Apparatus for determination of corneal astigmatism

US4172639A · kind A · utility

Assignee

• Carl Zeiss Stiftung · DE

Inventors

• Walter Lang · Oberkochen, DE
• Ortwin Mueller · Oberkochen, DE

Key dates

• Filing date: Sep 21, 1977
• Grant date: Oct 30, 1979
• Expiry date: Sep 21, 1997

Classification

• Technology area (CPC A): Human Necessities
• CPC primary: A61B3/13
• WIPO field: Medical technology
• WIPO sector: Instruments

Abstract

Apparatus for use with an operating microscope employed in observing the cornea of the human eye, for example in connection with cornea transplant operations. A plexiglass tube surrounds the objective of the microscope and is fed with light from a suitable source, so that an image of the circular illuminated lower end of the plexiglass tube is reflected by the cornea of the patient back into the microscope and is observed by the person using the microscope. The character and extent of distortion of the reflected image is an indication of the corneal astigmatism. The eyepiece of the microscope is provided with a reticle in connection with which the reflected image is observed. In one form of the invention, the recticle has diametrical crossed lines and concentric circular lines. In other form of the invention the recticle has a diametrically extending linear scale, and is used in connection with an eyepiece attachment having means for rotating the recticle to align the linear scale with any desired axis of the reflected image and micrometer means for moving a pointer to measure the length of the reflected image along such axis.