Theoretical influence of decentered ablations on induced Coma aberrations

• Autores: Samuel Arba Mosquera, Diego de Ortueta
• Localización: Journal of Emmetropia: Journal of Cataract, Refractive and Corneal Surgery, ISSN-e 2171-4703, Vol. 2, Nº. 3, 2011, págs. 153-158
• Idioma: inglés
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• Resumen

  • PURPOSE: Analysing the theoretical impact of decentered ablations on induced Coma aberrations, and defining proper centering references.

    SETTINGS: Private practice.

    METHODS: This theoretical background includes theoretical impact of decentered ablations on induced Coma aberrations, development of optimised centering references, and considerations on optical zone selection for corneal refractive surgery. MathCAD™ was used for simulations and Microsoft™ Excel for graphs and calculations. Results were evaluated in terms of wavefront aberration and asphericity.

    RESULTS: Theoretically, aberration-free profiles should be centered referred to corneal apex, whereas customised treatments should be centered according to the diagnosis reference.

    Nevertheless, main high order aberration effects (coma and spherical aberration) are coming from the «edge» effects, the strong local curvature change from OZ to TZ and from TZ to non-treated cornea. It is necessary to emphasise using huge OZ (covering scotopic pupil size), and smooth TZ.

    CONCLUSIONS: Results presented here are valid into theoretical frame. They do not consider sources of aberrations as eye-tracking or corneal biomechanics. Line-shapes may account for 18% of induced aberrations after refractive surgery. To get more realistic values, theoretical comatic effects have been «pseudo-empirically» enhanced by 3-fold factor