Aim: To evaluate the biometric difference between eyes with acute angle-closure (AAC) attack, their uninvolved fellow eyes and eyes with chronic angle-closure glaucoma (CACG). Methods: Patients with prior laser iridotomy on both eyes for unilateral AAC attack or CACG were recruited. We compared ocular biometric parameters by A-scan ultrasonography of the acutely affected eyes with those of the uninvolved fellow eyes and with eyes affected by CACG. Results: Thirty-three patients with unilateral AAC attack and 41 patients with CACG were included. The eyes with AAC attack had a significantly shallower anterior chamber depth (ACD), thicker lens, shorter axial length, higher lens/axial length factor and more anteriorly positioned lens than the eyes with CACG. The uninvolved fellow eyes had a significantly shallower ACD, shorter axial length and higher lens/axial length factor compared with the eyes with CACG. Acutely affected eyes had a shallower ACD and more anteriorly positioned lens than did the uninvolved fellow eyes. Conclusion: Eyes with AAC attack had a more crowded anterior segment compared with uninvolved fellow eyes and those affected by CACG. In addition to ACD, relative lens size, represented by the lens/axial length factor, and relative lens position appear to play important roles in the development of AAC attack.