Reference	Colloidal Carriers	Description
[9]	Liposomes:	The amount of concentric alternating layers of phospholipids and aqueous phases decides that the liposome is either unilamellar or multilamellar.
[25]	Nano Particles	They have diameter of less than 1 micrometer consisting of various biodegradable polymers or non-biodegradable metals, lipids or phospholipids. Depending upon whether the drug has been coated with a polymeric material or has been uniformly dispersed, they can be classified as nanocapsules or nanospheres.
[26]	Bioadhesive Nanopolymers	The interaction of bioadhesive polymer chains with mucin and the potential entrapment of particles in the mucus layer of ocular surface are the basis of the development of particulate systems for ophthalmic drug delivery.
[25]	Microparticulates	Micron sized polymeric particles that contain the drug and are suspended in a liquid medium, or the drug can be dispersed in a polymer backbone physically.
[27]	Microemulsions	They have 20 - 200 nm droplet size usually, and are isotropic, transparent, translucent, thermodynamically stable system of oil, surfactant and water.
[5]		They appear as clear transparent dispersions and comprise of larger swollen micelles that contain the internal phase.
[28]		Eg. Polyanhydride microspheres, polyadipic acid.
[25]	Niosomes	The power of irritation of surfactants decrases in the following order: cationic > anionic > ampholytic > nonionic, therefore the nonionic surfactants are preferred. For mutually hydrophilic and lipophilic drugs, niosomes are a suitable delivery system.
[29]	Nanocrystals	The mean diameter of pure solid drug nanocrystals is below 1000 nanometer.
[25]	Nanosuspensions	Nanosuspensions are inert in nature and usually consist of colloidal carriers like polymeric resins.
[30]	Dendrimers	Dendrimers are macromolecules or nanosized, radially symmetric molecules having repeated tree like arms or branches, having well defined homogenous and monodisperse structure and they can resolve the increasing challenges of newly developed drugs such as bioavalability, permeability and poor solubility.