Chapter 17: Treatment of Irregular Astigmatism

Treatment of Irregular Astigmatism, Asymmetric, non-orthogonal bow tie, Hemidivision, Irregular astigmatism presents a challenge for refractive surgeons. How can this be best treated with LASIK surgery? Well we are really looking for the perfect treatment and I describe in detail the reduction of astigmatism by vector planning in my book. The technique of Vector Planning can be applied to the whole cornea or each half of the cornea using different treatment parameters for the, superior and inferior halves, This aims to regularize the cornea and potentially improve the best corrected vision. Is the regularization of the cornea based on topographic assessment? The regularization part of it is purely topography, actually designing a treatment on the topography to regularize the cornea by treating each half 90° apart. In other words, the two treatments being diametrically vectorially opposite to each other changes the shape but does not change the refraction. It just improves the shape of the cornea and then reducing it This is then followed up in the same ablation by a maximal reduction of astigmatism. You mention there the potential for getting an improvement in best corrected visual acuity and I presume this relates back to reducing the corneal aberrations having reduced the amount of irregularity. Would that be true? Yes I would say that to me as a corneal specialist and a corneal surgeon it makes sense to reduce higher order aberrations. By reducing the amount of irregularity on a cornea you are going to reduce the higher order aberration because it is really the irregularity that creates these higher order aberrations.