Measurement of protein concentration of aqueous humour in vivo: Correlation between laser flare measurements and chemical protein determination

Abstract

We studied the correlation between laser flare cell meter photon count/ms and actual protein concentration both in vitro and in vivo. Laser flare cell meter measurement of human albumin concentrations of 0 to 10 g/l showed photon counts/ms from 0.3 ± 0.3 to 78.9 ± 3.9. There was a statistically highly significant linear correlation between photon count/ms and human albumin concentration (r = 0.98, p = 0.0001). Laser flare cell meter measurements were done on 39 cataract patients with the mean age of 77.9 ± 6.7 years. Aqueous humour obtained by peroperative paracentesis was analysed for total protein. The mean photon count/ms before pupillary dilatation was 11.93 ± 6.03. There was a significant linear correlation (r = 0.4, p = 0.019) between the photon count/ms after pupillary dilatation (mean 14.73 ± 12.9, range 2.6-62.4) and anterior chamber protein concentration (mean 0.62 ± 0.27, range 0.23-1.3 g/l) with the linear regression formula being y = 0.231 x - 1.105 where y = log protein concentration (g/l) and x = log of photon count/ms. Laser flare cell meter photon counts/ms may be converted into an equivalent anterior chamber total protein concentration using this formula.