[Quantitative real time measurement of iris configuration in living human eyes]

To evaluate the intraobserver and interobserver reproducibility of real time measurement of iris morphology in living human eyes.

Based on the platform of software (Autocad, version 12), we developed an ultrasound biomicroscopy (UBM) image assistant measuring system. Using the system, we can perform the iris configuration quantitative measurement in living eyes. The measuring parameters include: iris rest length, radius of iris curvature and the thickness of different part of iris. Ten anterior segment images of one normal individual were obtained by a single operator to evaluate the intraobserver reproducibility of image capture, and ten times of measurement of one image were performed by a single operator to assess the reproducibility of image measurement. The measurements of three independent observers were compared to investigate interobserver reproducibility in quantitative measurement. Intraobserver and interobserver reproducibility of measurement were assessed by calculating the coefficient of variation for each individual observer and by using F test to detect a difference among the observers. The iris configurations of 96 subjects (192 eyes) were measured.

Intraobserver reproducibility ranged from 0.9 - 4.9% in all measured parameters. Interobserver reproducibility for some of the measured parameters varied considerably and was affect by subjective interpretation of visualized anatomic landmarks. The preliminary measured parameters in Chinese show that iris rest length is 3.699 +/- 0.397 mm, radius of iris curvature is 9.101 plus minus 1.408 mm, the average thickness of iris is 0.406 +/- 0.042 mm.

The intraobserver reproducibility and the measured accuracy can fit the requisition of the ocular biometry, physiology and pharmacology studies. The method supplies a new assistance for UBM image measurement.