The technology

Ocular Response Analyzer (ORA) G3 (Reichert Technology) is a dynamic bidirectional applanation device used to measure corneal hysteresis.

ORA G3 is table-mounted and controlled by a healthcare professional through an in-built operator display. The patient positions their head in a headrest, which is adjusted to allow for measurements of the left or right eye. The device blows a short puff of air to slightly flatten the cornea, which then returns to its original shape. During this the device takes 2 measurements: the force needed to flatten the cornea and the force needed for it to reshape. The difference between the 2 measurements is defined as the level of corneal hysteresis (measured in mmHg).

ORA G3 can also be used to measure intraocular pressure, but this briefing focuses on its use to measure corneal hysteresis.


ORA G3 is currently the only device that can measure corneal hysteresis. Unlike other tests, it does not need contact with the eye, specialist training or the use of eye drops.

Current NHS pathway

The NICE guideline on glaucoma recommends several tests to diagnose and manage glaucoma (see table 2). The guideline does not include recommendations on measuring corneal hysteresis specifically, but some evidence suggests that lower levels of corneal hysteresis may be linked to the development or progression of glaucoma.

Population, setting and intended user

ORA G3 is intended as an additional option for diagnosing or managing suspected glaucoma, or for monitoring established glaucoma. It is possible to have open angle glaucoma without raised intraocular pressure, so measuring corneal hysteresis could be more useful in this patient group. Assessments using ORA G3 would usually be done in secondary care by a healthcare professional or trained technician. The company has stated that minimal training is needed to use the device.


Technology costs

The estimated cost per test with ORA G3 is £0.20.

This has been calculated by dividing the total cost of the device, service and maintenance fees, and consumables by the number of patients that would have the test in 10 years (the predicted lifespan of the device; this equates to 75,000 patients). The estimated cost per test does not include the time of a healthcare professional.

Table 1 Costs for ORA G3



Additional information

ORA G3 device


The expected lifespan of the device is 10 years.

Biannual service and maintenance

£395.00 per service

Over 10 years, 4 services would be needed.

Alcohol wipes

£0.02 each

The company estimates that around 30 patients would have an ORA G3 test each day.

All costs were provided by the company.

Costs of standard care

Table 2 shows estimated costs for each of the tests recommended by NICE as an option for diagnosing and managing glaucoma. The estimates do not include the cost of consumables or the time of a healthcare professional. Excluding these, the average cost per test is £0.09.

Table 2 Costs of tests to diagnose and manage glaucoma


Cost per patient

Measuring intraocular pressure using Goldmann applanation tonometry


Optic nerve assessment and fundus examination




Measuring central corneal thickness


Visual field assessment using standard automated perimetry


Resource consequences

The resource impact of ORA G3 would be greater than standard care at first because the test is more costly. However, the company claims that after the first year, ORA G3 becomes cost saving for the rest of the device's lifespan (that is, 10 years). If corneal hysteresis were proven to be a risk factor for glaucoma, and ORA G3 enabled earlier diagnosis, there may be associated cost savings from starting treatment sooner.

If ORA G3 were adopted by the NHS, ophthalmology care providers would need to accommodate the device in examination rooms or clinic areas.

ORA G3 is currently being used in 8 NHS hospitals.