Anterior Chamber And Angle Structures Changes After Posterior Chamber Phakic Intraocular Lens Implantation

Purpose:To study the changes of angle structures anterior chamber after implantable contact lens(ICL) for high myopia using ultrasound biomicroscopy(UBM).Methods:A Staar implantable contact lens (ICL) was implanted in 13 patients (26 eyes) with high myopia. The patients were followed for one year. Spherical equivalent (SE) refraction, best correct visual acuity (BCVA), intraocular pressure (IOP) were performed after surgery. All eyes were examined by UBM one year after surgery:central anterior chamber depth (ACD), trabecular-iris angle (TIA),ICL peripheral distance-lens and angle opening distance at points 500 microm (AOD 500) were measured.Results:The preoperative mean SE was -17. 99 ± 4. 97D, the postoperative mean SE was -1.69 ± 0.98D. The postoperative BCVA was better than the preoperative one .The percentage of eyes that improved two or more lines of BCVA was 73. 1%. Intraocular pressure change from (13. 94 ± 2. 37)mmHg before surgery to ( 14. 42 ± 1.86)mmHg at 1 week, 14.96 ±2. 18mmHg at 1 months , 14. 38 ± 2. 34mmHg at 3 months , 14. 33 ± 2. 79mmHg at 6 months and 14. 17± 2. 99mmHg at 12 months. There was a statistically significant increase ofthe IOP at 1 month after surgery (t= - 3. 418, p=0.002) , which normalized completely at 3 months after surgery. Endothelium distance-ICL (central section) is 2. 22 + 0. 20mm; endothelium distance-lens (central Section) is 2.97 ± 0. 12mm, there were significant differences between them (p < 0. 005. TIA large than 30 degrees in 46.2% to 65. 4%(mean 56. 7%). ICL central distance-lens (central section) is 0.64 ± 0. 16mm. ICL peripheral distance-lens at 12:00,3:00,6:00 and 9:00 were 0.45 ± 0.15mm, 0.46 ± 0.13mm, 0. 37 ± 0. 13mm and 0. 46 + 0. 12mm. No contact was found between the ICL and the crystalline lens.Conclusions:Posterior chamber phakic intraocular lens implantation for the surgical correction of high myopia is a safe procedure with regard to immediate visual and refractive results. We found the reduction of the iridocorneal angle, and the depth of the anterior chamber after surgery. The distance between the crystalline lens and ICL is generally large and the ICL contact with the iris confirmed by UBM. However, there was no direct influence on IOP. Studies with longer follow-up periods must be carried out to determine the long-term safety of this lens implant.