Photoacoustic Measurements for Characterisation of the Eye

Conventional pulse echo ultrasound techniques are widely used to obtain dimensional information on the position of interfaces within the eye and for imaging lesions. High-resolution biomicroscopy employing high frequency (> 20 MHz) ultrasound measurements is possible for the front portion of the eye. However, such high frequency signals do not penetrate to the retina and beyond. Hence, a lower frequency transducer is normally used to measure these larger dimensions, giving rise to a loss of relative distance information. In this paper, we report on a novel ophthalmic laserultrasound probe that has been employed in-vitro to measure the intra-ocular distances within bovine eyes. We have assessed whether the use of laser-induced ultrasound would be able to overcome the aforesaid problem. The results of these measurements reveal that laser-generated ultrasound is capable of delivering high-resolution measurements for all the interfaces in the eye and beyond the retina.Distances that have been deduced from the temporally resolved profile of the photoacoustic transients received by the probe have good greement with actual dimensions. Also presentedin this paper for comparison purposes are A-scan biometry results obtained using a commercially available ultrasonic ophthalmic scanner.

کلیدواژه ها:

Photoacoustic ، Laser ultrasound ، Ultrasonography ، Ophthalmology