21
Summary
The Keeler TonoCare Non-Contact Tonometer (NCT) was
compared with the Perkins Applanation Tonometer (AT) in order
to assess whether the TonoCare meets the requirements of ISO
8612 (comparable to ANSI Z80.10) in design compliance testing.
The Perkins AT uses the same basic principle as the Goldmann
AT, namely, varying the force applied to applanate a fixed area
of the cornea. Both instruments have an applanating ‘cone’
comprised of two prisms with apices joined together to apply an
external force to the cornea to indent and flatten its surface.
There are several scientific articles referring to both instruments
as reference standard tonometers and specifically the Perkins AT
as the portable counterpart to the Goldmann AT (Wessels,I.F et
al.,1990), (Carlos Garcia-Resua et al 2006), useful in domiciliary
visits and for patients with mobility issues.
Two experienced observers acquired data from 144 qualifying
eyes, measuring IOPs ranging from 7mmHg-23mmHg in 50
participants and IOPs greater than 23mmHg in 22 participants.
The results of the study show that the IOP measurements taken
with the TonoCare NCT when compared to the reference Perkins
tonometer (AT) do not exceed the ±5mmHg tolerance in the
three IOP ranges in 143 eyes with only 1 eye exceeding this
tolerance for IOP measured >23mmHg. This falls well below the
requirement that no more than 5% of the paired differences
between TonoCare and the reference tonometer should be
outside the ±5mmHg tolerance in the three IOP ranges.
Overall the mean of IOP differences between TonoCare and
Perkins AT was <0.01 mmHg, with a median of -0.2mmHg,
indicating that the TonoCare NCT is equivalent to the
applanation tonometer.
3.2.6 Clinical performance data
Summary of Contents for Tonocare
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