axial length measurement in asteroid hyalosis: comparing laser interferometry and ultrasound a-scan

purpose : to compare laser interferometry (li) and ultrasound a-scan in measurement of axial length ( al ) in eyes with asteroid hyalosis methods : twenty three patients with unilateral moderate to severe asteroid hyalosis determined by b-scan ultrasonography images participated in the study. the al measurements were obtained by li and ultrasound a-scan in both asteroid hyalosis and noninvolved eyes. the measurements were performed by the two methods as well as for affected and contralateral normal eyes and were statistically compared using the paired t-test. a p-value less than 0.05 was considered significant. results : the ultrasound al measurements were taken in every case but measurement with the li method was not possible in 4 eyes with asteroid hyalosis (17.3%). there was a high correlation between li and ultrasound a-scan measurements in both asteroid hyalosis and noninvolved eyes (r2=0.97, p<0.001 and r2=0.95, p<0.001 respectively). there was no significant difference between al taken by either method in asteroid hyalosis and noninvolved eyes. conclusion : the failure rate of al measurement using li was relatively high in eyes with asteroid hyalosis. there was a high correlation between al measured by ultrasound a-scan and li method in both asteroid hyalosis and noninvolved eyes.   iranian journal of ophthalmology 200921(1):29-34 © 2009 by the iranian society of ophthalmology