Abstract
Abstract: :
Purpose: To study the differences in the intraocular position and anatomic relationships of 2 models of posterior chamber phakic intraocular lens (PCP–IOL) for myopia using ultrasound biomicroscopy. Methods: The UBM 840 (Zeiss–Humphrey, 50 MHz) was used to examine 2 groups of 12 eye–matched eyes (24 eyes; 14 patients). The eyes were matched according to preoperative anterior chamber depth (± 100 µm). Group 1:12 eyes, 7 patients (5 women, 2 men); mean age 28,29 SD 4,4 yrs; mean spherical equivalent:–16,1 SD 4,8 D. Group 2:12 eyes, 7 patients (6 women, 1 man); mean age 31,8 SD 5,1 yrs; mean spherical equivalent: 14,8 SD 2,3 D. Group 1 underwent PRL (Medenium Inc) implantation and group 2 ICL (Staar Surg) implantation. PCP–IOL was implanted in both groups through a clear cornea temporal incision. UBM exams were performed 6–12weeks after surgery. Hourly radial and transversal sections were taken, thus, providing 360º coverage of the anterior chamber and a central section of the anterior chamber through the corneal apex and centered in the pupil was performed. We determined PCP–IOL position, and measured ACD (corneal endothelium to PCP–IOL anterior surface) and crystalline lens–PCP–IOL distance in the minor axis of the PCP–IOLs (superior and inferior PCP–IOL–crystalline distance). Mann–Whitney U test was used to compare means (SPSS 11.5). Results: No statistical differences between groups were found for age, preoperative ACD and spherical equivalent (Preop. ACD in group 1: 3116,6 SD 146,7; in group 2: 3145,5 SD 133,2). Significant differences were found between groups for postoperative ACD (Pospop. ACD in group 1: 2108,7 SD 240,3; in group 2: 2831,4 SD 138,3; p<0,0001) and for crystalline lens–PCP–IOL distance (PRL–crystalline superior distance:671,8 SD 220,2; ICL–crystalline superior distance:105,8 SD 84,6. PRL–crystalline inferior distance:733,0 SD 205,7; ICL–crystalline inferior distance:107,4 SD 86,5; p < 0,0001. No contact between PRLs and crystalline lens was found. 7 eyes (58,3%) had contact between ICL and crystalline. Conclusions: PRLs are located further away from crystalline lens by means of a considerable decrease of ACD and angular opening. ICLs produce a smaller decrease of anterior chamber and are located further away from corneal endothelium, but some presented contact with crystalline lens.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • refractive surgery: phakic IOL • imaging/image analysis: clinical