Ординатура / Офтальмология / Английские материалы / Master's Guide to Manual Small Incision Cataract Surgery (MSICS)_Garg_2009

bag and the anterior chamber with viscoelastic. While slowly injecting the viscoelastic, the viscoelastic tip can be used to polish the posterior capsule. I prefer 2% methyl cellulose since it is less likely to produce a postoperative IOP problem if any viscoelastic inadvertently remains behind. Once the IOL is secure in the capsular bag the viscoelastic is aspirated and the IOP is brought to normotensive levels with BSS.

Finally, the conjunctiva is brought down and coapted with wet field cautery.

Phacosection, manual small incision no stitch cataract removal has been utilized in many areas of the world where phacoemulsification has not been available or is cost prohibited. This technique is the modern way to do extracapsular cataract surgery. There is absolutely no need now in the 21st century do perform 180 degree incisions with 10 nylon suture closures. There is no need to subject any patient to the prolonged and somewhat risky postoperative course of large incision recovery.

In the last two decades the cataract surgery has seen tremendous advancements. With the advent of phacoemulsification, Kelman predicted that incisions 3 mm wide be astigmatism-neutral because of their reduced size. However, within a very short time after the introduction of phacoemulsification, intraocular lens (IOL) implants became more common. This necessitated enlargement of the phacoemulsification incision to 6.5 to 7 mm for lens implantation.

Kratz is generally credited as the first surgeon to move from the limbus posteriorly to the sclera, increasing appositional surfaces to enhance wound healing and attempt to exert less traction on the cornea, thereby controlling surgically induced astigmatism. Girard and Hoffman were the first to call the posterior incision a ‘scleral tunnel incision’ and were perhaps the first to make a point of actually entering the anterior chamber from a slightly corneal location.

The 7.5 mm incision continued for long till foldable lenses became available. Before that the 3 mm incision was increase to 5.5 mm in order to implant a nonfoldable IOL of 5.5 mm optics.

There are various techniques of manual phaco like phacosandwich, Blumenthal’s technique, microvectis technique and fishhook technique, in which the nucleus is removed as a whole. Although surgeons claim that they can remove the nucleus through a 5.5 mm incision, but Indian cataracts are hard and their nucleus is large, which necessitates the enlargement of incision to 6.5 to 7.0 mm to prevent the damage to corneal endothelium during delivery of nucleus. Decrease in the size of wound can be achieved by reduction of the nuclear volume within the anterior chamber by fracturing nucleus in smaller pieces or fragments. Kansas

introduced the technique of phacofracture using his vectis and trisector. The technique involves breaking the nucleus into smaller pieces in anterior chamber by two instruments and then viscoexpressing them.

My method combines elements of phacosandwich as made popular by Luther Fry and the phacosection as practiced by Peter Kansas.

ANESTHESIA

Peribulbar anesthesia is used.

INCISION

The aim is achieving a 6 mm self-sealing corneoscleral wound. I use a crescent, 3.2 mm keratome and 5.5 mm extending keratome. A half thickness depth incision is fashioned with a razor fragment 6 mm in length and 1.5 mm behind the limbus. Crescent is then moved in this half depth thickness in the sclera towards the cornea. Once we reach the cornea the direction of the movement is changed slightly anteriorly taking care of the contour of the cornea. It goes about 1.5 mm in the cornea. Then a sweeping movement is made in the cornea laterally. The crescent is then withdrawn. Now the 3.2 mm keratome goes in the same plain. Once it reaches the desired point, the keratome is pushed towards the chamber. At this point of time a dimple is seen at the tip of keratome. Now, gently keratome is forced into the anterior chamber taking care that it does not hit the lens.

CAPSULORHEXIS

Air bubble is injected into the anterior chamber. About 0.2 cc of trypan blue is injected beneath the bubble to

stain the anterior capsule. The anterior chamber is first washed with BSS and then viscoelastic is injected at 6 o’clock so that the air bubble goes out of the chamber. A large capsulorhexis is then fashioned. In case it is small, two relaxing cuts are made at its margin at 10 and 2 o’clock.

HYDROPROCEDURE

It is performed to separate the nucleus from its capsular attachments. The anterior capsule is elevated with a 26- G cannula attached to a 2 ml syringe filled with BSS and the fluid is injected slowly and continuously beneath the edge of capsulorhexis to create a fluid wave that passes across the red reflex. The fluid wave is not visible in dense cataracts. In such cases, when hydrodissection is completed, the nucleus appears to move forward following which it must rotate freely inside the capsular bag.

NUCLEAR LUXATION

If the capsulorhexis is 6 mm, the nucleus can be easily luxated into the anterior chamber by injecting the BSS by hydrodissection cannula at 9 o’ clock and at the same time slight pressure is applied to lift the nucleus and shift the nucleus towards 3 o’ clock. This brings the nucleus out of the rhexis margin. Thereafter little rotatory movement will bring part of the nucleus in anterior chamber. This movement is performed by visco cannula. The viscoelastic is injected between the visible edge of the nucleus and posterior capsule. That helps in further lifting the nucleus. Now the nucleus is rotated clockwise and anti-clockwise. This breaks any attachment with capsule. Then nucleus is rotated in one direction to bring the nucleus out of the bag. If it does not come out of the bag, then more viscoelastic is injected on top of iris with pressure backwards with cannula on iris. Once the margin of nucleus is visible all-round, more viscoelastic is injected behind the nucleus and also on the top of nucleus. These steps help in pushing the posterior capsule behind and protecting the corneal endothelium. Now lens is ready for fracture and delivery.

NUCLEUS DELIVERY

I perform the maneuver with the help of an irrigating vectis and Sinskey. My first instrument that enters into anterior chamber is Sinskey. It is kept on the anterior surface of lens. Then irrigating vectis is passed beneath the nucleus. At this point I ensure that the hold of

nucleus between the two instruments is strong. With the lens held nicely sandwiched between two instruments (Figure 10.1). I try to deliver the nucleus out. It usually breaks close to the wound. The upper broken fragment comes out sandwiched between two instruments. Remaining lower part of the nucleus is then pushed back. Its long axis is horizontally placed. This fragment is then moved in such a way that its long axis becomes vertical (Figure 10.2). Now, the visco cannula is taken towards 6 o’clock and viscoelastic is injected. At the same time the cannula is slightly pushed backwards on the sclera at the entry site. This will open

Figure 10.1: Lens sandwiched between the two instruments

Figure 10.2: Long axis of the nucleus fragment in verticle meridian

the wound a little and positive pressure created by the viscoelastic within the anterior chamber will force the fragment of the nucleus out of the anterior chamber. This maneuver is called viscoexpression. The remaining debris is epinucleus, small pieces of nucleus and cortical matter. Epinucleus and small fragments of nucleus are delivered out of the chamber by viscoexpression. Cortical matter is then aspirated out with two way Simcoe cannula. Once the posterior capsule is clean and free of any debris or cortical fiber the IOL is implanted in the usual fashion.

COMPLICATIONS

Most of the complications are similar as described in the phacosandwich technique. The only difference is in the chances of injury to the corneal endothelium, which may be a little more in this technique of fracturing the nucleus and then taking them out than in the phacosandwich technique, where nucleus comes out in one go.

BIBLIOGRAPHY

1.Blumenthal M, Ashkenazi I, Fogel R, Assia EI. The gliding nucleus. J Cataract Refract Surg 1993;19:435-7.

2.Fry LL. The phacosandwich technique. In: Rozakis GW, (Ed): Cataract Surgery; Alternative Small-Incision Techniques. Thorofare, NJ, Slack, 1990;91-110.

3.Kansas PG, Sax R. Small incision cataract extraction and implantation surgery using a manual phacofragmentation technique. J Cataract Refract Surg 1988;14:328-30.

4.Singh Kamaljeet. The Phacosandwich technique in Small Incision Cataract Surgery (Manual Phaco) Kamaljeet Singh (Ed) New Delhi, Jaypee Brothers.

5.Sinha R, Bhartiya P, Vajpayee RB. Manual Phacofracture in Small Incision Cataract Surgery (Manual Phaco) Kamaljeet Singh (Ed) New Delhi, Jaypee Brothers.

6.Vajpayee RB, Sabharwal S, Sharma N, Angra SK. Phaco-fracture versus phacoemulsification in eyes with age-related cataract. J Cataract Refract Surg 1998;24: 1252-5.

WHAT IS NEW IN CATARACT SURGERY?

The three most important invents in modern cataract surgery are self-sealing sutureless tunnel, CCC and endothelial protection during nucleus management. They have made the surgery safe, predictable and controlled. Phacosection is a type of SICS which specialises in making the surgery simple, friendly, elegant, repeatable and risk-less, and in addition offers total independence from the machine. The surgical instruments needed are few and effectively sterilizable. High quality results can be achieved irrespective of the status of the cataract. It is perfect for every type, immature to morgagnian, posterior capsular to rocky hard and pseudoexfoliation to subluxated. It is costeffective and suits high volume cataract surgeries, which is the need in developing cataracts. During last few years there has been an up-surge to re-discover manual techniques in phacoemulsification too.

PREPARATION

A complete local and systemic pre-cataract surgical evaluation is essential. I routinely do a dim light, distance fixation swinging flash test with a point light to detect subtle relative afferent pupillary defect and any associated eye illness in its early stages. Dilatation is done to evaluate the cataract and the posterior segment. I start Tab. Vitamin C 500 mg several days before and eye drops Flurbiprofen and Ciprofloxacillin tid 1 day prior the surgery. No systemic medications are given. Diabetes is well controlled, with Glycated Hb under 7 and 2 hour PPBS under 200 mg%.

Any form of anesthesia is fine. I prefer mild hypotony and a good parabulbar block to facilitate

patient comfort and safety. Adequate Betadine cleaning of the eye and 0.5% Betadine wash of the conjunctival sac is only possible after this block! With topical anesthesia, there is always an incomplete cleaning of ocular and adnexal surfaces. 2.5 ml of xylocaine with soda bicarbonate and 1 ml of bupivacaine with hyaluronidase are taken into a disposable syringe. Injection site is between the globe and the inferior orbital margin, at the middle of lateral half of the lower lid. Feel the orbital margin, pass 1/3rd of the 1 inch 23 G needle vertically, than tilt the syringe to direct the needle tip towards the orbital apex and than pass the rest of the needle. If the technique is correct, the needle will not touch the inferior orbital wall, and passes through the tissues effortlessly. Inject slowly and watch for a progressive, supratarsal fullness of raising orbital septum. This is an excellent sign of a true intraconal injection which results in good sensory block and moderate akinesia. If this does not happen and the inferior lid swells up, than you have achieved a peribulbar block, with its moderate sensory block and poor motor block. If this happens, its effect can be improved by gentle massage over lower lid, so that the anesthetic percolates into the muscle cone. A 1-inch needle used exactly with the above technique would never hit the optic nerve or its sheath. It is important to palpate the most important landmark before injecting, the inferior orbital rim and inject in the space above it.

Inducing Hypotony continues to be important in my technique where several steps are performed in an open chamber situation, at atmospheric pressure. I gently apply a soft miniature rugby rubber ball toy wrapped in a tissue on the closed eye with an adhesive tape, for about 20 to 30 minutes. The IOP raises to about

25 mm Hg, and would not obstruct ocular blood flow. This is particularly important in compromised states such as glaucoma and diabetes. Why the anesthetic cocktail? I realised several years ago that the needle does not ‘sting’ the patient as much, but the medicine itself causes enormous pain as it gets into the tissues. This is due to the pH of Xylocaine which is 4.0 and that of Bupivacaine which is 5.8. With Hyaluronidase the pH becomes 3.0 Sodium Bicarbonate neutralises the acidity, eliminates stinging pain and enhances the potency of the mixture. Additional surface anesthesia is of paramount importance. A small amount of sterile cotton, soaked in 2% Xylocaine is placed on the surgical site and cornea for about 1 minute, after applying the lid margin isolating draping and wire speculum. There is no need for SR bridle suture.

INSTRUMENTATION

In Phacosection, the aim is:

A.To give maximum protection to the endothelium by meticulous visco-surgery and by removing the epinucleus and much of cortex along with the nucleus.

B.To maintain the corneal architecture, by avoiding injuries to the tunnel. The non elastic collagen fibers of the cornea and the minimally elastic sclera are not stretched, torn or broken.

To achieve this, the best of microsurgical instruments need to be handpicked for the surgery, without compromising on their quality. All the instruments, including the sharps, are autoclaved and there are no tubings that go in and out of sterile area. Avoid flash autoclaving as the standard autoclaving is the surest way to sterilize instruments. Chemical lotions and formaline chambers are not to be used. Meticulous asepsis is easy to achieve in Phacosection. The cannulas are flushed soon after their use. The few instruments needed for Phacosection are:

straight stream.

7.19 G cannula.

8.Wire Vectis; long and pear shaped

9.The Sinskey hook with blunt tip

10.HPMC visco, BSS and an infusion set

11.Irrigation and 0.3 mm aspiration Simcoe cannula, straight, right and left. Simcoe bulb.

12.Two 5 ml syringe and one 2 ml disposable syringe.

TUNNEL

Identify the perforating anterior ciliary arteries and carefully avoid damaging them. If they are very close to limbus, avoid that zone. These vessels nourish the ciliary body and iris, and it is important to retain them. A fornix based, 6 mm long, combined conjunctiva + tenons+ episcleral flap is created in the upper temporal quadrant, 1 mm away from the limbus, sparing the limbal stem cells. The 3 layers are incised together, directly exposing the sclera. A straight edged rectangular tunnel is created with a double bevel crescent blade. The tunnel measurs 6 mm in width and 2.5 mm in length and saddles on the limbus. Phacosection does not need side pockets or flaring of the edges of the tunnel. The AC is entered with a 6 mm wide keratome. There is no need for a side port as it is a single incision surgery (Figures 11.1 and 11.2).

CCC

Do an anterior capsulorhexis by a technique that you are familiar with. There are two thoughts. If the rhexis is made smaller than the diameter of the IOL, the actively proliferating anterior capsular edge is spatially separated from the posterior capsule by the IOL optic. If the rhexis is larger than IOL, the fibroblastic activity that occurs at the edge of CCC completely bonds the anterior capsular edge to the posterior capsule. This fibrotic ring is the best barrier for the cellular migration from equatorial region to the central posterior capsule.

Figure 11.1: 6 mm long conjunctival incision

Figure 11.2: 6 mm sclerocorneal tunnel incision

The cellular PCO that occurs 1 to 2 years after the surgery is more often seen with smaller CCC.

CCC is best performed under air in a closed eye system. Before the AC is entered with the keratome, a 26 G cystitome is penetrated into the AC at the limbus through the floor of the tunnel. Air in the 2 ml syringe is slowly injected and a 30 G needle at 3 o‘ clock clear cornea allows the aqueous to escape. Once the aqueous air exchange is complete, a controlled rhexis can be performed on any type of cataract. The alternative is to use Utrata’s forceps under visco after the AC is entered with the keratome (Figures 11.3 and 11.4).

Figure 11.3: Aqueous air exchange

Figure 11.4: CCC under air in a closed eye

NUCLEUS MANAGEMENT

As soon as the anterior chamber is entered, it is completely filled with HPMC, a dispersive viscoelastic. Start at 6 o’ clock and withdraw the cannula slowly as the AC is deepened. This technique will coat the endothelium evenly, and protects it throughout out the surgery. A dispersive visco is superior to a cohesive viscoelastics as the latter gets easily washed out with turbulences in the AC.

Hydroprocedures: Perform only the hydrodissection, to cleavage a plane between the cortex and capsule. This

important step has nothing to do with nucleus management, but immensely facilitates cortical aspiration. Avoid hydrodelination (which separates cortex from epinucleus) and hydrodelamination (separates epinucleus from nucleus and dissects layers within the nucleus). These two procedures leave behind large amounts of cortex and epinucleus after nucleus extraction. Do not aim to achieve a golden ring. The cortical separating hydrodissection do not produce a golden ring. It is the Hydrodelineation and delamination that produces golden rings, due to the total internal reflection at the genu of the fluid sheet as it bends from anterior cortex to posterior cortex. Golden ring is a disadvantage, as the epinucleus gets separated from the nucleus, needing a separate and difficult management.

Hydrodissection is an open chamber procedure. Every drop that is injected into the eye is to be balanced by a drop coming out of the eye. This avoids steep increase in the pressure anterior to lens diaphragm which can be disastrous if the posterior capsule or zonules are weak. A 26 G cannula is introduced under the anterior capsule at 3 o’ clock meridian, without disturbing the cortex. The tip is directed towards the equator of the lens, which is about 3 mm behind the iris plane. By this the shaft of cannula confirms to the downward slope of the anterior capsule from the centre towards the equator. The jet of fluid hits the equator and takes a U turn to dissect the posterior capsule from the cortex. Just before injecting the fluid, the whole length of the cannula is lifted up, towards the iris. This tents the anterior capsule, creating a funnel. Watch for any of the following: (a) A ‘fluid pass’ across the red reflex of the pupil. (b) Irregular shallowing of the AC with lifting up and tilting of the nucleus at 9 o’ clock.

(c) Prolapse of the nucleus into AC. The injection has to be slow but continuous. Every time you stop the hydrodissection, it needs more effort to restart, due to inertia. The fluid has to freely flows out of the capsular bag and out through the open tunnel. If you direct the cannula parallel to the iris plane, a good hydrodissection cannot is not achieved. An open chamber ensures that the quantity of fluid being injected need not be restricted till a good and complete hydrodissection is obtained. When properly performed, the posterior capsule never gives way, even with a posterior polar cataract.

The contents with in the capsular bag are in three layers and their relative sizes and texture depends upon the patients’ age and state of cataract. In the very young there is no hard central ‘nucleus’. In older patients more and more of cortex gets incorporated into the nucleus. The gelatinous, pliable epinucleus is the transitional

Figure 11.5: Phacosection

material between cortex and nucleus. Indeed epinucleus management is the trickiest thing, as it is too soft to be handled like nucleus and too tenacious to be aspirated like cortex! It is best to remove it along with nucleus. A complete capsulocortical cleavage by good hydrodissection does not disrupt the integrated anatomy of the hard nucleus, epinucleus and cortex and greatly facilitates meticulous nuclear management.

To deliver the nucleus into the AC, use the following maneuvers (Figures 11.5 to 11.7):

a.Right hand holds 26-G cannula mounted on a 2 ml visco filled syringe. Left eye holds the blunt Sinskey hook.

b.Bimanually rotate the nucleus within the capsular bag in an anticlock direction, like you rotate the steering wheel of a car. The ‘steering column’ permits you to only rotate the wheel, and in the eye bimanual rotation prevents even a subtle traction on the zonules. Rotation separates peripheral from inner cortex. What is being rotated is removed along with the nucleus and what is left behind is aspirated later. During hydrodissection, if one edge of nucleus has prolapsed out of bag, push it back into the bag before rotating it. If there is fluid still trapped behind the nucleus, it needs to be burped out of the bag before rotating the nucleus.

c.Engaging the nucleus in its centre with your left hand Sinskey hook, and push the nucleus to its left by a mm or so. Pass the tip of your right hand 26 G cannula under the right edge of the nucleus and lift it to a plane just in front of the anterior capsule. Bimanually rotate the nucleus anticlockwise, using

Figure 11.6A: 12 o' clock Simcoe cannula

Figure 11.6B: Cannulas

Figure 11.6C: Simcoe cannula with bulb

Figure 11.7: Heminucleus visco delivery

both the instruments. The cannula supports the nucleus at its equator, and the Sinskey hook gives the rotating movement in an anticlock direction. As the right edge of the nucleus is held lifted up, rest of the nucleus gets rotated out of bag, like a screw coming out of a bolt. You actually ‘walk’ on the equator of the nucleus with these two instruments, with a slight lifting force. This is a bimanual procedure and as the nucleus remains in the centre of the bag all the time, there is no stretch at all on the zonules. This safety is extremely useful in mature and brown cataracts and in myopes, pseudoexfoliations and subluxations. The epinucleus and majority of cortex remain attached to the nucleus during these maneuvers.

d.In very soft nuclei, like in posterior capsular or subcapsular cataracts, pass the cannula right into the center of the nucleus, like the stick inside a lollypop, and nudge and maneuver the entire nucleus into the AC. It is very easy and works in most of the nueclei upto the age of 45 years.

e.Endothelial protection is paramount. This is done by continuous injection of dispersive visco through out the next few steps. Visco refills the space between the nucleus and cornea.

f.Once the entire nucleus is in the AC, change the left hand instrument to wire vectis. The right hand holds the syringe such that the thumb is on the piston and ready to continuously inject visco.

g.Tip the 12 0’ clock nucleus anteriorly and pass the wire vectis under the nucleus. Remember that the nucleus is biconvex, and your movement should be

in conformity with the bulge in its back. Hitting the bulge with wire vectis pushes the nucleus towards 6 o’ clock and stretches the superior zonules. Avoid lower end of the vectis going under the iris, which results in iris trauma and an iridodialysis. The shiny vectis is visible through all types of nuclei, and keep a watch on its lower end!

h.Pass the 26-g half-inch cannula in front of the nucleus. Stay away from endothelium, and continuously inject visco.

i.Hold the vectis steady, supporting the exact middle of nucleus. Press the cannula towards the vectis so that its shaft bisects the nucleus. This motion should be slow and steady. There is no need for see-saw movement! You will be surprised to see that the shaft can bisect any nucleus, however hard it may be! Continuously inject visco through out this procedure. Inject visco between two halves of nucleus and confirm the two halves are fully separated. If any connections are remaining, nudge them with cannula. Otherwise, the 2nd half tends to follow the first half during extraction, which is not desirable.

j.Now slide the vectis under the left half of nucleus. The cannula is positioned on the front surface of the nucleus, continuously injecting visco. A sandwich containing vectis behind, nucleus in between and cannula in front are slowly glided out of AC through the tunnel. The upper pole should not engage the scleral valve, and this is achieved by tipping the upper pole of the nucleus anteriorly and depressing the posterior lip of the tunnel incision. The line of movement should be in line with the tunnel, till the entire nucleus has come out of the tunnel. The visco is continuously injected through out to prevent AC from collapsing and to maximally protect the endothelium.

k.Now inject visco in front of the right half of nucleus and move it to the center of AC, in line with the tunnel. It is again sandwiched between the wire vectis and visco injecting cannula and gently taken out of eye in a similar movement.

The size of capsulorhexis and nucleus do not matter, as the capsule is quite elastic. However during the learning period, if the rhexis is grossly undersized, don’t try to force the nucleus out, but perform a single relaxing incision at 10 o’ clock before proceeding. Nick the edge of rhexis with a cystitome. Usually the tear extends till equator, but never proceeds to the posterior capsule because of centripetal attachment of the equator to the zonules. Keep the cortical removal at this site at the end so that the cortex holds the cut capsule togther.

At times a nuclear fragment can break off in the tunnel. A small fragment can be removed with viscoexpression, guided by a vectis. A large and tightly placed fragment is best pushed back into the AC with visco, with the cannula placed in front of the lens fragment. Align the fragment in line with the tunnel and than viscoexpress it. If any resistance is met during extraction of the nuclear fragment, do not persist with the extraction. Check if the upper pole of nucleus has gone under the scleral valve, through the hole in the vectis. If the nucleus is extra big and hard, don’t hesitate to enlarge the tunnel to an adequate size. The beauty of the scleral tunnel is that you can simply withdraw all instruments at any stage of the surgery, and lo! it is a water tight chamber now. Nothing can get in and nothing can come out!

CORTICAL MANAGEMENT

As most of the cortex is already removed, and as the posterior cortex is totally separated from the capsule, cortical management is relatively easy. Inject dispersive visco just before cortical aspiration. Simcoe bulb and bimanual IA cannula are excellent tools for quick and complete cortical aspiration. As phacosection has no side ports, straight, right and left Simcoes IA cannulas are needed to reach all the corners of the equator. Complete cortical aspiration is the key to quiet postoperative course.

IOL IMPLANTATION

All the IOLS are compatible to phacosection. Completely fill visco in the AC before implanting your choice IOL into the capsular bag. Diffraction multifocal IOLs have given me excellent and consistently predictable results, as the corneal topography do not alter with this beautiful technique. At the end of surgery, aspirate all the visco from under the IOL, nook and corners of AC and from underneath the endothelium. The tunnel closes on its own with positive pressure in the eye, and does not need hydration (Figures 11.8 to 11.10).

GUIDELINES TO BEGINNERS

The techniques and instrumentations in cataract surgery are changing rapidly. It is important to initially try out as many methods as you can, under proper guidance. Learning phacoemulsification formally gives good foundation, particularly in the fluidics and nuclear management. Write down the difficulties you had with every surgery, and watch your own videos critically. Don’t let go even a small difficulty!