Color Stability of Ocular Prostheses Subjected to Artificial Aging

Stock ocular prostheses (SOP) do not represent a wide range of human iris colors. Custom-painted ocular prostheses are expensive and time-consuming. Objectives: To measure the color stability of the iris of commercially available SOP and printed digital-image iris ocular prostheses (DOP) by spectrophotometrically evaluating color before and after artificial aging. Methods: Four SOP control specimens were selected: Blue (Bl), Green (Gr), Blue-Gray (BG), and Brown (Br). Digital images were captured of the iris from control specimens. Using image capture software on a desktop PC, 10 specimens on 2 types of each inkjet paper were printed. Of the 80 paper specimens, 5 were randomly chosen to represent the color of each of 4 control SOP specimens. The experimental DOP (N=20) were made using printed paper specimens. Specimens were artificially aged in a Weather-O-Meter chamber. CIE L*a*b* values were measured by spectrophotometer. Color differences (ΔE*) at 150 kJ/m² were subjected to ANOVA. Means were compared by Fisher's PLSD intervals at 0.05 level of significance. Results: CIELAB perceptibility and acceptability on 50%-50% color difference thresholds of colored maxillofacial elastomer specimens were 1.1 and 3.0, respectively. Mean ΔE* values of control (SOP) Bl, Gr, BG, and Br after aging were 0.007, 0.005, 0.004, and 0.005, respectively. Mean ΔE* values of experimental (DOP) Bl, Gr, BG, and Br after aging were 0.984, 0.933, 0.734, and 0.866, respectively. All were less than 1.0 ΔE* units, which indicates that they were below a visual level of perceptibility. Conclusion: The printed digital-image iris ocular prostheses are color stable when subjected to artificial aging. The inkjet-printed digital image iris is easy to produce as a mirror-image and offers an alternative to stock ocular prostheses or a custom painted iris. The study was supported by NIH grant T32DE015355.