Ophthalmic pachymeter and method of making ophthalmic determinations

A densitometer for aiding in determining the thickness and relative optical density of the cornea of an eye on a real-time basis, said densitometer comprising:

• a) slit projector means for illuminating portions of the cornea of the eye;
• b) imaging means for generating a series of television images of sequential individual segments of the portions of the cornea of the eye illuminated by the slit projector means;
• c) converter means for converting the television images into digitally encoded images;
• d) illumination means for illuminating individual preselected areas of the cornea of the eye in which the digitally encoded images are to be generated and which operates in conjunction with the slit projector means;
• e) processing means for receiving the digitally encoded images from the slit projector means and generating data used in the determination of the thickness and of the optical density of the cornea said processing means generating the data related to the digitally encoded images at substantially the same time that the digitally encoded television images of the eye are being generated;
• f) storage means associated with the processing means for receiving and storing the processed digitally encoded television images in digital format;
• and
• g) means operatively connected to the storage means for regenerating the images which were stored in the storage means.

A system for producing surface contour maps of the cornea of the eye comprising:

• a) a projection illumination means for illuminating areas of the cornea for producing a definable spatial delineation of corneal contour;
• b) slit image means moveable across and relative to the surface of the cornea in which a contour image is to be generated;
• c) video signal generating means for rendering the illuminated areas into electrical analog signals;
• d) digitizer means for conversion of the said analog signals into computer acceptable digital signals;
• and
• e) computer means for processing the digital signals and generating data to provide a determination of the corneal surface shape from said digital signals and generating control signals for generating a map of the surface contour of the cornea of the eye.

A densitometer for aiding in determining the thickness and relative optical density of the cornea of an eye on an real-time basis, said densitometer comprising:

• a) optical projector means for illuminating a portion of the cornea of the eye;
• b) an optical slit associated with the projector means for creating slit illuminated portions of the eye;
• c) signal generating means for generating a series of optical images of a section of the cornea of an eye;
• d) converting means for converting the video images into equivalent digital signals representative of the video images to create digitally encoded images;
• e) fiducial means operating in conjunction with the converting means for delineating portions of the video images which are to be converted into digital signals;
• f) processing means for receiving the digitally encoded images and providing data for determination of the thickness and relative optical density of the cornea, said signal generating means generating video images at essentially the same time as the processing means enables such determination so that the densitometer makes such determination on a real time basis;
• and
• g) storage means for receiving the digitally encoded images and storing same for later regeneration of such stored images.

In an ophthalmic pachymeter of the type which has a light source for illuminating a portion of the cornea and imaging means to enable generating television images of the cornea in conjunction with a slit moving with respect to the plane of the cornea and generating such images during the movement, an improved circuit arrangement comprising:

• a) analog to digital converter means for converting analog video signals to corresponding digital signals;
• b) computer interfacing means for connection to a digital computer;
• c) a data memory operatively connected to said interfacing means and said analog to digital converter means for storing the corresponding digital signals;
• d) a mode controller operatively connected to said computer interfacing means for determining and controlling sequence of operations;
• e) driving means operatively connected to said computer interfacing means for driving a fixation light means for maintaining a fixation of the eye of a subject in relation to a slit moving with respect to the plane of the cornea.

An ophthalmic instrument for determining physical characteristics of an eye to aid in identifying exact and precise locations of optical discontinuities and/or aberrations of the eye, said instrument comprising:

• a) a light projector means for illuminating a portion of an eye;
• b) electronic imaging means for obtaining an analog signal image of illuminated portions of the eye;
• c) slit means optically interposed between the light projector means and the electronic imaging means;
• d) means causing relative movement of the slit means relative to the eye to enable a plurality of slit image exposures of the eye during such relative movement and generation of video image signals of such slit image exposures;
• e) converter means for converting the video image signals into digital signals for digital processing;
• and
• f) processing means receiving the digital signals from the converter means for processing the signals to identify discontinuities and optical aberrations of the eye.

A method for ascertaining the extent of an optical aberration or an optical discontinuity of tissue of the eye comprising the steps of:

• a) selectively illuminating the tissue area to be analyzed;
• b) receiving and quantifying an image of the said tissue;
• c) delineating the portions of the image which contains the optical aberration or optical discontinuity and also delineating a reference area;
• d) converting said delineated area into digital data;
• and
• e) analyzing the relative numerical magnitude of said digital data to ascertain the severity of the optical aberration or optical discontinuity.

A method for ascertaining a physical characteristic of an eye comprising the steps of:

• a) selectively illuminating tissue area of the eye to be analyzed;
• b) generating a series of successive images of successive portions of the illuminated tissue area;
• c) receiving and quantifying the images of the said tissue area;
• d) delineating portions of the images and a reference area;
• e) conversion of the said portions of the images in the delineated areas into digital data;
• and
• f) analyzing the relative numerical magnitude of the said digital data to ascertain the physical characteristics of the eye.

A method for aiding and determining the thickness and relative optical density of the cornea of an eye on a real-time basis, said method comprising:

• a) illuminating a preselected area of the cornea of the eye to enable generation of digitally encoded images;
• b) generating a series of digitally encoded television images of a section of the cornea of an eye;
• c) processing edge data contained in the digitally encoded images to enable a display of corneal contour and thickness from said digitally encoded video images;
• d) generating a display of the corneal thickness and corneal surface contour;
• e) receiving and storing the processed digitally encoded images in a storage means;
• f) recreating the images which were stored in the storage means;
• and
• g) using the digitally encoded images to enable the determination of thickness and relative optical density of the cornea of the eye at essentially the same time as the digitally encoded images are generated.

A method for aiding in determining the thickness and relative optical density of the cornea of an eye on a real-time basis, said method comprising:

• a) illuminating a preselected area of the cornea of the eye in which images are to be generated;
• b) generating a series of video images of a section of the cornea of an eye;
• c) converting the video images into equivalent digital signals representative of the images to create digitally encoded images;
• d) delineating portions of the video images which are to be converted into digital signals;
• e) receiving the digitally encoded images and storing such images in a digital format;
• and
• f) using the digitally encoded images to enable a determination of the thickness and relative optical density of the cornea of the eye and at essentially the same time as the digitally encoded images are generated.

A method for determining physical characteristics of an eye to aid in identifying exact and precise location of optical discontinuities and/or aberrations of the eye, said method comprising:

• a) illuminating a portion of an eye with a light projector means;
• b) obtaining an analog signal image of illuminated portions of the eye with an electronic imaging means;
• c) optically interposing a slit between the light projector means and the electronic imaging means;
• d) causing relative movement of the slit relative to the eye and across the eye;
• e) causing a plurality of slit image exposures of the eye during such relative movement;
• f) generating video image signals of such slit image exposures;
• g) converting the video image signals into digital signals for digital processing thereof to identify discontinuities and optical aberrations;
• and
• h) processing the digital signals representative of the video image signals to determine the precise location of optical discontinuities and/or aberrations of the eye and at essentially the same time as the video image signals are generated.

A densitometer for aiding in determining the thickness and relative optical density of the cornea of an eye on an real-time basis, said densitometer comprising:

• a) optical projector means for illuminating a portion of the cornea of the eye;
• b) an optical slit means associated with the projector means for creating slit illuminated portions of the eye;
• c) means for causing movement of the optical slit means relative to and across the cornea to obtain images of individual sections of the cornea;
• d) optical slit signal generating means for generating a series of optical images of sections of the cornea of an eye;
• e) converting means for converting the video images into equivalent digital signals representative of the video images to create digitally encoded images;
• f) fiducial means operating in conjunction with the converting means for delineating portions of the video images which are to be converted into digital signals;
• g) processing means for receiving the digitally encoded images and providing date for determination of the thickness and relative optical density of the cornea, said signal generating means generating video images at essentially the same time as the processing means enables such determination so that the densitometer makes such determination on a real time basis;
• and
• h) storage means for receiving the digitally encoded images and storing same for later regeneration of such stored images.

A method for aiding in determining the thickness and relative optical density of the cornea of any eye on a real-time basis, said method comprising:

• a) illuminating a preselected area of the cornea of the eye in which images are to be generated;
• b) generating a series of individual successive series of video images of individual successive sections of the cornea of an eye;
• c) converting the video images into equivalent digital signals representative of the images to create digitally encoded images;
• d) delineating portions of the video images which are to be converted into digital signals;
• e) receiving the digitally encoded images and storing such images in a digital format;
• and
• f) using the digitally encoded images to enable a determination of the thickness and relative optical density of the cornea of the eye and at essentially the same time as the digitally encoded images are generated.