Title of Invention

"AN APPLANATION TONOMETER FOR MEASURING THE LEVELOF INTRAOCULAR PRESSURE"

Abstract This invention relates to an applanation tonometer for measuring the level of intraocular pressure comprising a housing (9) for supporting a movable prism (1), said prism (1) adapted to bear against the cornea of an eye, fulcrumed rod (10) disposed within housing (9) said prism (1) held to one end of said rod (10), a counter weight (6) held to the opposite end of said rod (10), an observation lense (3) provided an face or side of housing (9) opposite to prism (1), opposite to said prism, a light source with said housing adapted to be connected to a power source; a constant pressure member for applying a constant pressure to said prism.
Full Text FIELD OF INVENTION
This invention relates to a tonometer for providing a measurement of the level of
intraocular pressure.
PRIOR ART
A Goldmans applanation tonometer is known in the art and comprises a cone shaped prism, one of the sides of the prism being adapted to be pressed against the cornea of a patient. The pressure applied on the cornea through the prism is increased or decreased by a parallelogram of forces applied onto said cone shaped prism so as to cause a flattening of the cornea. When two spheres are pressed against each other, and the area of applanation or flattening is 3.06 mm diameter, then the pressure inside the two spheres is equal. Thus, the force applied for obtaining such a flattened surface is equal to the intraocular pressure. The tonometer has an operable knob, which increases or decreases the applied force. Thus, the force is increased gradually till the area of applanation has a diameter of 3.06 mm.
A disadvantage associated with such a known tonometer is that it is to be used with a slit lamp biomicroscope. Further, such a tonometer is not portable.
Yet another applanation tonometer known in the art is the Perkins applanation tonometer, which is a modification of the Goldmans tonometer. Such a tonometer also employs a prism. However, it avoids the use of a slit lamp biomicroscope. A disadvantage associated with such a tonometer is that it is expensive.
Yet another tonometer known in the art is a Schiotz tonometer, which is an indentation tonometer. Such a tonometer is not very accurate and the patient must be in a lying down position for a measurement.
The tonometers described hereinabove are eye contact type tonometers. However, non contact type tonometers are also known in the art. Such instruments are not portable. Further, such instruments are expensive and the accuracy of their measurements are questionable.
OBJECTS OF THE INVENTION
An object of this invention is to propose a novel construction of a tonometer for
measuring the level of intraocular pressure.
Another object of this invention is to propose a tonometer which has the advantages of an applanation tonometer.Still another object of this invention is to propose a tonometer which is accurate.
Yet another object of this invention is to propose a tonometer, which is inexpensive.
A further object of this invention is to propose a tonometer, which is portable.
A still further object of this invention is to propose a tonometer, which can be used at any posture for a measurement.
A still further object of this invention is to propose a tonometer and to which a digital camera can be attached.
Yet a further object of this invention is to propose a tonometer which is efficient.
DESCRIPTION OF INVENTION
According to this invention there is provided an applanation tonometer for measuring the level of intraocular pressure comprising:
i) a housing for supporting a movable prism, said prism adapted
to bear against the cornea of an eye, ii) fulcrumed rod disposed within housing said prism held to one
end of said rod, a counter weight held to the opposite end of
said rod, iii) an observation lense provided an face or side of housing
opposite to prism, opposite to said prism, iv) a light source with said housing adapted to be connected to a
power source; v) a constant pressure member for applying a constant pressure to
said prism.
DESCRIPTION WITH REFERENCE TO DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein:
Fig.l shows the tonometer of the present invention Fig.2 shows the form for effecting a measurement.
Reference is made to fig.l which illustrates the tonometer of the present invention to comprise a housing 9 supporting a prism 1. Prism 1 is adapted to bear against the cornea of a patient for effecting a measurement of the level of pressure. A fulcrumed rod 10 is disposed within housing 9, one end of rod 10 held to prism 1 and the opposite end held to a counterweight 6. An observation lense 3 is provided on face or side of housing 9 opposite to prism 1.
A light source such as a light emitting diode 2 is provided below of prism 1 and adapted to be connected to a power source 7 through a switch 4. Thus, prism 1 and counter weight have a movement or displacement about fulcrum 5.
A spring 8 is disposed within housing 9, one end of spring 8 adapted to bear against rod 10, the opposite end of said spring held to housing 9. Spring 8 is a constant force spring which constantly applies a force, for example, of 2000 mg on prism 1 which is equal to 20 mmHg pressure, where applanation surface diameter is 3.06 mm. However, if applanation surface has a diameter greater than 3.06 mm, it reflects that the pressure is less than 20 mm Hg.
Reference is made to Fig.2 in order to effect a measurement of level of intraocular pressure. A ring of green colour is formed around the area of applanation of the cornea due to the stained tear film protecting the cornea, which forms a ring corresponding to the applanation surface. A stain results by applying sodium flurosecent to the eye. Thus, when switch 4 is actuated into an operable position and lamp 2 is connected to power soruce 7, the blue light makes the stain glow green. As it is difficult to measure the ring size, the two halves are cut by the system of prisms 1. When the size of ring is 3.06 mm, then the two halves interlock as shown in fig.2a. However, if the diameter is greater than 3.06 mm diameter then the two halves overlap as shown in Fig.2b and when less than 3.06 mm diameter then the two halves do not touch each other as shown in Fig.2c. Thus, the tonometer of the present invention provides a level of the intra ocular pressure. The prism is a freely floating prism, when the spring is not applied.











I CLAIM;
1. An applanation tonometer for measuring the level of intraocular
pressure comprising:
i) a housing (9) for supporting a movable prism (1),
said prism (1) adapted to bear against the cornea
of an eye, ii) fulcrumed rod (10) disposed within housing (9)
said prism (1) held to one end of said rod (10), a
counter weight (6) held to the opposite end of said
rod (10), iii) an observation lense (3) provided an face or side
of housing (9) opposite to prism (1), opposite to
said prism, iv) a light source with said housing adapted to be
connected to a power source; v) a constant pressure member for applying a
constant pressure to said prism.
2. An applanation tonometer as claimed in claim 1 wherein said
prism (1) is a free floating prism.
3. An applanation tonometer as claimed in claim 1 wherein said pressure member comprises a constant pressure spring held at one end to the rod (10) and at the opposite end to the housing (9).

Documents:

2301-del-2005-Abstract-(09-11-2010).pdf

2301-del-2005-abstract.pdf

2301-del-2005-Claims-(09-11-2010).pdf

2301-DEL-2005-Claims-(30-12-2010).pdf

2301-del-2005-claims.pdf

2301-del-2005-Correspondence-Others-(09-11-2010).pdf

2301-DEL-2005-Correspondence-Others-(30-12-2010).pdf

2301-del-2005-correspondence-others.pdf

2301-DEL-2005-Correspondence-PO.pdf

2301-del-2005-Description (Complete)-(09-11-2010).pdf

2301-del-2005-description (complete).pdf

2301-DEL-2005-Drawings-(30-12-2010).pdf

2301-del-2005-drawings.pdf

2301-DEL-2005-Form-1-(30-12-2010).pdf

2301-del-2005-form-1.pdf

2301-del-2005-form-18.pdf

2301-DEL-2005-Form-2-(30-12-2010).pdf

2301-del-2005-form-2.pdf

2301-DEL-2005-GPA-(30-12-2010).pdf

2301-del-2005-petition-138.pdf


Patent Number 246992
Indian Patent Application Number 2301/DEL/2005
PG Journal Number 12/2011
Publication Date 25-Mar-2011
Grant Date 23-Mar-2011
Date of Filing 26-Aug-2005
Name of Patentee SATISH CHANDER GUPTA
Applicant Address 16 BANGLOW ROAD, KAMLA NAGAR, DELHI-110 007, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 SATISH CHANDER GUPTA 16 BANGLOW ROAD, KAMLA NAGAR, DELHI-110 007, INDIA.
PCT International Classification Number A61B 3/16
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA