**4. Conclusions**

The nanoemulsion system of moxifloxacin was successfully formulated by developing pseudoternary phase diagram of different proportions of ethyl oleate, Tween 80, Soluphor P and water. It is inferred from the contour plot that particle size is minimum when the water component is at a higher level (1) and oil and surfactant components are at lower level (0). The developed nanoemulsions have optimum viscosity for instillation in eye. They show transmittance value >95% which proves the transparency of the system and the droplets are in nanometer dimensions. The optimized nanoemulsion (MM3) showed adequate antimicrobial effect of the entrapped moxifloxacin and is safe for ocular application. The moxifloxacin level in the aqueous humor was prolonged by MM3 which is greater than the minimum concentration necessary for the therapeutic efficacy (i.e., 0.2 μg/mL or >>>MIC90 for aerobic gram-positive and gram-negative pathogens responsible for causing eye infections), signifying the importance of nanoemulsion for ocular therapy. In a nutshell, the optimized nanoemulsion formulation (MM3) could be a promising and viable drug delivery system for effective delivery of moxifloxacin for treatment of various bacterial eye infections.

**Author Contributions:** Formulation and in vivo evaluation, J.S., R.K.P. and H.S., Experimental design, writing and data processing, A.B.N. and S.J.; In vitro, ex vivo studies and data processing, T.M.S. and M.A.M.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors are highly thankful to Institute of Pharmacy, Nirma University, Ahmedabad for support.

**Conflicts of Interest:** The authors declare no conflict of interest.
