[Increase in aqueous flare by a therapeutic dose of mannitol in humans]

To evaluate the effects of mannitol on aqueous flare (aqueous protein concentration), we administered an intravenous clinical therapeutic dose to normal young adults (average age, 20.1 years), to normal older adults (average age, 61.3 years), and also to patients with diabetes mellitus, systemic hypertension, or pseudoexfoliation syndrome who were about to undergo intraocular surgery (average age, 66.4 years). Protein and cell levels in the aqueous fluid were determined with a device that measures laser light scattering in the aqueous fluid. Mannitol increased aqueous flare intensity. In all subjects, aqueous flare intensity was greatest around one hour following drug administration; the magnitude and the duration of the aqueous flare increase were significantly greater in normal older subject than in normal young adults; the magnitude was essentially the same in older adults with and without diseased barrier. The effect was reversed within 6 hours of drug administration in normal subjects. We considered the findings to represent changes in actual aqueous protein concentration and discussed the possible causes of this phenomenon.