TORIC LENSES: WHAT’S THE ATTRACTION?
What are toric lenses? Let’s start with astigmatism. Many are afraid of the word, but in principle it’s a natural phenomenon. The cornea isn’t spherical but aspheric. This is natural in the sense that nothing is perfect. With astigmatism, the cornea has the shape of a watermelon or a football.
Astigmatism is regular and irregular, and the first can be corrected. Glasses or contacts neutralize it. By correcting astigmatism of the cornea or lens, light passes through the glasses or contacts of the same shape, but opposite. This method compensates for the effect.
When we do cataract surgery, we measure the possibly-existing astigmatism. If it was all in the lens, we replace the cloudy lens with an artificial one and solve the problem.
There is special diagnostic equipment that allows for accurate measurement in a fraction of a second. The patient sees a flash, like from a camera. The machine then separates the astigmatism into its components. How much is in the cornea? How much is in the lens?
HERE’S WHERE TORIC LENSES COME INTO PLAY
With this information, the surgeon can see that there’s astigmatism in the cornea, one diopter or less for example. If the operation is done with laser, it then makes an incision in the cornea. If it’s more than 1.5 diopters, though, laser cannot be used and we turn to toric lenses.
These are artificial lenses with built-in astigmatism correction, but they still need to be properly focused and directed. Most doctors use measurements made in the office. At BEI, though, we use the aforementioned ORA machine, and it recommends the most accurate toric lens.
The lens is then embedded and the machine furthermore tells you how to best configure it. The surgeon sees in real time how to correct the astigmatism. During an operation, the machine will tell you to “stop, do not turn”.
And in 99% of patients, they can see better than they ever have before, immediately after the operation.
Photograph by BEI assistant Lana Shekhtman