10 Mar Better Results with the Toric IOL
A toric IOL is used to decrease astigmatism after cataract surgery.
Astigmatims and the Toric IOL
Symptoms of Astigmatism
The symptoms of Astigmatism include blurry and distorted vision. Astigmatism makes your vision out of focus. Double vision and streaks of light in your vision at night are also potential symptoms. Many patients choose a toric IOL to decrease these symptoms.
What is Astigmatism?
Astigmatism can be caused by an irregularly shaped cornea, an irregularly shaped lens inside your eye, or both. If it is caused by the shape of your lens, then the removal of your cataract would also remove the astigmatism at the same time and a toric IOL would not be needed.
If your astigmatism is in your cornea, then removing the cataract would not remove the astigmatism and a toric lens could be considered to improve your vision.
Astigmatism Treatments
Astigmatism can be treated with glasses, contact lenses, LASIK, Limbal relaxing incisions, or a toric IOL.
A toric IOL is a great way to correct astigmatism after cataract surgery. A standard intraocular lens does not correct astigmatism. If you chose to have your astigmatism reduced at the time of cataract surgery, your surgeon could use an IOL that contains astigmatism correction called a toric IOL. We have a large selection of different powers of toric IOLs available so we can match it to the specific needs of your eye at the time of cataract surgery.
Measuring Astigmatism for the Toric Lens Implant
Measuring Your Eyes for Your Toric IOL
We can measure your astigmatism with the standard glasses machine (you know, which is better, one or two). This works great for glasses but not for picking a toric IOL. This is because the glasses machine measures your total astigmatism whether it comes from the cornea or your lens. In cataract surgery we remove your lens so we only need to focus on the amount in your cornea.
The traditional approach to picking a toric IOL is to measure the amount of astigmatism on the outer surface of your cornea. The astigmatism is measured by projecting a series of ring lights onto your cornea. As the reflections of the ring lights bounce back, a camera records them. A computer analyzes the shape of the rings. If they have been distorted, you have astigmatism. The machine notices the amount and direction of the distortion. This tells us the amount and the axis of your astigmatism.
We use four totally different machines to measure the amount of astigmatism on the front surface of your cornea to help us choose the right toric lens implant for your eye. This is still the most common approach for surgeons choosing a this product for your cataract surgery. This has been a great strategy and has given good results for most, but we want great results for all.
The error in the traditional approach to measuring the astigmatism and choosing toric IOLs is that we were only measuring the front surface of the cornea while the back surface can also add astigmatism. Usually the amount on the back surface is around 0.5 diopters which small amount.
Recently Dr. Koch put out a table based on his research to help us better guess the amount that is there on average. This works great, except when it doesn’t work at all because occasionally there is a large amount of astigmatism on the back surface.
Great Accuracy for Your Toric IOL
We now have a system called the ORA from wavetech that helps us know the combined amount of astigmatism. This has increased our accuracy in choosing the correct power for your eye.
Here is how the system works. Once the lens has been removed from your eye during cataract surgery, all the remaining astigmatism comes from your cornea, whether it is on the front surface of the back surface. A group of cleaver engineers have invented a wavefront machine that attaches to the surgical microscope. After the lens removal, I raise the pressure in your eye to the normal range and then the machine uses very sophisticated wavefront technology to measure your total astigmatism.
The device does a serious of complex calculations and then recommends the toric IOL power and the correct axis. I call out the lens we will use and a technician grabs it from our inventory, confirms it with us, and then we all watch as they unwrap it and load it before I can place it in your eye. This adds a great deal of time to the surgery, but the extra accuracy is worth it to improve accuracy.
Once I place the toric IOL in your eye I need to rotate it to the correct position to treat the astigmatism. The Ora machine projects a grid onto your eye to show me the correct spot. Once I have the implant there, I do another measurement with the ORA, which tells me to rotate it a bit to the left or a bit to the right. I make the recommended adjustments until it says its just right.
The system is not perfect, but it is a measured, obvious, and proven step forward in accuracy for the toric IOL. The Eye Center of Northern Colorado, was the first to use this in Colorado though gratefully a few other offices have now acquired the device around the state since 2012 when we started using it. I have been very impressed and have become a consultant for the company.
The Future of the Toric IOL
The Eye Center of Northern Colorado has been selected to be the fourth eye center in the world to receive the Verion Visual System. This will give us another method to measure the amount of astigmatism at your preoperative visit. In addition, it takes an HD photo of your eye at the same time it measures your astigmatism. When you are in the OR for your cataract removal it will line up the image of your eye with the image taken at your preop and show the correct position for the toric IOL and the ideal place to center the intraocular lens. Amazing!
There is another IOL in FDA trial at this time that can be adjusted after surgery. This is called the light adjustable lens. If this is FDA approved in a couple of years, we could place your toric lens implant and then if a small amount of astigmatism remained after you healed, we could adjust it with a light treatment delivered in the clinic.
Complications of the Toric IOL
It is rare to have complications or problems. The toric lens implant could leave you a bit near sighted, far sighted, or you could have some amount of residual astigmatism. If this happens you could consider glasses, contact lenses, LASIK, limbal relaxing incisions, or IOL exchange. On very rare occasions, the toric lens implants rotates out of position after leaving the operating room. I have had to go back to the operating room a couple of times to rotate the lens back to the correct position for patients to improve their vision.
The toric lens implant could have any of the other complications that can happen with intraocular lenses.
If I can answer any other questions about the toric lens, please leave a comment or set up an appointment to meet with me.
No Comments