Rosemary Essential Oil Microemulsion for Fungal Keratitis Treatment.

This study investigated the use of Rosmarinus officinalis (rosemary) essential oil in a microemulsion (ME) formulation for the treatment of ocular fungal keratitis, a serious infection that can lead to blindness. The ME was characterized in terms of pH, stability, homogeneity, osmolarity, and other physicochemical properties. The Hen's Egg Test-Chorioallantoic Membrane assay was used to assess ocular irritancy, and antifungal efficacy was evaluated using the minimum inhibitory concentration method. The oil extraction yielded 1.2%, with eucalyptol (37.89%) as the major compound. The formulation showed a suitable pH (6.96), particle size of 11.35 nm, good stability, and was classified as non-irritant with an irritation score = 1.5. It exhibited strong antifungal activity against Candida parapsilosis (96.1%), C. krusei (100%), C. albicans (99.1%), Fusarium graminearum (90.5%), and Aspergillus parasiticus (79.5%). The results highlight the potential of rosemary essential oil as a base for developing eye drops for the treatment of fungal keratitis.