Detection of the anterior segment biological parameters of primary angle closure glaucoma and the normal eyes by optical coherence tomography

Objective

To measure quantitatively and analysis the differences in the anterior segment biological parameters between the normal subject and patients suffering primary angle closure glaucoma (PACG), as well as the distinction among different stages of PACG by using anterior segment optical coherence tomography (OCT).

Methods

A retrospective case series study was designed.Medical records of 217 cases (217 eyes) from The Second Hospital of Hebei Medical University from December 2013 to December 2014 were recruited, including 5 groups as follows: 35 cases (35 eyes) with pre-clinical stage acute primary angle closure glaucoma (APACG), 32 cases (32 eyes) with remission period of APACG, 35 cases (35 eyes) with early stage of chronic primary angle closure glaucoma (CPACG), 35 cases (35 eyes) with progress period of CPACG and 80 cases (80 eyes) coming for regular eye health examination in general clinic.The anterior segment biological parameters of each group was measured by Heidelberg Spectralis OCT, including the anterior chamber width (ACW), angle opening distance (AOD), trabecular iris area (TISA), iris thickness (IT) and crystalline lens rise (CLR).

Results

The IT and CLR of APACG and CPACG were significantly greater than normal control group, while other anterior segment parameters were significantly smaller, with significant differences between them (all at P<0.01). The IT and CLR of APACG was bigger than those of CPACG, with significant differences between them (both at P<0.05), the ACW, AOD, TISA of the two gruops showed no significant differences.The AOD and TISA of remission period of APACG were significantly decreased than those of pre-clinical stage (all at P<0.01). The IT and CLR of remission period APACG was significantly greater than pre-clinical stage (both at P<0.01). The difference in ACW of the two group was not statistically significant (P>0.05). Compared with progress period of CPACG, the IT of the early stage of CPACG was thicker, while the CLR was smaller (both at P<0.01). There was no significant difference in ACW, AOD and TISA between the two groups.The IT_{2 000} and IT_max of pre-clinical stage of APACG were significantly smaller than those of early stage of CPACG (both at P<0.01). There was no significant difference in other parameters between the two groups (P>0.05). The IT₇₅₀, IT_{2 000} and IT_max of the pre-clinical stage of APACG were significantly thicker than those of progress period of CPACG (all at P<0.05). There was no significant difference in other parameters between the two groups (P>0.05).

Conclusions

Compared with normal people, the PACG patients have a more crowding anterior segment structure, smaller AOD, smaller TISA, thicker IT and more anterior located lens.The APACG patient at remission period has a more crowding anterior segment structure, smaller AOD, smaller TISA, thicker IT and more anterior located lens than APACG patient at per-clinic stage.The CPACG patient at progress period has a higher CLR, but thinner IT than patient at early stage.The APACG patients at per-clinic stage has thicker IT and a more crowding anterior segment structure than the CPACG patient at early stage, and the APACG patient at remission period has thicker IT than CPACG patient at progress period.