Basic Operation Video 4

This is Video 4 on the basic operation with
your Medmont E300 Corneal Topographer. You’ll note that your database is along
the left hand side, all patient information will be stored here. Under patient name Case, initial A, we can click on that patient name and bring up the main patient window, we also know that there’s a plus sign
next the patient name which indicates that there must be information inside that
file. You can open up the patient file by
clicking once on the plus sign or, double clicking on the patient name. In opening up the file we can see that
there is one right Topography inside that file. If you click on that Topography it will be
dropped on the main active window here. Once we do that you can analyze these topographies a
number of different ways. In the first way we might do so is to look at the
Sim K readings This is our Keratometry readings as determined
by your Medmont Topographer. In this case the Flat K is 42.2, Steep K 43.6. The Flat K is along axis 1, Steep K at axis 91. We can also see that this cornea has 1.4 Diopters of Corneal Astigmatism. Next we can click our cursor in the center
of the Topography and determine the radius of curvature at that point in
this case 42.9. We could click our cursor at any point on the map and determine the curvature at that
point, in this case 43.5 just inferior of the Apex, and where the cursor has been clicked were 1.30 millimeters away from the center of the Topography. The center of the Topography would be the
Visual Axis, this would be the point the patient is fixating at the moment the map is taken. We could look at the 3 millimeter
5 millimeter and 7 millimeter white rings and the pupil which is in black, here. We can use either the pupil or the rings to determine the position, shape, or size of any
anomalies in relationship with the visual axis, with the pupil, or to a certain diameter away from the Apex. Next we could look at the Eccentricity Value here. Eccentricity is a measure of the
rate of Corneal Flattening of the eye. From the Apex to the periphery how high is that rate of change, the higher the Eccentricity the flatter the Cornea becomes as you move toward the periphery. In this case from the center taking this white axis line observe the
graph down below. Along the Horizontal Meridian we go from, steepest curvature in the
center, to flattest curvature toward the periphery. .86 is the measured Eccentricity. Now change your axis line to the Vertical Meridian, and notice there’s very little rate of
change from center to periphery along the Steep Meridian as compared to
the Flat Meridian. That gives us a much lower Eccentricity Value. We will focus on Eccentricity later in the video series to better
understand what this tells us about the eye shape and how it can help us in terms of contact lenses. Next we can look at the scale range
along the left hand side. Notice the Topographer is showing us the
flattest it can read is 35.23 Diopters here, steepest it can read is 43.61 Diopters here. The scale is set for a Normalized Scale range. Meaning the Topographer will show from the steepest to the flattest that can be read on the
selected maps along this left hand side. If you select a Topography that has
much steeper curvature or much greater range of curvature the scale will adjust for each
individual patient eye. Normalized Scale is the best way to
interpret maps to get the best definition on each individual eye. You can also click on this down arrow and
select from anyone of the Absolute Scales. For instance you could select the Standard Power Scale which changes the scale range to 35 Diopters up to 50 Diopters. Now we have a 15 Diopter scale range that’s absolute, absolute, meaning it will always be from 50 to 35. And you can determine where that
patients falls within that scale the redder the colors of the map the steeper the Corneal Topography. The bluer or colder the colors are the flatter the Topography. In this case we have green contours near the center this is a pretty median cornea, but notice in Absolute you lose a lot of definition that the Normalized Scale would provide.
So let’s go back to Normalize Scale and use that as our default for all maps that we analyze. This concludes the Basic Section on your Medmont E300 Corneal Topographer.

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