formed by the first lens) in an opposite direction to use the lens portions between the other lens edge and center. Deflected rays in the lens system utilize marginal portions of the lens between the center and one edge only; neither the non-deviating portion of the spherical lenses nor the opposite side of the spherical lenses are used. The lenses are non-concentric. Consequently, the lenses can be further minimally rotated as required for optimum flare rejection.

Wide angle lens system having flare rejection properties

An objective refractor for the eye is disclosed in which knife-edge optics are utilized. The knife-edge optics cause characteristic illumination of the retina so that components of sphere and astigmatism can be identified. Provision for remote reading of the characteristic images is provided with the result that two orthogonally disposed knife-edge images can identify the sphere, cylinder and axis required for prescriptive patterns giving the direction and magnitude of required prescriptive change. A system of at least two orthogonally disposed, (and preferably four), knife edges with weighted lighting is disclosed for detection. Utilization of the knife-edge images is made possible by the detection of the low light level images at a detector having low noise level. A photo-sensitive element divided into a plurality of photo-discrete segments has light from the images proportionally dispersed over its surface. Such dispersion occurs through a matrix of wedge-shaped segments or alternately in the form of optical elements having cylindrical components. This dispersion of the light when used in combination with push-pull knife-edge patterns herein disclosed produces detectable low level refractive signal. An embodiment using an optic having a plurality of side by side optic elements, each element having the effect of crossed cylinders, is disclosed with the detector. Separate independent and non-interactive positional information on one hand, and refractive information on the other hand, is provided. Consequently the disclosed refractor is insensitive to adjustment and can accommodate a large range of pupil configuration with insensitivity to local retinal variations in light emission.

Objective refractor for the eye

A method for use with an eye examination instrument for automatically aligning the eye under examination with the instrument optical axis. An operator initially aligns the instrument optical axis manually with the eye under examination. A first adjustment to the initial alignment is then automatically made in the optical train of the instrument so as to laterally align the eye under examination. The size of the lateral adjustment is determined, and an axial adjustment of the optical train is automatically effected by an amount controlled by the size of the lateral adjustment so as to axially align the eye under examination, whereby the requisite axial adjustment is determined directly from the accomplished lateral adjustment without the need for intervention of the operator.

Method for aligning an eye examination instrument with the eye under

A field tester wherein a patient's tested eye is located at the center of an interior hemisphere defining a projection surface and wherein a light spot is projected onto said surface from an eccentric location is disclosed. Optics in common with the projector assure that the off-center projected light is of constant intensity and diameter as selected for each test sequence according to test criteria. Specifically, a filament light source is projected to a collimating lens. The light source is re-imaged to a system lens stop. There is a movable aperture between the collimating lens and the first lens of telescopic optics for projecting the image of the aperture onto the projection surface of the sphere. By using a coordinate transform to predict the distance from the point of light source projection to the projection surface of the sphere, the movable aperture is registered to a conjugate distance with respect to the telescope optics. Aperture registration insures projection of a constant image of the aperture to any point along sphere surface. There results a field testing spot of constant diameter and intensity, according to selected image criteria, in spite of a continuously changing distance between the point of projection and projecting surface on the inside projection hemisphere. An apertured finder for centering of the patient's eye is also disclosed wherein relay optics projecting a real image of the patient's eye as viewed through a peep hole assure a wide angle view of the eye being tested. The eye is viewed through an aperture having a sight that does not significantly interfere with the test being conducted.

Field tester

A keratometer is disclosed in which at least some of the light entrance and exit paths have both peripheral entrance and exit paths. Eye positional information and sphere, cylinder and axis information for each sampled area (preferably in the order of 3) are obtained by analysis of the reflected and returned light. Sample of a multiplicity of areas on the eye occurs simultaneously without eye panning and generates a topographical measurement of the eye useful for contact lens fitting eliminating most of the incidence of refit on patients in placement of prescribed contact lenses. In one embodiment, a moving boundary locus sweeps an area of light emission from a plurality of coded, spaced apart point light sources. The area of light swept is imaged from the source to the cornea. The locus in its occulting sweep is incident upon the eye at a conjugate point image and reflected from the eye in a diverging light bundle to a plurality of detectors each with its own aperture for sampling the image of that part of the moving boundary locus which is deflected by the particular eye curvature and spacing to the detector aperture. In another embodiment, multiple apertures each image a plurality of coded and spaced apart light sources. These light sources are imaged from their source to the cornea. The light sources in reflection from the cornea are imaged to a vidicon tube in a pattern of reflection where image size and spacing yields telltale information relating to eye curvature and spacing. In both embodiments, identifiable light source patterns resulting from triangulation give eye positional information. Likewise in both embodiments, identifiable two dimensional image shapes and size give sphere, cylinder and axis information. Provision is made for light source coding by either modulation or shape.

Keratometer having peripheral light entrance and exit paths

An analysis of the corneal shape through the combination of several keratometer measurements is disclosed. The eye is preferably scanned to a nasal angular position, a central angular position and a temporal angular position. The central position is straight ahead along the patient's line of sight. The temporal and nasal positions are in the broad range of up to 5.degree. to 22.degree.; the intermediate range of 10 to 15.degree.; and the narrow range of 12.degree. to 14.degree. on either side. Measurements in sphere, cylinder and axes are taken. Astigmatism is in the more preferable format of 0.degree.-90.degree. astigmatism and 45.degree.-135.degree. astigmatism. When each individual point is measured with its respective estimate for sphere and cylinder components, these measurements are fitted to an idealized parameter. Then the three sets of curvature measurements taken at the specified locations are reduced to a set of adjusted, idealized curvatures all fitted to an elliptical model. Thereafter, these fitted values create final corneal shaped parameters, the particular process here including the creation of intermediate parameters. Finally, readings of central 'k', corneal shape, apex position, cap size, vault height, corrected central 'k' and goodness of fit are all set forth.

Growing community of inventors

San Leandro, CA, United States of America

William E Humphrey