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The New York Times reported today on a study of a laser-based procedure for cataract surgeries in PLoS One. The original study is here. In the battle between humans and lasers, I always bet on humans.

Cataracts are the world’s leading cause of blindness. They involve an opacification of the eye’s lens that makes it difficult to see. Cataracts are usually treated by removal of the lens and implantation of a plastic Intraocular Lens (IOL). Outcomes are fantastic and the surgery can be very, very cheap. That is because a skilled surgeon can perform the operation quickly and effectively (often in 5 minutes or less) and the material required for each surgery can be obtained cheaply. A number of Indian companies have specialized in manufacturing low-cost ophthalmic equipment that has driven down developing world prices.

Kessel and colleagues apparently disagree. The premise of their approach’s utility is that cataract surgeries are currently inaccessible because they are too expensive. The New York Times puts it like this:

Cataracts can be treated by lens-replacement surgery, but the procedure is invasive and costly, requiring special treatment and skilled eye surgeons. To make cataract treatment available to more people around the world, a less-invasive, less-expensive technique is needed.

It is true that cataract surgery requires special treatment and skilled eye surgeons. It is invasive.

But I vigorously dispute the claim that it is costly. At the Aravind Eye Hospital, the pioneer of the low-cost and high-volume approach, a recent study indicates that provider cost for the recommended manual small incision cataract surgery is $17.03. (Muralikrishnan et al, Ophthalmic Epidemiology, 2004)

What about the authors’ approach? Their idea is to provide a low-frequency, low-intensity laser pulse to deopacify the lens. In cataracts, proteins in the lens misfold and become able to absorb light in the visible spectrum–keeping light from passing through to the retina. The authors’ hypothesis was that this laser pulse would change the absorptive properties of lens proteins, clearing up the lens.

The study is a proof of concept, at best. To put it simply, donor lenses from patients were subjected to laser treatment. Because the lens gets more yellow with age, the authors wanted to show whether treating it with a laser would reduce the yellow and let light get through. It seems that this yellowing occurs as a precursor to the formation of cataracts. The authors demonstrated that treating the lens with a laser did in fact allow more light to get through afterwards. However, it does not appear that they considered whether scattering effects might still occur. Moreover, the study does not really address safety, though it seems that this level of treatment should be OK. The authors mention that it is comparable to LASIK.

LASIK? Let’s pause for a second. If you think a scalpel, a microscope, and a lens are too high-tech, what would you make of the equipment necessary for LASIK? I think that a laser is actually quite a sophisticated piece of equipment. The claim that one could create a mobile clinic to do these surgeries using this kind of technology seems highly suspect, especially if we’re going for a price point that beats $15.

As for the level of training required: Who is going to wield this new laser? My guess is you’ll still need an ophthalmologist. It’s not like we’ve appointed an army of LASIK technicians without medical degrees to go around shaving people’s corneas at will. Similarly, I think we’ll need ophthalmologists to zap people’s cataracts. It also strikes me that this fairly sophisticated approach will require training, as different types of cataracts will need different laser power, etc.

To make matters worse, the authors suggest that they estimate such a procedure would take no more than 30 minutes. A feasible cataract surgical intervention in the developing world better not take 30 minutes. That is a huge use of the biggest expense, surgical time, and it’s not fast enough to scale up efficiently. This is true even in the hospital, where one has a little bit more control over pacing. In the setting of an eye camp, there is no way people will wait around for this kind of procedure. To do just 10 or 15 patients, what should be no more than a couple of hours’ work with surgery, would become an all day task. Done in a mobile clinic, it would mean that the surgeon would be tied up with surgery all day, not to mention diagnostics and travel. If he has clinical responsibilities at a more central hospital, those would be abandoned entirely on camp days.

I think it is often the case that we look for technical solutions to problems that have management solutions. Is there a problem with the delivery of cataract surgeries in the developing world? Absolutely, but not because the treatment we have is not good enough. Cataract surgery, in fact, is an example of an intervention perfect for the developing world. With its low cost, speed, and great outcomes, it benefits from economies of scale that make it possible to reverse blindness for many people in a sustainable way.

The right solution for cataracts is to build human resources, not lasers.

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