Iris and trabecular meshwork pigment changes after posterior chamber phakic intraocular lens implantation

Purpose: To evaluate the changes in laser iridotomies, intraocular pressure (IOP), angle structures, and pupil diameter after implantable contact lens (ICL) (Version 4 Staar Surgical) implantation in myopic Asian eyes. Setting: Department of Ophthalmology, Chung-Ang University Yongsan Hospital, Seoul, Korea. Methods: The ICL was implanted in 81 eyes of 43 patients with spherical equivalent greater than -6.00 diopters. Gonioscopy examination was performed 1 day after laser iridotomy and 6 and 12 months after ICL implantation. The changes in laser iridotomy sites, IOP, and pupil diameter were also evaluated. Results: Ten eyes (12.3%) had occlusion or narrowing of the laser iridotomy sites. The angle width was more than 30 degrees in all cases preoperatively but narrowed to less than 20 degrees in 16 eyes (19.8%) 6 months postoperatively. The mean pigment, measured by the semiquantitative method (grade 0 to 4), was 2.03 in the inferior angle, 0.18 in the nasal angle, 0.12 in the temporal angle, and 0.00 in the superior angle 12 months postoperatively. The pigment in all quadrants increased temporally as a result of the laser iridotomy or iris rubbing by the ICL; however, the pigments absorbed gradually and decreased to values before laser iridotomy 12 months postoperatively. There was a temporary increase in IOP from the instillation of steroid eyedrops 1 week and 1 month postoperatively; IOP returned to the preoperative level and remained there 12 months postoperatively. There was a significant decrease in pupil diameter 1 and 3 months postoperatively; the diameter returned to the preoperative size at 6 and 12 months. Pigment dispersion syndrome and pigmentary glaucoma were not seen. Conclusion: Implantation of the ICL narrowed the angle width but did not increase trabecular pigmentation compared with values after laser iridotomy, indicating ICL implantation is safe regardless of the pigmentary changes in the trabecular meshwork.