Aqueous cytokine and growth factor levels do not reliably reflect those levels found in the vitreous

PURPOSE Recent studies have illuminated the vitreous proteome as a potentially important diagnostic tool that will predict disease progression and response to treatment, in eyes with retinal disease. Studies to date have demonstrated correlations of protein levels between vitreous and aqueous humor. Because these results are un-expected and analysis was only done on a few endpoints, the present study further analyzes the relationship between aqueous and vitreous by probing a wide array of proteins in patients with posterior segment diseases. METHODS Anterior chamber aqueous fluid was obtained using a limbal approach with a 30 gauge needle. Immediately following, the vitreous sample was obtained via a pars plana approach. A 25 gauge needle with a 1 ml syringe was directed into the mid-vitreous cavity and vitreous fluid was gently aspirated. Aqueous and vitreous samples were then analyzed using the quantitative native protein analysis method called reverse phase protein microarray technology (RPPM). RESULTS The entire sample population (n=11) was probed against 34 proteins, revealing 8 proteins that significantly correlate, 3 proteins that trend to correlation but fell short of significance and 23 proteins that have no correlation between the vitreous and aqueous humor. CONCLUSIONS Proteins in the aqueous cannot be assumed to correlate with their counterparts in the vitreous.