In our last Buyers’ Guide article in April, I focused on B-scan ultrasound devices. This month, the focus will be on Amplitude (A) scan ultrasound biometry devices.
A-scan ultrasound is a routine diagnostic test commonly used by optometrists and ophthalmologists. A-scans provide data on the length of the eye, which is essential for calculation of intraocular lens power and also in some common sight disorders. A-scan devices can also be used to determine the size and characteristics of ocular and orbital masses. The hand piece requires direct contact with the cornea, however a non-contact instrument is available.
Below is a discussion of some of the A-scan devices on the market.
DGH Technology 6000 A-Scan Scanmate
DGH Technology’s 6000 A-Scan Scanmate has a measurement algorithm for axial length, anterior chamber depth, and lens thickness. There is audible feedback that assists the user to achieve proper probe alignment. The software then acquires and ranks measurements based on the quality of the waveform, and also allows the user to review recorded waveforms and manually perform measurements. The DGH 6000 can perform measurements using water immersion or direct contact techniques. There is also an adjustable compression sensitivity setting that helps reduce corneal compression during direct contact measurements. Customized reports can be created and saved to a database, exported to an EMR system or sent directly to a networked printer. The IOL calculator includes modern formulas, including SRK/T, Hoffer Q, Holladay 1, and Haigis, and there is also a post-refractive calculator. This unit is portable and can be connected to a laptop or tablet. It includes a probe mount, cord wrap and custom carrying case. And the DGH 6000 can integrate with the DGH 8000 B-Scan. (Image courtesy DGH Technology)
Micro Medical Devices A-Scan Biometer with IOL Calculator — Palmscan A2000T
The PalmScan A2000T A-Scan from Micro Medical Devices can perform both applanation and immersion biometry through the use of the E-Z Tip Immersion Shell. The A2000T is able to measure the thicknesses of the anterior chamber, lens, and axial length to calculate the required IOL needed for cataract surgery. Another feature is the Contact/Applanation mode where the PalmScan utilizes a “Corneal Compression Detection” technique that warns the user of any corneal compression, decreasing the risk of taking inaccurate measurements. This device is capable of measuring dense cataracts and is compatible with traditional scleral immersion shells. The A2000T is battery-operated, includes an IOL calculator with modern formulas, allows for correction of keratometry for post LASIK eyes, has a 10 MHz probe with a blinking fixation light and comes with a tablet PC. (Image courtesy Micro Medical Devices)
Micro Medical Devices PalmScan A2000 Pro AScan Biometer
The new features of the A2000 Pro AScan Biometer from Micro Medical Devices include additional internal rechargeable batteries, capability for an external charger during use, or through use of a provided power supply or Micro USB charger. This device also has a built-in USB hub which allows up to 3 external connections to use different probes or with a USB keyboard, mouse or external printer. (Image courtesy Micro Medical Devices)
Micro Medical Devices PalmScan AK2000 Pro AScan and Keratometer
Micro Medical Devices’ PalmScan AK2000 Pro AScan and Keratometer is useful for measurements of the corneal radius of curvature (average R, R1, R2) and corneal power (average K, K1 and K2) at the central 3mm zone. It also measures the steep and flat axis of the cornea, axial length, anterior chamber depth and lens thickness for use in cataract lens power calculations. The results are automatically integrated with the A2000 A-Scan device for IOL calculations and lens selection. Each capture includes an image of the cornea. The adjustable capture threshold allows scanning of all types of eyes. This unit is portable so can be used in multiple locations and for pediatric or wheel chair bound patients. Due to its application for disabled patients, it qualifies for the ADA Tax Credit in the US. (Image courtesy Micro Medical Devices)
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