Abstract: A corneal topography slit image alignment system 10, includes a half-slit projector 14 for projecting half-slit images onto a patient's eye 16. Half-slit images 28 and 30 are aligned into a single slit image. A camera 18 captures an image of the aligned slit image. Processor 20 including a memory 26 connected to the half-slit projector 12 and the camera 18 analyzes the alignment of the half-slit images 28 and 30. An edge detector 22 detects the edges of each captured half-slit image and determines an amount of misalignment of the half-slit images 28 and 30 relative to half-slit images being aligned into a single slit image. This amount of misalignment allows computer processor 20 to correct the three-dimensional coordinates of the slit images obtained by a slit beam system 14.

Abstract: A corneal topography slit image alignment system 10, includes a half-slit projector 14 for projecting half-slit images onto a patient's eye 16. Half-slit images 28 and 30 are aligned into a single slit image. A camera 18 captures an image of the aligned slit image. Processor 20 including a memory 26 connected to the half-slit projector 12 and the camera 18 analyzes the alignment of the half-slit images 28 and 30. An edge detector 22 detects the edges of each captured half-slit image and determines an amount of misalignment of the half-slit images 28 and 30 relative to half-slit images being aligned into a single slit image. This amount of misalignment allows computer processor 20 to correct the three-dimensional coordinates of the slit images obtained by a slit beam system 14.

Abstract: An ophthalmic placido pattern 10 is used to determine a curvature of an anterior surface of a cornea of an eye. The pattern 10 includes a series of alternating light and dark concentric rings 12 and 14 centered about a central point 16. A series of shaped geometric shapes 18 and 20 are placed about at least some of the concentric rings 12 and 14. The shapes 18 and 20 are of a contrasting color with respect to the ring 12 or 14 on which the shape 18 or 20 is placed.

Abstract: An ophthalmic eye evaluation system 10 includes a pattern 12 of alternating light and dark areas. An illumination source 14 projects the pattern 12 onto a patient's eye 16. A camera 18 captures one or more images of the pattern 12 reflected from the eye 16. A memory 20 is connected to the camera 18 for storing the images of the reflected pattern. An edge detector 22 determines a transition point where the stored reflected pattern alternates from a light area to a dark area. The edge is determined as being at a point 50% between a maximum stored intensity level and a minimum stored intensity level.

Abstract: A placido pattern 10 for use in obtaining a topography of an eye, includes a series of spaced arcuate segments 12 centered about a central point 14 and a series of spaced radial lines 16 emanating from the central point 14. Each pair of adjacent radial lines 16 defines a boundary of a portion of the arcuate segments 12.

Abstract: A placido pattern 10 for use in obtaining a topography of an eye, includes a series of spaced arcuate segments 12 centered about a central point 14 and a series of spaced radial lines 16 emanating from the central point 14. Each pair of adjacent radial lines 16 defines a boundary of a portion of the arcuate segments 12.