Astigmatism treatment options: What are some options for treating astigmatism?
Our options for treating astigmatism depend very much whether we’re dealing with one of our laser eye surgery patients or lens surgery patients/cataract surgery patients.
When we are dealing with laser eye surgery whether it’s LASIK or SMILE, incorporating the patient’s astigmatism (that they have in the spectacle correction) into that treatment profile is integral. It’s an essential part of getting that great outcome for the patient. We have to address astigmatism, but it’s very, very simple. It’s just measuring the spectacle prescription and putting it into the treatment profile. That’s always part of our LASIK and SMILE treatments, and we’re looking separately all the time at our outcomes for astigmatism treatment and finding that nomogram to get it as accurate as we possibly can.
When we’re dealing with our lens surgery patients, it is quite a different approach. Often there is some relevance in knowing what the patient’s astigmatism was before surgery, but we’re going to change things completely for them with the removal of that lens. What’s most relevant to us is the corneal astigmatism, so this is the shape of the front lens, the cornea, the window or the front of the eye. And that astigmatism is typically a result of that cornea being rugby ball shaped, it’s steeper in one direction than the other. And so what we do is take really accurate measurements, customized software and calculate a bespoke lens for that patient’s eye. So, the lens we implant not only has plus/minus power to bring that focus on the back of the eye, but also has differential power in two different directions. So the lens we put in has astigmatism to balance the astigmatism in the cornea and this is really key to getting a great outcome for patients whether having cataract surgery or lens surgery as a refractive procedure. So these are patients who are having a purely refractive lens exchange they may not have much in the way of cataract. Their main motivation is in obtain maximum independence from spectacles.
With those patients as a group, in particular, eliminating the astigmatism is critical. If we’re using a multifocal lens implant to share the light out, to create distance focus, intermediate and near. If that light is also being smeared by astigmatism, we’re going to degrade the quality optics; we’re not going to get the performance we want, we’re going to get magnified glare and halo effects at nighttime. And so, incorporating that astigmatic correction is really key.
One of the little traps that are out there for cataract surgeons, when they’re running busy cataract practices, is missing the fact that patients have corneal astigmatism, but may not have astigmatism in their spectacles. Now, this isn’t a common situation, but around in about 1 in 50 to 1 in 100 patients, we measured their spectacles beforehand and there’s no astigmatism. So these patients are not used to having astigmatism in their correction or in their vision, but when you measure their cornea, the window in the front of the eye, the window, the lens that we’re going to leave behind, we find they do have some significant corneal astigmatism. And what this means is, for that patient; it just so happens that nature created a balance in astigmatism.
The crystalline lens inside their eye just happens to have the right amount of astigmatism opposite to the astigmatism in the cornea. But if you then simply take that legs away and put in around ordinary cataract lens you are suddenly going to give that patient new astigmatism that they haven’t experienced before, that they’re not used to, and it is going to degrade the quality of vision in a way they really don’t like. And so, just being aware of that, taking those careful measurements and ensuring that you do restore that balance astigmatism for those patients as part of your cataract surgery is really key to getting a great outcome for them.
