Possible case of capsular block syndrome

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I read with great interest the case report by Srinivasan and coauthors1 on the role of ultrasound biomicroscopy (UBM) in managing pseudophakic pupillary block glaucoma. The authors describe a case of pseudophakic “pupillary” block glaucoma due to adhesions of the anterior capsule to the iris inner surface demonstrated on UBM and discuss other causes of pseudophakic pupillary block. They do not, however, include capsular block syndrome (CBS) as a possible cause. This case has all the prerequisites for developing CBS—a capsulorhexis smaller than the 6.0 mm intraocular lens (IOL) optic made of silicone, making it more likely that the anterior capsule would adhere to the IOL surface rather than the iris. Indeed, the UBM photograph appears to show a close apposition between the anterior capsule and the IOL. Late CBS occurs 18 months postoperatively or later2 and has been observed 5 years after surgery.3 This is thought to be due to fibrosis between the IOL optic and the anterior capsule that leads to a closed chamber forming within the capsular bag. This leads to distension of the bag and may cause anterior IOL displacement sufficient to cause pupillary block. While pupillary block has not been described in late CBS, it is well known in early CBS4 and anterior IOL displacement does occur even in late CBS. Laser iridotomy can relieve the pupillary block, but neodymium:YAG capsulotomy of the peripheral anterior capsule (if the pupil dilates) or posterior capsule would relieve both the pupillary block and the capsule block. I presume that in this case, CBS was ruled out by confirming the absence of posterior capsule distension on slitlamp and UBM. I agree entirely that UBM is a valuable tool that with careful slitlamp examination after the pupil is dilated could determine the exact mechanism of pupillary block. Javeed Khan FRCS aBurton Upon Trent, England UK