Reichert Ocular Response Analyzer G3 (ORA)
Make a more confident glaucoma risk assessment, with Corneal Hysteresis.
Ocular Response Analyzer® (ORA) is the only tonometer that measures Corneal Hysteresis (CH), a superior predictor of glaucoma progression. Corneal Hysteresis is an indication of the biomechanical properties of the cornea differing from thickness or topography, which are geometrical attributes.
“CH measurements were significantly associated with risk of glaucoma progression. Eyes with lower CH had faster rates of visual field loss than those with higher CH.”1
In addition to Corneal Hysteresis, Ocular Response Analyzer provides Corneal Compensated Intraocular Pressure (IOPcc), a better indication of the true pressure, proven to be less influenced by corneal properties than Goldmann or other methods of tonometry.2
Effective January 1, 2015, CPT® Code 92145, was published specifically for the Corneal Hysteresis measurement provided by Ocular Response Analyzer.
Ocular Response Analyzer® G3 and Corneal Hysteresis:
Make a more confident glaucoma risk assessment, with Corneal Hysteresis. Ocular Response Analyzer®(ORA) is the only tonometer that measures Corneal Hysteresis (CH), a superior predictor of glaucoma progression. Effective January 1, 2015, CPT® Code 92145, was published specifically for the Corneal Hysteresis measurement provided by Ocular Response Analyzer.
The Ocular Hypertension Treatment Study (OHTS), and similar studies, have brought to light the relevance of corneal thickness in glaucoma. Numerous studies utilizing the Ocular Response Analyzer have confirmed the importance of the cornea in glaucoma decision making, demonstrating that the CH measurement is of even greater significance than CCT. Studies have proven that low CH is independently associated with glaucoma progression. As such, the CH measurement gives clinicians a new tool to help identify risk of glaucoma progression and to determine which patients may need to be treated more aggressively. The CH measurement has also been shown to be predictive of IOP response to medical therapy, making the CH measurement valuable in setting treatment goals and expectations.
Intraocular Pressure (IOP)
It is widely accepted that the measurement errors in Goldmann tonometry are due to the influence of corneal properties. However it has been determined that mathematical correction of IOP, by means of CCT adjustment algorithms, is invalid and this approach is not useful in individual patients. Quite simply, the thickness of the cornea is not a surrogate for its mechanical bending characteristics.
Ocular Response Analyzer's Corneal-Compensated Intraocular Pressure (IOPcc) takes biomechanical properties into consideration. IOPcc has been shown to be less dependent on corneal properties than other methods of tonometry and more associated with glaucoma status. The instrument?s unique ability to simultaneously provide a Goldmann-correlated IOP measurement (IOPG) and IOPcc provides clinicians with a better understanding of patient tonometry values.
The Ocular Response Analyzer enables clinicians to assess the cornea based on biomechanical tissue properties, rather than geometry only. It has been demonstrated that Corneal Hysteresis (CH) and Corneal Resistance Factor (CRF) measurements are significantly lower in keratoconus patients. Furthermore, CH and CRF are significantly reduced following refractive surgery as a result of complex biomechanical changes. CH and CRF provide a more complete characterization of corneal properties than CCT and topography alone, making these metrics useful in the pre-operative assessment of refractive surgery candidates.
What is Corneal Hysteresis?
Corneal Hysteresis (CH) is the difference in the inward and outward pressure values obtained during the dynamic bi-directional applanation process employed by the Ocular Response Analyzer, as a result of viscous damping in the cornea. It is a characterization of the cornea?s energy absorption capacity, which is a function of the biomechanical properties of the cornea.
Ocular Response Analyzer is the only instrument in the world capable of measuring corneal biomechanical properties and Corneal Compensated IOP.
How it Works
The Ocular Response Analyzer utilizes a dynamic bi-directional applanation process to measure biomechanical properties of the cornea and the intraocular pressure of the eye. A precisely metered collimated air-pulse causes the cornea to move inwards, past applanation, and into a slight concavity. Milliseconds after applanation, as the air pulse force decreases, the cornea begins to return to its normal configuration. In the process, it once again passes through an applanated state.
An electro-optical system monitors the curvature of the cornea throughout the deformation process taking 400 data samples during the 20-millisecond measurement. Two independent pressure values are derived from the inward and outward applanation events. Viscous damping in the cornea results in an offset between the inward and outward pressure values. The difference between these two pressure values is Corneal Hysteresis (CH).
Comprehensive Pressure and Cornea Information
IOPcc (Corneal Compensated IOP) - New IOP measurement less affected by corneal properties.
CH (Corneal Hysteresis) - Measure of viscous damping in the cornea, providing new indicators for disease diagnosis and management.
CRF (Corneal Resistance Factor) - Total visco-elastic response of the cornea.
IOPg (Goldmann Correlated IOP) - Traditional IOP measurement for historical reference.
Patented dynamic bi-directional applanation process enables the only direct measure of corneal biomechanical properties.
Eliminates operator variance by utilizing microprocessor control technology and objective measurement criteria.
Patient and Operator Friendly
No chinrest and a soft, quiet air puff make the Ocular Response Analyzer a comfortable, non-intimidating experience for your patients.
Fully automatic alignment and measurement provides fast, repeatable results, allowing any member of your staff to conduct an exam.
Powerful Software Package
Enables automatic data capture of all measurements for analyzing trends, treatment efficacy, and diurnal variations.
Comprehensive patient management database simplifies record keeping.
Comprehensive printout for hard-copy results.
Export data for use in other applications.