Retinitis pigmentosa is a heterogeneous group of retinal degenerations that result in gradual loss of photoreceptors in the retina and subsequent blindness. In the latter stages of disease, there is a prominent component of inflammatory signaling and damage.1 Retinitis pigmentosa has been associated with a statistically significant increase in anterior capsule contraction from 1 month to 1 year after standard cataract extraction with a manual capsulorhexis. This abnormal healing response has been attributed to the presence of increased cytokines in the aqueous of patients with retinitis pigmentosa as a result of the increased permeability of blood–aqueous barrier and blood–retinal barrier associated with retinitis pigmentosa. In addition, zonular fiber weakness might contribute to anterior capsule contraction postoperatively.2
Cataract surgery assisted by the femtosecond laser has gained significant attention in the past 7 years. Initial claims of improved safety and outcomes were largely theoretical. Its use was particularly advocated for cases of zonular fiber instability with the idea that a laser-assisted capsulotomy would decrease forces applied to the zonular fibers compared with manual capsulorhexis creation, thereby potentially improving safety.3 A recent large multicenter case control study using the European Registry of Quality Outcomes for Cataract and Refractive Surgery4 compared the use of the femtosecond laser with manual phacoemulsification techniques and concluded that use of the laser did not improve outcomes over standard manual phacoemulsification surgery. There was also a higher incidence of postoperative corneal edema, early posterior capsule opacification, and uveitis requiring treatment in the femtosecond laser–assisted cataract surgery (FLACS) group.
Little has been written about patient selection for (FLACS). However, most cataract surgeons will attest to the idea that different ocular conditions might benefit from different surgical techniques. We report a case of rapid capsule contraction syndrome (CCS) in a patient with retinitis pigmentosa treated with FLACS. The paired eye, which had manual phacoemulsification with continuous curvilinear capsulorhexis (CCC) creation, did not have CCS. We discuss the potential causes for this differing response.
A 50-year-old woman with retinitis pigmentosa had manual phacoemulsification for a visually significant posterior subcapsular cataract in the left eye. Neither eye had preoperative uveitis or pseudoexfoliation signs. The surgery was routine and included placement of a 1-piece 2-haptic hydrophobic acrylic intraocular lens (IOL) (Acrysof SN60WF, Alcon Laboratories, Inc.) in the capsular bag. The IOL had a 6.0 mm optic and 13.0 mm overall length. The postoperative course was uneventful and included a laser posterior capsulotomy for posterior capsule opacification.
Approximately 4 years later, the patient reported worsening vision in the right eye. The corrected distance visual acuity was 20/50 in the right eye and 20/80 in the left eye. Both eyes had cystoid macular edema and severely constricted visual fields consistent with retinitis pigmentosa, with approximately 15- to 20-degree central islands. Uneventful FLACS was performed in the right eye using a Catalys Precision Laser System (Abbott Medical Optics, Inc.). A 1-piece 2-haptic Tecnis ZCB00 hydrophobic acrylic IOL (Abbott Medical Optics, Inc.) with a 6.0 mm optic and 13.0 mm overall length was implanted in the capsular bag. Neither eye was treated with anterior capsule polishing at the time of surgery, and both received a month of topical nonsteroidal antiinflammatory and steroid drops.
At the 1-month postoperative visit, slight inferior displacement of the IOL and anterior capsule contraction were noted in the right eye. Three months after the procedure, the anterior capsule was markedly fibrosed and contracted, leaving only a 1.0 mm anterior aperture, with the IOL folded upon itself (Figure 1). Because of the extreme zonular fiber stretch and instability of the IOL, an anterior neodymium:YAG capsulotomy was deemed insufficient for treatment. Instead, the fibrosed anterior capsule was surgically removed with intraocular scissors and an anterior vitrectomy. Postoperatively, the anterior aperture was 5.0 mm. A laser posterior capsulotomy was performed several months after the anterior fibrosis excision.
Two years after surgery, the IOL maintained stability, the anterior and posterior capsule axes were clear, and the uncorrected distance visual acuity in the right eye was 20/50 (Figure 2).
Patients with retinitis pigmentosa are predisposed to anterior capsule contraction.2,5–7 Nikpoor and Stone6 reported a patient with retinitis pigmentosa who had manual phacoemulsification with implantation of a 1-piece IOL in both eyes. Within the first month after surgery, anterior capsule contraction developed and the IOL haptics were distorted bilaterally. The authors suggested that certain subsets of patients with retinitis pigmentosa might be at greater risk for this complication because the patient described in their case report had a similar degree of capsule contraction in both eyes. Our case is unique in that only the eye that had FLACS developed rapid capsule contraction requiring intervention because of its progressive nature, while the eye that had manual phacoemulsification did not develop contraction.
Multiple methods have been used to try to prevent CCS, including creation of a larger capsulorhexis, careful selection of IOL type, lens epithelial cell cleanup on the anterior capsule, creation of radial relaxing incisions in the anterior lens capsule, and placement of a capsular tension ring. Jin-Poi et al.5 described a patient with retinitis pigmentosa who had manual cataract extraction in both eyes. The first eye had rapid anterior capsule contraction that was treated with an anterior laser capsulotomy. Subsequently, in the fellow eye, the anterior CCC was purposefully enlarged (˜6.0 mm) with multiple radial incisions created intraoperatively; this eye did not develop capsule contraction, an outcome that was attributed to the surgical interventions as well as selection of different IOL.5 The initial eye with capsule contraction received a 1-piece 3-haptic acrylic IOL, while the fellow eye received a 1-piece 2-haptic model. Because CCS has been reported with many different IOL materials and designs, it is unlikely that a single IOL choice alone can prevent it from occurring.8 In our case, a 1-piece 2-haptic hydrophobic acrylic IOL was implanted in both eyes; thus, IOL design and material were unlikely significant contributors to the difference in the degree of capsule contraction between the eyes.
There is much contradictory information in the literature regarding capsule strength after femtosecond laser–assisted capsulotomy versus manual CCC.9,10 A large study of 4000 eyes11 found a small, but highly statistically significant risk for anterior capsule tear-out in FLACS cases compared with manual cases, presumably as a result of small tags that remained after femtosecond capsulotomy. In addition, a detailed analysis of femtosecond laser–generated capsulotomy segments and manual capsulorhexis segments, including scanning electron microscopy and atomic force microscopy, was performed by Reyes Lua et al.12 Using atomic force microscopy, the authors were able to derive quantitative information on capsule rim thickness and stiffness by assessing structural and biomechanical characteristics of harvested capsules. They showed that a femtosecond laser capsulotomy edge is less stable than a CCC edge because of the jagged nature of the femtosecond-generated capsulotomy, with the analogy that “notched paper rips more easily than a clean paper edge.”12 A recent study by Tagaki et al.13 found that femtosecond laser capsulotomies had significantly lower tensile strength than similarly sized manually created CCCs in a porcine model. Although capsule strength is important during the phacoemulsification portion of surgery, we postulate that a weaker overall structure of the anterior capsulotomy edge might also predispose the capsule opening to greater tensile contractive forces, leading to more significant capsule contraction in the femtosecond capsulotomy in susceptible cases.
Lens epithelial cells remain viable at the edge of the manual CCC, while cell death and subsequent release of inflammatory mediators occur as a result of generation of the capsulotomy in FLACS. A histopathologic analysis of anterior capsules after manual and laser-assisted surgery was performed by Mayer et al.14 who found that laser-assisted capsulotomies were associated with a demarcation line of nonviable cells damaged by laser energy. The demarcation line was larger with higher power laser application and virtually nonexistent in manual specimens. Inflammation after the femtosecond portion of cataract surgery has been evaluated by laser flare photometry, although the exact mediator(s) present in the anterior chamber postoperatively have not been established.15 Data from the literature on laser in situ keratomileusis indicates that femtosecond laser energy used during creation of the flap causes corneal epithelial cell damage, leading to the release of proinflammatory cytokines and growth factors (including transforming growth factor-β) that promote myofibroblast cell differentiation. Early femtosecond laser in situ keratomileusis flaps were notable for a highly opaque flap edge from the presence of large numbers of myofibroblasts.16 Capsule contraction syndrome develops as the capsulorhexis edge circumferentially contracts like a purse string, pulling the entire bag inward and stretching the zonular fibers, eventually deforming the IOL. This contraction process results from the presence at the capsulorhexis edge of myofibroblast cells, a cell type that is not normally present on the lens capsule. Presumably, lens epithelial become transformed into myofibroblasts when stimulated by transforming growth factor-β.17 This process has been well studied in eyes with high myopia with CCS.18 We propose that femtosecond laser–induced lens epithelial cell necrosis leads to transforming growth factor-β release, lens epithelial cell differentiation into myofibroblasts, and subsequent capsule contraction in susceptible patients.
This case illustrates a need for ongoing evaluation of the use of the femtosecond laser in unusual cases, including in eyes with an underlying inflammatory tendency such as retinitis pigmentosa or a history of uveitis. In our case, there was rapid anterior capsule contraction only in the eye that had FLACS but not in the eye that had manual phacoemulsification, with both eyes at risk for phimosis because of the underlying retinitis pigmentosa.
None of the authors has a financial or proprietary interest in any material or method mentioned.
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