[The diagnostic efficiency of tonography]

There are three methods for increasing the diagnostic efficiency of tonography: The improvement of tonographical technique, the combination of tonography with provocative tests and methods of mathematical differentiation. Our own bulbar-compression isotonographical method is described. This method allows a choice of different pressure gradients. Our method was applied to 28 normal and 40 glaucomatous eyes. This method was carried out twice on all patients using two pressure gradients: Pt = Po + 30 and Pt = Po + 10. Also, the outflow facility (L) was determined by Grant's tonography. Thus, 3 L-values were obtained with 3 varying pressure differences (Pt -- Po = deltaP). With this differential tonography the mathematical determination and the graphic representation of a real L-value (Ldiff) by deltaP = 0 are possible. With normal eyes the average L-values were indirectly proportional to the pressure differences. This relationship was found to be directly proportional to glaucomatous eyes. The tonographical coefficients Po/L, P3/L3-7,Po -- 10/L and Po/Lintegral were calculated on 104 normal and 312 glaucomatous eyes. The diagnostic efficiency of tonography is increased by the determination of Ldiff (percentage of positive values = 70%) and the calculation of Po/Ldiff value (95%).