Tip:
Highlight text to annotate it
X
the ocular response analyzer
utilizes a patented dynamic bi directional applanation process
to present the world's only direct measure of corneal biomechanical
properties
and a more accurate assessment up intra ocular pressure
dudes
there are four key components to the applanation system of the ocular
response analyzer
a solenoid driven airfield
and infrared light emitter a light intensity detector
and a pressure transducer
do at the start of the test sequence
the infrared light be mentored directs a beam of light onto the cornea
the convex shape of the cornea causes the reflected light
to be dispersed over a wide angle
the Airpump now delivers a column aidid stream of air directly onto the eye
as the cornea moves in words towards applanation
the reflected light beam begins to converge directing an increasing amount
of light
onto the detector when applanation is achieved
the reflected light is nearly column aidid and the detector registers a
signal peak
causing the pressure transducer to record the applanation pressure
following applanation the air flows continues to impinge upon the cornea
causing it to deflect into a state of slight can cavity
the reflected infrared light once again becomes dispersed
and the detector signal amplitude decreases
as the velocity of the air polls declines towards zero
the cornea returns to its natural shape and once again
passes through an applanated state
the reflected light again reaches maximum intensity
and causes a signal peak at the detector triggering the pressure transducer to
record the applanation pressure
a second time. the cornea completely returns to its normal configuration
and the sequences concluded
the entire measurement process takes approximately 20 milliseconds
the process results in a measurement signal
similar to this one. the internal pressure transducer
records the pressure required to flatten the cornea at the moment of each
applanation event
one might expect that the pressure measured at the inward and outward
applanation events would be the same
however due to its viscous nature the cornea resists the dynamic force at the
airpuff of
resulting in a damping effect that manifests itself
as a discrepancy between the applanation pressures. we refer to this phenomenon
as corneal hysteresis. the ability to measure this effect
provides us with the key to understanding the biomechanical
properties of the cornea
this new ocular parameter differs from person to person
and varries in the same person Diana Lee it is not strongly correlated to any
other known ocular parameter
including central corneal thickness and has been shown to be essentially
independent of pressure in normals
by Mel nearly everyone recognizes that the current gold standard for measuring
pressure
the goldman tonometer has considerable flaws: the goldman is significantly
affected by corneal properties
because the device was designed to provide accurate measurements
in eyes with average corneas but we now know that many corneas very more
significantly from average than previously thought
and in more complex ways than simply thickness alone
because the ocular response analyzer is capable of measuring the biomechanical
properties are the cornea
it is able to provide a pressure measurement that agrees with Goldman
measured I O P on the average
but is uninfluenced by corneal effects. this new measurement of I OP
called IO Pcc has essentially zero correlation with central corneal
thickness
and stays relatively constant post LASIK the ocular response analyzer is
convenient and easy for both the operator
and the patient the instrument sits neatly on any adjustable instrument
stand
and is controlled by a custom windows-based program providing
graphical analysis of the measurement results
the software includes a comprehensive database
that facilitates analysis of patient measurement data over time
this feature is invaluable for assessing treatment efficacy
disease progression and post-surgery data comparison
and it's extremely simple to operate
patient positioning is easy and comfortable thanks to the left right
sliding headrest
in the easy to find fixation target best of all
the ocular response analyzer utilizes a non-contact measurement methodology
so no anesthetic is required our patented hands-free automatic alignment
system
makes it easy for any member of your staff to perform the measurement
the instrument includes a convenient built-in
ultrasound pack emitter so operators can conduct multiple tests at the same
workstation
the CCT data are captured and stored along with all the other measurement
results
Subscribe BIomedEngg for more VIdoes
0