Surgeons await IOLs, tools for microincision surgery

Instruments for performing cataract surgery through an incision of less than 2 mm are appearing but have not yet been widely adopted.

The history of cataract surgery over the past 40 years has seen a progression toward ever-smaller incisions. Now the profession seems poised for another step along that path, pushing the incision size from around 3 mm down to below 2 mm – what some surgeons are calling microincision cataract surgery (MICS).

Although the ophthalmic industry has begun moving toward MICS, more work remains before such procedures can be used routinely. Lenses and instruments capable of passing through incisions of less than 2 mm are in early stages of use or still in development.

“MICS is starting. We are going to develop new phacoemulsification tips that will go through even smaller incisions. Fluidics will be improved. All our surgical practice is going to improve,” said Jorge Alió, MD, PhD, one of the early proponents of MICS, in an interview.

“Lenses will be adapted, and we shall certainly see new performance from these lenses, including multifocality and probably pseudoaccommodation. Progress will bring a cross-fertilization between science, professional practice and technology,” said Dr. Alió, professor and chairman of ophthalmology and medical director of the Instituto Oftalmologico de Alicante, Spain.

But according to the surgeons interviewed for this article, until these technological advancements are made, phacoemulsification through a 3-mm incision will remain the norm for cataract surgery.

Microincision surgery

Louis D. “Skip” Nichamin, MD, a cataract surgeon in practice in Brookville, U.S.A., currently uses a 2.5-mm incision for standard phaco procedures with a Microseal phaco tip and sleeve combination with the Bausch & Lomb Millennium phaco system. He said MICS is not so much a distinct entity unto itself, but rather part of a trend toward increasingly smaller, less traumatic and less invasive incisions, and less invasive surgery in general.

Recent attempts to further reduce incision size have resulted in the concept of bimanual phaco surgery, Dr. Nichamin said. He explained that most standard phaco routines technically are bimanual, using for instance a chopper in one hand and the phaco needle in the other. But the conventional coaxial phaco tip, which carries both infusion and aspiration, can be made only so small.

In the more recently developed bimanual techniques, infusion is separated from aspiration, one in one hand and one in the other. This allows the phaco needle, now carrying only aspiration, to go through an incision of less than 2 mm.

Dr. Nichamin noted that another difference from standard surgery is that in MICS the incision site has to leak slightly to cool the exposed phaco needle, reducing the risk of thermal injury.

“If the tunnel is not terribly long and there is adequate leakage of fluid around the needle, using advanced machines that decrease the amount of ultrasonic energy — with burst mode, for example — we can operate effectively in a true bimanual fashion without the infusion sleeve protecting the needle,” he said.

“We now have side-port irrigators designed to supply the infusion. It’s a dual-purpose instrument. There’s infusion coming in through the incision from the surgeon’s nondominant hand, through a device that also serves as a manipulator, or in my case a quick-chopper. That’s allowing us to get incisions down to the 1.5-mm range.”

Availability of tools

Noel A. Alpins, MD, an ophthalmologist in Cheltenham, Australia, said that although bimanual surgical techniques are not exceedingly difficult to perform, the need to change to new surgical instrumentation has prevented many surgeons from adopting it.

MICS is performed using ARC Laser Dodick PhotoLysis System. MICS is performed using low ultrasound with sleeveless phaco tip. Irrigation and aspiration is performed through two microincisions. IOL is implanted through microincision.

“You really need the tools to be able to do it,” he said. “The technique itself isn’t that difficult, but the tools are different. For example, instead of just a plain chopper you need an irrigating chopper … to be held in the left hand or right hand for insertion.”

Dr. Alpins also said that capsulorrhexis forceps, which normally would be used through a 3.2-mm incision, must be modified to work through a 1.5-mm incision. Hydrodissection also must be slightly more sophisticated. Most important, the phaco needle must be sleeveless.

But Dr. Alió, who regularly performs MICS for cataracts up to grade 4, said the equipment is currently available to perform MICS safely. He said modern phaco machines that use venturi pumps, such as the Alcon Accurus, allow elasticity and a high level of performance. Instruments that can be inserted through microincisions are also available, he said, including the Alió MICS set manufactured by Katena Instruments.

Important tools

In performing MICS, Amar Agarwal, FRCS, FRCOphth, an ophthalmologist in Chennai, India, who developed the bimanual microincision technique he calls phakonit, said the most important step is to create a good incision and thus a good valve. One way to do this, he said, is to use a 3-mm keratome marked at the point where it would create a 1.4-mm incision. This can create a better self-sealing incision, he said.

“This is a good idea, but one problem is that one can accidentally enter more than intended. Another way is to use the side-port knife, but the valve will not be as good,” Dr. Agarwal said.

To solve these problems, Dr. Agarwal and colleagues developed a knife specifically for their MICS technique. The knife, manufactured by Huco Vision, is a crystal knife with a blade 1.2 mm wide and 4 mm long with 60° angulation.

Dr. Agarwal said a well-constructed valve incision is important because a bad valve can result in iris prolapse. Such a complication can also be related to the air pump he uses in his phakonit technique to help prevent surge and maintain the anterior chamber.

“The solution is to have a good knife to create the valve. Both the incisions can be made with this knife,” he said.

Dr. Agarwal said one of the biggest concerns in performing MICS is destabilization of the anterior chamber. This was solved to a certain extent by using an 18-gauge irrigating chopper, he said. To further reduce the size of the chopper, he added an air pump to his phaco system to inject air into the infusion bottle. This pushes more fluid into the eye through the irrigating chopper, helping to prevent surge. This arrangement now allows the use of a 20-gauge irrigating chopper, he said.

This solves the problem of anterior chamber destabilization during surgery and increases the steady-state pressure of the eye, maintaining a deep anterior chamber, he said.

According to Edgardo Carreño, MD, an ophthalmic surgeon in Santiago, Chile, one factor that could retard the development of MICS, at least in some areas of the world, is a lack of interest by commercial firms in providing the necessary surgical equipment and implants.

“They might justify this situation by saying there are few surgeons interested in this technique, which is what makes the commercialization of those products profitable,” he said.

However, he said, although it may not be easy to acquire the tools and lenses to perform MICS, he has been using the technique for a year without major problems.

Preparing for MICS

Dr. Alpins said he believes there is a lack of interest in performing MICS at present, but many surgeons are already performing preparatory steps that can lead to its widespread practice.

“I think, for example, most surgeons would be practicing some sort of phaco chop, to physically disassemble the nucleus without requiring the larger amounts of ultrasound,” he said.

Other elements that could provide preparation for MICS include use of burst mode power modulation to reduce the amount of ultrasound employed in the eye and using higher vacuum rather than more power to disassemble the nucleus, he said.

“I’ve been doing this for many years. It’s kind of a dexterity technique to prepare you for microincision surgery,” he said. “When you take out the soft lens matter you often use two-handed irrigation and aspiration. If you are used to doing that, it really prepares your dexterity for two-handed phaco.”

However, although Dr. Alpins is prepared for the coming of MICS, he said it will still be some time before he can appropriately use the skills. IOLs capable of implantation through microincisions have to be further developed and approved by various regulatory authorities around the world, he said.

“We have been given plenty of warning for a surgical technique change,” he said. “If you have the instruments, a knife and fork as it were, the learning curve isn’t going to be too challenging in comparison to some of the learning curves we have had in other significant steps to modern cataract surgery. If all those other factors have been addressed … it’s not going to be too difficult of a challenge for a competent cataract surgeon who has kept his technique at a contemporary level.”

IOL availability

All surgeons interviewed for this article agreed that the biggest issue preventing widespread adoption of MICS is the lack of IOLs that can be implanted through microincisions.

At least two companies are developing lens technologies that can pass through a 1.5-mm incision, but the lenses so far are of limited availability. IOLs from both ThinOptX and Acri.Tec are available in Europe, but these lenses remain unavailable in Australia, Japan and the United States. The AcriTec lens is unavailable in South America.

Dr. Alió noted that the long-term performance of these lenses is not yet known. Long-term visual results, biocompatibility, stability and rate of posterior capsular opacification must still be investigated.

Dr. Alpins said regulatory approval allowing unrestricted access to IOLs capable of being implanted through microincisions must occur before MICS can be generally applied.

“It has little practical application when you have to enlarge the 1.5-mm incision after you finish the procedure to enable the insertion of the current implant we use, which is a foldable 5.5-mm diameter implant,” he said. “The need for this technology and technique really becomes compelling when the implants are freely available. Until then, there’s really little incentive for the majority of cataract surgeons to modify their technique and split the incisions for irrigation and phaco separately.”

Ideal lenses for MICS should be able to unfold fairly rapidly, Dr. Alpins said, so that positioning can be confirmed while the patient is on the operating table. Otherwise, a certain incidence of repositioning following surgery will result, he said.

The ThinOptX lens has a fairly rapid unfolding time of about 10 seconds, “which is manageable,” he added.

Dr. Carreño said he uses a different model, the Acri.Tec AcriSmart foldable acrylic IOL, which he inserts through an incision of 1.6 mm to 1.8 mm. He said the lens unfolds quickly and achieves excellent stability in the capsular bag. He has not experienced lens-related complications with the IOL, he said.

William F. Maloney, MD, a well-known surgeon and teacher of cataract surgery from Vista, Calif., said the current situation is similar to the advent of phacoemulsification 25 years ago.

“Phaco did not burst onto the scene in any appreciable numbers until we had a foldable implant that we were able to insert through an incision at least close to the 3-mm phaco incision,” he said. “The same principle holds true for going smaller still. It will not burst onto the scene until we have an implant that can be implanted so that the smaller incision does not have to be appreciably enlarged. Right now, if I do a microincision, I still have to enlarge that incision to something in the range of 3.5 mm to insert the implant.”

He said the technology will come into its own once a suitable lens is widely available.

No lens suitable for inserting through a microincision is currently approved for use in the United States. The situation is similar in Japan, where it can be even more difficult for new lenses to gain approval for sale.

Hideharu Fukasaku, MD, of Yokohama, Japan, said he currently prefers standard cataract surgery because of the lower costs and because no IOL and injector system capable of fitting through a microincision is available in Japan.

“It may [take] some years to get approval to sell them inside Japan,” he said.

Losing a tool

Although surgeons cite several advantages to using smaller cataract incisions — less invasiveness, less trauma, faster recovery — some say the use of a smaller, astigmatically neutral incision also takes away a useful surgical tool.

Dr. Alpins noted that many surgeons, like himself, use an incision on the steepest corneal axis to reduce existing astigmatism. With an astigmatically neutral cataract incision, the patient’s astigmatism would have to be addressed separately, either with limbal relaxing incisions or an additional refractive procedure following cataract surgery, he said.

“You may find you need, for example, a bioptics procedure where you need to perform LASIK on the eye 4 to 6 weeks after cataract surgery to eliminate remaining astigmatism,” he said.

“A cataract incision as we now use it can really reduce the existing astigmatism on an eye, anything from 0.5 D to about 1.5 D,” he said. “You can probably reduce most of the astigmatism to a tolerable level so the eye doesn’t require any refractive correction for what remains. However, by eliminating that tool, by reducing the incision size further, you are not going to have as much control over the astigmatism at the time of surgery,” he said.

Limbal relaxing incisions (LRI) could be used for the residual astigmatism, but the incision needed to make a significant change in astigmatism can be large, sometimes requiring application of the LRI over whole quadrants, he said. Predictability can also be an issue, as it was with astigmatic keratotomy (AK), he said.

“Because you are performing the procedures at the time of cataract surgery, the predictability of AK is less than the predictability of AK purely for refractive purposes by itself. The ability to get it on-axis and the ability to determine how much astigmatism to correct by incisional means is more challenging, so the results are less effective. You tend to get more variability in the outcomes in a similar way with LRIs, just in identifying the steepest axis,” Dr. Alpins said.

Currently, Dr. Alpins prefers to do astigmatic correction using the excimer.

“As a general trend in surgery we are moving away from incisional surgery because it is so much more gross in comparison to what we can do with a refined technique of LASIK surgery,” he said. “It seems an anachronism that here we are making the incisions for the cataract surgery smaller and smaller, but you are going to use the LRIs larger and larger to cope with the amount of astigmatism remaining. The whole idea is for minimally invasive surgery, and LRIs are not minimally invasive.”

Surgical time

Another concern expressed by surgeons is the length of time needed to perform MICS.

Dr. Fukasaku noted that MICS takes him longer to perform than standard cataract surgery. Using standard phaco, he said he can perform a routine cataract case in 3 to 5 minutes.

“I designed the irrigation vertical chopper (Katena Products) to reduce the surgery time; however, MICS requires more surgical time because it takes longer to roll and implant the IOL,” he said.

“I think we need to improve or modify these products, because we need to shorten the operational time in order to operate 50 to 60 cases per day and obtain a more stable refraction after implantation. There is an advantage to obtaining the self-sealing condition easily and with less astigmatism; however, we also can obtain the same condition using a 3-mm incisional technique,” Dr. Fukasaku said.

“I must say, there is small advantage over 3-mm standard small-incision surgery at this point. If they develop a good injector and a good IOL to shorten the operational time and obtain stable refraction, this microincision technique will be more important. Also, if the cost is cheaper, it will be more popular,” he said.

Takayuki Akahoshi, MD, of Tokyo, said he too prefers to perform standard phaco because it is a faster procedure than MICS. Although he said some surgeons would be willing to accept longer surgical times to achieve the benefits of MICS, he cannot because it would add too much extra time in the operating room each day.

“My surgical time for most regular cataracts is about 3 minutes through a 2.6-mm or 3-mm incision using a conventional phaco technique. If I perform bimanual phaco through 1.5-mm incisions it would be 6 minutes. I have to operate 40 eyes a day. If it takes 6 minutes for one case, it will require 2 hours more,” Dr. Akahoshi said.

He said he would be willing to adopt a 4-minute surgical procedure performed through a 2-mm incision if he had a good IOL to implant without having to enlarge the incision.

For Your Information:

• Jorge L. Alió, MD, PhD, can be reached at Instituto Oftalmológico de Alicante, Universidad Miguel Hernández, Avda, Dénia 111, 03015 Alicante, Spain; +(34) 965-150-025; fax: +(34) 965-151-501; e-mail: jlalio@oftalio.com. Dr. Alió has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Louis D. “Skip” Nichamin, MD, can be reached at the Laurel Eye Clinic, 50 Waterford Pike, Brookville, PA 15825 U.S.A.; +(1) 814-849-8344; fax: +(1) 814-849-7130; e-mail: nichamin@laureleye.com. Dr. Nichamin is a paid consultant for Bausch & Lomb.
• Noel A. Alpins, MD, can be reached at 7 Chesterville Rd., Cheltenham, VIC 3192, Australia; +(61) 3-9584-6122; fax: +(61) 3-9585-0995; e-mail: alpins@newvisionclinics.com.au. Dr. Alpins has no direct financial interest in the products mentioned in this article nor is he a paid consultant for any companies mentioned.
• Amar Agarwal, MS, FRCS, FRCOphth, can be reached at Dr. Agarwal’s Eye Hospital & Eye Research Centre, 19 Cathedral Road, Chennai-600 086, Tamil Nadu, India; +(91) 44-2811-6233/2811-3704; fax: +(91) 44-2811-5871; e-mail: dragarwal@vsnl.com. Dr. Agarwal has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Edgardo Carreño, MD, can be reached at Centro Oftalmaológico Carreño, Cerro Colorado 5030, Oficina 104, Santiago, Chile; +(56) 2-420-0100; fax: +(56) 2-420-2266; e-mail: edcarreno@entelchile.net. Ocular Surgery News was unable to determine whether Dr. Carreño has any financial interest in any of the products mentioned, or if he is a paid consultant for any companies.
• William F. Maloney, MD, can be reached at 2023 West Vista Way, Suite A, Vista, CA 92083 U.S.A.; +(1) 760-941-1400; fax: +(1) 760-941-9643; e-mail: williammaloney2000@yahoo.com. Dr. Maloney has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Hideharu Fukasaku, MD, can be reached at Yokohama S.T. Building, 1-11-15 Kitasaiwai, Nishi-ku, Yokohama 220-0004, Japan; +(81) 45-325-0055; fax: +(81) 45-325-0054; e-mail: h-f-eye@po.iijnet.or.jp. Dr. Fukasaku has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Takayuki Akahoshi, MD, is director of ophthalmology at Mitsui Memorial Hospital. He can be reached at Mitsui Memorial Hospital, Chiyodaku, Tokyo, 101-8643, Japan; +(81) 3-3862-9111; fax: +(81) 3-5821-2446; e-mail: eye@bg.wakwak.com.

• Acri.Tec GmbH, maker of the AcriSmart lens, can be reached at Lindenstrasse 22/24, D-16548 Glienicke b. Berlin, Germany; +(49) 330-56610-0; fax: +(49) 330-56610-10; e-mail: info@acritec.de.
• ThinOptX, maker of the ThinOptX lens, can be reached at P.O. Box 784, Abingdon, VA 24212 U.S.A.; +(1) 276-623-2258; fax: +(1) 276-623-5661; e-mail: ThinOptX@naxs.net; Web site: www.thinoptx.com.