Abstract: An ophthalmic apparatus has instrumentation for performing an ophthalmic procedure on a patient's eye when the patient and the instrumentation are aligned with each other with respect to orthogonal X, Y, and Z axes. The Z axis specifies the distance of the eye from the instrumentation. A signal generator generates an initiation signal to initiate alignment of the instrumentation and the eye. An X-Y alignment apparatus and a Z alignment apparatus each respond to the initiation signal to cause alignment along their respective axes and then determine when the instrumentation and the eye are in predetermined relative positions along the Z axis. The X-Y alignment apparatus and the Z alignment apparatus each generate a respective alignment signal. A controller receives the Z alignment signal and the X-Y alignment signal and issues a control signal to the instrumentation to perform an ophthalmic procedure in response to the alignment signals.

Abstract: A microscope having a high effective numerical aperture (NA) is achieved in an apparatus in which a real, three-dimensional image is formed of an object placed in an aperture at the apex of one of two facing, axially-aligned concave mirrors. The three-dimensional image is acquired by a video camera positioned in a counterpart aperture at the apex of the other mirror and the acquired image is processed by computer. The processing corrects the acquired image using the point spread function of the mirror system which was previously obtained by positioning a point source of light throughout the object space and measuring the pixel values recorded by the camera's array of sensing element while the camera was positioned at different axial distances in the image space.

Abstract: Processing of the two-dimensional image of a three-dimensional object, such as the human cornea, that has been illuminated with a structured light pattern. A specially filtered Fourier transform and inverse transform are processed to yield the instantaneous spatial frequencies of the illuminated pattern. The instantaneous spatial frequencies are mapped to the instantaneous dioptric powers or depth coordinates of the object's surface.

Abstract: Quantitative measurement of corneal surface topography is obtained by processing a two-dimensional image of the surface which reflects a quasi-periodic illuminated pattern, such as series of concentric rings, from a Placido disk source. The local spatial phases exhibited by the image of the illuminated pattern when reflected from the corneal surface and when reflected from standard specular surfaces are obtained by processing the images which includes use of specially filtered Fourier and inverse transforms. The distances at which predetermined local spatial phases are observed in the image from the cornea are compared with the distances at which these same phases are observed in the images of the standard surfaces. The distances are also compared with certain corresponding distances on the Placido disk source and converted to reveal the dioptric powers of refraction of the corneal surface without the need for parametric interpolation.

Abstract: Method for accurately displaying the location of the pupil perimeter on a corneal topography map such as is disclosed in the prior art Gersten et al., U.S. Pat. No. 4,863,260. In the process of deriving such topographic information, the process disclosed in that patent obtained a two-dimensional video image of the cornea. In the method of the present invention, the background illumination of the video image is sampled and the video signal is corrected for the effects of camera distortions, artifacts, and specular glare. The corrected data is analyzed and the point at which the greatest rate of change in background illumination occurs is determined to be a point on the periphery of the pupil. The peripheral points so determined are then displayed in superposition to the corneal topographic map thereby indicating the pupil outline.

Abstract: A cylindrical keratoscope is provided with an improved structure for illuminating the rings disposed along the length of its bore by having the light-transmitting rings defined as the lands between a series of opaquely coated, incised circular grooves in the bore. A circular, fluorescent, light tube is disposed in an aluminum light box having a semi-toroidal concavity provided with a light-reflecting surface to direct or collimate the light from the tube toward the light-receiving base of the device.

Abstract: A device for causing concentric circles of illuminated light to be reflected from the human cornea. The device includes a cylindrical surface which is open at both ends. At one end the eye looks into the cylinder of the device and at the other end a camera or observer can view the illuminated rings on the cornea. The cylinder is advantageously made of transparent plastic or glass having an opaque coating. A lamp box is affixed to an uncoated portion of the device. The coating of the cylindrical surface through is interrupted to define clear rings on the cylindrical surface which light from the lamp box is conducted to be reflected from the cornea.