Orbital form analysis: problems with design and positioning of precontoured orbital implants: A serial study using post-processed clinical CT data in unaffected orbits

3D CT computer model of a left orbit comprising the two evaluated regions (FMW, blue; pFMW, red). Homology in different datasets was obtained (i) by manual determination of anatomical landmarks at the corners of the FMW (yellow), (ii) by calculating interpolated equidistant anatomical-mathematical boundary pathway landmarks (blue) and (iii) by computation of identical located and numbered mesh points (i.e. mathematical landmarks, (black)).

Lateral (1st row) and frontal view (2nd row) of average models of 140 unscaled FMW (left) and pFMW (right), showing maximum deviation (red and yellow) at the boundaries of the orbital floor/medial wall region for FMW and at the anterior lateral orbital floor for pFMW (mm). pFMW is visualized in a larger scale than FMW.

Lateral view of average model of the FMW (left) and its posterior partition (pFMW) (right) with standard deviations of homologous points shown as colour maps (mm); pFMW is visualized in a larger scale than FMW.

FMW (left) and pFMW (right) scatterplots of form coordinates for females (blue dots) and males (red dots). The 1st PC (1st row) shows high correlation between size values (Frobenius norm) and form coordinates in FMW, indicating that most relevant form variation was due to size variation. 2nd row: in most other PCs shape variation was the predominant variation factor, as shown for 2nd PC.

Cumulative percentage of total form variance of the first 15 PCs showing the contribution of each PC to the overall form variation. The 1st PC comprised most significant variation for both regions (FMW (left) and pFMW (right)).

Mean distance deviations (mm) of all 140 FMW calculated from the corresponding FMW mean form (left); corresponding scatterplot with better fit values for pFMW (right); females (blue dots), males (red dots).

Curvature graded CT reconstruction showing characteristic orbital/floor medial wall patterns in given orbits. 1st row: frontal views with different inter-individual shape patterns in the transition area between the orbital floor and medial wall: with a sharp bend (left), intermediate (middle) and virtually flat transition area (right). 2nd row: lateral views of sagittal cuts reveals typical orbital floor form patterns, considered to be a function orbital floor length, different shapes (i.e. different lazy-s-shapes) and medial wall related degree of floor inclination.