Morphological Findings of Intraocular Lens with Haptics Detached from Optics Following Cataract Surgery

Introduction

The optical zone of the anterior capsule sometimes becomes narrow and occluded due to contraction of the lens capsule following cataract surgery.^1–3. Here, we report a rare case in which the optical zone of the anterior capsule was completely closed and the haptical portion of the intraocular lens (IOL) completely detached from the optical portion 3 months after surgery due to severe capsular contractions.

Case Report

The patient was a 55-year-old woman in general good health. Her right eye had a nuclear cataract and her visual acuity (VA) was 20/200, whereas refraction was −5.0 diopter (D). The retina showed moderate retinochoroidal atrophy in the posterior pole. Pseudoexfoliation was not observed preoperatively. Phacoemulsification, aspiration, and implantation of an IOL (VA-60CB, HOYA, +19.0 D) were performed on the right eye on August 11, 2002. During surgery, performed by one of the authors (YS), continuous curvilinear capsulorrhexis with a diameter of 4.5 to 5.0 mm was performed, and the tension of the lens capsule, especially the zonules of Zinn, appeared weak. The IOL was completely inserted into the capsular bag (Fig. 1A). A distinguishing characteristic of this IOL is that its acrylic optics and polymethylmethacrylate (PMMA) haptics are attached by polymerization without a bonding agent.

Figure 1. (A) the Intraocular (IOL) was Completely Inserted into the Capsular Bag, with the Edge of the Anterior Capsule Stretched Toward the IOL Haptics. (B) the Anterior Capsule Became Contracted, and the Continuous Curvilinear Capsulorrhexis Closed. (C) the Haptics of the IOL Became Detached from the Optics.

Following surgery, right-corrected VA was 60/200, and the anterior capsule was gradually contracted until 1 month later. However, the optical zone of the capsular bag was completely closed (anterior capsular phimosis) at 3 months postoperatively, which resulted in the IOL remaining set in the bag, and the bilateral haptics got separated from the optics (Fig. 1B and C). The corrected VA of the right eye was reduced to 2/200. We extracted the IOL and the capsular bag from the eye, making it aphakic, and the corrected VA recovered to 20/40. Presently, the patient generally uses a contact lens and has no desire for a secondary IOL implantation procedure.

Observation under a stereomicroscope revealed that the extracted IOL had no marked damage on the surfaces of the optics and haptics, which had become completely detached (Fig. 2A). Furthermore, scanning electron microscopic findings showed concentric circular channels on the surfaces of the detached acrylic optics and PMMA haptics, which matched (Figs. 2B and C). In addition, a portion of the detached acrylic optics on the surface was defective.

Figure 2. (A) Macroscopic Findings Showing No Remarkable Damage to the Detached Surfaces of the IOL (B) Scanning Electron Microscopic Image Showing Channels and Dimples on the Surface of the Detached Optics. (C) Scanning Electron Microscopic Image Showing Channels and Optic Portion Remnants on the Surface of the Detached Haptics that Matched Those on the Optics.

Discussion

Anterior capsule fibrosis and phimosis are considered to be related to weakness of the lens capsule in patients with pseudoexfoliation⁴. However, this case had no such evidence preoperatively; thus, an IOL was selected and inserted in the same manner as in other similar cases. This IOL is a new type that uses polymerization to fix the acrylic optics onto the PMMA haptical area. It has been favorably evaluated as easy to handle, and the design allows for easy insertion into the capsular bag during surgery. There are two major models with the same diameter optical zone (6.0 mm); the VA-60CB, which has a large-diameter haptical area and was the initial model produced, and the latter model VA-60BB, which has a smaller haptical diameter. In this case, we employed a VA-60CB with thick and hard haptics, as it was the only model available at the time of surgery, and the subject had weak zonules of Zinn, for which postoperative capsular contraction was expected. Although we anticipated that such contraction could be prevented postoperatively, the optics and haptics of the IOL became detached due to capsular contraction, which required its extraction.

For cases in which postoperative capsular contraction is anticipated, an anterior capsulotomy procedure using a YAG laser might avoid putting strain on the IOL once capsular contraction begins.² In this case, because the progress of capsular contraction was faster than expected, the appropriate time for YAG laser treatment had already lapsed by the time the patient visited our hospital.

Immediately after we presented a detailed report of this case in mid-2003, the manufacturer modified the production process by making the interface between the optics and the haptics less smooth to decrease the likelihood of detachment of the optics and the haptics.