DGH Technology, Inc.’s Pachmate is lightweight and portable and fits easily into a lab coat pocket.
Reichert Technologies’ Tono-Pen AVIA takes very accurate measurements with minimal training.

Portability can be the key to an instrument’s success as you treat and monitor your patients.

Glaucoma is a common ocular condition in which the optic nerves and fiber layers of the retina become damaged, which can lead to peripheral vision loss. High intraocular pressure (IOP) is a leading risk factor, as its effect on optic nerves can precipitate tissue damage. Efficient and accurate, handheld devices are becoming increasingly popular for in-office IOP measurements, and their portability helps with patients who are unable to sit at a slit lamp.

For screening, our practice uses Icare USA’s Icare’ handheld tonometer. Its small lightweight probe contacts the cornea, then calculates IOP based on movement parameters such as deceleration. Because the Icare tonometer’s movement is quicker than the corneal blink reflex, no numbing agents are required.

Unlike the gold standard Goldmann Applanation tonometer (GAT) from Haag-Streit, the Icare requires minimal training for proficient use and a 2008 study found that for IOPs less than 22 mmHg, the Icare can be as accurate as a GAT, according to the company. Another option is Reichert Technologies’ Tono-Pen AVIA, which is easy-to-use and takes very accurate measurements.

Tonometers overestimate IOPs on corneas with high central thickness while the opposite’s true with thinner corneas. A baseline pachymetry reading, then, is recommended on all glaucoma and ocular hypertensive patients. We like the Pachmate DGH 55 (DGH Technology, Inc.) handheld pachymeter. After instilling one drop of a numbing agent in each eye, the probe’s gently placed on the center of the cornea, perpendicular to the pupil. It then takes up to 25 readings, displaying their average and the standard deviation, in microns.

The Pachmate has an optional IOP correction feature that displays the correction value of a patient’s IOP based on their measured central corneal thickness. There’s also an adjustable, removable probe for ease of measuring and cleaning, and it comes with a calibration box.

The last device we use is a gonioscopy lens. It’s important to assess the anterior chamber angle to ensure that poor aqueous drainage isn’t the underlying cause of elevated IOPs.

Several designs exist, and they all function on the principle of using mirrors to obtain a reflection of angle structures located 90° away from the mirror’s position. Some come with one, two, or four D-shaped mirrors that enable views of the angle. To obtain a 360° assessment of angle integrity, lens rotation may be necessary. Some designs include trapezoidal mirrors for viewing the mid-peripheral retina, rectangular mirrors to view the far peripheral retina, or central Hruby lenses for visualization of the posterior pole. Since the lens makes prolonged contact with the cornea, a numbing agent is required and a drop of artificial tears into the lens may enhance patient comfort.

Katherine Shen is an associate at Specialty Eyecare Group in Seattle and Kirkland, WA. Colleen Largent is a fourth-year student at Indiana University School of Optometry interning at Specialty Eyecare Group.


DGH Technology, Inc. •800-722-3883 •

Haag-Streit USA •800-787-5426 •

Icare USA •888-422-7313 •

Reichert Technologies •716-686-4500 •


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