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Clinical Evaluation of Corneal Biomechanical Parameters After Posterior Chamber Phakic Intraocular Lens Implantation

Ali, Mohamed MD*,†; Kamiya, Kazutaka MD, PhD*; Shimizu, Kimiya MD, PhD*; Igarashi, Akihito MD, PhD*; Ishii, Rie MD, PhD*

doi: 10.1097/ICO.0000000000000088
Clinical Science

Purpose: The aim of this study was to quantitatively assess the changes in corneal biomechanics after posterior chamber phakic intraocular lens (Visian ICL; STAAR Surgical) implantation for normal and keratoconic subjects.

Methods: We retrospectively examined 29 eyes of 16 consecutive patients (mean age ± SD, 32.4 ± 7.3 years) undergoing implantable collamer lens (ICL) implantation through a 3.0-mm temporal corneal incision. We longitudinally assessed the values of corneal hysteresis (CH) and corneal resistance factor (CRF) using an Ocular Response Analyzer. We also investigated the relationship between these biomechanical parameters and central corneal thickness (CCT) preoperatively, and at 1 week, 1 month, and 3 months postoperatively.

Results: The CH was 9.2 ± 1.4 mm Hg preoperatively, and 9.2 ± 1.4 mm Hg, 9.3 ± 1.7 mm Hg, and 8.8 ± 1.3 mm Hg at 1 week, 1 month, and 3 months postoperatively, respectively. The CRF was 8.4 ± 1.6 mm Hg preoperatively, and 9.0 ± 1.5 mm Hg, 8.8 ± 1.7 mm Hg, and 8.8 ± 1.6 mm Hg, at 1 week, 1 month, and 3 months postoperatively, respectively. Multiple comparisons demonstrated no significant differences between measurements made preoperatively and postoperatively (P > 0.05, Dunnett test). Both CH and CRF were significantly correlated with CCT 3 months postoperatively [Spearman correlation coefficient (r) = 0.48, P = 0.01 for CH; r = 0.84, P < 0.001 for CRF].

Conclusions: We found no significant changes in CH or CRF after ICL implantation, not only in normal eyes but also in keratoconic eyes, suggesting that this surgical technique does not significantly affect corneal biomechanical factors. The CCT may play some role in corneal biomechanics even in eyes undergoing ICL implantation.

*Department of Ophthalmology, University of Kitasato School of Medicine, Kanagawa, Japan; and

Department of Ophthalmology, Faculty of Medicine, Minia University Hospitals, Minia, Egypt.

Reprints: Kazutaka Kamiya, Department of Ophthalmology, University of Kitasato School of Medicine, 1-15-1, Kitasato, Sagamihara, Kanagawa 228-8555, Japan (e-mail:

K. Shimizu has received consultancy fees from the STAAR Surgical Company. The others authors have no funding or conflicts of interest to disclose.

Received October 27, 2013

Accepted January 10, 2014

© 2014 by Lippincott Williams & Wilkins.