Purpose:
To show actual applications of quantitative area topography(QAT) in normal and pathologic corneas.
Methods:
By the Orbscan II (B&L, Salt Lake City, Utah) statisticanalysis device the average, SD (dispersion of values), slope(rate of variation), and volume (pachymetry as function of analyzedarea) were assessed from annular or circular zones with selectedsize, concentric or not, centered to a referential corneal point(map center, apex, fixation, or thinnest point), to a non–cornealreference (pupil boundary), or to any place of pachymetry, curvature(power) or elevation maps.
Results:
Applications of this method identified so far are:assessment of a reliable central corneal power in keratoconusand after refractive surgery applied to IOL power calculation;recovering of original preoperative corneal power after myopicLASIK or PRK; identification of keratoconus and postoperativekeratectasia; analysis of power, elevation and pachymetry changesafter refractive surgery; study of spatial variation of cornealthickness, and preoperative evaluation of intracorneal segments.
Conclusions:
QAT is a new term that identifies a new approachin topographic analysis distinct to assessment of punctual values.Orbscan II is the only topographic system that presently allowsQAT. QAT is a method that can be applied to improve our knowledgeof normal, post–surgical, and pathologic corneas, reducingbias derived from system error or from quantitative punctualoptical topography.
Keywords: topography • refractive surgery • keratoconus