Simultaneous bilateral cataract surgery (SBCS) is steadily growing in popularity worldwide. So much so that in September 2008, some of its practitioners formed the International Society of Bilateral Cataract Surgeons (iSBCS) to share information and promote safe procedures in SBCS. At the same time, bilateral cataract surgery has become the subject of heated debate. Since we routinely perform bilateral LASIK, bilateral strabismus surgery and generally bilateral "whatever needs to be done" in medicine and surgery, why is there such a fuss over immediately sequential bilateral cataract surgery (ISBCS)? Sometimes if we try to look at a problem or issue a bit differently, from another angle or in a different context, we gain new understanding. Let's try in this case. What are the real issues here? Why are proponents of both sides of the argument so adamant? Are we missing something? Why are some of us moving to ISBCS? It seems that we finally have delayed sequential bilateral cataract surgery (DSBCS) down to a fine system with few complications, so what's the problem?
Background
The practitioners of bilateral cataract surgery commonly refer to it as ISBCS to differentiate it clearly from DSBCS. In my home province of Ontario, Canada, I performed almost half of all ISBCS cases in the government data collection in the fiscal year from April 2003 through March 2004, which made up 1 percent of all cataract cases in the province. In the 2008-2009 fiscal year, despite no significant change in my ISBCS case volume, I contributed less than 20 percent of all ISBCS cases in Ontario, which now exceed 2.1 percent of all cataract cases done in Ontario and 40 percent more than five years earlier.
In the United States, only 0.3 percent of American Society of Cataract and Refractive Surgery 2008 Leaming survey respondents admitted to performing SBCS, but the same survey showed that 5 percent of U.S. surgeons routinely perform ISBCS in refractive lens exchange procedures. In David Leaming's 2008 European Society of Cataract and Refractive Surgery (ESCRS) study, 10 percent of responding members stated that they routinely performed ISBCS. Clearly there is a big difference between private and public lens surgery in the United States, and between U.S. and European practices.
Nonzero-sum improvements
"Nonzero: The Logic of Human Destiny," is a brilliant book in which Robert Wright explains how things keep getting progressively complex in the world as long as there is some gain on both sides of the merging entities pushing them together, making the effort a positive nonzero-sum venture.1 As soon as the first self-replicating molecule appeared, it was inevitable that replication errors would eventually lead to mutation into a better self-replicating molecule. Over eons, this process led to binding to some other component, enhancing self-replication and the unstoppable evolutionary tree based on chemical natural selection, leading to ever-increasing but ever more functional complexity. Chemical soup became cells, eukaryotic cells imbibed prokaryotic mitochondria, multicellularity appeared, and after a few billion years, particular colonies of cells began thinking and called themselves humans, believing anthropomorphically that they were the "center of life" rather than simply "big colonies of cooperating cells" (kind of like cities) and just another step on the ladder of ever-increasing nonzero-sum evolutionary complexity. Our recorded human development of the last three millennia (a miniscule fraction of time) witnessed the evolution of villages to towns to cities to nation-states and now emerging globalization, simply further development of nonzero sums.
The history of surgery accurately follows the nonzero model. We have seen ever-increasing complexity and combinations of procedures enabling us to deliver continually improving results through single procedures. The recent addition of IOL implantation to all cataract surgeries is an obvious example of this.
Are there advantages to ISBCS that we may not have fully considered, driving the nonzero process? Proponents of ISBCS claim that their ISBCS patients are incredibly happy after the procedure compared with DSBCS patients. Why is there such a "wow" factor? Remember the "wow" factor with the first IOLs after we got rid of the terrible optical effects of aphakic spectacles? I think the "wow" pushing ISBCS is binocularity.
The importance of binocularity
As ophthalmologists, when we hear the name Purkinje (as in Jan Evangelista Purkyne or Purkinje, 1787-1869), we think perhaps of seeing our own image mirrored in our first girlfriend or boyfriend's pupils, but rarely of that eccentric bohemian who experimented upon himself, observing the visual effects of spinning and then belladonna and other drugs - the first experiments in a science later to become physiology. En route, he discovered many things about the eye, brain, heart and body. Among them, he was the first to recognize the existence of the vestibulo-ocular reflex and that it stabilizes images when we move. He also discovered how we interpret moving pictures as "movies," which he was the first to make. Despite Purkinje's early insights, the benefit of two eyes compared to one was not well understood until the mid-20th century.
Béla Julesz (1928-2003) developed the first random dot stereograms in 1959, demonstrating the undeniable difference between true binocular stereopsis and monocular depth perception using only environmental cues and parallax. Parallax is common among species, but stereopsis, the end result of normal development of the human binocular visual system, is unachievable monocularly and present only in a few lucky primate species.2 It seems fair to state that we have almost completely ignored the benefits of binocularity for our cataract patients.
Despite dizzyingly rapid advancements in our field, we ophthalmic surgeons seldom perceive that our concepts and behavior follow those of our times. It has long been an unchallenged dictum that cataract surgery is performed monocularly and that the second eye is done when the first eye has recovered.
I was a medical resident in the late 1970s, a time when the stereoscopy work of Julesz probably had not been taught to some of my older professors. How many of my mentors had actually read the latest edition of, "Adler's Physiology of the Eye," and how many had had their ophthalmological paradigms fixed when they were residents? Often I was told that fixing one eye of an older patient with bilateral dense cataracts was probably sufficient for the patient to function "well enough" with cataract glasses after the proposed intracapsular operation. Stereopsis was simply never considered. We are unwittingly the inheritors of this tradition. We have toiled to improve our cataract procedures, but how many of us have challenged and wrestled with the fundamental concepts of the broader paradigms we were taught?
At the same time that our understanding of stereopsis exploded, Hermann M. Burian, MD, Gunter K.von Noorden, MD, and many others were working to understand the developmental stages of our visual system in order to better treat strabismic children, an investigative effort that considerably accelerated after World War I.3 We have slowly learned the details of the stepladder development of binocular vision, which culminates in stereopsis. We now understand that if we test a patient for stereopsis and find it to be normal, other developmental steps must have been completed successfully in early childhood. But if a child fails the stereopsis test, we must turn to a collection of tests of intermediate steps that allow us to pinpoint where arrested development occurred and why and devise treatment modalities. And yet we cataract surgeons ignore much of this wisdom, continuing to repair eyes monocularly, as if fixing one eye was fixing the whole visual system.
The costs of not performing ISBCS
ISBSC fixes the ocular system, not one of its peripheral receptors, in one sitting. Mats Lundström, MD, and colleagues have shown that the improvement in visual performance observed within a few days of ISBCS is not apparent until four months after the second eye is completed with DSBCS.4 Tiina Leivo, MD, of Helsinki, Finland, showed during a presentation at the 2008 annual ESCRS meeting in Berlin that performing all cataract surgery as DSBCS to prevent bilateral simultaneous endophthalmitis (BSE) after ISBCS (the chief reported dreaded risk with ISBCS), would cost the Finnish health care system $1 billion USD per theoretical BSE case prevented. (No cases of BSE have actually occurred in Finland.) Furthermore, mathematically, the same theoretical patient would still suffer bilateral endophthalmitis after DSBCS, just at different times (if we can achieve true infective risk independence of the two ISBCS cataract procedures). Unpublished data from iSBCS shows that we are close, with unilateral endophthalmitis rates among iSBCS members of about 1:17,000 cases and no bilateral infections when intracameral antibiotics are used.
The benefits to visual rehabilitation, combined with the poor logic and ridiculous cost of avoiding ISBCS, are compelling reasons to perform ISBCS. The procedure is common in Finland, where in many hospitals half of cataract surgeries are ISBCS; in Sweden its frequency approaches 5 percent; and on the Canary Islands, all patients undergo ISBCS unless there is a good reason not to. The largest number of iSBCS members are from the United Kingdom, which does not have data on the frequency with which ISBCS is performed there. Many surgeons in Turkey, Poland, Canada, Austria, China, Iran, India and South Africa commonly practice ISBCS with increasing frequency, but exact data is not available. Americans frequently perform ISBCS as refractive lens surgeries, but not as Medicare-paid cataract surgery.
To the external observer and surely to many Americans, the situation in the United States defies logic. The U.S. Medicare program pays surgeons only half as much for same-day second-eye surgery as for second-eye surgery performed on another day. Medicare also pays only half as much for the facility fee and even the IOL fee with ISBCS. Additionally, my colleagues and I have shown in a soon-to-be-published article that the hospital or Ambulatory Surgery Center (ASC) costs in Canada are about 34 percent higher (about $240 million per million eyes) for DSBCS than ISBCS. If we add these to the medical costs for extra visits and procedures, we can see that it probably costs about $2 billion more per million operated eyes to perform DSBCS compared with ISBCS. The U.S. government could potentially save billions of dollars per year by encouraging and paying for ISBCS.
How to get started with ISBCS
ISBCS is easy once each step of cataract surgery has been optimized, including sterility and infective prophylaxis, IOL measurement, operating room function and reliability, incisions, capsulorhexis, phacoemulsification, I/A, IOL implantation, astigmatism correction, treatment without patching and rapid visual rehabilitation. In my quest to achieve this in my own practice and teaching, I have been giving a lecture called, "Every complication you see, you caused." I believe that this challenging statement is almost true. By studying each step of our surgery and making adjustments so it is as consistent and safe as possible, an extremely low complication rate is possible. This makes ISBCS safe and simple.
Wright's book, "Nonzero," tells us that we are headed toward repair of the visual system and not single eyes. Purkinje, Julesz, von Noorden and others have ascertained that we will only restore vision when we fix both eyes, and Lundström has demonstrated that minimizing the time between procedures on both eyes greatly accelerates full recovery. Shelve the older books. It's time for a paradigm shift.
iSBCS is currently formulating, "General Principles for Excellence in ISBCS." The current version is posted on the organization's Web site (www.isbcs.org). I've included below my own suggestions for performing ISBCS successfully.
Suggestions for Performing ISBCS
Changing the surgical routine to permit the successful performance of ISBCS involves a few steps:
- Read up on ISBCS, think about your own experiences in cataract surgery and believe that your patients will benefit from the change.
- Review the iSBCS suggestions for ISBCS on the organization's Web site and try to conform to as many as possible.
- Review your surgical procedure in great detail. Make sure that each step is optimized. Make any necessary changes before proceeding to ISBCS.
- Successful performance of ISBCS also means that each surgeon must be aware of the limitations of his own and his staff's equipment. There will always be cases that are better done as DSBCS, but they will become a small minority with time.
Review your surgical routine in order to optimize it. Following are examples of some related issues and how I have resolved them.
Which eye first and draping routine
When performing ISBCS, changing from the first to the second eye must be simple and easy. I use simple Alcon drapes, which I fold in half so the adhesive surface catches the upper lashes, then open onto the eye and cut along the interpalpebral fissure, folding the upper and lower flaps under the lids (covering the lashes) with a Lieberman speculum (Katena K15678). We always do the left eye first because in our OR layout this achieves the greatest distance between the open left-eye tray and the covered right-eye tray during the first surgery. Removing the drape is easy - I merely roll it off temporally and administer the topical 0.2% carbachol, prednisolone 1% and Vigamox drops that I use routinely. I then apply 1% tetracaine drops from a sterile minim into the second (always right) eye and prep it with 10% betadine solution (patients receive topical 5% betadine drops in both eyes before entering the OR).
Incisions
I insist upon tight incisions because they yield much better control of the surgical environment. Wound leakage destroys any effort to achieve the set phaco fluidic parameters, making surgery much more difficult. I use only diamond knives and have designed my own Arshinoff "soft shoulder" knives that I know make incisions that seal well. I perform the side port incision first, inject 0.1 cc of intracameral nonpreserved isotonic lidocaine (Astra polyamps) and use the same side port at this time if I want to use intracameral phenylephrine or dissect posterior synechiae (using the tip of the lidocaine cannula, etc.). The lidocaine injection also pressurizes the eye, and I then make the main phaco incision 90 degrees away while grasping the pressurized globe using 0.12 forceps at the side port. I always inject OVDs through the main incision, as the looser incision (compared to the side port) allows the surgeon to create any OVD environment desired. (For example, aqueous can be left in the eye by beginning injection of OVD at the wound, or it can be taken out by beginning OVD injection remote from the incision.) Variants of soft shell techniques are easy to create through the main incision but often very difficult through the side port because the high OVD viscosity blocks the incision, preventing aqueous egress. I always hydrate incisions at the completion of surgery and make sure the eye maintains a pressurized status.
IOL implantation and OVD removal
There are many ways to implant an IOL. I prefer using an injector and the second step of the "ultimate soft shell technique."6 After the I/A is completed and the posterior capsule cleaned, the anterior chamber is filled about 30 percent with OVD, preferably a viscoadaptive, adjacent to the incision, avoiding its injection into the capsular bag. Balanced salt solution (BSS) is injected through the OVD to fill the capsular bag. This filling, seen as dewrinkling and deepening of the bag, is easily observed, as the BSS is trapped behind the OVD and stays in the eye. When the IOL is injected into the bag, the shooter is inserted sufficiently to seal the incision, and optionally can be inserted further.
Careful observation is needed to ensure that the leading tongue of OVD, emerging from the injector ahead of the IOL, goes into the bag to lubricate the entry of the IOL. The IOL then follows easily without snagging the posterior capsule. Immediately after the IOL departs the shooter, it is exchanged for the I/A. The pressure of infusion forces the IOL backward into the bag, where it opens, now that the haptics are not surrounded by OVD. Simultaneously, the OVD is aspirated from the anterior chamber by the I/A and incisional leakage in a few seconds. As no OVD was placed behind the IOL, it does not need to be removed from there. Occasionally, a little OVD can be trapped behind the IOL, but it rapidly exits with a bit of "rock 'n' roll" of the I/A tip; going behind the IOL is rarely necessary. I use straight I/A tips with silicone sleeves, as they seal the wound better than metal I/A tips. I give all patients one drop of topical 0.2% carbachol (which is easily made up by the hospital pharmacy) at the end of surgery, as cholinergics are the most effective drugs to prevent postop IOP spikes, carbachol lasts for 24 hours and patients appreciate the excellent vision they get with miosis immediately postop.
Additional information
An article I wrote with Silvia Odorcic provides a lot of background information and advice about bilateral cataract surgery. It appeared in the January 2009 edition of Current Opinion in Ophthalmology.7 The PDF is available here.
References
- Wright R. Nonzero: The logic of human destiny. New York, NY: Vintage; 2001.
- Ings S. The Eye: A Natural History. London, England: Bloomsbury Publishing PLC; 2007.
- Burian HM, von Noorden, GK. Binocular Vision and Ocular Motility: Theory and Management of Strabismus. St. Louis, MO: Mosby; 1974.
- Lundström M, Albrecht S, Nilsson M, Aström B. Benefit to patients of bilateral same-day cataract extraction: Randomized clinical study. J Cataract Refract Surg. 2006;32(5):826-830.
- Haynes AB, Weiser TG, Berry WR, et al. A Surgical Safety Checklist to Reduce Morbidity and Mortality in a Global Population. N Engl J Med. 2009;360(5):491-499.
- Arshinoff SA. Using BSS with viscoadaptives in the ultimate soft-shell technique. J Cataract Refract Surg. 2002;28(9):1509-1514.
- Arshinoff SA, Odorcic S. Same-day sequential cataract surgery. Curr Opin Ophthalmol. 2009;20(1):3-12.