Abstract
Purpose: :
Corneal topography analysis based on illuminated rings (CT) are still the gold standard for pre and post-operative evaluation of curvature in cases of astigmatism and other high order aberrations (i.e. keratoconus). Anterior segment tomography based in rotational slits (AT) has been used for combined diagnostics of area pachometry and surface elevation. Based on algorithms it is possible to transform elevation data to curvature. The objective of the present study is to compare qualitative curvature data produced by CT to data simulated by AT, among different ages and clinical expertise.
Methods: :
Fifteen sagital-curvature-corneal maps generated by the EyeSys (Houston, TX, USA) were compared to 15 sagital-simulated-anterior-corneal maps generated by the Pentacam (Wetzlar, Ger) from the same patient in the same day. Six patterns were presented: aspheric, regular astigmatism, irregular astigmatism, asymmetric astigmatism, asymmetric and irregular astigmatism (keratoconus suspect) and keratoconus. Isolated color-maps were enlarged to match and shuffle. Forty volunteers from four groups (children between ten and thirteen years-old (CH), non-physicians adults (AD), ophthalmologists (OP) and refractive surgery specialists (RS)) were asked to match the maps. The RS group was also asked to give a diagnosis from a list of eighteen possibilities. Results were analyzed using a single proportion test, the level of significance of 0.05 was corrected by Bonferroni correction procedure to 0.02.
Results: :
Statistical results showed that CH was the only group significantly different from the others (CH vs. AD p=0.01; CH vs. OP p=0.005; CH vs. RS p=0.0004), while the other groups showed no significantly difference between them (AD vs. OP p=0.37; AD vs. RS p=0.09; OP vs. RS p=0.52). The comparison between the KS group match and diagnosis also showed no statistical difference (p=0.23).
Conclusions: :
Pattern recognition increases with the age of observer, but are not dependable on clinical expertise. EyeSys and the Pentacam can be interchangeable without changes on diagnosis; thus the Pentacam sagital-simulated-anterior-corneal maps may replace the axial curvature EyeSys maps, according to this limited and controlled study.
Keywords: refractive surgery: corneal topography • topography