employing the Medmont E300 Corneal Topographers, Contact

Lens Module.

Lets open up a patient file,

select a Topography.

Click on 'Home',

and then,

'Contact Lens'.

When you first start out select the manufacturers that are available from

North America, (or your Country)

you'll note

the boxes presently checked are all the manufacturers available

from North America

that have put their Contact Lenses designs into Medmont Studio.

You can click 'Ok'.

You won't have to open up this manufactures icon

unless a new manufacturer has been added

to a recent

release of the Medmont Studio software.

Otherwise you're just going to enter the patient's RX if it isn't

already entered in the patient file, so on the main window

where you enter patient information, if you

punch in your

patient Spectacle RX it automatically comes up in the contact lens design

window.

Next let's select

the

specific lens we want to fit on this eye.

Let's design for this patient a simple Multi Curve that we can get from any

lab in the world.

Say 'Okay'.

The software will then drop a theoretical contact lens on top of your

patients eye, and it

will

default the Base Curve generally very close to Flat K.

You will

manipulate the

contact lens parameters

to produce

the best possible

Fluorescein pattern.

And we start

by first determining

Visible Iris Diameter,

and we click on 'Annotate',

and then ,Ruler',

and

measure

Visible Iris Diameter.

We are getting a

close to 12 Millimeter

HVID.

We'll select to delete that annotation and you can do that by, right-clicking,

and then deleting.

Next let's pick up the contact lens,

and place it some more near the,

Geometric Center.

So ignore the Placido, and center the contact lens

in relationship

with the Sclera.

So looking at the white of the eye

around here

and placing your contact lens as it appears centered, not

to the Placido Rings that you can see

just outside of the lens, but more so

to the Iris or

Limbus.

Next

lets choose the lens diameter that we would prefer.

In this case we fit the patient with a 9.5.

'Apply'. And

click your cursor in the center

and measure the Tear Film Clearance, or 'TFC' along the right hand side

here.

It's indicated to be 24 Microns.

For Fluorescein to be seen by

the human eye

it must be

in excess of 20 Microns.

In other words, for us to see Fluorescein behind our Slit Lamp,

we must have a

thickness of Tear Layer

and density of Fluorescein Molecules

somewhere in the neighborhood of 20 or more Microns.

If you want to see a nice even central Fluorescein Pattern

on your actual fit

you must have a Tear Film

Clearance at the Apex of at least

20 Microns.

With 24 Microns

that would be comfortable, we are looking for somewhere between 20 to

25 on a normal eye.

Next

take this white axis line and find the point on the graph

where the lens seems to land

on opposing sides,

and it appears

that on our , With the Rule Corneal Astigma,

this lens lands

very close to nine o'clock,

and again on its opposing

side at three o'clock,

so we have Apical Clearance of approximately 24 Microns

down to touch

at nine o'clock, you see the dotted section of the line here corresponding

with the dotted

section on the graph,

solid section of the line here corresponding

solid section there.

So we have our

24 Microns Apical Clearance

heading down to three o'clock we have our touch

and then our edge lift,

our Apical Clearance

toward nine o'clock,

with our edge lift.

So this is

and ideal relationship to keep the lens on lateral center.

Then we take our axis line and drag it to the Vertical Meridian and we can see

that this patient has a fair amount of Tear Layer Clearance

heading toward twelve

and heading toward six o'clock,

dotted section of the line here corresponding with the dotted section of

the line here,

solid section of the line there corresponding with solid section here. If

we click our cursor at the edge of the inner pink circle which is

the, Optic Zone Junction.

we're showing 41 Microns heading North,

and

85 Microns heading South, or inferior.

This is a

significant amount of Inferior Clearance and would likely cause

the lens to tilt and rock across the Vertical Meridian because there is

excessive

lift of the lens at twelve and six o'clock.

This is a Fluorescein pattern of the actual lens on eye

designed from our Medmont,

and you can see that

this contact lens

has an acceptable level of Apical Clearance.

Fluorescein can just be seen under the center of the contact lens, so this is

good, we have landing at nine o'clock and landing at three o'clock

with a healthy edge lift on both sides.

The problem however; is the

significant Inferior Lift,

and Superior Lift, that's causing the lens to tilt and also

ride high.

This patient needs a Toric GP Lens.

So let's go back to our contact lens and try to better designed it from our Medmont

software.

Click on 'Display' to bring up the, 'Edit' box again,

and select

'Toric'.

Now we create two

Meridians of Curvature,

and 'Apply' that.

The same rules apply to the,

Toric Contact Lens.

We want to create a lens that lands at three and nine o'clock,

and lifts at twelve and six o'clock.

Presently our contact lens is

not landing across the Horizontal Meridian, the Horizontal Meridian,

you can also see is our Flat Meridian by that blue line.

So let's steepen the Base Curve along the Flat Meridian

by a half Diopter step.

On the Vertical Meridian,

we appear to be very near to bearing or definite bearing at, twelve and six.

We want our contact lens to lift so it can freely move with each blink

and create a good Tear Pump.

So let's

flatten the lens across the Steep Meridian

so that our contact lens will

be able to move with each blink. And

click 'Apply'.

Now we have a lens that lands at

three and nine o'clock

and along the Vertical Meridian it lifts

at twelve and six o'clock.

This would be ideal for a good RGP fit.

The last thing that one might do is adjust the, Optic Zone Size,

to soften its Peripheral Landing. Notice this narrow,

Point of Bearing,

and a very steep angle as the lens comes back toward the Cornea and touches.

Lets increase the Peripheral Curve Width,

reduce the, Optic Zone Size, slightly

and see what that does to those Points of Bearing. When we apply

notice how you shallow out

how that lens comes back towards the Cornea,

and creates a much wider

softer Area of Bearing.

Now here's the actual lens that was fit

by these same parameters,

and you notice

you've got virtually 360 Degrees of alignment, but

appears to be a very thin channel

at twelve and six o'clock which would allow the lands to freely

move

with each blink.

So the Tear Film definitely shows

what appears to be bearing at

three and nine o'clock and then

that bearing thins out throughout twelve and six o'clock to allow for the lens

to freely move

in the Vertical Meridian.

And we also have much better centration then we had

with the Spherical GP Lens.

This concludes

the section on Using the Contact Lens Module in your Medmont E300

Corneal Topographer