Capsule contraction syndrome is a complication of continuous curvilinear capsulorhexis created during phacoemulsification that usually occurs within the first 3 months following surgery.1 More than its optic or haptic design, the intraocular lens (IOL) material appears to be a major risk factor for capsule contraction syndrome.2 Silicon and acrylic hydrophilic2 IOLs seem to be more frequently associated with such a complication. Some preexisting disorders, such as retinitis pigmentosa,3 exfoliation syndrome, diabetes melitus,4 myotonic muscular dystrophy, pars planitis, and high myopia,5 also seem to increase this risk. Capsule contraction syndrome may lead to impaired vision through complete occlusion of the anterior capsulotomy,6 lens decentration or tilt, lens dislocation,3 or hyperopic shift7 due to posterior displacement of the lens. We present a case with a fairly unusual presentation of capsule contraction syndrome.
A 64-year-old woman was seen in consultation in our clinic for corticonuclear cataract. Her preoperative corrected distance visual acuity (CDVA) was 20/80 with −22.50 (−1.00 × 20°). The anterior segment examination revealed the presence of corticonuclear cataract but was otherwise normal. Fundus examination was unremarkable. Her preoperative axial length was 32.55 mm. The mean keratometric measurement displayed by the IOL-Master 700 (Carl Zeiss Meditec AG, Jena, Germany) was 44.71 diopters (D), with a corneal cylinder estimated at (−1.21 × 0°). The postoperative refraction target was −2.50 D and the IOL power calculated using the SRK-T formula was 0.00 D with an A-constant of 118.
Cataract surgery of the right eye under topical anesthesia was scheduled. Uneventful coaxial phacoemulsification was performed using the Stellaris Vision Enhancement System (Bausch & Lomb, Rochester, NY). A 2.2-mm corneal incision was performed and a dispersive ophthalmic viscosurgical device (Viscoat; Alcon Laboratories, Inc., Fort Worth, TX) was injected. A centered continuous curvilinear capsulorhexis of approximately 5.5 mm in diameter was performed using forceps. After phacoemulsification, a CT ASPHINA 509M (Carl Zeiss Meditec AG) with 0.00 D optical power was implanted. The one-piece foldable hydrophilic acrylic IOL had a plate haptic design with an optic diameter of 6 mm and overall diameter of 11 mm. At the end of surgery, the ophthalmic viscosurgical device was removed by coaxial irrigation aspiration. Postoperative topical therapy included a combination of two antibiotics and steroids for 1 month.
Three weeks after surgery, CDVA was 20/25 with −1.75 (−1.25 × 5°) and slit-lamp examination showed a quiet anterior chamber and a centered IOL located in the capsular bag. Six weeks after surgery, the patient consulted for decreased visual acuity in the eye that had surgery. CDVA was limited to 20/63 with +1.25 (−4.50 × 15°). After pupil dilation, slit-lamp examination revealed anterior capsule fibrosis and an oval-shaped rhexis (Figure 1A).
Multimodal imaging and modeling of the intraocular lens (IOL) (A–D) before and (E–G) after capsulotomy. (A) Slit-lamp photograph shows the oval-shaped anterior capsulotomy and capsule fibrosis that are predominant in the inferior and superior regions. Cross-sections of flat and steep axes of the IOL are imaged using ultrasound biomicroscopy (UBM) (D left column) and Visante optical coherence tomography (OCT) (Carl Zeiss Meditec AG, Jena, Germany) (D right column). IOL shape is modeled in three dimensions (B). IOLMaster 700 swept-source OCT (Carl Zeiss Meditec AG) (C) shows a horizontal cross-section of the IOL before capsulotomy. After capsulotomy, (E) slit-lamp photograph, (F) three-dimensional modeling, and (G) IOLMaster 700 swept-source OCT show restoration of normal shape of IOL. (Illustrations by Damien Gatinel).
OPD scan III (Nidek, Gamagori, Japan) examination showed internal astigmatism of (−3.27 × 23°), calculated by subtracting the anterior corneal cylinder from the total cylinder measured by aberrometry (Figure A, available in the online version of this article).
OPD-scan III (Nidek, Gamagori, Japan) representation of total (first column), corneal (second column), and internal astigmatism (third column) before (top) and after (bottom) Nd:YAG capsulotomy. Red ellipses show numeric changes in total, corneal, and internal astigmatism before and after capsulotomy. After capsulotomy, the corneal component remains almost constant, whereas total astigmatism is reduced and is represented mainly by the corneal astigmatism. Three-dimensional representation (fourth column) shows the bended IOL before (top) and after (bottom) laser capsulotomy. Light rays refracted by the IOL steep and flat axes are represented in blue and red, respectively. (Illustrations by Damien Gatinel.)
An optical coherence tomography (OCT) examination (Visante; Carl Zeiss Meditec AG) focused on the IOL plane revealed its bended shape along its long axis, thus creating a cylinder that was concave anteriorly with its flat and steep axes oriented around 110° and 20°, respectively (Figure 1D, right). Ultrasound biomicroscopy (Figure 1D, left) showed an uninterrupted hyperechogenous flat structure parallel to the iris plane corresponding to severe anterior capsule fibrosis and confirmed the folded aspect of the IOL observed by OCT.
We decided to perform Nd:YAG laser anterior capsulotomy. The anterior capsule was sectioned horizontally in its nasal and temporal quadrants. Anterior capsulotomy alone did not allow improving capsular bag contraction. Its extension to the posterior capsule released capsule tension and allowed IOL flattening with recovery of its original unfolded shape (Figures 1D, 1F, and 1G). The OPD scan performed after capsulotomy showed the complete reduction of internal astigmatism (Figure A). Residual manifest refractive astigmatism mainly resulted from corneal astigmatism.
Capsule contraction syndrome may induce changes in the shape of hydrophilic IOLs because of their flexible nature, which makes them more susceptible to bending induced by capsule contraction stress. Capsule contraction syndrome may result in the anterior flexion of hydrophilic IOL haptics, which results in a posterior shift of the optic and induces a hyperopic shift.7,8
In this case, capsule contraction syndrome induced a selective bending of the IOL along its long axis. The resulting toric shape of the IOL could have induced internal astigmatism. An IOL with a 0.00 D power has a planar optic, whereas biconvex lenses with positive optical power have a thicker center. This could have facilitated IOL bending. However, an IOL with a plate haptic design could be more likely to bend along its short axis where there is less material to be bended, and therefore less resistance. Indeed, bending this type of IOL along its short axis implies overcoming the resistance provided by the IOL optic alone, whereas bending it along its long axis would require overcoming the resistance provided by the optic and both plate haptics. The reason why it preferentially bent along this axis is not clear. Both the plate haptic design and the IOL's hydrophilic material might be responsible for the lens folding. Plate haptic IOLs might be easier to fold because they are usually inserted in that same folded configuration using microincision injectors. The plate haptic design also implies a large surface in contact with the capsular bag, thus triggering a more important capsular reaction. We could assume that the anterior capsule covered both plate haptics in the superior and inferior regions almost completely and the optic edges in the temporal and nasal regions only slightly. The capsule contraction process could have started and been more severe in the plate haptic region where the contact area between the IOL hydrophilic material and the capsule was the largest. When the contraction is more important in one segment of the anterior capsulotomy, the corresponding capsulotomy arc could shorten more than the other segments. In this situation, the superior and inferior regions of the capsulotomy (in contact with the haptic plates) could be more shortened than the nasal and temporal regions, thus bringing the nasal and temporal regions closer. The slit-lamp photograph (Figure 1A) shows that the oval capsulotomy and capsule fibrosis predominated above the IOL plate haptics, which supports this theory. Because the anterior capsule slightly covered the optic edges, the IOL hydrophilic material could have locally triggered capsule fibrosis, thus attaching the temporal and nasal optic edges to the anterior capsulotomy edges. This local attachment of the IOL optic to the anterior capsule fibrosis was suggested on the ultrasound biomicroscopy cross-section (Figure 1).
Optically, it should be noted that the IOL bending induced mixed astigmatism (Figure A). Indeed, the anteriorly concave nature of the IOL along its short axis induced a reduction in optical power along the meridian located at 22°, whereas the total optical power along the 112° meridian was mostly conveyed by the corneal direct astigmatism and was not affected by the flat nature of the IOL along its long axis.
Treatment of capsule contraction syndrome is usually based on anterior Nd:YAG capsulotomy,9 but IOL replacement may be needed in case of severe IOL dislocation.8 Femtosecond laser capsulotomy has also recently been described as a suitable treatment option.10
This case suggests that the use of hydrophilic IOLs with a low or null power should be avoided in patients at risk of capsule contraction syndrome.
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