State of the art: Taking a new look at cataract incision construction

John A. Hovanesian, MD, FACS, interviewed I. Howard Fine, MD, about cataract incision architecture and infection prophylaxis.

A note from the editors:

John A. Hovanesian

Ocular Surgery News is pleased to debut a new column, “State of the Art.” In this column, OSN Cornea/External Disease Section Member John A. Hovanesian, MD, FACS, will conduct in-depth interviews with thought leaders in an effort to demystify new technologies or clinical concepts in ophthalmology.

He recently spoke with I. Howard Fine, MD, OSN Cataract Surgery Section Member, about proper incision construction and profile in phacoemulsification. Here are excerpts from the interview.

John A. Hovanesian, MD, FACS: Dr. Fine, can you tell us what is wrong with clear corneal cataract incisions?

I. Howard Fine, MD: I do not know that I can say what is wrong with clear corneal cataract incisions, but what I can say is that not all clear corneal incisions are the same. You cannot say clear corneal incisions are more likely to end up with problems than scleral tunnel incisions because all of them are not the same. We tend to see them lumped together as though they were the same, and people talk about the results with clear corneal cataract surgery, or bad outcomes as a result of it, without specifying anything about incision construction, architecture and profile.

Dr. Hovanesian: What is the difference between each of these?

Dr. Fine: There was a picture that was developed quite a while ago, perhaps as long ago as 1994, that depicted clear corneal incisions in three ways. One was a so-called single-plane incision, another was the so-called grooved incision. Single-plane incision was the one that I used.

Dr. Hovanesian: This entails just entering the anterior chamber straight with some type of keratome blade.

Dr. Fine: That’s right. And the other is the so-called grooved incision, which is really the product of Chuck Williamson’s work. The third way was the modification of that by David Langerman – the so-called deeply-grooved incision.

So if you think of what the incision looked like in the eyes of many people, a single-plane incision was sort of iris parallel and the grooved incision had a groove first and then almost iris parallel.

In the deeply-grooved incision, midway into the groove, an incision into the anterior chamber is made. There were arguments about which is more stable and what way, shape, or form they are more stable.

I first introduced clear corneal incisions in 1992, and my incision construction has not changed. It is basically starting the incision in clear cornea, meaning anterior to the conjunctival insertion. I actually was avoiding blood vessels initially, but now I do not care if I knick a blood vessel.

That is part of the vascular arcade that is still considered to be clear cornea. But I touch the eye at the location that I want to make the incision, and then I advance the blade in the plane of the cornea. And when I am looking down at it, I am seeing the chord length of that incision, but the incision actually is an arcuate incision, which is not unlike tongue-and-groove paneling.

What we see is that these incisions are much longer than they were assumed to be because we are measuring in arc length rather than chord length. We also note that because of this anatomy, there is the tongue-and-groove added stability compared with two flat planes, which could easily slide over each other.

And, perhaps most importantly, what we have found is that stromal hydration, which created whitening around the incision, thickens the stroma of the cornea and forces the floor of the incision up against the roof of the incision, which facilitates endothelial pumping through the incision and allows for the vacuum seal of the incision.

That is the most important thing in the early postoperative period because these take a long time to heal. The epithelium with a single-plane incision may actually heal overnight, but we still need that vacuum seal from endothelial pumping.

Stromal hydration lasts for longer than 24 hours, even though whitening goes away within perhaps a half-hour, and that has led many people to assume that stromal hydration is only effective for a half-hour or an hour. But we used optical coherence tomography to examine these incisions 24 hours postoperatively, and there was still substantial swelling around the incision from stromal hydration, which helps facilitate the sealing in the early postoperative period.

We also looked at grooved incisions because they are popular. The real advantage to a grooved incision is that if you are going to suture it, there is a buttress against which you can suture. But in looking at them, we have known for a long time that the groove tends to gape on the first day postop, and we found there is a similar effect at the internal edge of the incision. It is a nidus for mucus and other debris pooling. It also creates foreign body sensation.

Dr. Hovanesian: Do you think grooved incisions are also more astigmatically neutral?

Dr. Fine: I do not know the answer to that because the groove is actually quite shallow. I do not know that there is a difference. We have not really tested that, but what we found was the architecture that we get, we could do with any blade that is out there. The key is making the incision in the plane of the cornea and giving us this arcuate profile. So when we measured the length of the incision, what we see when we look down on an incision and we measure the internal incision’s distance from the external incision, we are actually measuring the chord length. So for a 2-mm chord length we probably have a 2.5-mm arc length, which adds great stability.

Dr. Hovanesian: How does a surgeon construct one of these?

Dr. Fine: Basically by staying in the plane of the cornea until the knife is in 2 mm, and then pointing the tip down toward the Descemet’s membrane and incising it at that point.

I. Howard Fine

You do not want to tear the edge. If you are too abrupt, you can create an effect like a can opener where you tear Descemet’s. And if you are lifting the heel of the knife rather than depressing the blade, you will tear the exterior part of the incision.

In addition to that, I never looked at clear corneal incisions as a so-called routine or standard technique. I have always thought of them as an advanced technique.

In order to be maximally prophylactic against endophthalmitis, we need to incorporate proper preoperative antibiotics. At this time, this means fourth-generation fluoroquinolones for 3 days preoperatively.

Preparation of the surgical field is also essential, and this means povidone iodine as well as draping over the meibomian opening in the lids.

Surgical technique is important, including use of power modulations that minimize heating of the incision, use of proper oar-locking techniques so that we do not stress the incision and opening the incision wide enough to implant the lens without stretching or tearing the incision.

We must test closure of the incision, after stromal hydration. Finally, postoperative antibiotics are important. With a clear corneal incision and topical anesthesia, we are giving those antibiotics on the day of surgery. We do it four times a day. It is not unreasonable to give drops every 2 hours the day of surgery.

Use of anti-infectives

Dr. Hovanesian: Do you use any other anti-infectives, such as Betadine (povidone iodine, Purdue Pharma), topically at the end of surgery?

Dr. Fine: At the end I do not, but that is not a bad idea. I have been a little leery because I worry about the corneal epithelium postoperatively. I think the more comfortable a patient is, the less likely they are to rub their eye or to be irritated by it.

Dr. Hovanesian: Do you think that there is a difference between topical or intracameral anesthesia and peribulbar or retrobulbar anesthesia in terms of endophthalmitis risk?

Dr. Fine: I do not know that we have real data on this yet. Matteo Piovella, MD, of Italy recently published a paper saying that there was no difference in the incidence; yet one advantage of topical anesthesia is not having to patch the eye, facilitating frequent instillation of antibiotic drops in the immediate postoperative period.

Dr. Hovanesian: Do you use any intracameral antibiotics at the end of the surgery?

Dr. Fine: I do not, although there is an increasingly good argument for it. There are lots of sub-issues involving how you prepare it and the potential for mischief and miscalculation. But certainly the data out of the ESCRS study using cefuroxime has documented that there has been a decreasing incidence of endophthalmitis in spite of increasing use of clear corneal incisions.

So I think there is certainly a role for intracameral antibiotics at the end of the case. We still use antibiotics in the bottle – which may or may not have efficacy – and which the Centers for Disease Control and Prevention recommends against for hospitals and surgery centers doing other kinds of surgery.

We never have contaminated cases in our operating room, so we are not likely to grow out resistant flora, and we still use vancomycin and gentamycin in the bottle. There is a really good argument that the concentrations in the transient transit time are not going to be efficacious; however, in actual fact, the cost is small and, at least in survey data, it appears that it compares favorably to the absence of antibiotics in the bottle.

Testing the wound

Dr. Hovanesian: What factors do you use in making a decision to place a suture at the end of surgery?

Dr. Fine: If it leaks, we always test with fluorescein. We do not actually push on the eye anymore because in actual fact we can make a 1-mm-wide, 1.5-mm-long paracentesis leak if we push on it.

But we have to push on it with something that is not pinpoint, and even with a 2.5-mm incision, a knuckle is probably going to be bigger than you would be able to create a leakage with. Yet I can make all incisions leak if I am aggressive enough, with pinpoint forces.

Dr. Hovanesian: Do you also hydrate the stroma around the paracentesis?

Dr. Fine: Absolutely. And what we recently saw was that our side-port incisions were not as good as we anticipated. We were a lot more nonchalant with our side-port incisions until we studied them with OCT and we found out that they looked more like the single-plane incisions depicted by the artist. So we started to take the same care and trouble in making those incisions, and they give us the same beautiful arcuate shape that we were getting for our main incision.

Dr. Hovanesian: And you find that they seal better?

Dr. Fine: Much better.

Dr. Hovanesian: What about other methods of closing incisions besides sutures?

Dr. Fine: I think glue is going to be a spectacular thing, if we can get glue that will not be abrasive and not create a foreign body sensation but will hold the seal for the first couple of days and then slough off or disappear.

Dr. Hovanesian: Synthetic glues are promising, not just for cataract surgeons, but also for other corneal applications. There are already some really impressive polymers.

Dr. Fine: I certainly would be in favor of using a glue. We have gone longer than 10 years and more than 10,000 cases without an infection, so I think our incision construction and all of the other measures that we use for endophthalmitis prophylaxis are good. Many others have excellent track records as well. But I think our technique, which has not changed since early 1992, speaks for itself.

Dr. Hovanesian: It is terrific, and your results really bear that out. Dr. Fine, thank you very much for joining us and for taking the time.

For more information:

• I. Howard Fine, MD, is a clinical professor of ophthalmology at the Casey Eye Institute at Oregon Health & Science University in Portland and in clinical practice with Drs. Fine, Hoffman & Packer, LLC. He can be reached at 1550 Oak St., Suite 5, Eugene, OR 97401; 541-687-2110; fax: 541-484-3883; e-mail: hfine@finemd.com; Web site: www.finemd.com.
• John A. Hovanesian, MD, FACS, is a clinical professor at the UCLA Jules Stein Eye Institute and is in private practice in Laguna Hills, Calif. He can be reached at Harvard Eye Associates, 24401 Calle De La Louisa, Suite 300, Laguna Hills, CA 92653; 949-951-2020; fax: 949-380-7856; e-mail: drhovanesian@harvardeye.com.