Conductive Keratoplasty Hyperopia and Presbyopia Workup

Updated: Mar 15, 2016
  • Author: Manolette R Roque, MD, MBA, FPAO; Chief Editor: Hampton Roy, Sr, MD  more...
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Imaging Studies

Corneal topography development provides surgeons with effortlessly understood color-coded maps of corneal curvature, in addition to quantitative indexes of irregular astigmatism that correlate with potential visual acuity. [31] Modern instrumentation produces a videokeratograph (generally a color-coded contour map). [14] The use of keratography in preoperative and postoperative evaluation of all refractive surgery patients is valuable. Different manufacturers use different methods (eg, Placido, 40 scanned slits, combination Placido and 40 scanned slits, phase modified laser holography, raster stereography).

The pachymeter (eg, optical, ultrasonic) is used to measure corneal thickness. Accurate determination of corneal thickness preoperatively allows the surgeon to set the depth of incision to two thirds of the measured result. Orbscan II by Orbtek uses both 40 scanned slits and Placido methods to provide data on anterior and posterior corneal curvature and corneal thickness.

Ultrasonic biomicroscopy is used to measure corneal thickness (where available). Typically, it is used in clinical studies.