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Manual small-incision cataract surgery helps meet challenges in developing world
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Cataract surgery in developing countries can be a challenge. Phacoemulsification with disposable single-use cassettes may still have prohibitive costs, and extracapsular cataract extraction, with its large limbal incision and high induced astigmatism, is unacceptable for today’s standards.
A modified manual small-incision cataract surgery (SICS) technique, which combines steps typically applied during microincision phaco surgery and SICS, has proven to be a valid alternative.
“We routinely use this technique during our missions at the Comboni Hospital in Sogakope, Volta Region, Ghana. It is not an easy technique because it combines the skills of phacoemulsification surgery, ECCE and SICS. The main and ultimate goal would be to train local surgeons to use it and welcome more volunteers to join us there,” Paolo Lanzetta, MD, said in an interview with Ocular Surgery News.
Sogakope is the capital of South Tongu, a district of the Volta Region of Ghana. The area, situated along the estuary of the Volta River, is a floodplain with dense mangrove swamps, coastal lagoons and open ocean beaches. Here, in 1990, Rev. Richard Novati founded the Comboni Hospital.
“The location is unique, overlooking the Volta River, and ophthalmology volunteers can rely on the support of local trained nurses. The ophthalmology clinic is equipped with slit lamps and a biometer, while the operating room can rely on a working microscope. Intraocular lenses, OVDs and various surgical instruments are available,” Lanzetta said.
He explained that the OR was closed for some time and was reactivated recently with the support of Rotary International. Ophthalmology volunteers mainly come from Italy and Germany.
“SICS with IOL implantation has become the preferred technique, and many patients have very good vision the very day after surgery. Although many cases are hard cataracts, we have a very low rate of complications,” Lanzetta said.
The technique step by step
A fornix-based conjunctival flap is made by detaching the conjunctiva from the superior limbus. Minimal cautery is then applied. The scleral incision consists of three parts: the scleral groove or external incision, dissection of the sclerocorneal pocket tunnel, and entry into the anterior chamber or the internal incision.
A frown-shaped scleral incision is performed with a 30° keratome 1.5 mm to 2 mm posterior to the limbus, centered at 12 o’clock from 11 o’clock to 2 o’clock.
“The blade should always remain perpendicular to the sclera while cutting at regular and uniform depth. The groove should be neither too deep nor too thin, as the first may result in a difficult tunnel dissection and premature entry in the anterior chamber and the second may produce a button-holing of the sclera or cornea,” Lanzetta said.
The crucial points of the subsequent sclerocorneal tunnel are smaller external incision, large internal incision and large side tunnel dissection. This configuration will allow the extraction of large nuclei and at the same time an efficient valve closure and acceptable postoperative induced astigmatism. Dissection is made with a bevel-up angled crescent. The blade margin indents the groove and then is advanced into the sclera, dissecting an initial straight tract and then moving sideways to the right and left. Once the corneal plane is reached, the dissection should follow the plane by advancing 1.5 mm to 2 mm into clear cornea by creating a horizontal linear margin. Two side pockets into the sclera and cornea will facilitate the extraction of the nucleus from the anterior chamber.
“I recommend beginners of this technique to prefer a larger tunnel, especially in case of hard and bulky nuclei,” Lanzetta said.
After the tunnel has been completed, a side port with a 30° blade is made to perform the capsulorrhexis. In most cases there may be a lack of red reflex and the presence of intumescent cataract. Therefore, air is injected into the anterior chamber through the paracentesis. Subsequently the capsule is stained by injecting the dye over the anterior capsule. After a few seconds, both air and excessive dye are washed out by injecting viscoelastic into the anterior chamber. With a deep viscoelastic-filled anterior chamber, the capsule is opened with the aid of a 30-gauge needle. A capsular flap is lifted, and then a continuous circular capsulorrhexis (CCC) is performed with the forceps normally used during microincision cataract surgery.
“Advantages of CCC over other capsule openings have been extensively described. In the case of SICS, it allows safe manipulation of the nucleus during its lifting from the capsular bag into the anterior chamber. Obviously, CCC needs to be larger than during phacoemulsification. Therefore, multiple re-grasping of the capsule with forceps during the maneuver is recommended to avoid rhexis escape,” Lanzetta said.
From hydrodissection to IOL implantation
Once the CCC has been completed, it is preferable to enter the anterior chamber with an angled keratome through the anterior limit of the tunnel. Full opening of the tunnel should be avoided to prevent the excess of fluid and viscoelastic from escaping the anterior chamber through both the paracentesis and the tunnel during hydrodissection. By doing so, there will be no damage to the posterior capsule and zonule, and there will be enough pressure to lift the nucleus from the capsular bag into the anterior chamber. During this maneuver, Ringer lactate is injected behind the margin of the rhexis via an angled flat cannula until the crystalline lens is dislocated anteriorly. A 30-gauge needle with a bent bevel or a Sinskey hook may also be used to engage the nucleus and facilitate its rotation and manipulation out of the bag.
“Once the nucleus is completely in the anterior chamber, viscoelastic is profusely injected between the endothelium and the lens and between the lens and the posterior capsule. Hypromellose ophthalmic solution 2% is a good option as it is less expensive than other viscoelastics. In some cases, 1 mL adrenaline 1:10,000 (100 µg) may be injected beneath the nucleus before its extraction to maintain a proper dilation during cortex aspiration and IOL implantation,” Lanzetta said.
The angled keratome is reintroduced into the scleral tunnel and the previous anterior chamber opening after some viscoelastic has been introduced in the tunnel. The bevel of the blade is then lifted to dip the tip into the anterior chamber, and multiple entries sideways parallel to the iris are performed until the lateral end of the internal incision is reached.
“Now, the nucleus is ready to be pulled out of the anterior chamber. Use more viscoelastic if necessary and the fishhook technique, which was developed by Drs. Hennig and Tynovsky in 1997 at Lahan Eye Hospital in Nepal. A small hook made of a 30-gauge needle is used to extract the entire nucleus through the self-sealing tunnel. This will greatly simplify the delicate and crucial maneuver of lens extraction. The fishhook is inserted between the nucleus and the posterior capsule and then turned to engage the central lower nucleus. Thereafter, the nucleus is easily and elegantly extracted through the tunnel,” Lanzetta said.
Most cortex can be washed out by injecting Ringer lactate with an angled flat cannula and intermittent opening of the external incision. Remaining cortex can be removed by irrigation and aspiration with a Simcoe cannula through the side port, which will allow maintaining a deep anterior chamber.
At the time of IOL insertion, there are two main possibilities, Lanzetta said. The lens can be implanted either through the tunnel or through the side port by using an injector and a foldable lens. In the first case, after deepening the anterior chamber with viscoelastic, a single-piece PMMA lens is placed either in the sulcus or the capsular bag. In the second case, a more stable anterior chamber is available for implantation, and IOL insertion into the bag is easily done with an injector, similar to microincision cataract surgery.
In the majority of cases, sclerocorneal tunnels are self-sealing and hydration of the side port with a cannula is enough to maintain an adequate anterior chamber. The conjunctiva can be repositioned over the groove incision of the tunnel with cauterization.
Motivated people needed
“What we need here [in Ghana] is a group of experienced, but even more, motivated people who share our vision, work with enthusiasm, understand and respect the local culture, and are flexible enough to adjust to the needs, habits and different pace of the local team. We need professionals who also have the skills and predisposition to train local staff, who come here to solve and not to create problems,” Lanzetta said.
“I like our approach, which is to be very efficient but also cooperative and well-grounded in the reality we are dealing with. There is no point in behaving as if we were at home and having the expectations we would have in our societies. With sensitivity and concern for the individuals involved, we must achieve the best outcomes possible.”
Parties interested in joining the Comboni Hospital mission may contact Paolo Lanzetta, MD, and send a CV to paolo.lanzetta@iemo.eu.
Editor’s note: Please see accompanying video at https://www.healio.com/ophthalmology/cataract-surgery/news/online/%7bf996b124-01ac-4476-a52a-5d601c8b154d%7d/video-manual-small-incision-cataract-surgery-helps-meet-challenges-in-developing-world.
- For more information:
- Paolo Lanzetta, MD, can be reached at IEMO – Istituto Europeo di Microchirurgia Oculare, Via M.A. Fiducio, 8; 33100 Udine, Italy; email: paolo.lanzetta@iemo.eu.
Disclosure: Lanzetta reports no relevant financial disclosures.