Dexamethasone concentration in the subretinal fluid after a subconjunctival injection, a peribulbar injection, or an oral dose

Purpose: To determine dexamethasone concentrations in the subretinal fluid of patients after a peribulbar injection, a subconjunctival injection, or a n oral dose of dexamethasone and to compare the results with those of previ ous similar studies of dexamethasone concentrations in the vitreous. Design: Prospective, nonrandomized, comparative trial. Participants: One hundred forty-eight patients with a rhegmatogenous retina l detachment. Methods: Fifty patients received a peribulbar injection of 5 mg dexamethaso ne disodium phosphate, 49 received a subconjunctival injection of 2.5 mg de xamethasone disodium phosphate, and 49 received an oral dose of 7.5 mg dexa methasone at various time intervals before surgery. At the time of surgery, a subretinal fluid sample was taken from each patient. Main Outcome Measures: The dexamethasone concentration in the subretinal fl uid measured by radioimmunoassay. Results: The estimated maximum dexamethasone concentrations in the subretin al fluid after the peribulbar injection, the subconjunctival injection, and the oral dose were, respectively, 82.2 ng/ml (standard error, 17.6), 359 n g/ml (standard error, 80.2), and 12.3 ng/ml (standard error, 1.61). Correct ed for dose, the maximum dexamethasone concentrations after subconjunctival injection and peribulbar injection were, respectively, 120 (95% confidence interval, 54/180) and 13 (95% confidence interval, 6.8/20) times greater t han after oral administration. Conclusions: A subconjunctival injection of dexamethasone disodium phosphat e is more effective in delivering dexamethasone into the subretinal fluid o f patients with a rhegmatogenous retinal detachment compared with peribulba r injection or oral administration. The subretinal dexamethasone concentrat ions were higher than concentrations measured in the vitreous in previous s tudies with a similar setup after all three delivery methods. Ophthalmology 2000;107:1932-1938 (C) 2000 by the American Academy of Ophthalmology.