Quantitative assessment of changes in anterior segment morphology after argon laser peripheral iridoplasty: findings from the EARL study group.

IMPORTANCE: Argon laser peripheral iridoplasty (ALPI) could be effective in widening residual angle closure following laser peripheral iridotomy (LPI).

BACKGROUND: We investigated changes in angle parameters following ALPI and its safety profile in this study.

DESIGN: Retrospective, observational case series.

PARTICIPANTS: The records from a single centre, of 36 patients (60 eyes) who underwent ALPI, for residual angle closure following LPI, were reviewed.

METHODS: We analysed anterior chamber parameters in anterior segment optical coherence tomography (ASOCT) images using customized software pre- and post-ALPI. Paired t-test was used to compare changes.

MAIN OUTCOME MEASURES: ASOCT parameters analysed included angle opening distance (AOD 500 and 750), trabecular iris surface area (TISA 500 and 750), anterior chamber width (ACW), anterior chamber volume (ACV), angle recess area (ARA), anterior chamber area (ACA), anterior chamber depth (ACD) and lens vault (LV).

RESULTS: There was a mean increase in AOD 500 (0.05 vs. 0.16 mm, P < 0.001), AOD 750 (0.15 vs. 0.27 mm, P < 0.001), TISA 500 (0.010 vs. 0.038 mm2 , P < 0.001), TISA 750 (0.039 vs. 0.102 mm2 , P < 0.001), ACV (89.76 vs. 102.25 mm3 , P = 0.01), ARA 500 (0.015 vs. 0.033 mm2 , P < 0.001) and ARA 750 (0.044 vs. 0.088 mm2 , P < 0.001). There was no significant change in ACW, ACD, ACA and LV. Mean intraocular pressure (IOP) decreased post-ALPI (17.2 vs. 15.7 mmHg, P = 0.002). The mean follow-up duration was 2.1 years (range 0.5-5 years).

CONCLUSIONS AND RELEVANCE: ALPI results in changes to the angle morphology and lowered IOP in eyes with residual angle closure. Our findings suggest a possible role for ALPI in eyes with residual angle closure following peripheral iridotomy.