title: Application of corneal tomography before keratorefractive procedure for laser vision correction.
abstract: Ectasia after refractive surgery represents a major concern among refractive surgeons. Corneal abnormalities and preexisting corneal ectasia are the most important risk factors. Corneal topography and central corneal thickness are the factors traditionally screening for in refractive surgery candidates. Study of the anterior surface by Placido topography allows for identification of keratoconus before biomicroscopy. However, this is insufficient for the evaluation of pre-operative refractive surgery. There are cases of ectasia after laser in situ keratomilusis (LASIK) without identifiable risk factors such that there is a need to go beyond the corneal surface. A key requirement is quantifying susceptibility to corneal biomechanical instability and progression to ectasia. Tomographic indices derived from elevation maps and pachymetry spatial variation produce a Belin Ambrosio display final D index (BAD-D index), which has shown better results compared to surface curvature indices for detecting very mild forms of ectasia. A logistic regression formula, integrating age, residual stromal bed, and BAD-D (Ectasia Susceptibility Score, ESS) resulted in a significant improvement in accuracy, leading to 100% sensitivity and 94% specificity for detecting susceptible cases. A comprehensive corneal structural analysis based on corneal segmental tomography can detect susceptible corneas, which increases safety for refractive surgery patients.
authors.affiliation: Department of Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil. dr.allanluz@gmail.com.|Cornea and Refractive Surgery Department, Hospital de Olhos de Sergipe, Aracaju, Brazil. dr.allanluz@gmail.com.|Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil. dr.allanluz@gmail.com.
authors.forename: Allan
authors.initials: A
authors.lastname: Luz
authors.affiliation: Department of Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil.|Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.
authors.forename: Bernardo
authors.initials: B
authors.lastname: Lopes
authors.affiliation: Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.
authors.forename: Marcela
authors.initials: M
authors.lastname: Salomão
authors.affiliation: Department of Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil.|Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.|Instituto de Olhos Renato Ambrósio and Visare Personal Laser Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Renato
authors.initials: R
authors.lastname: Ambrósio
mesh_terms: D003315:Cornea / Q000033:anatomy & histology*; D003316:Corneal Diseases / Q000517:prevention & control*; D019781:Corneal Topography; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D011183:Postoperative Complications / Q000517:prevention & control
keywords: LASIK; corneal ectasia; corneal tomography; keratoconus; refractive surgery