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US4172639A Expired / Lapsed US ⏱️ 0.0 years remaining

Apparatus for determination of corneal astigmatism

Assignee: Carl Zeiss AG
•
Filing: 1977-09-21
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Granted: 1979-10-30
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Expires: 1997-09-21
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Abstract

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.

Inventors

  • 👤 Walter Lang
  • 👤 Ortwin Mueller

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-24 17:30
CPC Classifications
A; A61; A61B; A61B3/00; A61B3/10; A61B3/13

Claims Analysis

Total Claims: 4
Claim 1
Independent Claim 96 words
Apparatus for use in combination with an operation microscope having an objective lens and two eyepieces for determination of corneal astigmatism of the human eye, said apparatus comprising a circular plexiglass tube surrounding and concentric with said objective, light guide means for conveying light to said plexiglass tube, a reticle associated with one of said eyepieces of said microscope in such position that the image of said plexiglass tube reflected by the cornea back into the microscope may be observed with relation to said reticle, and an ocular micrometer mounted on the other of said eyepieces.
Claim 2
Dependent Claim 96 words
Apparatus for use in combination with an operation microscope having an objective lens and two eyepieces for determination of corneal astigmatism of the human eye, said apparatus comprising a circular plexiglass tube surrounding and concentric with said objective, light guide means for conveying light to said plexiglass tube, a reticle associated with one of said eyepieces of said microscope in such position that the image of said plexiglass tube reflected by the cornea back into the microscope may be observed with relation to said reticle, and an ocular micrometer mounted on the other of said eyepieces.
Claim 3
Dependent Claim 31 words
Apparatus as defined in claim 1, wherein said reticle is marked with diametrical cross lines perpendicular to each other and with a plurality of concentric circles radially spaced from each other.
Claim 4
Dependent Claim 20 words
Apparatus as defined in claim 1, wherein said reticle is marked with a graduated scale extending diametrically across said reticle.

References Cited (Backward Citations)

US1774832A Cited
US3482904A Cited
US3542458A Cited
US3598478A Cited
US3797921A Cited
US4046463A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1982-10-29 1983-04-30 1983-10-30 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1986-10-29 1987-04-30 1987-10-30 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1990-10-29 1991-04-30 1991-10-30 $7700.00 Window Closed / Lapsed

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