Abstract Objective To test whether topical thymoquinone and black cumin seed oil formulations improve signs of experimental dry eye in rats, and to compare their histopathology with standard treatment of dry eye disease (DED) Methods Seventy-two adult male Wistar-Albino rats were included in this study randomly divided into 12 groups with 6 subjects in each group. DED models were induced for all groups except the control group, using the most accepted cage method. One group remained untreated, the remaining groups were treated with balanced salt solution (BSS), cyclosporine 0.05% (CYC), CYC 0.05%+hyaluronic acid (CYC+HA), fluorometholone 0.01% (FML), TQ solution, TQ emulsion, TQ hydrogel, CO solution, CO emulsion. The Schirmer test for 1-min and Oxford corneal staining tests performed by a single masked grader, were conducted at the end of the first and third weeks. All tests were performed on each of the 12 groups of six rabbits at the end of the first and third weeks. Results There was no statistically significant difference in the ocular surface tests during the first-week among the groups. When the degree of ocular staining at third week obtained it was found to be significantly higher in the cases treated with BSS and CYC+HA compared to controls (respectively, Z=-2.298, p=0.022; Z=-2.298, p=0.022). TQ solution and CO hydrogel showed a significant decrease compared to week 1 in staining score (respectively, t=5.0, p=0.004; t=3.162, p=0.025). In the third week, ocular surface tests revealed a statistically significant improvement in the group treated with TQ emulsion compared to the control group (Z=-2.127, p=0.033). Conclusions Thymoquinone solution improved tear and staining metrics in this model. Emulsions and hydrogels showed mixed efficacy and higher histopathologic injury. These findings support reformulation and vehicle-controlled testing before translation. The observed improvement in ocular surface parameters may be attributed to the anti-inflammatory properties of TQ and cytotoxic effects may be ameliorated by different formulation types or doses.
Dikmetaş et al. (Tue,) studied this question.