Ultrasound Biomicroscopy of Anterior Segment Accommodative Changes with Posterior Chamber Phakic Intraocular Lens in High Myopia

To investigate changes in anterior chamber depth (ACD) and the distance between the Visian implantable Collamer lens (ICL) and the crystalline lens during pharmacologic accommodation in high myopia.Prospective, comparative case series.Thirty-three phakic eyes of 18 high myopic patients (range, -8.63 to -23.86 diopters) with a mean age of 29 years (range, 20-44 years) were examined at least 1 year after ICL implantation.Ultrasound biomicroscopy was used to measure distance changes between the corneal endothelium, the ICL, and the crystalline lens after inducing pharmacologic accommodation with topical pilocarpine in 1 eye. The contralateral eye served as the control.Mean changes of ACD measured from the posterior corneal surface to the crystalline lens (ACD-L), from the posterior corneal surface to the anterior surface of the ICL (ACD-ICL), and the distance between the ICL and the crystalline lens (ICL-L) at the central and peripheral regions of the eye.For each eye, the ICL was in contact with the iris, but it was never in contact with the crystalline lens. At baseline, the mean distance between the ICL and the crystalline lens was 0.609 ± 0.165 mm at the central horizontal meridian, 0.588 ± 0.157 mm at the central vertical meridian, 0.281 ± 0.106 mm at the peripheral temporal sulcus, and 0.290 ± 0.098 mm at the peripheral nasal sulcus. After instillation of pilocarpine, a significant decrease in ICL-L was accompanied by a significant reduction in ACD-L and an increase in ACD-ICL (P<0.01). There were no significant changes in the control eyes (P>0.05). The central ICL-L reduction in the study group was significantly larger than that in the control group (P<0.01), but the peripheral ICL-L changes in the study group were not significantly different from those in the controls (P>0.05).During pharmacologic accommodation, the ICL and the crystalline lens came closer as the ICL was pushed backward by the iris as a result of pupillary constriction. Simultaneously, the anterior surface of the crystalline lens became more convex and moved forward. Reduction of the distances at peripheral sulci was not as obvious as at the center.The author(s) have no proprietary or commercial interest in any materials discussed in this article.