## 3 Results  
Sixty-two healthy eyes (36.7%) (control group, Ctrl) and 107 KC eyes (63.3%) (KC group, KC) were herein considered. Several subgroups were established in the KC group depending on the disease stage according to the RETICS grading system: grade I (44 eyes, 41.1%), grade II (18 eyes, 16.9%), grade III (15 eyes, 14.0%), grade IV (15 eyes, 14.0%) and grade Plus-V (15 eyes, 14.0%). The main demographic information in the control and KC subgroups are displayed and summarized in Table 1. No significant differences were found in age and gender terms among all the groups. Table 2 summarizes the descriptive analysis outcomes obtained for all the quantitative variable analyses in the control vs. RETICS I and the control vs. KC groups. The descriptive analysis indicated that most variables did not follow normal distribution. Statistically significant \(p\)-values were found for all the variables between the control group (Ctrl) and the RETICS grade I group, except for age (\(p\) = 0.665). When testing for differences within all the groups (Ctrl and RETICS grade I to V), every \(p\)-value was significant, except for age (\(p\) = 0.344). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & **Ctrl** & **I** & **II** & **III** & **IV** & **V** & **P** \\ \hline Number of cases & 62 & 44 & 18 & 15 & 15 & 15 & \\ Age in years (mean \(\pm\) SD) & 37.5 \(\pm\) 14.4 & 41.2 \(\pm\) 16.6 & 47.4 \(\pm\) 22.5 & 40.3 \(\pm\) 12.6 & 34.0 \(\pm\) 14.3 & 36.3 \(\pm\) 18.0 & 0.161 \\ Female/Male & 32/30 & 12/32 & 6/12 & 7/8 & 6/9 & 4/11 & 0.146 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Demographic information for healthy individuals (Ctrl) and the RETICS-classified keratoconus patients, graded between I and V. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Variables** & **Mean** & **SD** & **Median** & **Range** & **Normality** & \
\begin{tabular}{c} **Ctrl vs.** \\ **RETICS I** \\ \end{tabular} &
\begin{tabular}{c} **Ctrl–RETICS** \\ **I–II–III–IV–V** \\ \end{tabular} \\ \hline \hline
**Demographic** & & & & & & \\ \hline Age & 39 & 16 & 38 & 7–98 & \textless{}0.001 & 0.665 & 0.344 \\ \hline
**Optical** & & & & & & \\ \hline CDVA & 0.77 & 0.32 & 0.96 & 0.05–1.20 & \textless{}0.001 & \textless{}0.001 & \textless{}0.001 \\ Coma-like & 1.85 & 2.15 & 1.01 & 0.08–13.0 & \textless{}0.001 & \textless{}0.001 & \textless{}0.001 \\ Q8 mm & \(-\)0.63 & 0.70 & \(-\)0.45 & \(-\)2.80–2.82 & \textless{} 0.001 & 0.025 & \textless{}0.001 \\ Spherical-like & 0.70 & 0.93 & 0.44 & 0.15–7.20 & \textless{}0.001 & \textless{}0.001 & \textless{}0.001 \\ RMS total & 3.22 & 3.09 & 2.38 & 0.33–15.6 & \textless{}0.001 & \textless{}0.001 & \textless{}0.001 \\ High-order & 2.02 & 2.33 & 1.12 & 0.24–13.8 & \textless{}0.001 & \textless{}0.001 & \textless{}0.001 \\ Astigmatism & 2.31 & 2.25 & 1.57 & 0.04–11.22 & \textless{}0.001 & \textless{}0.001 & \textless{}0.001 \\ \hline \hline
**Pachymetry** & & & & & & \\ \hline Central thickness & 499 & 62 & 508 & 285–633 & \textless{}0.001 & \textless{}0.001 & \textless{}0.001 \\ Temporal & 545 & 50 & 546 & 385–645 & 0.073 & \textless{}0.001 & \textless{}0.001 \\ Nasal & 579 & 48 & 579 & 451–692 & 0.835 & \textless{}0.001 & \textless{}0.001 \\ Superior & 591 & 50 & 590 & 408–695 & 0.062 & \textless{}0.001 & \textless{}0.001 \\ Inferior & 559 & 57 & 563 & 332–762 & \textless{}0.001 & \textless{}0.001 & \textless{}0.001 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Descriptive analysis for the quantitative variables and \(p\)-values for normality and differences between RETICS groups. CDVA: Corrected Distance Visual Acuity; Q: asphericity; RMS, root mean square The multivariate logistic regression model results are summarized in Table 3 with the coefficients for each variable. The variables that made a statistically significant contribution in the model are shown below: gender, coma-like, central thickness, high-order and temporal.