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Nermine Said Aly Madkour, Maged M Roshdy, Sherine S Wahba; Rotating Scheimpflug Camera Curvature Decentration Indices. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1906.
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© ARVO (1962-2015); The Authors (2016-present)
To study the accuracy and correlation between different curvature decentration indices; anterior corneal curvature (A) both Inferior minus Superior value (I-S) astride horizontal meridian (h) and I-S value astride flattest meridian (f), posterior corneal curvature (P) I-S value astride horizontal meridian (h) and Index of Height Decentration (IHD).
In a retrospective study; history taking, clinical examination, and rotating Scheimpflug camera scanning (by Oculyzer II equivalent to Pentacam HR) were done to 94 eyes; 57 normal, 20 forme frust keratoconus FFKC (apparently normal cornea whose fellow eye with evident keratoconus(KC)) and 17 KC. All cases of corneal scars or previous corneal surgeries were excluded. I-S value was calculated manually from 10 points astride the horizontal and flat meridians for anterior corneal curvature and astride the horizontal meridian for posterior corneal curvature. IHD is calculated automatically by the device software 1.17r119.
The mean values of A I-S h in normal corneas versus (vs) FFKC and KC eyes were 0.19 ±0.62 vs 2.19 ±3.03 (P<.001), A I-S f 0.10 ±0.60 vs 1.64 ±1.94 (P<.001), P I-S h -1.25 ±3.83 vs 0.45 ±0.50 (P=.002), and IHD 0.113±0.794 vs 0.032 ±0.041 (P=.444). The four indices were highly correlated (P<.0001). The highest correlation coefficient was between A I-S h and A I-S f (r 2 =.913) and the least was between IHD and A I-S f (r 2 =.621).
All the three commonly used topographic decentration indices are correlated. The three types of I-S indices are more useful in detection of KC and FFKC than the IHD.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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