Purpose To investigate the correlation between decentration index (index of height decentration, IHD) automatically calculated by the Pentacam HR software and the manually calculated inferior minus superior (I‐S) value. Setting Al Watany Eye Hospital, Cairo, Egypt. Methods In a retrospective study, history taking, clinical examination, and rotating Scheimpflug camera scanning (by Oculyzer II equivalent to Pentacam HR) were done to 128 eyes: 82 normal, 24 forme fruste keratoconus FFKC (apparently normal cornea with evident keratoconus in the fellow eye), and 22 keratoconus (KC). All cases of corneal scars or previous corneal surgeries were excluded. The (I‐S) value was calculated manually from 10 points astride the horizontal meridian. The IHD is calculated automatically by the device software 1.17r119. Results The mean (±SD) of (I‐S) value in normal, FFKC, and KC eyes were 0.30 ± 0.93, 0.11 ± 2.03, and 4.62 ± 3.89, respectively, and those of IHD were 0.008 ± 0.004, 0.011 ± 0.005, 0.066 ± 0.067, respectively. The two indices were highly correlated (p < 0.0001) with a correlation coefficient (r2 = 0.874). Deduced regression formulae linking the two indices were calculated. Conclusions The two topographic decentration indices are highly correlated. Deduced formulae were proposed linking them.

PurposeThe aim of this study was to find indices for keratoconus (KC) detection with higher sensitivity and specificity than the currently available ones with the rotating Scheimpflug imaging (Oculyzer I, Pentacam) software.Patients and methodsData of 103 normal and 73 KC eyes imaged by Oculyzer I, including slit-lamp examination, refraction, Scheimpflug images, and follow-up data were collected. Logistic regression was done to find new indices with higher area under receiver operating characteristic curves using the currently available ones.ResultsThe Corneal Assessment Index from Relational thickness and other OCULUS Values 9 (CAIRO 9) index, deduced from the Ambrosio relational thickness-maximum and the anterior elevation at thinnest point from 9 mm best-fit sphere, and the CAIRO 8, deduced from Ambrosio relational thickness-maximum and anterior elevation at thinnest point from 8 mm best-fit sphere, have a very high area under receiver operating characteristic curves for KC detection (0.997 and 0.995, respectively).ConclusionNew corneal assessment index is deduced with better sensitivity and specificity for KC detection.

Purpose: To obtain an expression of the adjusted IOL power (P IOLadj ) in keratoconus eyes associated with minimal errors in IOL power calculation. Materials and methods: This retrospective study included a total of 25 eyes of 25 patients with ages ranging from 20 years to 76 years. The following IOLs were implanted: Acrysof IQ Toric, Acrysof SA60AT in 9 eyes, Sensar in 3 eyes, Tecnis 1 in 4 eyes, and Tecnis Toric in 2 eyes. The P IOLadj is based on Gauss equations, using adjusted keratometric index (n kadj ) specific to keratoconus eyes. From this n kadj, an adjusted keratometric corneal power is calculated (P kadj ). The P IOLadj calculation was performed after estimating the effective lens position (ELP) using a mathematical expression obtained by multiple regression analysis (named ELP adj ). Comparison between the P IOLadj and the real intraocular power implanted in each patient (P IOLreal ) was carried out. Results: No significant differences between P IOLreal and P IOLadj were found. However, differences could be clinically relevant up to of 2.54 D as P IOLreal increases. But, in the range of P IOLreal between 0 and 20 D, differences were lower than 1.5 D, being most of them below 1 D. Conclusion:A new formula of IOL power calculation (P IOLadj ) based on the use of an adjusted keratometric power (P kadj ) that considers a variable keratometric index due to the influence of the posterior corneal surface (n kadj ) and adjusted effective lens position (ELP adj ) is useful for estimating IOL power in low-to-moderate keratoconus, with more limitation in the most advanced keratoconus.