AIM:To establish a model of meibomian gland dysfunction in rats induced by eyeliner tattoo and investigate its potential mechanisms.

METHODS:A total of 40 SD rats were selected, with 30 randomly chosen to have eyeliner tattoo applied their right eyes and designated as the eyeliner group. The remaining 10 rats were not given any treatment and served as the normal group. The corneal morphology of both groups was observed using a slit lamp at 1, 2, and 4 wk after establishment, and the tear film break-up time(BUT), Schirmer I test(SIt), corneal fluorescein staining score, and corneal irregularity score were calculated. The corneal Placido rings were examined using an ocular surface analyzer, and the corneal tissue structures of both groups were observed under a confocal microscope. After 4 wk and completion of clinical indicator recording, the eyeballs and upper and lower eyelid tissues were taken for pathological examination. The meibomian gland structures were observed through HE staining, the conjunctival goblet cells were observed using PAS staining, and the lipid droplets were observed with ORO staining.

RESULTS:The slit lamp examination results showed that the eyeliner group rats exhibited in situ black pigmentation in the eyelids, with no eyelid deformation or scarring. The corneal epithelium was rough, with positive fluorescein staining, presenting as spotty staining that worsened over time. Compared with the normal group, the BUT was significantly shortened, tear secretion volume was significantly decreased, and the corneal fluorescein staining score and corneal irregularity score were significantly increased at 1, 2, and 4 wk after modeling in the eyeliner group(all P<0.01). The corneal confocal microscopy results showed a decrease in corneal epithelial cells in the eyeliner group, with the appearance of abnormally bright cells, and inflammatory cell infiltration visible in the stromal layer. The ORO staining results revealed a decrease in lipid droplets in the eyeliner group, showing a downward trend with increasing observation time. The HE staining results showed that pigment blocked the meibomian gland openings in the eyeliner group, and the density of meibomian gland acini showed a downward trend over time. The PAS staining results showed a decreasing trend in the number of PAS-positive cells in the eyeliner group.

CONCLUSION:Eyeliner tattoo can induce meibomian gland dysfunction, and the blockage of meibomian gland openings caused by the pigment particles used may be an important cause of meibomian gland dysfunction.