Effects of pigment location in tinted contact lenses on the ocular surface

Purpose. To evaluate the effects of the location of pigments in decorative tinted soft contact lenses on the ocular surface. Methods. Thirty test subjects were enrolled in this study. All subjects wore the following types of contact lenses, classified according to the location of the pigment layer, in one eye in three different testing sessions: conventional clear lenses, tinted lenses with a pigment layer embedded in the lens matrix, and tinted lenses with an exposed pigment layer on the surface. Tear samples were collected, the ocular surface status was evaluated, and subjective symptoms were surveyed after lens wear for 8 hours. Results. The tinted lenses with surface pigments resulted in a greater increase in epidermal growth factor and interleukin- 8 levels compared with the clear lenses and tinted lenses with embedded pigments (p < 0.050). Ocular surface parameters and subjective symptom scores were significantly different among three lens types (p < 0.050), with the clear lenses showing superior results compared with the two tinted lenses (p < 0.050). The tinted lenses with exposed pigments resulted in a greater degree of conjunctival redness and ocular surface staining and poorer symptom scores compared with the tinted lens with embedded pigments (p < 0.050). Conclusions. Our results suggest that the presence of surface pigments in tinted contact lenses increases ocular inflammation and results in a poorer ocular surface status and greater discomfort compared with clear lenses and tinted lenses with an embedded pigment layer.