Potentiality of microemulsion systems in treatment of ophthalmic disorders: Keratoconus and dry eye syndrome – In vivo study

[Display omitted] •Microemulsions are potential ophthalmic delivery vehicle.•Microemulsions can transfer riboflavin through intact eye epithelium into the stroma.•Omega-3-loaded microemulsion formulations relieve dry eye syndrome.•Microemulsions are a basis for convenient aqueous formulation of omega-3 fatty acids. Microemulsions are widely studied as potential ocular drug delivery vehicles. In the present study we show the versatility of possible use microemulsions as ocular delivery vehicle. The ME is loaded with a hydrophilic drug, riboflavin phosphate (RFP) and a lipophilic, docosahexaenoic acid in triglyceride form (TG-DHA), each separately. These drugs treat keratoconus and dry eye syndrome, respectively. The advantage of using ME loaded with RFP is in overcoming eye epithelium debridement during collagen cross-linking therapy for treatment of keratoconus. ME loaded with lipophilic TG-DHA provides convenient dosage in liquid aqueous form of administration of highly lipophilic TG-DHA, which is known as a protective molecule in dry eye syndrome. The capability of RFP-loaded MEs was demonstrated in terms of improvement of biomechanical strength of the rabbit cornea, as a result of successful penetration of RFP through the intact epithelium. TG-DHA-loaded microemulsion applied topically onto an eye with induced dry eye syndrome showed the significant relief of the dry eye condition.