Late-Onset Hyaloideocapsular Block Syndrome

Case Report 

An 80-year-old woman presented with a complaint of blurred vision with correction in the left eye 16 years after standard ECCE without IOL implantation. Extracapsular cataract extraction was performed using a can opener capsulotomy and the surgery was uneventful. The preoperative best-corrected visual acuity (BCVA) was 20/200 with −8 −0.50 × 90. The postoperative BCVA was 20/30 with +6 −3 × 100.

Seven years after ECCE, the patient underwent a trabeculectomy of the left eye and a capsular polishing of Elschnig pearls without capsulotomy at the same time. The patient’s BCVA in the left eye 1 month postoperatively was 20/30 with +5.50 −3 × 100. Intermediate examinations by the patient’s ophthalmologist were uneventful with a stable visual acuity corrected with spectacles. No medical therapy was required for pressure control. No history of systemic or ocular disorders or trauma was reported.

At presentation, the patient’s visual acuity in the left eye with spectacles (+5.50 −3 × 100) was counting fingers. Her uncorrected visual acuity was 20/200 and the BCVA was 20/80 with +2 −3 × 100. Intraocular pressure by applanation tonometry was 13 mmHg. Slit-lamp examination revealed a filtering bleb, a clear cornea, and a deep anterior chamber. No cell or flare was detected in the anterior chamber. After maximal dilation, the posterior capsule was visible and clear, except for a few small regions of fibrosis located superonasally and at the periphery in the circular adherent zone between the anterior and posterior capsules (Fig 1). The posterior capsule was pushed forward by a milky fluid accumulation between the posterior lens capsule and the anterior hyaloid membrane, giving an unusual “neocrystalline lens” appearance (Fig 2). Fundus examination revealed myopic retinopathy with a posterior vitreous detachment.

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Figure 1. Hyaloideocapsular block syndrome in an 80-year-old woman. Diffuse illumination reveals a circular pocket limited by a fibrosed ring in the central portion of the posterior capsule (arrowheads), where the milky white substance had accumulated. Note the fibrosed anterior capsule opening.

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Figure 2. Slit-lamp biomicroscopic appearance. A, The slit-lamp beam strikes the homogenous milky fluid between the posterior capsule (solid arrow) and the anterior hyaloid membrane (hollow arrow). Note the adherence between the posterior capsule and the anterior hyaloid membrane (arrowhead) next to the milky fluid accumulation. B, Photograph shows light reflection of the slit-lamp beam on the superonasal capsular fibrosis with fluid accumulation behind.

During 6 months of follow-up, there was no change in the appearance of the milky fluid, and the blurred vision persisted. With the patient’s consent, a neodymium:yttrium-aluminium-garnet (Nd:YAG) laser hyaloidotomy was performed on the inferior peripheral anterior hyaloid membrane. A Peyman contact lens (OPYG-12/12, Ocular Instruments, Inc., Bellevue, WA) was applied to the eye. After a single pulse application at 1.0 mJ with a 1.0-millisecond duration, the milky fluid leaked into the vitreous cavity. Further pulses were applied to enlarge the opening. The posterior lens capsule was left intact. One week later, slit-lamp examination revealed the complete disappearance of the milky fluid. The myopic shift disappeared with an improved visual acuity of 20/40 with +5.50 −3 × 110. Intraocular pressure remained stable.

Discussion 

The condition we describe is the first capsule-related fluid accumulation reported in an aphakic patient. It differs from CBS, in which the pathogenesis involves the IOL. We called this condition hyaloideocapsular block syndrome because of the common clinical features it shares with both early and late CBS.7 The accumulated substance was milky white as in late postoperative CBS,8, 9 rather than transparent as in early postoperative CBS.1, 2 Unlike eyes in late postoperative CBS, however, refraction revealed an induced myopia. The mechanism of this myopic shift might be due to the refractive power of the fluid collection, which is the result of the sum of refraction at these 2 interfaces and of its transmission properties, rather than to the forward IOL displacement that occurs in CBS. Because the fluid accumulation extended to both sides of the posterior capsular plane, pushing the anterior hyaloid membrane backward and the posterior capsule forward, the anterior chamber was not shallow.

The pathogenesis of this condition is unclear. A closed chamber might have formed behind the posterior lens capsule by a central detachment of the anterior hyaloid membrane still adherent to the posterior lens capsule by a fibrosed ring. In the normal condition, the lens is attached to the anterior vitreous surface along a circular zone approximately 1 to 2 mm in width and 8 to 9 mm in diameter called the hyaloideocapsular ligament or ligamentum pectinatum.10 This circular attachment is firm in youth and weakens with age. The potential space of Berger lies within the hyaloideocapsular ligament where the capsular lens and vitreous are apposed. The particular shape of the neocrystalline lens was due to the enlargement of this space in this aphakic patient. It is not clear how the fluid was drawn into this space. The source and composition of the accumulated material is unknown. We suggest that oncotic pressure was created in the space by migrating residual lens epithelial cells and their protein or proteinaceous byproducts. The resulting osmotic gradient allowed for the aqueous humor to permeate the capsule. This is one mechanism explaining the postoperative cases of CBS.4, 7 We suggest a possible posterior migration of lens epithelial cells via pseudometaplasia or proliferation. The capsular polishing, even without a capsular tear, could have supported this migration as well as the central detachment of the anterior hyaloid membrane from the posterior capsule. We assumed that there was no association between the onset of fluid accumulation with the ECCE procedure, especially because of the delay between them. It is thus unclear whether this syndrome can exist after pure ECCE without IOL implantation and capsular polishing. Trabeculectomy with capsular polishing might have changed the anatomy to allow for this condition to occur.

As with late postoperative CBS, this complication might be a chronic phenomenon. We believe that the hyaloideocapsular block syndrome was subclinical in the initial stages and presented later when fluid accumulated.

We initially refrained from intervention because the situation often resolves spontaneously without specific treatment in many CBS cases.4, 9 In the present case, the milky fluid seemed unchanged over 6 months of follow-up and Nd:YAG laser anterior hyaloidotomy was successfully performed. We did not perform a posterior capsulotomy because we wanted to maintain a barrier between the anterior and posterior segments in this glaucomatous aphakic patient.

The treatment of choice is Nd:YAG laser capsulotomy for pseudophakic CBS.3, 4, 7, 8, 9 Likewise, we believe that Nd:YAG laser peripheral anterior hyaloidotomy is an effective, simple, and minimally invasive procedure for hyaloideocapsular block in the absence of an IOL. Whereas the liquid material in the capsular block typically accumulates between the IOL and the capsule, it might accumulate in the absence of an IOL and under certain circumstances between the capsule and the hyaloid, necessitating a hyaloidotomy rather than a capsulotomy. In the hyaloideocapsular block syndrome, it seems preferable to preserve the capsule when possible and to therefore disperse the liquid material into the vitreous instead of the anterior chamber.