US3879113A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photo-refractometer and methods for ophthalmic testing of young children
Assignee: Individual
•
Filing: 1973-05-07
•
Granted: 1975-04-22
•
Expires: 1993-05-07
Abstract
Abstract Because the retina of the normal eye is an imperfect absorber of light, a portion of the light that reaches the retina is reflected back through the lens. If one''s eye is focussed at a point source of light, the retroreflected light is concentrated by the eye in a small circle surrounding the source; the more accurately focussed the eye, the smaller the spot. Eye testing apparatus and methods are described in which the source is the tip of a fiber optic probe, and the retroreflected light is captured by a camera lens surrounding the probe. The eye defects are quantified by a plurality of cylindrical sector lenses arranged pie-slice fashion around the probe, each of which forms the arm of a star pattern on the film which is a measure of the amount and kind of refractive error. The apparatus is extended by the use of fixed reflectors on eyeglass frames so that phoria may be measured from pupil spacing and position relative to the fixed images of the reflectors. The methods take advantage of inherent chromatic abberation of the eye.
Inventors
- 👤 Howard C Howland
- 👤 Bradford Howland
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:29
CPC Classifications
A; A61; A61B; A61B3/00; A61B3/10; A61B3/103; A61B3/1035; A61B3/14
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
97 words
A method of testing the eyes of a subject comprising the steps of a. directing a flash from substantially a point source toward the eyes of said subject, b. capturing the retroflected light from the retina of an eye by a photographic camera having a lens and a plurality of cylinder lenses overlaying said camera lens surrounding said source, and c. measuring the size and ellipticity of the beam of retroflected light from said eyes for at least two colors whereby saId size and ellipticity is a function of the refractive and astigmatic states of said eyes.
Claim 2
Independent Claim
97 words
A method of testing the eyes of a subject comprising the steps of a. directing a flash from substantially a point source toward the eyes of said subject, b. capturing the retroflected light from the retina of an eye by a photographic camera having a lens and a plurality of cylinder lenses overlaying said camera lens surrounding said source, and c. measuring the size and ellipticity of the beam of retroflected light from said eyes for at least two colors whereby saId size and ellipticity is a function of the refractive and astigmatic states of said eyes.
Claim 3
Dependent Claim
58 words
The method of claim 1 d. wherein said flash is of red light transmitted through a fiber-glass guide to the center of said camera lens, e. together with the step of directing through said guide a second flash of blue light, f. wherein said retroflected light from said two flashes are captured in successive frames of photographic film.
Claim 4
Dependent Claim
20 words
The method of claim 2 g. wherein said measuring step comprises converting said retroflected light to star images for measurement.
Claim 5
Dependent Claim
49 words
For the detection of hyperopia the method of Claim 3 in further combination with the steps of (h) furnishing the subject with strong reading glasses, (i) directing a third flash toward said eyes, and (j) measuring the extent and density resulting star images of the pupils of said eyes.
Claim 6
Independent Claim
149 words
A method for the detection of phoria in a subject, a. fixing to the head of the subject a pair of retroflectors one near each eye, b. covering one eye with a color filter to transmit a first color and to absorb a second color, c. presenting a target illuminated by said second color, d. while said subject is observing said target illuminated with said second color, directing a flash from substantially a point source toward the eyes of said subject, e. capturing the retroflected light from the retina of said eyes by analyzing means surrounding said source, f. recording said retroflected light, and g. measuring the size and position of the beams reflected from said eyes relative to the reflections from said retroflectors whereby the size and position of the reflected beams relative to the reflections from said retroreflections are a function of the phoria of said subject.
Claim 7
Independent Claim
149 words
A method for the detection of phoria in a subject, a. fixing to the head of the subject a pair of retroflectors one near each eye, b. covering one eye with a color filter to transmit a first color and to absorb a second color, c. presenting a target illuminated by said second color, d. while said subject is observing said target illuminated with said second color, directing a flash from substantially a point source toward the eyes of said subject, e. capturing the retroflected light from the retina of said eyes by analyzing means surrounding said source, f. recording said retroflected light, and g. measuring the size and position of the beams reflected from said eyes relative to the reflections from said retroflectors whereby the size and position of the reflected beams relative to the reflections from said retroreflections are a function of the phoria of said subject.
Claim 8
Dependent Claim
104 words
Apparatus for eye testing comprising, a. a camera for taking photographs having a large objective lens aperture, b. a point source of light positioned effectively at the center of said objective and directed along the camera axis toward a subject to be tested, and c. an analyzer lens assembly comprising a plurality of cylinder lens sectors situated pie-slice fashion around said source to intercept said light retroflected from the retina of the eyes of said subject whereby the characteristics of the reflected light on said analyzer lens assembly means is a function of the refractive and astigmatic states of the eyes of said subject.
Claim 9
Dependent Claim
104 words
Apparatus for eye testing comprising, a. a camera for taking photographs having a large objective lens aperture, b. a point source of light positioned effectively at the center of said objective and directed along the camera axis toward a subject to be tested, and c. an analyzer lens assembly comprising a plurality of cylinder lens sectors situated pie-slice fashion around said source to intercept said light retroflected from the retina of the eyes of said subject whereby the characteristics of the reflected light on said analyzer lens assembly means is a function of the refractive and astigmatic states of the eyes of said subject.
Claim 10
Dependent Claim
44 words
Apparatus as defined by claim 6, d. wherein said aperture is greater than 20 mm. in diameter, e. said source is the tip of a fibre-optic light guide not more than 5 mm in diameter, and said sectors have at least three non-parallel axes.
Claim 11
Dependent Claim
29 words
Apparatus as defined by claim 6, in further combination with d. filter means for limiting the spectral content of said source to a small fraction of the visible spectrum.
Claim 12
Dependent Claim
31 words
Apparatus as defined by claim 8 in further combination with e. means to present with light from another fraction of the visible spectrum an image to be viewed by said subject.
References Cited (Backward Citations)
US3519338A
Cited
US3602580A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |