Laser flare intensity in diabetics: correlation with retinopathy and aqueous protein concentration

The laser flare intensity in diabetics, measured with the scattering of a light beam, was evaluated and compared with actual aqueous protein concentration obtained during surgery. Measurement of the laser flare intensity in 120 diabetics and 108 normal subjects was performed with the laser flare cell meter (FC1000 Kowa, Tokyo). Aqueous protein concentration in 26 diabetics and six controls who underwent intraocular surgery was measured by the method of Bradford. No significant difference in the laser flare intensity was found between normal subjects and diabetics without retinopathy. A significant increase in the laser flare intensity was observed after six decades in diabetics with background retinopathy and all with proliferative retinopathy. The laser flare intensity correlated with the duration of diabetes mellitus. There was a significant linear relation between the laser flare intensity and actual aqueous protein concentration. The linear regression formula was X = Y1.39 x 1.02 (X = protein concentration, mg/dl; Y = flare intensity, photon counts/ms). The precise value of the laser flare intensity provides a new indicator to evaluate the diabetic change in the function of the ocular barrier.