Influence of anterior chamber depth and vault on anterior chamber angle morphology after phakic posterior chamber intraocular lens implantation.

PURPOSE: This study aims to investigate the influence of anterior chamber depth (ACD) and vault on the anterior chamber angle (ACA) morphology in myopic individuals implanted with posterior chamber phakic intraocular lenses.

METHODS: This retrospective case series involved 231 eyes receiving a 13.2-mm implantable collamer lens (ICL). Preoperative anterior chamber anatomy was assessed using anterior segment optical coherence tomography (AS-OCT) and optical tomography, while postoperative evaluation employed AS-OCT. ACA morphology was characterized pre- and postoperatively through trabecular iris angle (TIA750 ), ACA distance opening (AOD750 ) and trabecular iris space area (TISA750 ). The influence of ACD and vault was examined by categorizing the sample into ACD (shallow, average and deep) and vault (low, optimal and high) groups.

RESULTS: Preoperative ACA morphology varied based on ACD, with shallower ACDs exhibiting narrower TIA750 , smaller AOD750 and TISA750 . ICL implantation induced greater ACA narrowing more in the deep ACD group (TIA750  = 20.1 degrees; AOD750  = 0.82 mm and TISA750  = 0.44 mm2 ) compared to the shallow ACD group (TIA750  = 15.2 degrees; AOD750  = 0.44 mm and TISA750  = 0.21 mm2 ). Postoperatively, deeper ACDs showed larger ACAs. Increasing vault magnitude led to increased ACA narrowing, with the low vault group exhibiting smaller closure (TIA750  = 14.3 degrees; AOD750  = 0.56 mm and TISA750  = 0.29 mm2 ) compared to the high vault group (TIA750  = 20.8 degrees; AOD750  = 0.73 mm and TISA750  = 0.36 mm2 ). The magnitude of ACA narrowing associated with the vault had a consistent effect across different ACD groups.

CONCLUSIONS: Posterior chamber intraocular lens implantation results in ACA narrowing, the extent of which is contingent upon preoperative anterior chamber and ACA morphology, with additional influence from vault magnitude.