The invention relates to a method of treating parasitic etiologies of ophthalmic diseases in the eyelash, eyelid, or cutaneous tissue surrounding the eyelash or eyelid by topically applying to the eyelash, eyelid, or cutaneous tissue surrounding the eyelash or eyelid a formulation of antiparasitic agents such as macrocyclic lactone parasiticides, comprising of suspended particles of ivermectin and polymer solid dispersion in a suitable pharmaceutically carrier. The formulation may include particles of ivermectin and a polymer having a D90 particle size below about 10μ preferably between about 800 nm and about 4μ. The polymer may be an extended release polymer. The formulation may further include mineral oil and an anhyd. gel. The formulation may have a viscosity between 30,​000 cP and about 100,​000 cP preferably between about 40,​000 cP and about 90,​000 cP.