This is Video 6 on Analysis with your Medmont E300 Corneal Topographer.
Let's start by selecting a patient, we can click once on the plus sign to
open up the patient file,
or double click the patient name.
We can see we have one right Topography, lets select that Topography.
With your display window open,
we have a number of different analysis options we talked about in Video
5, Axial, Tangential,
Refractive, Elevation, and others.
When you're getting started with your Medmont,
it may be recommended to use 'Axial Power' as a way to interpret your
Corneas.
Axial Power is very helpful
in understanding how the Anterior Surface of the eye may
contribute to a patient's
Refraction and Visual Acuity.
For instance,
this patient has, With the Rule, Corneal Astigmatism.
We can see with Simulated K readings the Flat Axis is at
1
Degrees,
and the Steep Meridian is at 91 Degrees.
We can see we have 1.4 Diopters, Corneal Cylinder.
Steep Meridian running vertically, Flat Meridian running horizontally.
This would be a, With the Rule, Corneal Astigmat.
We can also interpret from the Axial Map that this is an Apical Astigmatism.
The Figure Eight or Bow Tie shaped Astigmatism is very much central
or centralized within the pupil.
Compare that
to this particular patient where you see, Against the Rule, Corneal Astigmatism,
of a very similar amount of Corneal Cylinder,
1.6 Diopters on, This Against the Rule, eye.
But again,
we see Centralized Corneal Astigmatism.
Compare this Apical or Centralize Corneal Astigmatism, to what's described as,
Limbus to Limbus Corneal Cylinder or Astigmatism.
In this particular case the Figure Eight or Bow Tie is not centralized to the
pupil, it very much extends from one side of the eye
to the other.
We can observe that this patient has, With the Rule, Corneal Cylinder, but
dissimilar to the first patient analyzed
it is not centralized, it is Limbus to Limbus.
When you have Limbus to Limbus Corneal Astigmat
you may want to click on the, 'Analysis'
and 'Details',
and compare the
'Weighted Average Height'
or the Sagittal Depth
in the
'Flat' Meridian,
verses the 'Steep' Meridian.
Notice,
1587 Microns on the 'Flat',
1825 Microns on the 'Steep'. There is a
huge differential between
the depth of the eye horizontally and the depth of the eye
vertically.
When fitting Contact Lenses this would be profound in
trying to fit this
Limbus to Limbus
4.2 Diopter Corneal Astigmat with a Spherical GP Lens, clearly a
Toric Lens
would be required.
Both because the, Corneal Astigmatism is high,
but also because it's Limbus to Limbus Corneal Cylinder,
and
because you have a very high differential between the 'Flat'
Meridian and 'Steep' Meridian
in-depth of eye.
For a Keratoconic Eye,
you would see a map
looking more like this where we don't see a defined
Flat and Steep Meridian,
and we don't see a Bow Tie shaped Astigmatism.
We see a typical Ectasia, where
the steepest
point of curvature is inferior of the Apex.
For more information on understanding diseased eyes,
go to Video 7
on Analysis
on Asymmetrical and Disease Eyes.
This concludes Video 6.