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CR

The Glaucoma Tonometer


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What sets it apart?

Reicherts 7CR Auto Tonometer + Corneal Response Technology takes corneal

biomechanical properties into consideration, providing Corneal Compensated IOP (IOPcc) -

a pressure measurement that is significantly less affected by the cornea than other methodsof tonometry.

The 7CR is based on Reicherts patented dynamic bi-directional applanation technology,

which is the foundation of the revolutionary Reichert Ocular Response Analyzer (ORA).

The ORA is the first instrument capable of measuring corneal bio-mechanical properties and

is supported by over 100 peer-reviewed publications in the medical literature.

Corneal properties such as elasticity, viscosity, and thickness can affect the accuracy of

Goldmann IOP values by as much as 17 mmHg in normal eyes and more than 20 mmHg in

eyes with corneal pathology. The ORA, and now 7CR, are the only devices in the world

that can account for these properties.

IOPcc is patented technology (US 7, 481, 767 B2)

Overview


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What sets it apart?

The 7CR presents you with a tremendous opportunity to sell a unique product that has

strong clinical utility and essentially NO COMPETITION.

7CR is THE Glaucoma tonometer. This is not a screening device, as NCTs were

perceived to be in the past. 7CR should be positioned as the tonometer of choice for the

management of glaucoma for ODs and MDs alike.

The 7CR is superior to Goldmann or any other IOP measurement.

Reichert 7CR Provides more clinically relevant tonometry measurements in:Normal Tension Glaucoma patients(subjects who have glaucoma but measure low on Goldmann)

Primary Open Angle Glaucoma patients(typical high-pressure glaucoma subjects)

Post-LASIK and refractive surgery patients(subjects with biomechanically altered corneas)

Patients with Fuchs or Edema(very spongy corneas that measure inaccurately on Goldmann)

Keratoconus patients(biomechanically weak corneas that measure inaccurately on Goldmann)

Patients with thick, thin, or otherwise biomechanically atypical corneas

Overview


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Tonometry is used to measure the Introcular Pressure (IOP), which is a risk

factor for Glaucoma. Higher IOP increases the risk for glaucoma.

IOP is the ONLY modifiable risk factor for glaucoma. This means that oncea patient has been diagnosed with glaucoma, the only thing doctors can do

is try to lower the pressure. Regular monitoring of IOP is essential to

determining efficacy of treatment in glaucoma patients.

As such, accurate measurement of IOP is CRITICAL for the proper

diagnosis and management of glaucoma.

Tonometry


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The Goldmann Tonometer has long been considered the

gold standard for measuring pressure, but its accuracy is

widely questioned today.

Tonometry

Goldmann Design Assumptions

- Cornea is infinitely thin and perfectly flexible

- Tear-film and corneal thickness effect cancel each other out

Flaws- Experimentation done on cadaver eyes (not representative of live eyes)

- Variations in corneal thickness is significantly greater than assumed

- Variations in corneal biomechanical properties unaccounted for

Accordingly, Goldmann cannot compensate for differences in thickness,

elasticity, and other biomechanical parameters that influence accuracy


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Cant we calculate true IOP using pachymetry (CCT)?

NO!Central Corneal Thickness based IOP adjustment algorithmsDO NOT WORK. These formulas have been scientifically discreditedand the glaucoma opinion leaders of the world are cautioning clinicians

against using them.

As such, CCT correction tables and pachymeters and tonometers thatprovide CCT-based corrected IOP values are OBSOLETE.

Why CCT-based IOP correction is flawed

Correction nomograms that adjust GAT IOP based solely on CCT are neither

valid nor useful in individual patients- Pg 18. Robert N. Weinreb, James D. Brandt, David Garway-Heath and Felipe Medeiros

World Glaucoma Association on Intraocular Pressure; Consensus Series 4; May 5, 2007


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Why CCT-based IOP correction is flawedOHTS and other recent studies have investigated the relationship between

central corneal thickness (CCT) and IOP values. They have found a

relationship between CCT and GAT measured IOP.

Thicker corneas tendto measure higher on GAT and Thinner corneas tend

to measure lower.

However, the relationship between CCT and measured IOP is only valid

when observing large data sets. When applied to individual patients,

corneal thickness IOP correction formulas present a 40% chance of

adjusting the IOP in the WRONG DIRECTION!


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Data courtesy New England College of Optometry

Very thin corneas tendto measure low IOP

Very thick corneas tend

to measure high IOP

But SCATTER in the data makes accurate mathematical

adjustment of IOP impossible for individuals!


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Thick and thin is WRONG. Think weak and strong


Corneal Resistance to bending is not dependant thickness, but on material properties


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CR


The 7CR IOPcc measurement is not based on the overly-simplistic Corneal

Thickness correction approach.

7CR quantifies the corneas biomechanical properties, and then reduces the

effect of these on the IOP measurement process


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Dynamic Bi-Directional Applanation

Goldmann and other tonometers only determine one number, but they

are affected by two things: IOP and cornea.

You cant measure two things with one number!

The 7CR makes a dynamic measurement, monitoring the in/outmovement of the cornea in response to a rapid air impulse.

The Bi-Directional Applanation results in two IOP measurements inrapid succession (one as the cornea moves in, and one as the cornea

moves out). This permits determination of corneal properties, enabling

the 7CR to provide a more accurate IOP measurement.


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Undisturbed

Cornea

IR Light Emitter

IR Light Detector

Auto alignment is achieved. instrument is ready to measure


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Air-JetApplanated

Cornea

IR Signal Peak

Air pulse is delivered, inward applanation is recorded


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Corneal Concavity

Air-Jet

Cornea passes through applanation into mild concavity


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IR Signal Peak

Air-JetApplanated

Cornea

IR Signal Peak

Air pulse reduces, cornea returns, outward applanation is recorded


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Undisturbed

Cornea

IR Light Emitter

Air tube

IR Light Detector

Measurement process complete


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Applanation Signal Plot7CR Measurement Signal

Inward

ApplanationOutward

Applanation

Corneal

Hysteresis


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HysteresisHysteresisA property of materials or systems that do not instantly follow

forces applied to them, but react slowly, or do not return

completely to their original state. The phenomenon was identifiedby Sir James Alfred Ewing in 1890. This term is commonly used

to describe material properties in engineering and architecture.

Corneal Hysteresis (CH)

A characterization of thecorneas biomechanical tissueproperties. It is a result of visco-elastic damping (energy

absorption) as the cornea moves rapidly in and out.

This is what enables the 7CR to quantify and minimize the

corneas influence on IOP measurement.Discovered by Dr. David Luce of Reichert Inc


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HysteresisMany common visco-elastic materials and systems exhibit hysteresis.

- Automotive struts

- Foam mattresses- Viscous fluids like honey and oil

- Door dampers (closers)

The Cornea is visco-elastic like these examples


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IOPccCorneal-Compensated Intraocular Pressure

IOPcc is patented technology (US 7, 481, 767 B2)

7CR utilizes the information provided in the

Corneal Hysteresis measurement to determineIOPcc, which is less affected by corneal

properties than other methods of tonometery,

such as Goldmann (GAT).

7CR also provides IOPg which is similar to anactual Goldmann measurement. Seeing these

values simultaneously gives clinicians a better

understanding of patient tonometry values.


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IOPccCorneal-Compensated Intraocular Pressure

IOPcc is still a Goldmann correlated IOP

measurement. It agrees with Goldmann on average,

but is not influenced by the cornea in the same way asGoldmann and other tonometers are.

Therefore IOPcc has the same scale as a Goldmann

measurement, but is more clinically relevant because

it is not contaminated by corneal artifacts.

Note: The PASCAL DCT, which claims independence

from corneal properties is NOT Goldmann correlated.

As such, the clinical relevance of the DCT IOP

measurement is questionable.

h Gl


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7CR IOPCC vs CCT 184 Normals

Data courtesy New England College of Optometry

IOPcc is not influenced by the thickness of the cornea

Th Gl T t


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Data courtesy Dr. David Castellano, MD / Dr. Jay Pepose, MD

28 eyes Pre/Post LASIK IOPCC

IOPcc ignores the change in corneal properties cause by LASIK and provides

similar IOP measurements in pre and post refractive surgery subjects

IOPappears to be lower after LASIK

with Goldmann

Th Gl T t


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Is IOPcc Better than GAT?

Th Gl T t


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Evaluation of the Influence of Corneal Biomechanical Properties on

Intraocular Pressure Measurements Using the Ocular Response Analyzer.

Felipe A. Medeiros, MD and Robert N. Weinreb, MD

J Glaucoma 2006;15:364370.

Clinical Publications

Conclusions: IOPg agrees with Goldmann very

well. IOPcc seems to provide an estimate of IOP

that is less influenced by corneal properties than

those provided by GAT

IOPg, IOPcc correlation with Goldmann and CCT

GAT

IOPcc



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Ocular Response Analyzer in Subjects with and without Glaucoma.

Sullivan-Mee M, Billingsley SC, Patel AD, Halverson KD, Alldredge BR, Qualls C.

J Optom Vis Sci. 2008 Jun;85(6):463-70.

In Glaucomatous eyes IOPcc was significantly higher than GAT. Thisrelationship was also true in Glaucoma suspects. However, in normal eyes and

OHT eyes, IOPcc, IOPg, and GAT were all similar.

This indicates that IOPcc is a better indicator of glaucoma presence

IOPcc differentiates Glaucomatous Eyes



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Intraocular pressure measured by dynamic contour tonometer and ocular response analyzer in normal tension glaucoma

Tetsuya Morita & Nobuyuki Shoji & Kazutaka Kamiya & Mana Hagishima & Fusako Fujimura & Kimiya Shimizu

Graefes Arch Clin Exp Ophthalmol DOI 10.1007/s00417-009-1169-4


Conclusions: Only IOPcc was ableto distinguish the NTG eyes from

the true normal eyes.

IOPcc can differentiate NTG eyes from normal eyes

True normal eyes and eyes with NTG (normal tension glaucoma) were

measured with GAT, DCT, IOPg, and IOPcc



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Summary of IOPcc advantagesIOPcc correlates strongly with GAT on the average

HOWEVER, IOPcc has the following advantages over GAT

Not affected by CCT

Not affected by corneal biomechanical properties (rigidity)

As such, it is more accurate in KC, Fuchs, OHT, NTG eyes

In addition, it has less measured IOP reduction post-LASIK

No operator bias



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Important Service Note:7 CR cannot be calibrated using rubber eyes like previous

generation Reichert tonometers. A device called a TCT

(Tonometer Calibration Tool) must be used.

Service and calibration training will be provided at another time

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