Tonometry Technology Comes Home
For glaucoma suspects, as well as established glaucoma patients,
a helpful technology is available that allows them to measure
their own IOP. It works by taking advantage of the pressure
phosphene phenomenon: when focal pressure is placed on the
globe, a phosphene light phenomenon is produced in the opposite
field of vision.
With this tonometer, increasing pressure is applied through
the superior nasal portion of the closed eyelid until the subject
detects a phosphene in the inferior temporal field. The “pressure
phosphene tonometer” is calibrated to the Goldmann standard
and has acceptable accuracy, which will vary slightly from
person to person.
The ProView Eye Pressure Monitor is available from Bausch & Lomb,
for approximately $100. (For more information, call 1-800-553-5340,
or go on-line at www.bausch.com.) Because the ProView tonometer
is relatively new to the market, we have had only limited personal
experience. Based on all we have read, it appears this technology
may be what we all have been seeking for a long time.
The following quotation from a journal article nicely summarizes
the role of this home tonometer: “Pressure phosphene tonometry
is potentially easily administered in outreach clinics, at
bedside, for patients who are fearful of applanation tonometry,
and in situations in which Goldmann is impractical. In clinical
use, it is rapid, however, it does require brief explanation
to the patient the first time it is administered, and requires
subjective response.
“In summary, the FPT appears to offer a practical alternative
and adjunct for IOP measurement. It is relatively inexpensive
and safe. Asepsis is less critical as it is applied through
the eyelid. It is portable, requires no power source, and is
easily maintained. In addition, the FPT allows for the possibility
of home self-testing, which may be useful both for the routine
monitoring of IOP and for generating intermittent diurnal pressure
curves.”
For years, we have been waiting for an accurate, inexpensive
technology whereby patients can monitor their IOP outside the
clinical setting. We think this technology has arrived.
Fresco BB. A new tonometer--the pressure phosphene tonometer:
clinical comparison with Goldman tonometry. Ophthalmology 1998
Nov;105(11):2123-6.
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