Although the mechanics of doing a PRP can be daunting—and will be covered at length in the next chapter—perhaps the most difficult aspect of performing this procedure involves the informed consent. It can be very hard to provide an effective informed consent that gives the patient a fighting chance of actually understanding what on earth you are about to do to them. The general principles discussed in the section on informed consent for diabetic macular edema also apply here. However, a PRP is much more intense, and the results of treatment are even more likely to confuse the patient, so this chapter will emphasize points specific to doing a PRP.
As with macular edema, you have to start by educating the patient about the nature of the disease. This is easy if you have a sophisticated patient who has already read an entire retina textbook on the internet. If you have such a carriage-trade practice, with nothing but wealthy, educated patients, you don't even need to read this section—just tell them about the pathophysiology of retinopathy and the complications and you are done.
For those who practice in the real world, though, recognize that the nuances of proliferative retinopathy can be quite confusing to patients. So you might as well start with the basics, and this includes pointing out the irreplaceable nature of the retina. (You will find patients that truly believe that they will be able to get a total eye transplant if your laser doesn't work. Really. Educate them about this right at the start, so they are not surprised later—it will also help motivate them to take better care of themselves.)
Next, you need to relay the relentless (and asymptomatic) way that diabetes kills off the distal retinal blood vessels, which in turn causes ischemia and the generation of vasoproliferative factors, which in turn causes bad blood vessels and bleeding, etc., etc. The absolute key is to inform them that the goal of the laser is to get rid of these vasoproliferative factors, and that you are not going to "laser their blood vessels." It is very difficult to convey the "indirect" nature of this treatment, but the importance of making sure they understand this cannot be stressed enough.
First of all, if patients think you are simply going in and cauterizing the bad blood vessels, they will assume—if they hemorrhage subsequent to the laser—that you must have failed in your task. It is hard enough taking care of diabetics as it is— you don't want them thinking you are incompetent for the wrong reasons.
Second, if they can really understand that the goal is to eliminate the bad chemicals, and that only then will the bad blood vessels start to shrink, they then may be able to understand why they can have hemorrhages even after multiple laser sessions: The blood vessels may not completely disappear in spite of treatment because the laser can only indirectly convince them to go away. It also helps patients to understand why the problem can be controlled for a period of time, but then it can come back. In this case more of their peripheral retina dies off over time and there is a renewed stimulus for vascular growth. As a result, even more laser is required to control the problem.
You have to take the explanation a bit further, though, because some patients will still have hemorrhages with maximal laser. Explain that some of the new vessels can be stuck to the vitreous, and as the vitreous contracts, it can pull at the blood vessels, resulting in recurrent bleeding. This becomes a mechanical problem that no amount of laser can control. The management of this problem is discussed in the chapter on referral for vitrectomy, but this concept has to be conveyed to the PRP patient so they can understand the limits of the laser and why they may still have problems.
Successfully conveying all of the above is way harder than doing the stupid treatment. You really need to drive home the point that you will be doing everything you can to control things, but in some ways treating proliferative retinopathy is like making a bed with a 30-foot pole—you can push things in the right direction but it is not clear how well everything will end up.
And this is only the beginning of a complete discussion with the patient...
For instance, depending on the situation there are variations to the consent. The touchiest presentation is if the patient has disease that needs treatment but they have never had any symptoms. You have nowhere to go but down in this case, and education is crucial. Having an angiogram is helpful, because you can at least show them the massive leaking thunderheads of neovascularization that are building up on the horizon of their vision. These patients really need to understand where they are headed without treatment, i.e., severe, permanent vision loss, and they need to understand that the laser does not completely eliminate the risk of transient hemorrhages or gradual blurring over time, though it will very likely allow them to avoid blindness.
Occasional patients will have an annoying problem that is especially bad if you are treating them before they have symptoms: As the new vessels begin to contract from the PRP, they can hemorrhage. In other words, you start with an asymptomatic patient, and a week or two after their first laser they get their first vitreous hemorrhage (which can be truly frightening—these people have been living in dread of both blindness and other complications of their disease; see Chapter 20). If you haven't prepared them for this type of hemorrhage, you may lose the patient to follow up. This would not be so bad if they then just went to someone else; you would deserve to lose patients for being so obtuse. However, the usual pattern is for them to wander off after such a hemorrhage thinking that all doctors and lasers are crazy and they don't follow up with anyone. They then show up a year or two later with really awful disease that may not be fixable. The point is that treating diabetes is like three-dimensional chess: You have to be able to anticipate not only what the disease might do to the patient, but also what the disease might do after you try to treat it; and then you especially need to anticipate the patient's emotional response to all of this. You may be the best laserist in the world, but if you do not prepare them in advance for hemorrhages and thereby lose the patient's trust, you will end up being the worst laserist in the world.
Another problem occurs when patients show up late in the game with a lot of neovascular tissue. Such patients usually have had at least a few symptoms, but often the symptoms do not give them any idea how bad the situation really is. You have to prepare these patients for a real rollercoaster ride. First of all, any patient with severe disease will usually have intermittent hemorrhaging in spite of laser—big vascular fronds just do not give up without a fight. In addition, any patient who has a great deal of neovascular tissue will inevitably develop tractional forces from the fibroblasts that ride along with the vessels. These forces tend to show up several months after your laser. They may be mild, but with advanced proliferative disease they are usually strong enough to create metamorphopsia, or even a tractional retinal detachment involving the posterior pole. It is important to give the patient advance warning about this. Then if they do need a vitrectomy they are prepared for the possibility and realize that it is a consequence of their proliferative disease and not your laser.
The point is that whatever degree of proliferative retinopathy they have, you have to warn them that things may get darker before the dawn. If you start lasering them without really drilling this possibility into their heads, you can imagine the charitable thoughts they will have about you as you try to explain the above problems after the fact. Then just imagine what they will think if they go on to get tractional problems with permanent changes in their vision—or even if they have a little bit of vitreous haze from a hemorrhage that never completely clears. You will be congratulating yourself on having avoided severe blindness while they are remembering how great they could see before you started lasering them. Welcome to the fundamental patient-doctor disparity in the world of retina—we can be screamingly happy and they think we are monsters. Constant repetition of the nature of the problem and the potential for trouble—even with successful treatment—is your only hope of having the patient at least partially on your side.
Finally, they need to understand something about the time frame of treating proliferative disease. If they have mild disease that you are treating preemptively this is not much of an issue because usually you will treat them and save them and nothing much happens. The time frame is much more of an issue if they have aggressive disease with active hemorrhaging, or if they have big vessels that are likely to hemorrhage and/or scar up. Proliferative disease like this does tend to eventually burn out—but it usually takes a year or two for things to really settle down.
Of course, this does not mean that they can mark their calendar and assume that in two years they will be done—even burned-out retinopathy needs long-term monitoring and occasional tweaks. This also assumes that their disease is not rampant and that the patient is religious about their follow up and their systemic control. (If they have bad disease the battle can go on forever but this is usually something that your friendly neighborhood retina specialist will need to deal with, not you.) They need to understand that they are beginning a long-term process and although there is usually light at the end of the tunnel it takes a lot of time and effort to get there.
So—all of the above covers what might happen if things go right. What if things go wrong?
This is an annoying area to bring up, because you can spin an exhaustive tale about the nature of the disease and the importance of PRP, but once you mention that the laser can make things worse, you can pretty much assume that it is the only thing the patient and family will remember. Hopefully by following the teachings of your mentors, and from your own experience, you will be able to treat these patients with only minimal side effects. Still, there is that chance that they could sit back from your laser and be permanently worse—and you cannot avoid discussing this. The actual means by which vision can worsen is discussed at length in Chapter 16—your job is to cover the possibilities in the consent, but never ever have to actually deal with them.
To start with, even if you don't have a true complication there are potential nuisances that patients my notice after a PRP that they need to be informed about. For instance, some patients may notice changes in their side vision, night vision, focusing ability, and increased glare symptoms. If they have already had a hemorrhage, they won't mind these things too much because, like Ebenezer Scrooge meeting the Ghost of Christmas Future, they have had a taste of what is coming and they tend to view things like needing reading glasses in the proper perspective.
However, if you happen to be treating them prior to their having had any symptoms, and if they develop some of these problems, they will think you are an idiot. They were doing fine before you started lasering them, and now look at the mess you have gotten them into: reading glasses, sunglasses, night driving trouble, etc. You have to prepare them for these side effects, and you have to repeat the rationale for treatment at every laser to remind them what would happen without treatment. If you have done a careful informed consent, the patient will understand the need to be treated, and they will stick with you. Fortunately, with careful treatment you can usually avoid inducing these side effects, but you never want anything to come as a surprise to a patient.
It is also worth mentioning that the above problems cannot be blamed entirely on the laser—they are also part of having a sick diabetic eye. In other words, symptoms like changes in side vision, night vision, focusing ability, and resistance to glare are also part of what happens when most of the retina is slowly suffocating due to diabetes. It is one of the great ironies that by discussing these potential side effects of a PRP you have pretty much guaranteed that if they ever have these symptoms, they will blame your laser—even if the laser saved them and even if the laser is only partly responsible for the symptoms. This is why communication and repetition are so important when it comes to treating diabetics. Patients can easily draw unfair conclusions, and you have to anticipate this to keep them from wandering off and getting lost to follow up.
Also, remember that other doctors may look in your patient's eye and demonstrate their examination skills by saying something useful like, "Gee, you would not believe all the laser scars you have in the back of that eye!" (Review Chapter 5 for a full discussion on this.) Even if the patient does not have such an experience, they still tend to imagine that your PRP is gradually steamrolling away all of their retina, so you need to make sure they understand that your treatment is well away from the center of their vision, and that you are treating dead and dying retina that is good for nothing but poisoning the eye.
Finally, when discussing complications, remember to point out that the most feared "complication" is that the laser just plain does not stop their retinopathy, in which case they will definitely get worse—not from the laser, but from the disease.
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Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...