Abstract: Objective To analyze the association of the iVue OCT Signal Strength Index with the blur degree of fundus photographs in cataracts and to explore the feasibility to evaluate the severity of the cataract using the index． Design Evaluation of diagnostic methods. Participants 162 patients (324 eyes) with cataract  at Beijing Tongren Hospital in 2013． Methods All cases were confirmed by slit-lamp microscope examination. Fundus photographs and anterior segment photographs were taken with the non-mydriatic fundus digital camera. The grade of fundus photographs was based on the blur degree. The ratio of the diameter of the pupil and corneal diameter was obtained according to anterior segment photographs. The Signal Strength Index was obtained by the iVue OCT. Main Outcome Measures The grade of fundus photographs, the grade of the Signal Strength Index, sensitivity, and specificity． Results  With the increasing of the fundus photographs blur degree, the Signal Strength Index of iVue OCT decreased (r=0.891, P<0.001).  The sensitivity of high Signal Strength Index  evaluating the 0 degree of cataract fundus photographs was 89% and the specificity was 78%. The sensitivity of the moderate Signal Strength Index evaluating the 2 degree of cataract fundus photographs was 88% and the specificity was 67%. The sensitivity of the  low Signal Strength Index evaluating the 4 degree of cataract fundus photographs was 100% and the specificity was 94%. There is no significant correlation between pupil size and the Signal Strength Index (P=0.989). Conclusion The Signal Strength Index and the blur degree of fundus image in cataract have a good correlation. The Signal Strength Index of iVue OCT could accurately evaluate the blur degree of fundus photographs in the mild and severe cataracts.

Key words: cataract, iVue OCT ；Signal Strength Index, blur degree of fundus photographs