Article
Corneal first-surface aberration analysis of biomechanical effects of astigmatic keratotomy and a microkeratome cut after penetrating keratoplasty
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Published: | September 22, 2004 |
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Outline
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Objective
A 35-year-old male patient with high astigmatism following penetrating keratoplasty (PK) for keratokonus applied for LASIK to reduce his high astigmatism in his right eye.
Methods
Astigmatic keratotomy (AK) was performed. To correct the residual refractive error after AK, a two-step LASIK approach was planned. Three months after AK, the cut was performed without any complications with the Hansatome™. We did not perform any excimer laser ablation as the patient was happy with the result and refused further treatment.
Results
AK led to a dramatic decrease of astigmatism while corneal higher order aberrations (HOA) increased. One day after the microkeratome cut, a decrease of 2.75 diopters of spherical equivalent (SE) was noted. While lower-order and spherical aberrations were only affected marginally, a marked decrease in coma and other HOA could be observed. One month after the cut, the spherical equivalent was unchanged.
Conclusions
The present report shows that AK cuts can induce higher order corneal aberrations. Moreover, a single microkeratome cut performed in corneal grafts could have strong biomechanical effects, both on lower- and on higher-order aberrations. If LASIK is planned after PK, a two-step approach is recommended to anticipate biomechanical effects to avoid over- or undercorrection.