Icare rebound tonometer to measure intraocular pressure

About the technology

Costs and use of the technology

Information on the cost of using the technology has been sourced from the manufacturer. The capital components of each Icare tonometer system have the following prices, excluding VAT:

The probe bases for each system have the following prices (excluding VAT):

The disposable probes for each system cost (excluding VAT):

A staff training session is included in the price of an Icare tonometer if needed.

No other practical difficulties have been identified in using or adopting the technology.

The manufacturer suggests that the lifespan of these 3 technologies is 'tens of years'; a lifespan of 15 years has been assumed in this briefing. Both the Icare TA01i and Icare ic100 use 4 AA batteries, which cost an average of £1.06. The Icare HOME needs 2 CR123 batteries, which cost about £3.23. No routine maintenance or calibration is needed for any of the Icare tonometers, but the probe base and batteries should be replaced every 12 months for Icare HOME, Icare TA01i and Icare ic100. The probe base (and connected probe holder) should be replaced every 6 months for Icare PRO.

If a monitoring session with a healthcare professional takes 15 minutes, up to 30 Icare TA01i, ic100 or PRO measurements could be taken per day (7.5 hours), and 7,200 taken in 1 year (240 annual working days). Icare HOME measurements (self‑monitoring) are typically taken 5 times per day (Asrani et al. 2011). Assuming that the Icare HOME is loaned to a different patient each week, this leads to 1,825 monitoring sessions per year. Using the standard annuity method with a discount rate of 3.5% gives the following costs per IOP assessment (inclusive of capital cost and costs of regular replacement of probe base, batteries and disposable probe):

No unit cost for GAT is reported in nationally representative sources. The NICE guideline on glaucoma uses the national tariff figure for follow‑up visit to an outpatient ophthalmology clinic as the cost for a monitoring session. It notes that these monitoring sessions can include measurement of IOP with GAT. This method gives a cost of £59 (NHS National Tariff 2014/15; WF01A, 130), which may indicate the unit cost of GAT and includes a variety of resource uses (for example, the ophthalmologist's time).

Likely place in therapy

Icare rebound tonometers would be used for measuring IOP as a replacement, or addition to, existing tonometry methods.

Specialist commentator comments

Two specialist commentators stated that Icare tonometers may be most useful in paediatric and community care settings; one of the commentators noted that Icare tonometers could also be useful in secondary care ophthalmology clinics. Two commentators stated that fast pressure measurement is particularly important in paediatric ophthalmology and one of these commentators also noted that Icare tonometers could be useful for paramedics. Two commentators noted that anaesthetic eye drops are not needed when using Icare tonometers, which one commentator felt would be preferred by most children, and it also allows them to be used by trained non‑medical personnel. However, according to another specialist, the Icare tonometer is unreliable when used in children's glaucoma clinics because the results do not correspond to those obtained with GAT. One commentator added that there is evidence that Icare is useful in the neonatal setting, specifically in the special care department, citing the study by Rodrigues and Chan (2014). Two commentators stated that Icare tonometers can also be used in patients with disabilities, and are easy to use.

Two specialist commentators stated that Icare may not be useful in clinical settings already using GAT, which is likely to be the preferred measurement method. One of the commentators considered that GAT may be used to supplement IOP results if the Icare reading is unusual or a more accurate reading is needed. Another commentator reiterated this point, stating that in the hospital setting, Icare should only be used for patients in whom GAT measurements are unobtainable, whereas in primary care, the indication for using Icare should be similar to that of other non‑contact tonometers.

Two specialist commentators stated that Icare is useful as a screening tool, whereas a third specialist noted that additional technologies would be needed alongside Icare for screening in a hospital clinic. A fourth specialist commentator stated that more research should be done to evaluate the effectiveness of Icare for screening. One specialist commentator noted that GAT is the preferred tool for monitoring IOP in people who have confirmed glaucoma.

One specialist commented on the poor repeatability reported in the published Icare studies discussed in the briefing, stating that it may be a result of users not positioning the device in the centre of (or perpendicular to) the cornea. This was supported by another specialist who stated that ensuring the centre of the cornea is 'hit' with the probe is more difficult to guarantee with Icare than with a conventional tonometer. The commentator explained that rebound tonometry is affected by corneal hysteresis (a biomechanical property of the cornea relating to its elasticity), which is why peripheral measurements can give erroneous results (although these will not necessarily be clinically significant).

Two specialist commentators noted that other potential causes of incorrect Icare IOP readings include biomechanical changes to the cornea caused by medicated eye drops to treat glaucoma, and 'stiff' corneas associated with diabetes. These specialist commentators also noted that Icare readings may be affected by different corneal biomechanics and other visual pathologies (including myopia), and such inaccuracies can often result in false referrals for these people. One of the commentators stated that this problem can also happen with non‑contact tonometers, but less often. Three commentators emphasised the importance of measuring CCT, because this influences IOP measurement and will vary across a population. One of the commentators specified that Icare will overestimate GAT where CCT is high and underestimate it where CCT is low.

One commentator discussed costs, stating that it is unlikely that monitoring sessions will take place every day of the week and there will be high variability in the frequency of tonometer use depending on the setting. They also noted that it is unlikely that Icare HOME would be used as often as 5 times per day every day of the year. A second commentator stated that Icare is affordable and a third commentator noted that Icare may be associated with a reduction in costs because, unlike GAT, it does not need clinically qualified staff time (clinical assistants can use the device). Additionally, the commentator stated that the cost per measurement of the Icare devices (about £1 based on the cost of the disposable probe) is similar to the cost of using GAT with a disposable prism and topical anaesthetic.

Equality considerations

NICE is committed to promoting equality, eliminating unlawful discrimination and fostering good relations between people with particular protected characteristics and others. In producing guidance, NICE aims to comply fully with all legal obligations to:

Vision loss may be classified as a disability depending on its effect on the ability to carry out normal day‑to‑day activities. Disability is a protected characteristic defined in the Equality Act (2010). People who are registered as blind or partially sighted are automatically considered to be disabled under the Act.

People with diabetes are more likely to develop OHT and glaucoma and, therefore, may particularly benefit from Icare devices. Diabetes is a chronic disease. Chronic disease is treated as a disability if it has a substantial and long‑term adverse effect on a person's ability to carry out normal day‑to‑day activities. Older populations and people of African and African‑Caribbean family origin are also at increased risk of developing OHT and glaucoma. Age and race are protected characteristics defined in the Equality Act 2010.