June 12, 2017
3 min read
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PCO treatment would disrupt cataract surgery

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The No. 1 unmet need in cataract surgery today is a safe and effective method to prevent posterior capsular opacity. Our inability to conquer the biology of the lens capsule and subcapsular epithelium after cataract surgery, which includes epithelial cell proliferation, fibrous metaplasia of cells resulting in capsular haze/fibrosis and secondary capsular contraction, is not only a cause of significant vision loss for our patients but also a major barrier to the development of a functional accommodating IOL. Amazing to me, no major strategic has focused significant resources on solving this problem.

In the U.S., Medicare statistics suggest that the incidence per year of YAG laser capsulotomy is about 25% the incidence of cataract surgery. We do 4 million cataract surgeries a year in the U.S. and just under 1 million YAG laser capsulotomies. That generates a cost of about $400 million to our medical system, not including the costs of time off for patients, family and caregivers. And while YAG laser capsulotomy is certainly a straightforward procedure, it is not totally without complications, and it definitely places a significant burden on patients, families and third-party payers.

Many, if not most, patients with high-quality Snellen visual acuity and contrast sensitivity at 3 months after cataract surgery later suffer a slow but continuous deterioration in the quality of their vision from PCO, similar to the visual loss they experienced when they first developed a cataract. They are disappointed when they require a second procedure to treat it. Even worse, in emerging countries where YAG laser capsulotomy is simply not available, patients with poor understanding and access to care can suffer from a repeat of the visual disability their cataract caused secondary to PCO with no opportunity for treatment.

Many attempts have been made to prevent or reduce PCO over my 40-year career. These include cryotherapy, radiation, irrigation of the capsular bag with distilled water or antimetabolites, and immune therapy, to name a few. Careful polishing of the posterior capsule and undersurface of the anterior capsule mechanically or with laser or ultrasound can be helpful, but it is not preventive. A square-edged posterior chamber lens can retard but not prevent PCO. Separation of the anterior and posterior capsule, as done by the Visiogen Synchrony IOL, seemed to effectively reduce PCO in clinical trials, but no IOL that does this is FDA approved. Thus, there is really no truly effective treatment to prevent PCO today.

I was introduced to posterior chamber lens implantation during a fellowship with Bill Harris, MD, in 1978. There was no YAG laser, so we did our secondary capsulotomies in the office with a needle, usually through the pars plana. We also investigated primary capsulotomy done at the time of surgery. My technique was to bend a 30-gauge needle toward the bevel, attach it to a 3 cc syringe filled with balanced salt solution, tease in under the posterior chamber lens optic while irrigating fluid, turn the bevel toward the capsule, aspirate the capsule away from the anterior hyaloid face and make a 3- to 4-mm “Christmas tree” tear. Usually I could avoid vitreous prolapse and/or a vitreous strand to the wound, but not always. Outcomes were good, but studies by us and others showed a higher incidence of cystoid macular edema and retinal detachment with primary capsulotomy vs. leaving an intact capsule at the end of cataract surgery. So, we stopped doing primary capsulotomy. Fortunately , the invention of the YAG laser bailed us out.

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More recently, as discussed in the accompanying cover story, continuous tear posterior capsulotomy along with viscoelastic application to separate the capsule from the anterior hyaloid and perhaps application of a femtosecond laser is creating a resurgent interest in primary capsulectomy. Along with posterior optic capture, this can be an elegant and effective procedure. A prospective randomized clinical trial looking at the incidence of cystoid macular edema and retinal detachment with modern primary posterior capsulotomy and posterior optic capture vs. leaving an intact capsule at the end of cataract surgery is needed.

I am personally still hoping for an innovative breakthrough that maintains a clear and elastic capsule for a lifetime through investment of the financial and human capital required. The challenge is more one for the cell biologist than for the mechanical engineer, and unfortunately few scientists are currently engaged trying to resolve this critical issue. A treatment that prevents PCO and retains capsular elasticity will be truly disruptive to cataract surgery as we know it today. The individual or company that solves the PCO challenge will be rewarded with both fame and fortune.