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Capsular bag transparency could be future of PCO prevention
 Philippe Sourdille |
For the last 20 years, prevention of posterior capsular opacification has been a continuous fight with several approaches. Those include different IOL materials, multiple IOL designs, and pharmacological attempts to eliminate or decrease proliferation of lens epithelial cells (LECs). In the best of cases, we can effectively prevent the central posterior capsule from becoming opacified for a number of years. IOL optic circular square edge and capsular bending at the optic edge are the most efficient elements of this strategy.
Should we consider partial transparency of only one lens capsule as a sufficient anatomical status? Does it cover all our patients’ visual expectations with today’s sophisticated IOL optics?
With our current results, bent capsules opacify, and their attachment is not always strong enough to prevent formation of Soemmering’s ring in the long term. The portion of the anterior capsule on the IOL optic progressively loses transparency, and this often leads to undesired optical effects, such as glare and increased retinal straylight under mesopic and scotopic conditions. Complete visual access to the peripheral retina is not possible, and this partially fibrotic system is incompatible with accommodation.
It also seems that YAG capsulotomy incidence is currently higher than it was some years ago. In 2008, the Belgian cataract register indicated 101,966 interventions and 46,761 YAG capsulotomies, an incidence of 45.86%. This number of capsulotomies covers more than the year 2008 itself, but it indicates a trend toward a higher incidence of PCO and is not geographically isolated. This is related to two factors:
- Multifocal IOLs, in which a loss of contrast sensitivity added to a partial diminution of posterior capsule transparency does not meet the patient’s high visual expectations, with a subsequent earlier and more frequent need for YAG treatment.
- Development of so-called small-incision lenses, in which a thin optic edge, combined with hydrophilic or partially hydrophobic material, does not create an efficient dam to LEC proliferation.
Tsutomu Hara, MD, introduced the endocapsular ring in 1990, Albert Galand, MD, introduced posterior capsulorrhexis in 1996, Okihiro Nishi, MD, developed the capsular bending ring in 1998, Marie-José Tassignon, MD, introduced the “bag in the lens” in 2002, and Rupert Menapace, MD, developed posterior optic buttonholing in a posterior capsulorrhexis in 2007, which are all significant contributions to the PCO prevention battle. During the same period, different pharmacological approaches to eliminate LEC development were either toxic or inefficient. The Perfect Capsule device by Anthony Maloof, which seals the capsular bag during irrigation with active drugs, is an innovative approach but has not yet shown clinical results.
Capsular bag transparency would include transparent and supple anterior and posterior capsules. It would be an anatomical prerequisite for all IOL optics to benefit from recent improvements without nontransparent capsule-related side effects and with true accommodation. How would this be possible?
In 2000, we introduced the Concept 360 IOL (Cornéal Laboratoires), in which six angulated haptics tended to come into contact inside the capsular bag to equatorially prevent LEC migration, called the capsular ring effect, and to prevent anterior capsule adhesion to the IOL optic to keep it transparent.
The YAG incidence at 3 years was below 5%, and the anterior capsule remained distant from the IOL optic, with no significant opacification.
This “open bag” concept is currently under investigation through different approaches. The dual-optic Synchrony (Abbott Medical Optics), introduced in 2004, prevents capsular adhesion by inserting the anterior optic in the capsulorrhexis with a posterior optic apposed to the posterior capsule. Clinical results of capsular bag transparency are excellent at 5 years; both separated capsules remain clear. Experimental studies of a capsule adhesion prevention device from Anew Optics have also demonstrated much less LEC development in rabbit capsular bags. The capsule adhesion prevention ring, the CAPR by Nagamoto, had similar experimental results.
Capsular bag transparency combined with suppleness of the implanted capsular bag will provide better functional results and will pave the way to truly accommodating devices. It would also significantly decrease the incidence of YAG capsulotomy and partial treatment of capsular opacification.
- Philippe Sourdille, MD, can be reached at philippe.sourdille@wanadoo.fr.
- Disclosure: Dr. Sourdille has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.