Fs. Bodker et al., INTRAOCULAR DEXAMETHASONE PENETRATION VIA SUBCONJUNCTIVAL OR RETROBULBAR INJECTIONS IN RABBITS, Ophthalmic surgery, 24(7), 1993, pp. 453-457
Using high-performance liquid chromatography, we compared tissue level
s of dexamethasone in the aqueous, vitreous, retina, and choroid of ra
bbits, 1 and 4 hours following subconjunctival or retrobulbar injectio
n. One hour following injection, dexamethasone levels in all of these
tissues were similar in both the subconjunctival and retrobulbar group
s. Four hours following injection, the concentrations in the two group
s also were similar, except in the choroid, in which the subconjunctiv
al injection yielded significantly lower dexamethasone levels than the
retrobulbar injection. Tissue steroid levels were comparable ipsilate
ral and contralateral to the injected eyes in both treatment groups af
ter 4 hours, except in the retina, in which the levels were lower in t
he contralateral eye after subconjunctival injection. These data sugge
st that dexamethasone absorption and delivery is predominantly hematog
enous following both subconjunctival and retrobulbar injection, especi
ally in highly vascular tissues, such as the choroid. Hematogenous del
ivery of dexamethasone appears to peak earlier in the choroid and pres
umably in other intraocular tissues following subconjunctival injectio
ns, while retrobulbar injections provide more steady, long-term delive
ry.