A-scan quantitative echography of senile cataracts and correlation with phacoemulsification parameters

Abstract

Purpose. To study the echographic appearance of various types of senile cataracts using a-scan quantitative echography and correlate these findings with phacoemulsification parameters indicating surgical lens hardness. Methods. The study involved 71 eyes with senile cataracts and 20 additional eyes with normal human lenses. Cataract and clear lenses were studied using A-scan quantitative echography and with a tissue sensitivity gain setting of 74 db. We assessed the lens internal reflectivity in the A-scan echograms within a range of 0% to 100%, and calculated the mean of all spikes. All eyes with cataract underwent clear corneal phacoemulsification. At the end of the operation we recorded the phacoemulsification time and mean percent power. We determined the correlations of echographic and phacoemulsification data. Results. Quantitative echography in the 71 studied eyes with cataract revealed acoustic reflections having various configurations according to the biomicroscopic type of cataract, i.e. cortical, nuclear, corticonuclear, brunescent, white intumescent. The mean of all echographic spikes within the cataract lenses varied from 3% (in some brunescent very sclerotic lenses) to 53%. Echographic reflections were not observed in the A-scan echograms of 20 additional eyes with normal human lenses. The mean of internal lens spikes correlated negatively with phacoemulsification time (p < 0.001; r = -0.703) and mean percent phacoemulsification power (p < 0.001; r = -0.57). Conclusions. The results indicate that A-scan quantitative echography may be used as an adjunctive tool in the preoperative evaluation of cataracts, particularly in cases with compromized visualization of the lens (small pupil, corneal opacities).