The structure of the anterior segment significantly changes in patients with primary angle closure (PAC) after they undergo treatment with laser peripheral iridotomy (LPI), according to a study published in BMC Ophthalmology. The study suggests that patients’ lens thickness may be positively correlated with LPI treatment success.

The researchers evaluated changes in biometric parameters of the anterior segment and aimed to identify possible biometric predictors of the effect of LPI in eyes with PAC using swept-source optical coherence tomography (SS-OCT).

Using SS-OCT of the anterior segment, they measured angle opening distance (AOD500) and area, trabecular iris space area (TISA500) and volume, trabecular iris angle (TIA500), iridotrabecular contact (ITC) index and area, anterior chamber volume (ACV), anterior chamber depth (ACD), lens vault (LV), and lens thickness (LT) at baseline and 1 week after LPI. 


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A total of 52 eyes with PACG of 28 patients (68% women and 32% men) underwent LPI. The mean age of patients was 63.65±6.04 years (range, 54-74). The mean intraocular pressure (IOP) prior to LPI was 17.35±3.61 mm Hg.

The researchers reported no post-LPI complications. They found that the ACD, LV, and LT did not show significant changes. The team demonstrated that AOD500, AOD500 area, TISA500, TISA500 volume, TIA500, and ACV significantly increased and the ITC index and ITC area significantly decreased from baseline to 1 week after LPI. They found that LT was positively correlated with the change in the ITC index (β=0.239; P =.045).

Limitations of the study included a relatively short follow-up duration and small sample size, a population composed of all patients from China, variability in the measurement of some factors such as the time of IOP measurement, variability in the administration of IOP lowering drugs, and examinations performed with ambient lights on.  

Reference

Yu B, Wang K, Zhang X, Xing X. Biometric indicators of anterior segment parameters before and after laser peripheral iridotomy by swept-source optical coherent tomography. BMC Ophthalmol. 2022;22(1):222. Published 2022 May 16. doi:10.1186/s12886-022-02448-1