It is unusual to see an increase in corneal astigmatism after laser vision correction. Similar to myopic patients, a patient who has significant with-the-rule astigmatism prior to surgery can develop with-the-rule astigmatism after surgery.10 Oblique astigmatism cases are more worrisome. On rare occasions, increasing astigmatism is the first indicator for corneal ectasia.11
While an increase in with-the-rule astigmatism is often treatable with an enhancement procedure investigate first with corneal tomography for corneal stability. This test is sensitive for corneas that are developing ectasia. Testing is more important today because we can treat corneal ectasia early with corneal crosslinking (CXL) to reduce or prevent the devastating effects of vision ectasia.
For example, a patient who progresses to a refraction of +0.25-1.00 x 75 usually has reasonable uncorrected vision, and his best-corrected vision can be 20/20. If we find his eye is developing corneal ectasia, it can be treated with CXL and remain a low astigmat. If this patient goes untreated, the cornea can decompensate to a point where uncorrected vision is worse than 20/200 and best-corrected vision worse than 20/40 with spectacles.
Most patients who return to your office years after laser vision correction still enjoy wonderful distance vision from this procedure. Nevertheless, eyes change over time for various reasons, and it is important to understand why the refractive status is changing and how to best manage that refractive change.
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