Reichert Ocular Response Analyzer G-3

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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.

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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.