Sometimes the most prosaic things are also the most important things. Along those lines, I'm going to make two comments about stretchers, the first piece of equipment involved in the cataract operation.
It's just as easy for us to operate on a patient who's lying on a stretcher as it is to operate on one lying on a surgical table. So leave the patient on the stretcher; don't bother to move him or her on and off the surgical table.
Secondly, the money you save from your increased efficiency could wisely be invested in those wonderful new eye stretchers that have the head extension at the end and allow the patient to sit up both before and after the procedure. Few things make cataract surgeons more miserable than no knee room. These extensions are important for everyone, but they are particularly important if your surgeons have started operating at the side of the table rather than at the head (more than half now do).
Incidentally, if you are still forcing patients to undress for this procedure, stop. The patient only needs to remove his shoes and wear a loose-fitting blouse or shirt so that the leads can be attached.
Once the patient has mounted the stretcher, the next step typically is pre-op preparation, including dilation and anesthesia. As with just about every other step, we all do this differently. Here are the possibilities:
- General anesthesia. It's uncommon to use this form of anesthesia, but we still do it for patients who are completely uncooperative, those who request it, and complicated cases where any movement by the patient might blow the case (i.e. monocular patients, those with very small eyeballs, and those at risk for expulsive hemorrhagic events).
- Injectable anesthesia. About a quarter of all surgeons still use retrobulbar anesthesia; they place a needle all the way behind the eye and inject anesthetic to paralyze the muscles that move the eye as well as the optic nerve. This form of anesthesia does the best job of ocular anesthesia and movement prevention, but it's dangerous because you can't see where the needle is. It's possible to puncture the globe or cause a hemorrhage behind the eye.
At least another one-fourth use a form of injectable anesthesia called "peribulbar." Here, you only insert the needle to the equator of the globe. It's less risky than retrobulbar, but it takes a lot longer to take effect.
- Subtenons anesthesia. The eye and its muscle cone are wrapped in a layer called Tenon's capsule. If the surgeon snips the conjunctiva (the clear, vascular layer on the outside of the white of the eye) and injects anesthesia underneath, the substance will travel around the globe and cause anesthesia and muscle paralysis. This method is extremely safe, but it can cause bleeding, a post-op "foreign body" sensation, and billowing of the conjunctiva around the cornea. This form of anesthesia is relatively uncommon.
- Topical anesthesia. This is the up-and-coming anesthesia technique. It generally involves placing lidocaine or proparacaine drops or gel-or sponges soaked with the same-onto the ocular surface. I personally like the gel, as it's gentle to the ocular surface and because it has staying power. Only one administration is necessary.
Although I'm not one of them, most ophthalmologists who use topical anesthesia also inject some anesthesia into the anterior chamber, or front part of the eye. We may see this fade in popularity.
With topical anesthesia as with the other forms of local anesthesia, you need to give the patient IV, oral or intramuscular sedation. I still give intravenous, usually Versed and fentanyl.
One important facility decision here is whether anesthesia should be administered in the pre-op area or in the OR. If your goal is really to move volume through the OR, then it might be important to have an anesthesiologist or CRNA administer the anesthesia before the patient gets into the operating room or immediately upon arrival into the OR so that it has time to take effect during the set-up.
Once the patient is rolled into the OR, it's time to drape. Others may disagree with me, but I believe this is an opportunity to economize. Some drapes may be slightly superior to others, but I really can't tell the difference.
If you are running two rooms and working to achieve maximum throughput, it may be best to have a tech doing the draping. But if you're only working out of one room, as I usually must, the surgeon might as well be draping while the remainder of the room is getting set.
The next step is placing the speculum to keep the eyelids open. There are multiple speculum models, varying according to the surgeon's preference and incision location.
Once the patient is prepped, it's time to position him or her under the microscope. Never underestimate the importance of the microscope. Cataract surgery is a three-dimensional task, and depth perception is absolutely critical. The difference between an outstanding result and a lousy one may come down to a millimeter of depth perception. If an ophthalmologist complains that the microscope's light is poor, or the lenses are dirty, or the prisms are out of whack, take it seriously. Get your microscope serviced or purchase a new one.
I'm somewhat spoiled in that one of the facilities in which I operate features a ceiling-mounted microscope. I prefer these over floor-mounted versions, because it's extremely easy to put them where you want them, they never get in the way, and they are less likely to take abuse from being moved all over the OR. Floor mounted microscopes can be just as good, but they do require extra consideration with regards to placement so that everyone can maneuver around them efficiently.
Once it's time for the operation to begin, my first step is to make a paracentesis, a very small incision in the cornea on the opposite side of the main incision.
Next, I take a vial of viscoelastic, place the cannula through the paracentesis, and inject the substance into the anterior chamber. The function of this substance is twofold. First, it forms a protective coating over the delicate corneal endothelium. Cataract surgery creates a lot of turbulence inside the eye, and without protection these cells can get damaged and die. If enough do, the patient may need a corneal transplant.
The other function of the viscoelastic is to take up space. The eye is composed of two distinct parts, the anterior and posterior chambers. The anterior chamber is filled with a thin, clear liquid called aqueous and the posterior chamber is filled with a thicker substance called vitreous. Inside the intact eye, the pressure inside these two chambers is roughly equivalent. However, once you make an opening in the anterior chamber and allow the thin fluid inside to leak out, the pressure inside the posterior chamber becomes greater than that in the anterior chamber. The vitreous in the posterior chamber tries to push through the pupil, to fill the low-pressure area, bringing the ocular contents with it. The incisions we make are designed to be self-sealing, but during certain parts of the procedure, the wounds are not sealed. Viscoelastic is relatively thick, and will not leak out of the incision on its own.
The differences between different brands of viscoelastic may seem inconsequential to facility managers and it may be tempting to push for the cheapest one. It's not that simple. There are differences between the viscoelastics, some of them real, and some of them that might as well be real since a salesperson has created a perception of reality in the surgeon's mind. Some irrigate out of the eye more easily than others, and that can be a good or bad thing depending on technique. Some behave in just the opposite way and again that can be good or bad depending on technique. Most surgeons can adapt to different viscoelastics, but realize that changing is not some inconsequential decision in the surgeon's mind.
Once I've made my paracentesis and injected viscoelastic, it's time to make my phaco incision-the opening through which I will take out the crystalline lens.
Making an opening in the eye for this purpose might seem simple, but it's not. Ophthalmologists have different theories about where to make the incision and how to make it. In the late ?80s and early ?90s, nearly all of us were starting our incisions in the white part of the eye, called the sclera. Our incisions here were fairly complex affairs, requiring two or three different knives and cautery, since the sclera is covered by the vascularized conjunctiva. Today, the trend is toward "clear corneal" incisions. According to one survey, nearly half of us simply make an incision through the cornea itself, although again we differ in the way we do it and the knives we use.
The size of the knife you use depends on the size of the phaco probe and the size of incision you need to insert the lens.
Most of us use metal blades for this task. My technique requires two blades, but there are "dual-purpose" blades-push it in partway and it makes an opening big enough for the phaco probe, push it in all the way and it's wide enough to insert the IOL. But the typical surgeon uses two knives, and some use more.
About a third of all surgeons use diamond blades to make their cataract incisions. These make very clean incisions that seal well. However, they are very delicate. One chip can necessitate a thousand-dollar repair. In a cozy single-specialty ASC environment, where only highly trained personnel will be handling the knives, they may be an excellent investment, but in a hospital setting, where instruments go to a central sterilization department, they are impractical.
A word about reuse. Neither of the facilities at which I operate requires me to reuse blades. However, a third of my colleagues who use metal blades sterilize and reuse them. I would recommend never reusing blades labeled as single-use, because of the potential liability issues.
After I make my main incision, the next step is something called the capsulorhexis. The crystalline lens is enclosed in a clear, bag-like membrane. Twenty-five years ago, surgeons routinely took this entire bag out of the eye along with the lens. The problem was that this technique removed the barrier between the anterior and posterior chambers, and all sorts of problems resulted. Today, we all try our best to leave this bag, or capsule, in place and simply remove the contents.
In order to effect this, we have to make an opening in the anterior portion of the capsule. To do this, most of us, including me, reach into the eye with a bent needle and make a tear in the capsule. Then we reach in with a forceps and make a spiral shaped tear that results in a round opening in the front part of the capsule. A tip here for OR personnel: During this delicate part of the procedure, the patient absolutely must not move! You only get one chance to make a good capsulorhexis, and a bad one can result in serious complications.
Once the bag is open the surgeon places the syringe inside the eye and shoots balanced salt solution in. The aim is to use the fluid to separate the nucleus, or hard center, of the crystalline lens from the capsular bag. We do this because we literally need to be able to spin the nucleus inside the eye. Since most of us work through just two stationary incisions, we need to be able to bring the nucleus to our instruments.
Once we have the nucleus mobile, it's time to begin breaking up this hard little pea-sized tissue and sucking it out of the eye.
To help you understand this, it helps to have a rudimentary knowledge of the phaco machine.
You can think of this machine as having three basic functions:
- Ultrasound. At the end of the phaco probe is a sharp cannula. When the surgeon applies ultrasound, this needle vibrates, slowly pulverizing the lens material.
- Aspiration, or vacuum. At the same time, the machine is sucking fluid and debris through the end of the cannula.
- Irrigation. Another port on the needle permits balanced salt solution to flow into the eye and replace the fluid and debris that's being sucked out and to maintain equilibrium.
There are countless ways to use the phaco machine to get the lens out of the eye, and ophthalmologists will argue until the wee hours about which is best. The traditional and still most popular right now is a technique called "divide and conquer." This technique involves "sculpting" grooves in the shape of an X through the nucleus, breaking it into four pieces, and then latching onto each one and applying ultrasound to pulverize it and suck it out. The technique that's growing in popularity-the one I use-is called "chopping." You latch onto the nucleus with the phaco probe, then chop with one of any number of second instruments. This technique is definitely faster and may allow the use of a lot less ultrasound power inside the eye. The downside is that it's harder to learn and requires more surgical skill to do it safely.
After the nuclear material is gone, the surgeon needs to remove the cortex. Even though this material is softer, this step can be a challenge. It's necessary to get the material out; if you don't, post-op inflammation may result. However, because the material is so close to the capsule, it's possible to inadvertently suck the capsule into the irrigation/aspiration tip during cortex removal, again causing serious complications.
Just a brief word about phaco machines. All of them-even the older ones-perform the functions I listed above. Beyond that, however, there are endless variations on the theme. Older machines tied certain functions together; for instance, when you increased ultrasound power, you also had to increase vacuum. Newer machines allow individualization of the controls, a really nice feature. Some machines allow you to alter the behavior of the suction to suit each individual surgeon. Needles can get hot and burn the cornea; some machines have extra features that further protect against wound burn. Sometimes pieces of the lens get lodged in the cannula and are hard to break up; some of the newer machines allow you to ramp up vacuum without fear; as soon as the lens piece gets sucked in, the vacuum drops precipitously. There are many variations, so when it's time to buy a new machine, thoroughly consult your surgeons and make sure the ones you want to keep have a say.
Once all the lens material has been extracted from the eye, the surgeon places viscoelastic back in the eye. Some surgeons like to use a different kind of viscoelastic for this purpose-the kind that's very easy to remove.
Now it's time to insert the intraocular lens.
The first step generally is to widen the incision so that the lens can fit through. Different lenses require different widths. Non-foldable PMMA lenses may require a 5 to 6 mm incision. Foldable acrylic and silicone lenses inserted with a folder may require an incision ranging from 3.2 to 4 mm. The same kinds of lenses placed through an injector may require an incision that's as little as 2 mm in width. Someday soon the widening step may no longer be necessary; injectors may fit through the phaco incision.
The next step is inserting the intraocular lens. This replaces the refractive power of the old crystalline lens and sometimes improves upon it; patients who've been near- or farsighted their whole lives may be able to see 20/20 uncorrected with their new lens. It also protects the retina from ultraviolet light.
The question of what kind of IOL is best is an interesting one. I think nearly all of us would agree that the lens should be foldable, because it allows us to make a much smaller incision. About half of all surgeons would prefer that the optic be made out of acrylic; there is some thinking (although it's controversial) that the edge geometry of acrylic lenses does a better job of preventing posterior capsular opacification. This is when cells grow back between the lens and the posterior portion of the capsule, obstructing vision. Haptics-the projections on each side of the lens that allow it to center inside the capsule-need to be sturdy and not easily damaged during insertion, but there are many different ways to accomplish this. The vast majority of us prefer spherical IOLs, although lenses with special optical qualities, including "multifocal" IOLs and "toric" IOLs, have attracted followings among some surgeons.
Just about all the foldable IOLs on the market do the basic job of correcting vision, but each surgeon has his or her own preference-sometimes strong preference-for one lens or another. Again, consolidate your buying only after consulting the surgeons you wish to keep.
At least as important as the brand of lens is the facility's inventory of lenses. In recent years, we've become much more precise with measuring the patient's eye and picking the IOL power that will accomplish just the type of vision we want. After going to great lengths to do this, it's highly frustrating to show up at the OR and find that we have to "fudge" 0.5 diopters because the lens we wanted isn't in stock. Ideally facilities should have exactly the lens the surgeons want and a back up lens in case the first one is lost.
Most cases these days don't require a suture, and about four out of five surgeons now routinely use sutureless incisions. Occasionally a suture is still necessary, though, if the wound does not close properly.
After removing the I/A probe, we roll the patient out of the OR to his family. I do not give a patch or corneal shield, although some physicians do. If all goes well, the patient should be seeing clearly by the time he exits the facility.
From just about any perspective, cataract surgery may be one of the best operations that a surgical facility hosts. Today, a patient can walk into a surgical facility seeing poorly and have an excellent chance of walking out with at least 20/40 uncorrected vision two hours later. Done well, the procedure can be quite remunerative to both facility and surgeon. Surely with so much going for us, surgeons and facility managers can find ways to be happy together.