Letters

Abstract

Reply: We would like to thank Geyer and Lazar for pointing out that capsular bag contraction with ensuing hypotony may occur after extracapsular cataract extraction (ECCE) without an IOL in the bag, as was reported by them and other authors.1,2 In fact, at the time of their original letter (1983), techniques to open the anterior lens capsule differed quite a bit from the now-common capsulorhexis technique, originally described by Neuhann3 and Gimbel and Neuhann.4 Can-opener and letter-box openings did not have the superior properties of the genial round capsulorhexis opening, which ideally distributes tearing forces during surgery and in the postoperative healing period. It turns radial shearing forces into tangential ones, which do not disturb its integrity and are more evenly distributed. An edge within the anterior capsule opening, as in the letter-box opening, could lead to a tear radial to the center. Thus, centripetal forces as they occur in capsular bag contraction might be less evenly distributed to the ciliary body as well, creating more localized problems and not a complete ciliary body detachment. It is, however, not surprising that capsular bag shrinkage may occur if no IOL is implanted in the bag. The amount of capsular shrinkage is believed to be influenced by haptic design5 and IOL diameter as well as the IOL material. Ideally, the capsular bag would be distended in a round fashion postoperatively, once again as produced by nature at birth. This seems to be achievable with circular haptic designs as they mostly occur in silicone-plate IOLs,6 which have other design-associated problems, or by implantation of a capsular tension ring. The latter is usually implanted only in high-risk eyes. One example of this is zonulysis because of pseudoexfoliation syndrome or prior trauma to stabilize the bag during phacoemulsification. Such a capsular bag extended in a circular fashion should be less prone to capsular bag shrinkage postoperatively. Additionally, any IOL with reasonably shaped and sized haptics within the bag should be counteracting the centrally oriented shrinking tendency. If there is no IOL, no centrifugal force of the haptics is able to counterbalance the centripetal constricting forces, partly because of the regenerating lens epithelial cells. Thus, shrinkage of the bag in extracapsular surgery with hypotony was a rare occurrence but nevertheless described by several authors also after IOL implantation in the bag.7 Since it happens infrequently, no studies have been able to assess a difference in frequency with or without an IOL in the bag. It should be remembered, however, that an inadvertent cyclodialysis cleft was sometimes a reason for the hypotony experienced after ECCE.8 Of course, this situation was not ameliorated or resolved with anterior or posterior capsulotomy but rather by argon laser photocoagulation to the cleft or surgical cyclopexy.9 Ines M. Lanzl MD Carolin Kopp MD Manfred Mertz MD