Background: To compare the anterior biometry of eyes with secondary acute angle closure induced by occult lens subluxation (LS), misdiagnosed as acute primary angle closure (APAC) at the first visit, APAC, chronic primary angle closure glaucoma (CPACG), cataract. Methods: This retrospective case study included 17 eyes with PAC due to occult LS, who were misdiagnosed as APAC on their first visit, 56 eyes diagnosed as APAC, 54 eyes diagnosed as CPACG, and 56 eyes diagnosed as cataract. Axial length (AL), Central corneal thickness (CCT), anterior chamber depth (ACD) and lens thickness (LT) were recorded. Lens position (LP), relative lens position (RLP), corrected lens position (CLP) were calculated. Quantitative data were subject to one-way analysis of variance and correlation analysis. Categorical data were analyzed using the chi-squared test. Results: The patients in the LS group had a longer ocular axial length than those with acute angle closure and CPACG. Corneal thickness in the LS group was not significantly different from that in the APAC group, but was significantly different from those of the CPACG and cataract group. The APAC group had the smallest ACD, while the LS group had the smallest AD. The LS group exhibited significantly shallower ACD (P<0.01). The LS group had the largest lens thickness. Conclusions: This study revealed that LS secondary PAC patients had a shallower ACD, thicker CCT and lens thickness comparing to those of APAC, CPACG and cataract patients. A short depth (< 1.25 mm) and a thick lens thickness (> 5.13 mm) are crisis of lens subluxation in our data. LP and CLP can be helpful for differential diagnosis. Trial registration: NCT03752710, retrospectively registered.