Hayashi et al. reported on possible factors contributing to in-the-bag and out-of-the-bag intraocular lens (IOL) dislocation. The major factors predisposing to in-the-bag dislocation were pseudoexfoliation (most common), retinitis pigmentosa, status after vitrectomy, trauma, and a long axis, whereas those for out-of-the-bag dislocation were secondary IOL implantation (most common), surgical complications, mature cataract, and pseudoexfoliation. Spontaneous IOL dislocation in the absence of an ocular area with zonular weakness or trauma is uncommon. In addition, there have been no reports of spontaneous capsular bag dislocation into the anterior chamber without an IOL. We report a rare, interesting case of spontaneous capsular bag anterior dislocation, without an IOL, into the anterior chamber with no history of any genetic disease, ocular trauma, or pseudoexfoliation that might predispose to a zonular abnormality.
A 71-year-old male presented with decreased visual acuity in the left eye for 2-month duration. On ocular examination, the best-corrected visual acuity in the right and left eyes was 20/20 (MR−, +0.50Ds -0.50Dc Ax90) and 20/60 (MR-error), respectively. On slit lamp examination, an empty capsular bag with anterior continuous curvilinear capsulorhexis (CCC) was found in the anterior chamber [Fig. 1a]. In addition, the slit lamp examination showed downward subluxation of a three-piece IOL and some vitreous strands in the anterior chamber in the mydriasis test [Fig. 1b]. The medical history of this patient was as follows. In 2009, he was diagnosed with a senile cataract (posterior subcapsular opacity type) in both eyes and underwent cataract surgery on both eyes in our clinic. There was no zonular weakness or pseudoexfoliation in the crystalline lens on the preoperative examination. The cataract surgery consisted of one-stitch, a 2.8-mm temporal clear corneal incision, phacoemulsification, and implantation of a three-piece hydrophobic acrylic IOL (TECNIS ZA9003, Abbott Medical Optics, Santa Ana, CA, USA) in the left eye and a one-piece hydrophobic acrylic IOL (TECNIS ZCB00, Abbott Medical Optics, Santa Ana, CA, USA) in the right eye. He denied accidental trauma before or after the cataract surgery. He also had no hereditary genetic diseases, including Marfan syndrome, homocystinuria, spherophakia, and retinitis pigmentosa. However, he stated that he had a habit of rubbing his eyes.
Three years postoperatively, he presented with decreased visual acuity in the left eye and anterior dislocation of the capsular bag. The IOL was dislocated into the posterior chamber. We planned to reposition the IOL with scleral fixation of the existing lens. The dislocated capsular bag was extracted from the anterior chamber and spread on the corneal surface, and we observed a partial circumferential laceration along the equator of the capsular bag; that is, at the junction of the anterior and posterior capsular bags. The bag had an intact margin of anterior capsular curvilinear capsulorhexis [Fig. 2a and b]. To reposition the IOL, two partial-thickness, limbal-based scleral flaps were created about 1.5 mm from the limbus, under which sclerotomies were performed. The IOL was repositioned through two 1-mm side punctures made using two 23-gauge end-gripping micro-capsulorhexis forceps (Micro Surgical Technology, Redmond, WA, USA), and both haptics were externalized under the scleral flap with Colibri forceps. The haptic ends were tucked into intralamellar scleral tunnels made with a 26-gauge needle. The scleral flaps and conjunctiva were closed with fibrin glue (Tisseel; Baxter, Deerfield, IL, USA; [Fig. 3a]). The surgery was completed with an anterior vitrectomy. This method, called a glued intrascleral fixation of the posterior chamber of the IOL, was introduced by Kumar et al. The uncorrected visual acuity recovered to 20/30 in the left eye [Fig. 3b].
It is possible that the original cataract surgery in our patient was not completed successfully and left an occult defect at the capsular equator because no linear defect at the equator is visible under standard microscopic conditions. However, we postulated that two factors contributed to our unique case of out-of-the-bag IOL dislocation with anterior dislocation of an empty capsular bag. First, the patient had a habit of rubbing his eyes. This habitual behavior would create pressure that could push the capsular bag in an anterior-to-posterior direction and might result in progressive zonular dehiscence around the capsular bag. However, with a normal pupillary diameter, the IOL could not be extracted from the posterior chamber to the anterior chamber. Instead, in our case, the capsular bag with a circumferential laceration of the equator extruded into the anterior chamber via the pupillary space. Second, the implanted IOL was a sharp three-piece IOL with a polymethyl methacrylate (PMMA) haptic. Aqueous movement caused by external pressure would widen the break in the capsular bag, and the IOL might have escaped from the bag via the opening in the capsular wall. We postulated that misdirected aqueous via the capsular wall opening moved to the backside of the posterior capsular wall, and this pressured flow caused additional progressive dehiscence of the zonular fibers. Finally, the flow pushed the movable capsular bag without zonular support into the anterior chamber through the pupillary hole. This mechanism of capsular laceration caused by the haptic is illustrated in [Fig. 4]. Nevertheless, how could the large optic can pass through the smaller 4-mm opening at the equator? Since the TECNIS ZA9003 is a 6-mm optic, it might at first seem impossible for it to pass through the 4-mm opening of the capsular bag. The left eye did not develop IOL dislocation despite the mechanical stress of eye rubbing. Although it could be a coincidence, the capsular bag of the left eye contained a one-piece acrylic IOL with a blunt-tip haptic. Therefore, we reasoned that the blunt haptic could not pierce the capsular bag, despite the persistent external pressure. Without any predisposing factors for zonular weakness, such as ocular trauma or genetic disorders, out-of-the-bag IOL dislocation can occur via a linear circumferential laceration of the capsular bag caused by the sharp PMMA haptic of a three-piece IOL despite good CCC and good in-the-bag implantation of a posterior chamber IOL.
1. Hayashi K, Hirata A, Hayashi H. Possible predisposing factors for in-the-bag and out-of-the-bag intraocular lens dislocation and outcomes of intraocular lens exchange surgery Ophthalmology. 2007;114:969–75
2. Kumar DA, Agarwal A, Prakash D, Prakash G, Jacob S, Agarwal A. Glued intrascleral fixation of posterior chamber intraocular lens in children Am J Ophthalmol. 2012;153:594–601:601.e1
Source of Support: Nil.
Conflict of Interest: None declared.