Patent US4491398A successfully refreshed from Google Patents.
US4491398A
Expired / Lapsed
US
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Hand-held keratometer
Assignee: Advanced Vision Science Inc
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Filing: 1981-11-30
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Granted: 1985-01-01
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Expires: 2001-11-30
Abstract
Abstract A hand-held keratometer is formed of a handle mounting a circular ring of transparent material having a roughened surface to collect incident light and project a circle of light for use in measuring roundness and, therefore, astigmatism of an eye while being held in the hand of a surgeon, the keratometer carrying indicia to permit the surgeon to radially locate the axis of astigmatism and determine the extent of astigmatism.
Inventors
- 👤 John R. Karickhoff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 16:06
CPC Classifications
A; A61; A61B; A61B3/00; A61B3/10; A61B3/103; A61B3/1035; A61B3/107
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
82 words
A keratometer comprising: an elongate handle; and a circular ring of transparent material mounted on said handle and having a roughened surface to collect incident light and project a circle of light for use in measuring astigmatism of the eye; wherein said ring carries radially arranged indicia to locate the axis of astigmatism; and wherein said handle carries indicia shapes representative of standards of astigmatism to facilitate the determination of the extent of astigmatism present in an eye being measured by comparison.
Claim 2
Dependent Claim
82 words
A keratometer comprising: an elongate handle; and a circular ring of transparent material mounted on said handle and having a roughened surface to collect incident light and project a circle of light for use in measuring astigmatism of the eye; wherein said ring carries radially arranged indicia to locate the axis of astigmatism; and wherein said handle carries indicia shapes representative of standards of astigmatism to facilitate the determination of the extent of astigmatism present in an eye being measured by comparison.
Claim 3
Dependent Claim
68 words
A keratometer comprising: an elongate handle; and a circular ring of transparent material mounted on said handle and having a roughened surface to collect incident light and project a circle of light for use in measuring astigmatism of the eye; wherein said handle carries indicia shapes representative of standards of astigmatism to facilitate the determination of the extent of astigmatism present in an eye being measured by comparison.
Claim 4
Dependent Claim
68 words
A keratometer comprising: an elongate handle; and a circular ring of transparent material mounted on said handle and having a roughened surface to collect incident light and project a circle of light for use in measuring astigmatism of the eye; wherein said handle carries indicia shapes representative of standards of astigmatism to facilitate the determination of the extent of astigmatism present in an eye being measured by comparison.
Claim 5
Dependent Claim
141 words
A keratometer comprising: an elongate handle; and a circular ring of transparent material mounted on said handle and having a roughened surface to collect incident light and project a circle of light for use in measuring astigmatism of the eye; wherein said handle has a free end and a neck joining said ring having a width less than the width of said free end; wherein said ring is rectangular in cross section; wherein said ring and said handle are integrally formed of plastic material; and wherein said roughened surface of said ring carries radially arranged indicia for locating the axis of astigmatism, and said handle carries shape indicia representative of standards of astigmatism for determining by comparison the extent of astigmatism present in an eye being measured, said radially arranged indicia and said shape indicia being disposed to be simultaneously visible.
Claim 6
Dependent Claim
141 words
A keratometer comprising: an elongate handle; and a circular ring of transparent material mounted on said handle and having a roughened surface to collect incident light and project a circle of light for use in measuring astigmatism of the eye; wherein said handle has a free end and a neck joining said ring having a width less than the width of said free end; wherein said ring is rectangular in cross section; wherein said ring and said handle are integrally formed of plastic material; and wherein said roughened surface of said ring carries radially arranged indicia for locating the axis of astigmatism, and said handle carries shape indicia representative of standards of astigmatism for determining by comparison the extent of astigmatism present in an eye being measured, said radially arranged indicia and said shape indicia being disposed to be simultaneously visible.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-01-01 | 1988-07-02 | 1989-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-01 | 1992-07-02 | 1993-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-01 | 1996-07-02 | 1997-01-01 | $7700.00 | Window Closed / Lapsed |