Impact of anterior chamber depth on anterior chamber angle morphology after phakic posterior chamber implantable collamer lens implantation

Abstract

Objective To observe the impact of preoperative anterior chamber depth (ACD) on anterior chamber angle morphology after phakic posterior chamber implantable collamer lens (PPC-ICL) implantation. Methods One hundred and thirty-two eyes of 80 consecutive patients with myopia undergoing PPC-ICL implantation were enrolled in this retrospective study. The patients were divided into three groups according to preoperative anterior chamber depth: group A: ACD<3.0 mm; group B: 3.0≤ACD<3.5 mm; group C: ACD≥3.5 mm. Before surgery and 3 months after surgery, anterior segment optical coherence tomography (AS-OCT) was used to measure anterior segment morphology. The indexes observed included ACD, angle opening distance (AOD500), trabecular-iris space area (TISA500) and scleral spur angle (SSA) in the 0° and 180° positions. Analysis of variance, correlation analysis and a paired t-test were used for statistical analysis. Results For all the patients, the measured values of preoperative AOD500 (0°, 180°) (r=0.51, 0.47), TISA500 (0°, 180°) (r=0.55, 0.52) and SSA (0°, 180°) (r=0.46, 0.58) were positively correlated with ACD (P<0.01). Three months after surgery, the average ACD, AOD500, TISA500 and SSA values of the three groups had significantly decreased compared to preoperative values (P<0.05). The measurements of AOD500 (F=7.00, 5.08), TISA500 (F=6.42, 3.06) and SSA (F=7.20, 4.73) in the 0° and 180° positions in group A were significantly lower than those in groups B and C (P<0.05), and there was no significant difference between group B and group C. The postoperative AOD500, TISA500 and SSA in the three groups declined in the same proportion, and there were no statistically significant differences. The PPC-ICL vaults in groups A and B were lower than those in group C (F=5.37, P< 0.05). Three months after surgery, the changes (percentage) in AOD500 (r=0.54, 0.50), TISA500 (r= 0.49, 0.48) and SSA (r=0.60, 0.61) were positively correlated with ICL vault (P<0.01). No anterior chamber angle closure was found during the follow-up period, and there was no significant decrease in intraocular pressure in the three groups after surgery. Conclusion The morphology of the anterior chamber changes significantly after PPC-ICL implantation. Patients with a shallow anterior chamber will show a shallower anterior chamber depth and narrower anterior chamber angle after surgery. The change in anterior chamber morphology will be more obvious in patients with a higher vault. Key words: Myopia; Phakic intraocular lenses; Tomography, optical coherence, anterior segment; Anterior chamber depth