[Analysis of pre-operative factors affecting vault after posterior chamber phakic intraocular lens implantation]

Objective: To analyze the early changes in vault height and its influencing factors after implantation of posterior chamber phakic intraocular lenses (pIOL). Methods: A retrospective case series study was conducted, including patients who underwent pIOL implantation at Zhongshan Ophthalmic Center, Sun Yat-sen University, from September 2020 to August 2021, and completed a 3-month follow-up. Data were collected from myopic or myopic astigmatism patients. Preoperative ocular examinations, including Pentacam anterior segment analysis system, Sirius anterior segment analysis system, ultrasound biomicroscopy (UBM), and IOLMaster optical biometry, were performed to measure parameters such as refractive power, corneal curvature, corneal horizontal diameter, anterior chamber volume, anterior chamber depth, pupil diameter, sulcus-to-sulcus diameter (STS), and lens thickness. The degree and position of implanted pIOL, as well as vault height measured by anterior segment optical coherence tomography (AS-OCT) at 1 day, 1 week, 1 month, and 3 months postoperatively, were recorded. Statistical analyses were conducted using repeated measures analysis of variance, Pearson correlation analysis, and multiple linear regression analysis. Results: A total of 314 patients (314 eyes) were included, with 52 male (16.56%) and 262 female (83.44%) patients, and an average age of (26.44±4.60) years. The preoperative equivalent spherical power was (-8.09±2.41) D. Postoperative vault heights at 1 day, 1 week, 1 month, and 3 months were (671.88±273.02) μm, (652.26±272.21) μm, (615.08±259.69) μm, and (591.14±250.71) μm, respectively, with statistically significant differences among groups (P<0.001). Eyes with vault height>750 μm showed a greater decrease in early postoperative vault height (P<0.001). The eyes implanted with 12.1 mm pIOL had the lowest postoperative vault height, while those with 13.2 mm had the highest (P>0.05). Factors correlated with vault height at 1 day postoperatively included corneal horizontal diameter, anterior chamber depth, preoperative cylinder power, angle degree, lens thickness, and pIOL cylinder power. Factors correlated with vault height at 3 months postoperatively included corneal horizontal diameter, anterior chamber depth, preoperative cylinder power, anterior chamber volume, angle degree, lens thickness, axial length, pIOL spherical and cylinder power. Factors associated with changes in early postoperative vault height included corneal curvature K2, anterior chamber depth, anterior chamber volume, pupil diameter, horizontal STS, vertical STS, axial length, and preoperative spherical power (all P<0.05). Multiple linear regression analysis revealed that lens thickness significantly influenced vault height at 1 day postoperatively, anterior chamber volume significantly influenced vault height at 3 months postoperatively, and pupil diameter significantly influenced changes in early postoperative vault height (all P<0.05). Conclusions: Vault height after pIOL implantation is unstable in the early postoperative period and gradually decreases within 3 months. A higher baseline vault height is associated with a greater decrease. Anterior chamber volume, pupil diameter, and lens thickness are influencing factors on vault height during the first 3 months postoperatively.