Chapter 15: Irregular Astigmatism

What is Irregular Astigmatism, asymmetric, nonorthogonal topography, Topography What is meant by irregular astigmatism. Irregular astigmatism is when the bow tie of a topography map is a bit tweaked. It is either not in a straight line, which means it is non-orthogonal, or there is asymmetry between the two sides. In other words, you have a lot more colour on the topographic map on one side than the other, or you have a combination of the two. How did you envisage treating irregular astigmatism. I know we can treat the regular component of the irregular astigmatism but how do we actually address the highly regular component? Conventional treatments don’t address corneal irregularity. What can be done to address the irregularity is to divide the cornea into two hemidivisions with a corneal astigmatism magnitude and orientation for each of the two halves and with common manifest refraction So in effect you are doing vector planning for the two sides of the cornea separately and developing a TIA or a treatment for the two halves of the cornea separately and in this way you are able to regularize and reduce the astigmatism at the same time. Given you are treating the corneal irregularity one would imagine that there is potential to improve ap patients best corrected visual acuity. Would that be correct? I think that is absolutely true because not only are you going to have a reduction in the need for glasses but you can actually see better. If you are reducing irregularity and you are reducing astigmatism you have less of a tweak on the cornea, you are going to have less distortions and therefore you are going to actually have an improvement in the best corrected vision.