Ultrasonic measurement of transverse lens diameter during accommodation

A new method is introduced which makes possible in vivo measurement of transverse lens diameter (T.L.D.) with ultrasound. The horizontal T.L.D. was measured for 7 nearly emmetropic subjects at accommodation stimulus levels of 0,2,4,6 and 8 dioptres. The unaccommodated T.L.D. was found to be proportional to the axial length. The mean unaccommodated T.L.D. was found to be larger than in vitro measurements reported in the literature.