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Treatment of Irregular Astigmatism and Keratoconus with the VISX C-CAP Method

Irregular astigmatism is a very difficult and challenging problem for both patient and eye care physician due to the extremely debilitating symptoms it produces, including among others poor visual acuity not correctable with spectacle use; glare; halos; double or multiple vision; and reduced contrast sensitivity. This condition requires the use of rigid contact lenses in order to obtain improvement in quality of vision. However, a proportion of patients develop contact lens intolerance and they are left with only two options: limited vision with eye glasses or a corneal graft. Unfortunately, keratoplasty is not always the final answer for this disease. Frequently, an anatomically successful keratoplasty induces optical problems, such as residual spherical and cylindrical aberrations or irregular astigmatism, which may require the use of rigid contact lenses again. Also, a keratoplasty may have the risk of immune rejection or primary graft failure, situations that may hamper an optimal biological and visual result, with no more surgical options ahead. Bearing these facts in mind, we have developed a surgical technique intended to correct irregular astigmatism and keratoconus through a corneal topography assisted excimer laser ablation. This treatment has been performed as a customized ablation using the C-CAP (custom-contoured ablation pattern) method in the VISX Star S2 and S3 excimer laser systems. Herein we present the properties of the C-CAP program and the surgical technique to treat irregular astigmatism.