Instrument assisted diagnostics – biometry, topography and wave-front analysis

Patient selection and planning implantation of a toric intraocular lens requires sophisticated measurement of ocular biometry in order to facilitate a valid calculation of the implant. Biometric measurements such as videokeratometry or corneal tomography, may also assist in qualifying patients for toric lens implantation, e.g. detecting keratoconus, pellucide marginal degeneration or other contraindications. Keratometers mostly provide simulated keratometry values, which do not always reflect the amount of the regular astigmatism that could be corrected by a toric intraocular lens. Therefore, it is mandatory to differentiate between regular and irregular components of corneal astigmatism. Axial length measurements require additional attention, especially when using ultrasound biometry. Wave-front analysis may advance assessment of centration and rotation errors of toric implants.