Similar to most hydrophilic acrylic intraocular lenses (IOLs), the bag-in-the-lens (BIL) IOL is rarely associated with optic opacification.1–3 Opacification in hydrophilic acrylic IOLs is due to the formation of deposits or precipitates of calcium and phosphate within the IOL substance and may occur many years after implantation.4,5 Exchanging an IOL can be a difficult procedure, especially if the IOL has been in situ for an extended period of time. The capsule’s response to an IOL is typically a fibrotic reaction mediated by the residual lens epithelial cells (LECs).6
The BIL IOL (Type 89A, Morcher GmbH) is an acrylic monofocal IOL that has a 5.0 mm central optic and is suspended by anterior and posterior capsulorhexes.7 In the years following BIL implantation, the residual LECs proliferate in a ring around the BIL, holding it firmly, which both prevents posterior capsule opacification (PCO) and confers a high degree of rotational stability and centration.8,9 We describe a BIL IOL exchange technique that was performed more than 10 years after the original surgery.
A 74-year-old woman presented to ophthalmic services complaining of a slowly developing blur in her right eye. The corrected distance visual acuity (CDVA) was 0.5 (Snellen decimal) in the right eye and 1.0 in the left eye. Bilateral phacoemulsification surgery with BIL implantation had been performed 11 years earlier (+22.50 diopter IOL power). The patient was using regular topical lubrication but no other ocular medications. The systemic medications included a beta-blocker oral antihypertensive, low-dose aspirin, and a statin to control cholesterol. There was no history of hip or knee surgery. On examination, there was a large, dense, irregularly shaped central opacification on the BIL optic in the right eye (Figure 1). There were also opacities on the optic in the left eye; however, these were radial and milder and spared the visual axis (Figure 2). Based on the opacification in the right eye, the patient elected to have IOL exchange.
The surgery was performed initially under topical anesthesia (oxybuprocaine) (Video 1, available at: http://jcrsjournal.org). A standard 3-step temporal incision was made with a 2.8 mm disposable knife and was then widened to approximately 3.2 mm. The anesthesia and dilation were augmented with an injection of 0.1 mL adrenaline (1:1000) diluted in 0.9 mL xylocaine into the anterior chamber. An ophthalmic viscosurgical device (OVD) was used to fill and stabilize the anterior chamber. A paracentesis was created with a 1.0 mm keratome to facilitate bimanual IOL manipulation. Using an IOL rotator spatula (Bausch & Lomb) and the OVD cannula, the lens capsule was disengaged from the inter-haptic groove (Figure 3, A). The cannula was advanced through the gap, under the IOL, and a cushion of OVD was injected behind the IOL into the space of Berger (Figure 3, B). This step is essential to push the anterior hyaloid back and prevent vitreous prolapse by forming a barrier. The rest of the IOL was disengaged from the capsule and prolapsed into the anterior chamber (Figure 4).
A coaxial forceps (Simovision bvba) was used to grasp the IOL firmly and remove it though the main incision without cutting the optic (Figure 3, C). After the IOL was removed, the residual capsule formed a central opening and was able to receive the new IOL (Figure 3, D). The replacement BIL was injected into the anterior chamber and manipulated into the capsule opening. An injection of intracameral carbachol/carbamylcholine (Miostat) was used to induce miosis and prevent iris capture in the early postoperative phase. Residual OVD was aspirated from the anterior chamber, and the corneal wound was hydrated. After the wound was confirmed to be watertight, the surgery was completed with an injection of intracameral cefuroxime based on current cataract best-practice recommendations.10 The entire surgery lasted 12 minutes from first incision to wound closure.
The postoperative treatment consisted of a 2-week course of combined topical tobramycin and dexamethasone eyedrops 4 times a day and a 4-week course of topical diclofenac sodium. At the 5-week postoperative visit, the CDVA was 0.9 (Snellen decimal).
Examination of the Explanted Intraocular Lens
The BIL was examined using bright- and dark-field light microscopy (Axio Scope MAT, Carl Zeiss Microscopy GmbH) at ×25 to ×200 magnifications (Figure 5). There was a turbid region within the polymer matrix; it occupied approximately 30% to 50% of the IOL volume. The regions closest to the surface and the haptics remained clear. The IOL was then hemisected; one half was prepared for direct scanning electron microscopy (SEM), and the other half was coated with carbon for energy dispersive X-ray spectroscopy elemental analysis. The SEM examination of the IOL surface showed no inclusions or inclusion seam. The energy dispersive X-ray spectroscopy techniques confirmed the deposition of calcium, phosphorous, and oxygen approximately 40 μm below the surface (Figure 6).
The BIL technique has become the standard approach for adult cataracts in our department. It offers the advantages of long-term positional stability of the IOL and the absence of PCO because both capsule edges are locked in a groove around the IOL optic. The hydrophilic acrylic IOL material typically displays good biocompatibility but rarely may display opacification in situ. Similar opacities have been described in other hydrophilic acrylic IOL designs and are typically due to calcification associated with IOL flaws or interactions with the patient’s ocular microenvironment.
Intraocular lens exchange is considered a delicate surgical procedure with a higher complication rate than standard cataract surgery.11 Much of the technical complexity stems from the capsular bag, which becomes fibrotic over the years following the initial implantation. Residual LECs proliferate around the IOL and result in a more rigid and less predictable capsule. Disengaging the original IOL may be complicated by haptic shape and design, and preserving the capsule for the second IOL implantation is not always possible.
With the BIL design, the capsulorhexis edges are positioned on top of each other and captured in a groove surrounding the IOL optic. The reduced contact between the IOL and the capsule also simplifies the IOL exchange as no haptics have to be disengaged from the bag. The proliferation of residual LECs is thus restricted and creates a fibrotic ring the same size as the optic. In the case of the patient we describe, a Soemmerring ring was visible in the periphery of the capsule. Histologic examinations of post-mortem eyes with BILs show that the residual capsule space is sealed by a plug of fibrin fusing the edges of the anterior and posterior capsules within the edge of the BIL groove.8 If an IOL must be removed, the edge of the IOL can be manipulated out of the fibrin capsulorhexis ring. The ring is already the correct size to accept the replacement IOL as well as to contain the Soemmerring ring. We do not advocate aspirating the space between the capsules because the LECs pose no visual threat and the fibrin ring provides a stable platform for the IOL.
The blunt needle of the OVD syringe is positioned in the inter-haptic groove, retracting the capsulorhexis ring and pushing back the posterior haptic flange, creating a small gap. The OVD is then injected through the gap. This will prevent the vitreous from prolapsing and secure a safe working space to dislodge the IOL from the capsule. Anterior vitrectomy to remove prolapsed vitreous from the anterior chamber was not required in our case but may occasionally be necessary. After the IOL is in the anterior chamber, it can be removed in 1 piece or cut into 2 smaller pieces before removal through the main incision. Inserting and positioning the new IOL follows the procedure and technique used in primary BIL implantation surgery.
The analysis of the removed IOL revealed the presence of calcium, phosphorous, and oxygen 40 μm under the IOL surface. This indicates the presence of very fine calcium–phosphate crystals in the IOL as they could not be visualized using SEM. The dark-field and bright-field images were very similar to clinical images seen at the slitlamp. In our department, over 8000 BIL implantations have been performed since the approval of the IOL. In that time, 5 IOLs in 3 patients have required explantation because of calcification of the IOL material, resulting in an approximately 0.06% rate of IOL opacification. The exact reasons for the BIL opacifications are not currently known.
What Was Known
- The BIL surgical technique has been routinely used in cataract surgery at our department for more than 12 years. The technique provides a stable IOL position and eliminates the risk for PCO. Opacification of the IOL itself, although rare, does occur and is to be expected in hydrophilic acrylic material.
What This Paper Adds
- This is the first report of an opacified BIL and outlines the technique recommended for mobilization of the BIL from the capsular bag remnants, removal of the IOL, and replacement with a new IOL. The technique is bimanual and simple, and the length of time after original implantation does not appear to increase the risk of surgery. The risk for damaging the capsule support or being unable to implant another BIL is very small, an advantage that is specific to the BIL IOL.
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Video 1 Technique for exchange of a bag-in-the-lens implant.