Comparison of various routes of ocular drug administration: benefits and obstacles (Gaudana et al., 2010)

RouteBenefitsObstaclesDiseases/Disorders Treated
TopicalPatient compliance is high; self-administration and noninvasive natureCorneal barrier difficult to penetrate; dilution and efflux via tears is highConjunctivitis, keratitis, uveitis, episcleritis, scleritis, blepharitis
IntravitrealDirect delivery to retinal and vitreal structures; drug has high bioavailabilityPatient compliance low; risk of retinal detachment, hemorrhage, development of endophthalmitis or cataractsAMD, BRVO, CRVO, DME, CMV retinitis
Sub-TentonRelatively noninvasive, decreased risk of comorbidity compared with intravitreal delivery, maintains high vitreal drug levelsRetinal pigment epithelium is a barrier; subconjunctival hemorrhage, chemosisDME, AMD, RVO, uveitis
Posterior juxtascleralAdvantageous for drug depository; avoids intraocular damage, and macula can sustain drug level for 6 moRetinal pigment epithelium barrier, and surgical procedure required;AMD, risk of endophthalmitis
Systemic/oralPromotes patient compliance, noninvasive mode of deliveryRetinal and blood-aqueous barriers; low bioavailability leading to systemic toxicityScleritis, episcleritis, CMV retinitis, posterior uveitis
IntracameralReduces systemic and corneal side effects vs. topical steroid use; high anterior chamber drug concentrationToxic endothelial cell destruction syndrome and toxic anterior segment syndrome pose major risks to patientsAnesthesia, prevention of endophthalmitis, inflammation, pupil dilation
SubconjunctivalAnterior and posterior delivery method, ideal for depot formationChoroidal and conjunctival circulation of therapies increases toxicityGlaucoma, CMV retinitis, AMD
RetrobulbarMinimal IOP involvement, ideal for high local anesthetic administrationRespiratory arrest, retrobulbar hemorrhage, globe perforationAnesthesia
  • BRVO, branched retinal vein occlusion; CMV retinitis, cytomegalovirus retinitis; CRVO, central retinal vein occlusion; IOP, intraocular pressure.