Table 1 Comparison of various routes of ocular drug administration

Topical

High patient compliance, self-administration, noninvasive nature

Corneal barrier, dilution and efflux, low bioavailability, high dosing

Conjunctivitis, keratitis, uveitis, episcleritis, scleritis, blepharitis

Subconjunctival and transscleral administration

Anterior and posterior drug delivery, ideal for depot formation

Choroidal and conjunctival circulation increase toxicity subconjunctival hemorrhage

Glaucoma, AMD cytomegalovirus retinitis,

Intracameral administration

Reduce corneal and systemic side effects. topical steroid use; high anterior chamber drug concentration

Toxic endothelial cell destruction syndrome and toxic anterior segment syndrome

Anesthesia, inflammation, endophthalmitis, pupil dilation

Intravitreal injection

Direct delivery to the vitreous humor and retina, BRB avoidance, high bioavailability and acute dosing

Poor patient compliance, invasiveness, drug toxicity, retinal detachment, cataract endophthalmitis, hemorrhage

AMD, central/branched retinal vein occlusion, diabetic macular edema, cytomegalovirus retinitis

Retrobulbar injection

Selective delivery to both anterior and posterior segments, avoidance of corneal and conjunctival barriers, long duration of action, a site for depot formulations

Poor patient compliance, invasiveness, drug deposition,compliances including pain, bleeding, infection, scarring, eyeball or optic nerve damage

Anesthesia

Systemic administration

High patient compliance

Blood ocular barriers, low bioavailability, systemic toxicity caused by high dosing

Scleritis, episcleritis, cytomegalovirus retinitis