Astigmatism can be corrected several ways. Spectacles, which have been available for millennia, have a wonderful track record in correcting this optical irregularity. Modern day spectacles have reached an unparalleled degree of clarity and style and perform admirably in the correction of not just astigmatism but near and far sightedness as well.
Modern day techniques take a departure from spectacles and frames and bring us into the world of lasers and wavefront guided optics. Beyond spectacles, astigmatism can be corrected via LASIK, PRK, Arcuate Keratotomies, Limbal Relaxing Incisions and Toric Intraocular Lenses. If you have braved all those complex words and want to learn more, read on!
LASIK and PRK are cousin procedures that are performed with high performance and high precision lasers that re-shape the window the eye called the cornea. Simply put, an individual’s ‘refractive error’ or ‘eyeglass prescription’ is plugged into the laser and the laser does the rest. Along with astigmatism, nearsightedness and farsightedness are corrected as well allowing clarity without the need for spectacles. Of course, you have to ensure a patient has the right ocular qualities and characteristics (personality counts too!) before employing this technology.
Arcuate Keratotomies (AKs) and Limbal Relaxing Incisions (LRIs) are precision incisions that are made with a laser or by your friendly neighborhood eye surgeon’s hands with the aim of ‘relaxing’ the cornea. Why do you need to ‘relax’ the cornea? Well, as wonderful as the cornea is in providing you vision, it can be a bit misshapen at times (see image below and notice two focus points, instead of one) and AKs/LRIs can help achieve a more spherical shape to an, otherwise, oblong cornea.
Lastly, we have Toric IOLs. These intraocular lenses, by definition, come into play when one is having cataract surgery. Cataract surgery, for the uninitiated, is a mostly painless, 10-minute outpatient procedure that serves to clear up vision by way of removal of the natural, human lens and replacement with an artificial, permanent intraocular lens. For those of us who have egg-shaped corneas, a plain IOL isn’t ideal as it does not help corneal astigmatism. Toric IOLs, hence, can be utilized to neutralize one’s astigmatism (no matter how long you’ve had to live with it) and enable excellent vision, usually without the need for glasses. Here is what a Toric IOL looks like.
If you pay close attention, you will notice a line of small dots at the edges of the circular portion where the arms meet. We call the circular portion the optic and the arms the haptics. Those marks is where there is negative astigmatic power lies (read: where the magic of the lens is). Your surgeon uses those marks to align the lens during surgery matching where your astigmatism lies in an attempt to neutralize it. You are correct if you think it cannot be that simple – your surgeon actually spends much time studying and poring over maps and calculations to arrive at precise numbers used intraoperatively.
Toric IOLs have been revolutionary in the battle against our old foe, astigmatism. They have allowed many who have been burdened with significant irregularity in their optical system to see in a way they have never seen before. Imagine that person who has worn glasses for since 1st grade well into their 60s is suddenly unburdened of the need for spectacles to see clearly. What many who have astigmatism do not realize is that after cataract surgery, sometimes the only reason they are in glasses is because of their astigmatism. In other words, nearsightedness and farsightedness are often corrected completely and for someone without astigmatism, clarity without spectacles is the norm.
There are limitations to this technology. However. I have listed them below with a succinct explanation.