RPG contacts and Higher Order Aberrations?!
Question: I am planning on getting contacts for the first time in my life. In the past I have had problems getting perfectly clear vision with glasses and I was wondering how they fit RGP contacts? Do they do a topography before doing a specialty fit with contacts? I suspect I have Higher Order Aberrations, but I was wondering what I should tell the doctor or if I need to tell her anything to maximize the benefits of any possible vision problems on the cornea? I've heard that a certain power or fit of RGP can make a difference when dealing with HOA's. Is this true?
Regardless of whether or not RGP lenses get rid of my visual disturbances, I'm still planning on getting them for other reasons as well.
Answers: I am planning on getting contacts for the first time in my life. In the past I have had problems getting perfectly clear vision with glasses and I was wondering how they fit RGP contacts? Do they do a topography before doing a specialty fit with contacts? I suspect I have Higher Order Aberrations, but I was wondering what I should tell the doctor or if I need to tell her anything to maximize the benefits of any possible vision problems on the cornea? I've heard that a certain power or fit of RGP can make a difference when dealing with HOA's. Is this true?
Regardless of whether or not RGP lenses get rid of my visual disturbances, I'm still planning on getting them for other reasons as well.
One of the nice things about RGP lenses is that the exact degree of astigmatism, or irregularities or aberrations due to the front surface of the cornea*, do not have to be measured or specified as they effectively vanish as the tear film fills in the space between the back surface of the contact lens and
the front of the cornea.
Optically, the front surface of the cornea disappears so its exact shape does not matter, up to the point where the irregularities or astigmatism become a problem to the actual fit of the lens.
But that's a different issue.
Other considerations can cause visual distortions with any contact lenses, the most common one being the size of the optical zone: with large pupils this can cause haloes at night if the contact lens has too much of its peripheral area given over to thinnness/comfort, rather than to optical correction.
*and only the front surface of the cornea, but that accounts for about 90% of cases.
I love my RPGs. Nothing gets my vision as sharp as I get with RGPs. Soft contacts and glasses don't give me the vision I get with RPGs. They take a bit of getting used to, but you can't beat the price and the acuity of your vision. 2D