DGH 55 Pachmate

The DGH 55 serves optometry practices, ophthalmology clinics, glaucoma clinics and refractive surgery screening rooms, wherever corneal thickness is recorded in a consulting room or at a screening station. Its intended uses include glaucoma screening, laser refractive surgery screening,, and monitoring corneal swelling; thickness values feed the IOP correction function beside the pressure reading. Audible tones keep the operator's eyes on the patient, with a short tone for each stored measurement and two long tones when a group is complete.

Optometrists, ophthalmologists, orthoptists and eye clinic technicians operate it by hand. The probe is placed on the cornea, and the measurement starts as the tip applanates the surface. Continuous Average mode suits routine single-location thickness measurements, with the average and standard deviation displayed on screen. Mapping mode suits departments that record thickness at up to 33 positions across one cornea. Bilateral mode lets a technician switch between eyes in a single session, with the switch delay set between 1 and 9.5 seconds.

Upkeep is central to daily use. The CalBox runs once a day, the probe tip is wiped with 70% isopropyl alcohol after each patient, and two AAA cells power the unit. Because the probe detaches, labs replace a worn or damaged probe as a separate part while keeping the instrument in service. A lab coat pocket holds the unit between patients, and the manufacturer specifies an operating range of +18 to +40 °C, so it suits ordinary consulting rooms and screening stations.

A daily accuracy routine in the same kit

The CalBox presents test values from 200 to 1000 µm in 100 µm steps with a ±5 µm tolerance. The manufacturer recommends running it at least once a day, making calibration verification a quick step at the start of a session.

Measurement that starts on contact

The reading begins automatically as the probe tip applanates the cornea. The operator therefore keeps both hands on the instrument and the patient, and a tone signals each stored measurement.

Average and spread on one display

The two-line LCD shows the current measurement, the running average and the standard deviation. A technician reads the consistency of a group of readings at the same moment as the thickness itself.

Both eyes in one pass

Bilateral mode stores up to 25 measurements for each eye and switches between eyes automatically. The delay is configurable from 1 to 9.5 seconds so that the pace can match the operator.

Mapping across up to 33 positions

Mapping mode records one measurement per position and sounds a tone when the unit is ready for the next. Departments that record thickness at several points across a cornea hold the whole set in the unit before it is cleared.

Corrected pressure from the same visit

Holding ENT in Continuous Average mode shows an IOP correction value, based on a 545 µm reference thickness. Thickness and corrected pressure therefore come from one measurement routine.

Power from two common AAA cells

The unit takes alkaline or NiMH AAA cells, and a battery type setting selects alkaline or rechargeable. Standby after one minute and sleep three minutes later conserve the charge between patients.

A probe that detaches

The probe separates from the handle for cleaning and replacement. Upkeep of the part that touches the eye is therefore limited to one component, while the instrument body stays in daily use.

Pocket size at 112 g

At 175 × 43 × 21 mm, the DGH 55 fits a lab coat or shirt pocket. A single instrument can move between consulting rooms, screening stations and clinics through the day.

Corneal thickness from 200 to 1100 µm

The measurement range spans 200 to 1100 µm, covering the thickness values seen in routine corneal assessment. Every thickness value uses a corneal velocity of 1640 m/s.

±5 µm accuracy with 1 µm resolution

Accuracy is rated at ±5 µm, with 1 µm resolution. The CalBox tolerance of ±5 µm matches the same figure at its test values.

Echo spike technique at a nominal 20 MHz

The detachable piezoceramic probe works at a nominal 20 MHz, although the actual frequency can vary between probes. The echo spike technique times the returning ultrasound to give thickness.

Probe cone tip and rotator detents.

The probe ends in a plastic cone tip, and its rotator clicks into detents at 30, 45, 60, 75 and 90 degrees. The angle can be set to suit the operator's grip and the patient's position.

Continuous Average mode

The factory default mode takes up to 25 measurements at one location. It shows the average and, optionally, the standard deviation, and you can delete single measurements with DEL.

Mapping mode

Mapping stores one measurement per position, up to 33 positions. Two short tones tell the operator that the unit is ready to move on.

Biased thickness display

In Mapping mode, a biased thickness can be shown as a percentage of the measured value from 1 to 199%, with 100% as the default. The display is off until you enable it in the configuration.

Bilateral mode

Both eyes are measured in turn, with an automatic switch after a delay of 1 to 9.5 seconds. The default delay is 4.0 seconds.

IOP correction at 545 µm

The IOP correction value is based on a reference corneal thickness of 545 µm and appears when ENT is set to Continuous Average mode. Each unit ships with an IOP correction chart.

16 × 2 character LCD with adjustable contrast

The display shows the measurement, average, and standard deviation, and contrast is adjustable across 14 segments. Holding CFG displays the model, serial number, software version and option number.

Audible tones with 14 volume steps

A short tone marks a stored measurement, a long tone signals that applanation needs adjusting, and two long tones mark a completed group. Volume is adjustable across 14 segments.

Standby and sleep control

Standby begins after one minute by default and is adjustable from 0.5 to 9.5 minutes. Sleep follows three minutes later, and it retains stored measurements.

Non-volatile configuration memory

Configuration settings stay in non-volatile memory—measurements clear with the CLR key or when the unit is turned off.

Electronic CalBox verification

The CalBox presents 200 to 1000 µm in 100 µm steps with a ±5 µm tolerance, runs on a 9 V alkaline battery and switches off after 2.5 minutes. Holding PWR with DEL puts the instrument into CalBox mode.

Probe self-test at start-up

Probe quality is tested at each initialisation against the factory calibration. The operator starts every session knowing the probe has been checked.

Reported ultrasound output

The manufacturer reports an IIspta of 1.0 mW/cm², a thermal index (TIS, non-scan, aperture under 1.0 cm) of 0.0005 and a mechanical index of 0.052. The Ipa.3 at the maximum mechanical index is 2.4 W/cm².

The DGH 55 Pachmate suits optometry practices and eye clinics that want corneal thickness from a handheld instrument with a routine to keep it accurate. The daily CalBox run, detachable probe, and two-cell AAA supply keep upkeep to a short set of tasks each session. Continuous Average, Mapping and bilateral modes cover single readings, multi-point records and both eyes, and IOP correction adds a corrected pressure value from the same measurement. Standby and sleep settings conserve the cells between patients, and the manufacturer rates the unit for a 10-year lifetime. It works best at the point of care, where it measures a 112 g body from 200 to 1100 µm with ±5 µm accuracy.