Combining corneal and refractive parameters
leaving less corneal astigmatism postoperatively reduces symptoms of aberrations
You discuss vector planning in your book for the treatment of astigmatism. A lot of doctors out there will be asking or thinking at the very least why don’t you sculpt the spectacle refraction onto the cornea if you want to get rid of glasses in laser surgery.
And that is a very good question and that is the conventional thought ever since laser surgery has come into being for the correction of astigmatism back in 1992 and the thing that concerns me about that is it is really the optical solution but it actually disregards the corneal shape which is what the patient is left with. Leaving the cornea with less corneal astigmatism than treating by reactive cylinder parameters alone results in better visual outcomes.
By reducing the amount of corneal astigmatism remaining using Vector Planning, does this result in increased refractive cylinder postoperatively?
Well this is where I like to say you actually get something for nothing. Not only do you get less corneal astigmatism, but there is no penalty of increased refractive cylinder as you might expect. Maria Arbelaez’s study using Vector Planning showed this to be the case and this can be related to the better shape of the cornea when incorporating corneal parameters into the treatment plan and not just refractive cylinder alone.
You mentioned a Vector Planning study by Dr Arbelaez. Can you describe this study and the findings?
Well Maria Arbelaez from Oman performed a LASIK study on one hundred and sixty eyes with myopic astigmatism. She performed eighty eyes using vector planning, eighty eyes with conventional treatment using manifest refraction and she showed that not only did these corneas with the vector planning have less corneal astigmatism, they actually had better visual outcomes with less refractive cylinder.