3B Scientific UE9020100 Ultrasonic Biometry Instructions
- June 1, 2024
- 3B Scientific
Table of Contents
3B Scientific UE9020100 Ultrasonic Biometry
UE9020100 I ULTRASONIC BIOMETRY
EXPERIMENT PROCEDURE
- Measure the biometric ratios in the human model eye by using a pulse echo method.
- Calculate the geometry of individual objects in the eye.
OBJECTIVE
Determining the Internal dimensions in a model eye
SUMMARY
In this experiment a typical application of A-scan ultrasound biometry in
medical diagnostics used in ophthalmology is given. At an eye dummy all parts
of the healthy eye are measured and correction calculations shall be done.
REQUIRED APPARATUS
BASIC PRINCIPLE
Ultrasound is used also in ophthalmology. Its largest importance lies in the
area of biometry, in the measurement of distances in the eye. The distance
between cornea and retina is very significant for the calculation of the
characteristics of the artificial lens implanted to patients with cataract.
Sonography is necessary in this case since the cornea or the lens are too
cloudy for the use of optical methods. Investigations of the aqueous, vitreous
humor and the thickness of the lens are nowadays often done with new methods
of laser light or ultrasonic B-mode imaging.
The given measured time of flight of the echoes of the A-scan cannot be
calculated as distance in a simple way, because of different velocities in
the different media (cornea, lens, vitreous humor). Therefore a corrective
calculation is necessary. Two velocities are given for the dummy: -lens: 2500
mis, -humors: 141 0 m/s. These values and the time of flight from the measured
A-scan image shall be used to determine the distances with the help of the
following equation:
In medical diagnostics “averages” are often used known from experience. This average velocity shall be calculated for the dummy with the following equation:
Ultrasonic coupling gel is used to connect the probe to the cornea of the dummy. Slowly move the probe over the cornea to look for the optimal signals (2 large lens peaks and one smaller from the retina). After measuring the time of flight of the peaks the real distances can be calculated.
EVALUATION
The time of flight of each peak was measured and the averaged velocity was
calculated with the equation (2). The result was adjusted to the A-scan
device, it was switched to the depth scale and the depth of each peak was
measured.
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