When it comes to keratoconus and progressive lenses a few things should be considered. In this article, we will go threw them and explain the advantages and disadvantages in-depth.
Before we dive into the topic of progressive lenses you should know about the fact there are two forms of keratoconus. The first form is the more commonly known progressive form of keratoconus. People with this form of keratoconus experience extremely often changes in there prescription with glasses due to their corneas changing shapes.
Opticians and optometrists can easily check if your cornea has a changed shape by looking at the mirrorerd rings of a device called topographer. Those rings a perfectly even. If they are reflected uneven they see immediately if visual problems are likely.
When the shape of the cornea is changed this goes along with the typical fluctuations in astigmatism and the axis of astigmatism and myopia or hyperopia. This form is best corrected with contact lenses in combination with progressive lenses if they are necessary. This means you wear your contact lenses and on top of them, you wear progressive glasses.
Otherwise the change in the shape of your cornea will lead to poor vision with progressive glasses only. Please keep in mind keratoconus and the fluctuations that go along with it can be minimal to very severe.
However, there is also a second form of keratoconus and it is called forme fruste. This form usually comes with a very consistent visual experience. Because the shape of the cornea is conspicuously altered but the shape does not change from day today. So it does not produce fluctuations.
Depending on where the shape is altered on the cornea it could be possible to correct this type of keratoconus with progressive glasses only. But the altered shape has to be found outside of the center of the cornea. In some cases, the conspicuously altered shape is found in the periphery so it does not impact vision negatively.
When to Correct Keratoconus With Progressive Lenses?
When there are no fluctuations in the prescription progressive lenses are a valuable option as long as the altered shape on the cornea is not near to the pupil. This advice is highly dependable on the customer.
Look at the pictures below. Here you can see two vastly different eyes. On the left you can see a pupil that is very dilated and on the right the pupil is more undilated. When the shape is altered in the lower periphery the person with the undilated pupils will probably have no problems whatsoever because the light rays that are not passing directly into the eye and get blocked by the iris.
The person on the left however will definitely still notice the distortions from the altered shape of the cornea even if the change in shape is found in the periphery. When it comes to such dilated pupils there is no chance to correct the person just with progressive glasses.
However, the person on the right might get a decent visual experience with glasses assuming the shape of the cornea does not change. If this is true the experience will be not very different from someone with keratoconus and progressive lenses to someone without this condition.
But when the cornea should change the experience will be way different from someone with different eyes. The reason is the clear field of view as illustrated here on the picture with the color white. This white zones would be altered to your disadvantage if your corneal shape changes.
The green zones illustrate the blurry fields of view. They expand if the prescription does not compensate your prescription perfectly. And with all the fluctuations going on the surface of your eye progressive glasses just can not compensate this changes.
In some cases, the green zones expand so much that even the upper half is filled with it. The result then will be progressive glasses that can be barely used. Because you just can not find the spots for clear vision.
That is why if I consider progressive lenses an option I would at least get two appointments to see if we have changes in the prescription or changes in the shape of your eye.
Besides my personal measurements, it is also highly important to me to get information about the visual experience directly from my customers. Things like:
- Did you experience fluctuations?
- When did you experience them?
- How severe were those changes in the visual experience? Could you read something good and after a while it was impossible?
- How was your experience with your last glasses/contacts like?
- Do you experience dry eyes?
There are even more questions I ask. The questions might change depending on what I see on your eyes. The last question is also very important. Because dry eyes can also actually lead to fluctuations in the visual experience that are very similar to those described from keratoconus.
Even in the process of the measurements in combination with a dry eye can lead to fluctuations in the power of astigmatism and the axis of astigmatism. There is a lot to look at to evaluate the best solution for the customer. In some cases, it makes sense if the eyes are very dry to deal with this first and check back after a few weeks later and discuss the options again.
When to Correct Keratoconus With Progressive Lenses in Combination With Contact Lenses?
If you experience changes in your visual experience or the optometrist or opticians tells you about fluctualtions in your prescriptions contact lenses in combination with progressive glasses are your way to go.
The reason is the contact lens has the ability to compensate for the uneven shape of your cornea. Even when changes in shape take place on the level of your cornea you will then take no notice of any fluctuations because the contacts compensate this too.
And when distance vision is corrected best you could go with progressive glasses in addition. You might ask why not to go with multifocal contact lenses for keratoconus. And you are right. This is definitely an option. But this option comes with a drawback. The drawback is you will probably lose some contrast with your multifocal contacts in comparison to your single vision ones.
In addition to these things you experienced during the refraction without contact lenses like the double shadowing effects on characters during the eye test might come back. Because what the multifocal contact lenses do change the shape from the center of the lenses compared to the periphery to achieve good distance vision and reading all in one lens.
What Did My Experience Tell Me Talking to My Keratoconic Patients?
People’s intentions are extremely different when it comes to correcting their eyesight. Some want the most basic solution and just want to get going. If this means they save some time every day and they do not have to deal with contacts and they are able to do their work they are happy.
Others seek for the most sophisticated option and are not satisfied even if their visual acuity is higher with contact lenses compared to most people with healthy eyes.
That’s why it is so important to talk about the different possibilities and to know what my customers have in their minds when they lookout for a solution to their visual problem.
My father in law has keratoconus and he is a great example for someone who does not want to have to deal with contact lenses. Like most sufferers of keratoconus, he has this condition just in one eye. The other eye has a cornea that is perfectly fine. So although he could experience a bump in visual acuity on one eye he is not interested in it.
And if that is what makes him happy it is totally fine with me.
I wish you a great day.