Purpose: To evaluate the relationship between hardness of the human crystalline lens and its acoustic characteristics.
Setting: St. George's Hospital Medical School, University of London, London, United Kingdom.
Methods: Cataractous lenses from patients who had extracapsular cataract surgery were studied for hardness and ultrasonic characteristics. Lens hardness was assessed with an automated guillotine. Ultrasound velocity and attenuation were measured with a scanning acoustic macroscope using the pulse transmission reflection method.
Results: Thirty-seven lenses from 37 patients (mean age 75.5 years) were evaluated. Lens hardness was associated with ultrasound attenuation (r = 0.65, P <.0001) and attenuation frequency gradient (r = 0.67, P <.0001). The correlation of hardness with mean ultrasound velocity was not significant (r = 0.22, P =.2).
Conclusions: The attenuation of ultrasound waves by the human crystalline lens correlated with its hardness. Ultrasonography can be used to evaluate lens hardness.