Bilateral early capsular block syndrome following implantation of the new trifocal toric lens.

A young patient underwent phacoemulsification with endocapsular implantation of trifocal toric lens in both eyes (AT LISA tri toric 939 MP, Carl-Zeiss, Germany). One-week postsurgery, he developed capsular block syndrome (CBS) in both eyes. There was deterioration of uncorrected visual acuity at 1-week postsurgery, with a myopic shift of 2.5 diopters (D) in the right eye and 2.0 D in the left eye. The intraocular pressure was only elevated in the left eye. Neodymium: yttrium-aluminum-garnet laser posterior capsulotomy resolved the block successfully in both eyes. A thick lens with a plate haptic design may have contributed to the early CBS.

Introduction

Capsular block syndrome (CBS) is a rare and unique complication of cataract surgery and posterior chamber intraocular lens (PCIOL) implantation.[1] It is characterized by retention of particulate matter or viscoelastic substance between the posterior face of a PCIOL and posterior capsule in the presence of a continuous curvilinear capsulorhexis (CCC).[23] The retained material attracts fluid and distends the capsular bag, which displaces the posterior capsule backward and the IOL forward. This phenomenon may lead to a shallow anterior chamber (AC) and high intraocular pressure (IOP), due to angle closure.[14] In this case report, we describe bilateral early CBS in a patient who underwent cataract extraction, with the latest endocapsular AT LISA tri toric 939MP lens implants (Carl Zeiss, Oberkochen, Germany).

Case Report

A 35-year-old male patient underwent uneventful cataract surgery with in-the-bag implantation of trifocal toric lens in both eyes. Before surgery, his best-corrected visual acuity (BCVA) was 20/40 OD and 20/40 OS. His manifest refraction was+4.00 −3.00 × 005 OD and + 5.00 −2.75 × 175 OS. On slit-lamp examination, the corneas were clear and AC depth was 3.26 mm OD and 3.03 mm OS. The angle as measured by Pentacam (Oculus Optikgerate GmbH, Germany) was 33.7° OD ad 37.8° OS. There were posterior subcapsular cataracts in both eyes, and the rest of the examination was unremarkable. There was no significant medical or ocular history. Following informed consent, he underwent uneventful phacoemulsification and PCIOL in the right eye. The surgery was performed through a 2.2 mm clear corneal incision, and a foldable single-piece plate haptic design AT LISA tri toric 939 MP lens was implanted in the capsular bag. A cohesive viscoelastic (Provisc) was used during the procedure. There were no intraoperative complications. Postoperatively, topical steroids and antibiotics were prescribed 4 times a day. At 1-week postoperative visit, the patient uncorrected visual acuity (UCVA) dropped to 20/50 while improving to 20/25 with a manifest refraction of −2.50 sphere. On slit-lamp examination, the posterior capsule was seen to be displaced backward with a few microscopic cells and particulate matter floating around in the space behind the IOL [Figure 1]. The CCC was seen to be well opposed to the optic of the IOL. The IOP was measured to be within normal limits. The patient was kept on frequent dosing of steroid eye drops. Due to significant anisometropia, the patient soon underwent cataract extraction and PCIOL (AT LISA tri toric 939MP) in the left eye without any complications, using the same technique as the right eye. Meticulous attention was paid to complete removal of viscoelastic behind the IOL, and the capsule was polished 360° to remove any residual cortical material. At 1-week postsurgery, the UCVA was 20/60 and BCVA was 20/25, with a manifest refraction of −2.0 sphere. Similar to the right eye, the posterior capsule was distended with cells and particulate matter floating around behind the IOL [Figure 2]. However, the IOP was measured to be 36 mm of Hg. The frequency of topical steroids was increased, and an IOP-lowering agent was added to control the IOP. The slit-lamp examination of the right eye remained unchanged except that the lens bag was even more distended. An ultrasound biomicroscopy (UBM) was obtained that confirmed the diagnosis of early postoperative posterior CBS in both eyes [Figure 3]. The patient underwent a neodymium: yttrium-aluminum-garnet (Nd: YAG) laser posterior capsulotomy with difficulty due to poor focus on the displaced posterior capsular bag; however, the posterior capsule returned to its normal position immediately after the capsulotomy was completed. At 1 week after the laser to the right eye, the left eye underwent posterior Nd: YAG laser capsulotomy with similar repositioning of the posterior capsule of the right eye. The patient was followed up at 1 month after the surgery in the clinic. UCVA was 20/25 OD and 20/30 OS. The BCVA was 20/25 OD and 20/28 OS (MR: +0.50 −0.25 × 180 OD and −0.50–0.50 at 175 OS). The IOP was within normal limits in both eyes. The rest of the anterior segment examination was unremarkable.

Figure 1

Capsular block syndrome OD showing the distended posterior capsule (arrow)

Figure 2

Capsular block syndrome OS showing floating material behind the intraocular lens implantation and distended posterior capsule

Figure 3

Ultrasound biomicroscopy image showing the hyperflexed posterior capsule (thin arrow) and thick intraocular lens implantation touching the iris (thick arrow)

Discussion

The three types of CBS have been described as three different pathologic processes with dissimilar etiologies.[245] First, intraoperative CBS occurs during hydrodissection where a sudden increase in pressure inside the capsular bag leads to posterior capsular rupture and lens drops into the vitreous cavity.[6] Second, early postoperative CBS occurs due to retention of viscoelastic or particulate matter between the optic of the IOL and posterior capsule after an uncomplicated cataract extraction. Third, late-onset CBS can be months or years after an uncomplicated cataract extraction with in-the-bag IOL placement and CCC.[78] The retained particles act as osmotic agents to draw fluid into this space which leads to distention of the capsular bag and forward movement of the lens.[5] The anterior movement of the lens may lead to a myopic shift and an angle closure glaucoma.

This case report describes a bilateral early-onset CBS in a young patient that underwent uncomplicated cataract extraction with in-the-bag AT LISA trifocal toric lens. Anti-inflammatory medications failed to resolve the CBS and Nd: YAG laser successfully resolved the capsular block in both eyes. Similar capsular block has been seen with in-the-bag four haptic IOL designs such as accommodating lenses (1CU IOL, Human Optics AG) and Akreos lens (Bausch and Lomb).[39] The lens implanted in our patient was a plate haptic single piece, 25% hydrophilic acrylic with surface hydrophobic properties. The optic diameter was 6.0 mm and a total diameter of 11.0 mm with square edge design and 0° angulation. A very thick lens (+28 D of spherical and + 3.5 D of cylindrical power OD and 24 D spherical and 6.5 D cylindrical power OS) with a plate haptic design may have contributed to the capsular block along the anterior face of the IOL in our patient. As shown in the UBM, the thick edges of the IOL are seen to be in close contact with the iris [Figure 3].

The patient did not respond to increased frequency of the topical anti-inflammatory drops, which leads us to an acellular etiology of the CBS.[4] Meticulous attention was paid to complete removal of the viscoelastic material to prevent the occurrence of CBS in the second eye; however, the capsular block was more severe in the OS as compared to the right eye. Again, the thick lens design (left lens thicker than right lens) may well have prevented the fluid circulation around the optic of the IOL.

Long eyes and PCIOL with four haptics were identified as risk factors for developing early CBS by Kim and Shin.[4] In this case report, the patient had an axial length of 21 mm and a very high power IOL along with high cylinder correction was implanted in the capsular bag in both eyes.

Although CBS is a rare complication of phacoemulsification with CCC and in-the-bag IOL implantation, certain designs of lenses may be more susceptible to cause this syndrome. Follow-up without treatment is not effective in most cases.[10] Nd: YAG laser peripheral anterior capsulotomy or posterior capsulotomy is a proven effective and safe treatment.[11]

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Conflicts of interest

There are no conflicts of interest.