Objective: We try to establish a convenient, fast, inexpensive and accurate screening test and to make a grading standard.

Methods: 1. In 120 eyes, we measured axial anterior chamber depth (AACD), peripheral anterior chamber depth (PACD), antrior chamber angle (ACA) and took iris pictures under slitlamp microscope imitating the oblique flashlight test. The clear photos from 107 eyes were measured by computerized image analysis to determin the ratio of the width of nasal iris and nasal iris light band (ILBR). Then the linear correlation of ILBR with AACD, PACD and ACA was analyzed statistically. The ILBR was graded according to the analytic results.

Results: 1. Relationship of ILBR with PACD, AACD and ACA: the linear correlation analysis showed a positive correlation relationship among ILBR, PACD and AACD (r = 0.9451, P = 0.0001 and r = 0.8725, P = 0.0001), and showed a negative correlation relationship between ILBR and ACA (r = -0.7582, P = 0.0001). 2. ILBR grading standards: grade 1. ILBR < or = 1/5, the gonioscopy usually demonstrates a dangerously narrowed angle (N3-4); grade 2, ILBR > 1/5- < or = 1/4, the gonioscopy will always show a capable of closure angle (N2-3); grade 3, ILBR > 1/4- < or = 1/3, that angle is incapable of closure (N1-2); grade 4, ILBR > 1/3- < or = 1/2, the most angles show wide (W-N1); grade 5, ILBR > 1/2, the gonioscopy shows all wide angle. The linear correlation analysis also showed correlation relationship among ILBR grades PACD, AACD and ACA.

Conclusions: Through arational ILBR grades and a set of grading standard photos, it is found that the test is not only convenient, fast, and inexpensive, but also accurate as well. The test not only plays an important role in PACG screening, but also may be applied widely to estimate shallow AACD and narrow angle in the clinic.