Do you need a toric lens?
If you are having cataract surgery, correcting any astigmatism with a toric IOL is a safe and reliable way to improve your vision and reduce your need for glasses after surgery. Careful planning in clinic and precise lens positioning during surgery will ensure the best possible results.
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The purpose of this article is general information, and is not a replacement for personal medical advice. Discuss with your surgeon which IOL is most suitable for you.
Cataract surgery involves removing your natural lens and replacing it with a clear intraocular lens implant (IOL). The type of IOL you have will determine your vision after surgery. The choice between single vision, blended vision, or a trifocal IOL is based on your own lifestyle and visual demands, but everyone would agree that whatever you chose to focus on, it should be as clear as possible.
Toric IOLs allow precise control of that final focus, in order to achieve the best possible outcomes for each IOL type.
What is astigmatism?
More than 40% of people have corneal astigmatism. Astigmatism is a type of focusing error caused by the shape of the cornea, the clear front surface of the eyeball. With astigmatism, light is focused differently depending on the direction it enters in the eye. Just like short- and near-sightedness, astigmatism can cause the things to appear out of focus. Astigmatism can also affect vision in other ways, such as producing “ghosting” around the edge of objects and even double vision.
“Up to 50% of cataract surgery patients have enough astigmatism to be eligible for a toric IOL, however in Australia less than 20% of patients having cataract surgery will actually get one”
Astigmatism is quite common and most people notice the difference when it’s corrected. If you currently wear glasses it’s possible that there is already at least a small amount of astigmatism correction built into your prescription.
If you have astigmatism that is not fully corrected at the time of cataract surgery, you are likely to need glasses more often in your day-to-day life.
How does a toric IOL correct astigmatism?
A toric IOL is a lens implant that corrects astigmatism. The right toric IOL in the right alignment forms a complementary focus with a patient’s cornea that neutralises their astigmatism after surgery.
To the naked eye a toric IOL looks the same as any other lens, but under the high magnification of the operating microscope a toric IOL has markers indicating the correcting axis of the lens. The IOL must be precisely positioned so that this axis aligns with the steepest part of the cornea.
Perfect alignment is crucial — for every 3 degrees of misalignment the IOL is 10% less effective. I use the Alcon VERION™ Image Guided System to for precise IOL placement.
Toric IOLs are better… for some people
Toric IOLs are made by the same manufacturer, and are the same high quality as non-toric IOLs. The only difference is the type of refractive error that they correct.
If your eyes have significant corneal astigmatism (50% of the population) then a toric IOL is the better option. If you don’t have astigmatism then a non-toric IOL is the right lens for you.
Toric IOLs are under-utilised. Up to 50% of cataract surgery patients have enough astigmatism to be eligible for a toric IOL, however in Australia less than 20% of patients having cataract surgery will actually get one. Thankfully this is changing.
My approach is to give patients as much control over their vision as current technology allows. I use a toric IOL in every cataract surgery patient if they have astigmatism, providing no other eye conditions exist that would prevent its use.
Toric IOLs are more expensive
Manufacturer pricing for a toric IOL is around $300 more than a non-toric IOL.
For health fund patients this cost is covered by your insurance and there is no extra out-of-pocket expense for using a toric IOL. For self-funded patients the IOL is provided at cost, but the difference means the surgery is more expensive. This difference is about the same cost as a pair of multifocal spectacles.
For the best results, preparation is key
With all lenses, high quality pre-operative eye measurements are essential to calculating the correct IOL and getting optimal outcomes. Measuring astigmatism involves measuring the front surface of the eye, which can be affected by contact lenses, dry eyes, and some eye conditions. If you have any of these before your surgery I will often need to treat these and bring you back for repeated measurements. This might seem like a hassle but remember that these calculations are used to select the lens you will have for the rest of your life!
Sometimes pre-operative measurements identify a rare type of astigmatism called irregular astigmatism. This can be caused by corneal diseases, corneal surgery, and eye injuries. It cannot be completely reversed with glasses, and a toric IOL is not recommended.
It’s important to identify any signs of pterygium before cataract surgery. A pterygium is a growth in the corner of the eye caused by sun exposure. It can grow and change the shape of the eye, and must be removed in a separate operation before cataract surgery, especially if a toric IOL is going to be used. I perform sutureless pterygium surgery, and generally recommend at least 3 months’ recovery before going ahead with cataract surgery.
Thinking about surgery?
If you would like to talk about cataract surgery, and the right kind of lens for you, contact me for an appointment.