WO1998036680A1 - Non-contact tonometer having off-axis fluid pulse system - Google Patents
Non-contact tonometer having off-axis fluid pulse system Download PDFInfo
- Publication number
- WO1998036680A1 WO1998036680A1 PCT/US1998/001692 US9801692W WO9836680A1 WO 1998036680 A1 WO1998036680 A1 WO 1998036680A1 US 9801692 W US9801692 W US 9801692W WO 9836680 A1 WO9836680 A1 WO 9836680A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- axis
- fluid
- fixation
- tonometer
- eye
- Prior art date
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/16—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for measuring intraocular pressure, e.g. tonometers
- A61B3/165—Non-contacting tonometers
Definitions
- the present invention relates generally to ophthalmic instruments, and more particularly to a non-contact tonometer for measuring intraocular pressure (IOP) having a fluid axis which is angularly displaced from a fixation axis of the instrument.
- IOP intraocular pressure
- Non-contact tonometers for measuring IOP have been constructed for over twenty-five years to operate by forcing a fluid, such as air, through a discharge nozzle toward a cornea of a patient to flatten the cornea, a condition known in the art as applanation.
- the fluid impulse necessary to cause applanation is monitored and correlated to IOP.
- the fluid discharge nozzle defines a fluid axis which coincides with a fixation axis of the instrument.
- blink response time is on the order of 100 milliseconds, far slower than the 5 milliseconds required for measurement of even the highest IOPs, and thus the eyelid typically does not interfere with IOP measurement.
- clinical observers have found that in testing some individuals who naturally carry their eyelids substantially lower than a majority of the population, it is often necessary to manually raise the eyelid to prevent the eyelid from interfering with IOP measurement. Also, an inadvertent blink by the patient just prior to the fluid pulse may interfere with IOP measurement.
- a non-contact tonometer of the present invention includes a fixation axis having a fixation target presented therealong for fixing the gaze of the eye in the direction of the fixation axis, and a fluid axis forming a non-zero angle with the fixation axis.
- the fixation and fluid axes reside in a substantially vertical plane, with the fluid axis approaching the eye from below the fixation axis.
- Optical alignment means is provided for positioning the fluid axis normal to the comeal surface, and applanation detection means is provided for determining the condition of applanation caused by a fluid pulse.
- Fig. 1 is a schematic side elevational view of a non- contact tonometer formed in accordance with a preferred embodiment of the present invention
- Fig. 2 is a schematic top plan thereof
- Fig. 3 is a graph of average IOP measurements taken using an "off-axis" tonometer formed in accordance with the present invention against average IOP measurements for the same test subjects taken using a "straight ahead" tonometer of the prior art.
- a non-contact tonometer generally designated as 10 is shown schematically in an aligned position relative to an eye 2 for measuring IOP.
- Eye 2 is fixated on target light presented along a fixation axis 12 by a beam splitter 16 centered on the fixation axis which redirects light from a target light source 14 located remotely of the fixation axis, as is well-known in the art of tonometry.
- fixation axis 12 intersects comeal surface 4 at the comeal vertex 7.
- Tonometer 10 further includes fluid discharge means in the form of a nozzle 20 which defines a fluid axis 18 along which a fluid pulse travels to reach comeal surface 4.
- Nozzle 20 communicates in a conventional manner with air pulse generation means, such as a piston mechanism, not shown.
- air pulse generation means such as a piston mechanism, not shown.
- fluid axis 18 forms a nonzero angle ⁇ with fixation axis 12 , with a vertex located at the center of curvature 9 of comeal surface 4.
- fluid axis 18 is situated in the same vertical plane as fixation axis 12, and is below the fixation axis approaching eye 2.
- Non-zero angle ⁇ is desirably between 10 and 15 degrees, and most desirably 11 degrees, so as to move the point of incidence of the air pulse on comeal surface 4 further away from upper eyelid 6 relative to prior art tonometers, without involving lower eyelid 8, and without need to applanate a surgically altered comeal region in a PRK patient. Since the pressure of the fluid contained within the anterior chamber of the eye is the same at all points (neglecting the very slight effects of gravity) , IOP measurement is not changed by varying the point of incidence of the fluid pulse. Moreover, lower eyelid 8 is not prone to significant movement which would hamper or interfere with testing.
- Fig. 3 is a graphical representation showing the results of a micro-clinical trial in which twenty-nine eyes of fifteen test subjects were tested with a prior art non-contact tonometer having coincident (zero-degree angle) fluid and fixation axes, and also with a non-contact tonometer of the present invention having a fluid axis forming a ten-degree angle with a fixation axis thereof. A total of six measurements were made for each eye, three measurements with the zero-degree instrument of the prior art and three measurements with the ten-degree instrument of the present invention. The averages of each set of three measurements are plotted against each other in Fig. 3.
- the alignment system may provide a visual instruction to the practitioner for manual positioning of the test portion of the instrument, or it may provide signal information to automatic means for positioning the test portion of the instrument.
- a conventional applanation detection system is also provided, but like the chosen alignment system, it is arranged to accommodate for the novel angular orientation of fluid axis 18 relative to fixation axis 12.
- the applanation detection system includes an emitter 30 on one side of fluid axis 18, and a lens 32, a pin-hole occluder 34, and a photo-detector 36 on the opposite side of fluid axis 18.
- Emitter 30, photo-detector 32, occluder 34, and photo-detector 36 are preferably aligned in a common plane with fluid axis 18, such that when flattening of comeal surface 4 occurs in response to a fluid pulse, a peak flux is detected by photo-detector 32 in a known manner.
- a suitable applanation detection system is currently used in the XPERT ® NCT manufactured by Reichert Ophthalmic Instruments.
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Medical Informatics (AREA)
- Biophysics (AREA)
- Ophthalmology & Optometry (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Heart & Thoracic Surgery (AREA)
- Physics & Mathematics (AREA)
- Molecular Biology (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Eye Examination Apparatus (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA002269761A CA2269761A1 (en) | 1997-02-21 | 1998-02-02 | Non-contact tonometer having off-axis fluid pulse system |
EP98903815A EP1018929A4 (en) | 1997-02-21 | 1998-02-02 | Non-contact tonometer having off-axis fluid pulse system |
JP10536640A JP2001500419A (en) | 1997-02-21 | 1998-02-02 | Non-contact tonometer with off-axis fluid pulse system |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/804,004 US5754273A (en) | 1997-02-21 | 1997-02-21 | Non-contact tonometer having off-axis fluid pulse system |
US08/804,004 | 1997-02-21 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1998036680A1 true WO1998036680A1 (en) | 1998-08-27 |
Family
ID=25187949
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1998/001692 WO1998036680A1 (en) | 1997-02-21 | 1998-02-02 | Non-contact tonometer having off-axis fluid pulse system |
Country Status (5)
Country | Link |
---|---|
US (1) | US5754273A (en) |
EP (1) | EP1018929A4 (en) |
JP (1) | JP2001500419A (en) |
CA (1) | CA2269761A1 (en) |
WO (1) | WO1998036680A1 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5954645A (en) * | 1998-04-03 | 1999-09-21 | Leica Microsystems Inc. | Applanation detection system for a non-contact tonometer |
US7630612B2 (en) * | 2003-02-10 | 2009-12-08 | At&T Intellectual Property, I, L.P. | Video stream adaptive frame rate scheme |
JP5443225B2 (en) * | 2010-03-23 | 2014-03-19 | 株式会社トプコン | Non-contact tonometer |
JP6057621B2 (en) * | 2012-08-30 | 2017-01-11 | キヤノン株式会社 | Ophthalmic apparatus and control method thereof |
KR101358079B1 (en) | 2013-11-04 | 2014-02-04 | 차순호 | Blower |
US20150182291A1 (en) | 2013-12-30 | 2015-07-02 | L'oreal | Devices and methods for protecting the eye from adjacent skin treatments |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4834527A (en) * | 1986-09-24 | 1989-05-30 | Tokyo Kogaku Kikai Kabushiki Kaisha | Working distance alignment optical system for ophthalmological instrument |
US5502521A (en) * | 1993-04-30 | 1996-03-26 | Nidek Co., Ltd. | Ophthalmometric apparatus |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4881807A (en) * | 1988-08-05 | 1989-11-21 | Cambridge Instruments, Inc. | Optical alignment system |
-
1997
- 1997-02-21 US US08/804,004 patent/US5754273A/en not_active Expired - Fee Related
-
1998
- 1998-02-02 CA CA002269761A patent/CA2269761A1/en not_active Abandoned
- 1998-02-02 WO PCT/US1998/001692 patent/WO1998036680A1/en not_active Application Discontinuation
- 1998-02-02 EP EP98903815A patent/EP1018929A4/en not_active Withdrawn
- 1998-02-02 JP JP10536640A patent/JP2001500419A/en active Pending
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4834527A (en) * | 1986-09-24 | 1989-05-30 | Tokyo Kogaku Kikai Kabushiki Kaisha | Working distance alignment optical system for ophthalmological instrument |
US5502521A (en) * | 1993-04-30 | 1996-03-26 | Nidek Co., Ltd. | Ophthalmometric apparatus |
Also Published As
Publication number | Publication date |
---|---|
EP1018929A1 (en) | 2000-07-19 |
EP1018929A4 (en) | 2004-04-21 |
JP2001500419A (en) | 2001-01-16 |
US5754273A (en) | 1998-05-19 |
CA2269761A1 (en) | 1998-08-27 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6685320B2 (en) | Opthalmic characteristic measuring apparatus | |
US4799784A (en) | Visual vertex finder | |
EP1419729B1 (en) | Alignment guidance system | |
EP1767144B1 (en) | Eye refractive power measurement apparatus | |
CA2520222C (en) | Method and apparatus for eye alignment | |
EP0371590A1 (en) | Non-contact ultrasonic tonometer | |
US20060192921A1 (en) | Device and method for aligning an eye with a surgical laser | |
CN102843955A (en) | Purkinjie image-based alignment of suction ring in ophthalmic applications | |
EP1332712A1 (en) | Eye characteristics measuring device | |
EP0729327A1 (en) | Optical guide and measurement appliance | |
EP1147738A1 (en) | Non-contact tonometry method | |
US5754273A (en) | Non-contact tonometer having off-axis fluid pulse system | |
KR20190074637A (en) | Tonometer | |
JP4663148B2 (en) | Eye characteristics measuring device | |
JPH08103413A (en) | Ophthalmological measuring instrument | |
JP3108261B2 (en) | Ophthalmic instruments | |
JP3870150B2 (en) | Ophthalmic measuring device | |
US5024518A (en) | Ophthalmic contact lens with internal fixation light for examination of the optic nerve | |
US5101826A (en) | Noncontact type tonometer | |
US20210369105A1 (en) | Visual axis identification systems and methods | |
CN115397307A (en) | System and method for identifying human visual axis | |
JPH07231875A (en) | Optometrical device | |
JPH03176023A (en) | Ophthalmic apparatus | |
JPH0357204Y2 (en) | ||
Verdoorn et al. | Clinical evaluation of the Topcon CT10 tonometer |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): CA JP |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE |
|
DFPE | Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101) | ||
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
ENP | Entry into the national phase |
Ref document number: 2269761 Country of ref document: CA Ref country code: CA Ref document number: 2269761 Kind code of ref document: A Format of ref document f/p: F |
|
ENP | Entry into the national phase |
Ref country code: JP Ref document number: 1998 536640 Kind code of ref document: A Format of ref document f/p: F |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1998903815 Country of ref document: EP |
|
WWP | Wipo information: published in national office |
Ref document number: 1998903815 Country of ref document: EP |
|
WWW | Wipo information: withdrawn in national office |
Ref document number: 1998903815 Country of ref document: EP |