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

Figure 13.8: CCC

Figure 13.9: Internal incision completed

Figure 13.10: Hydrodissection

Figure 13.11: Dialing of the nucleus

Figure 13.12: Tumbling of the nucleus

gently into the anterior chamber (Figure 13.12). Hydrodelineation is performed with the viscoelastic cannula in the anterior chamber itself in the case of a soft cataract (Figure 13.13).

A curved cannula is then insinuated under the nucleus and viscoelastic injected beyond the inferior margin of the nucleus. All the while the posterior lip of the tunnel is gently depressed with the same cannula to make the tunnel open up and allow the nucleus to be slowly and smoothly expressed out of the eye (Figures 13.14 and 13.15). Similarly any epinucleus remaining in the anterior chamber is also expressed out with the help of the viscoelastic (Figure 13.16).

A J-shaped cannula is inserted at the 12 o’clock position to remove the subincisional cortex (Figures 13.17 and 13.18). A Simcoe irrigation/aspiration

Figure 13.19: Implantation of IOL

Figure 13.20: I/A of viscoelastic

cannula is then used to aspirate rest of the cortex. The posterior capsule is polished with the Simcoe cannula itself.

A 5.25 mm posterior chamber IOL is implanted through the tunnel into the capsular bag using curved lens holding forceps. If necessary it can be dialled and centered (Figure 13.19).

Viscoelastic is aspirated with the Simcoe cannula and the anterior chamber is formed with the balanced salt solution (Figure 13.20).

The conjunctival flap is replaced with an iris repositor or a cotton bud, to cover the external tunnel opening (Figure 13.21). It is then sealed at one end with the help of a bipolar cautery (Figure 13.22).

Postoperatively we always give a subconjunctival injection of gentamycin and dexamethasone.

Figure 13.21: Reposition of conjunctival flap

Figure 13.22: Conjunctival flap cautery

The advantages with this technique are:

1.No side ports are required and so the surgery is less traumatic.

2.The endothelium and the posterior capsule is protected during all the procedures because of the viscoelastic, which acts like a third invisible hand for the surgeon.

3.Posterior capsule rupture is rare because no instrument is inserted deep in the posterior chamber before the delivery of the nucleus.

In the initial cases we encountered complications like endothelial folds, striate keratitis, mild corneal edema, hyphema, posterior capsule rupture with vitreous in the anterior chamber, exudates in anterior chamber, raised postoperative intraocular pressure, in addition to a corneal ulcer in one case.

But now complications are far and few.

This technique has a smoother and easier learning curve; rather I would say there is NO learning curve for a surgeon who is already performing ECCE and implant surgery.

The final results with manual small incision cataract surgery with visco-expression of the nucleus and epinucleus are arguably the same as with phaco surgery.

DO’S AND DON’TS OF THE PROCEDURE

1.In addition to the use of digital massage, super pinky or balanced weight after local anesthesia, pre-operatively the patient is given Acetazola-

mide tablet 250 mg orally, to induce hypotension of the eyeball. Nucleus delivery by the viscoexpression technique in SICS requires a hypotensive eyeball.

2.The tunnel should be made of adequate length, so that the nucleus may engage easily.

3.The nucleus should be minified in the bag or in the anterior chamber by hydrodelineation, so as to make the visco-expression of the nucleus easy.

4.As the viscoelastic is being injected with the curved cannula into the anterior chamber, beyond the nucleus, the posterior scleral lip of the tunnel is gently pressed with the same cannula. This facilitates the smooth visco-expression of the nucleus.

INTRODUCTION

Cataract surgery has evolved with leaps and bounds over the last decade. Apart from visual restoration the surgery is also playing the role of refractive surgery. The focus today is on sutureless surgery with minimal surgically induced astigmatism. Manual is a highly skilled procedure. The various techniques for manual phacofragmentation need insertion of large instrument/s through the main incision. As a result, it becomes difficult to maintain the anterior chamber. This poses risk to the corneal endothelium and/or the posterior capsule. Phacofragmentation can be made safe if it is done in a ‘closed and deep anterior chamber’.

PROCEDURE

The procedure can be performed under the anesthesia of surgeon’s choice. I perform it under topical anesthesia. No sedation is used and a constant surgeonpatient communication is maintained. Patients are told to report immediately if they feel pain. In case of slightest pain, 0.75 cc of 2% Lignocaine is infused through a blunt cannula (hydrodissection cannula) in the subtenon space and if required at any stage of surgery, 0.5 cc of Lignocaine, free of preservative is irrigated in the anterior chamber.

An anterior chamber maintainer (ACM) is introduced near lower limbus through a clear corneal tunnel (prepared with a stiletto knife or MVR blade) and the BSS infusion line is kept ‘on’ to maintain positive pressure in AC. The height of the BSS bottle can be varied as per requirement during the procedure. After preparing a fornix based conjunctival flap and cauterization of bleeders, a 5.5 to 6 mm Frown’s scleral incision

is made. A scleral tunnel is prepared extending about 1.5 mm in cornea to prepare a clear corneal valve. The tunnel is funnel shaped and is about 7 mm wide in clear cornea. The anterior chamber is not entered at this stage through the tunnel. Scleral pocketing is not required. About 5.5 mm capsulorhexis is performed using 27G/ 30G bent needle introduced through a side port incision at 10 o’clock. Conventional hydrodissection and then hydrodelineation are carried out and the nucleus is rotated and partially prolapsed out of the capsular bag. If the nucleus is small it is extracted out using Sheet’s glide. (Blumenthal’s Mini Nuc Technique).

For large nucleus, a ‘Closed chamber manual phacofragmentation’ is performed. The surgical nucleus is partially prolapsed out of the capsular bag by the technique of surgeon’s choice. The nucleus should be positioned in such a way that the left (surgeon’s) and upper part remain out of bag and the opposite part remains in the bag. Using a Stiletto knife a very small initial entry (0.9 mm) is made into the anterior chamber about 1.5 to 2 mm to the left of midline (Figure 14.10). An iris repositor is glided under the nucleus a little to the left of the midline. The surgeon gets sufficient space between the nucleus and the posterior capsule due to positive pressure in anterior chamber and the closed chamber maneuvering. Another instrument, ‘Boramani’s axe chopper’ is introduced through side port at 10 o’clock and is positioned on the nucleus a little to the right of midline (Figures 14.1 and 14.11). Boramani’s axe chopper is basically like a lens/IOL manipulator (Figure 14.8), but the distal portion (or shaft) is little more thick to make the instrument more sturdy and the tip resembles a small axe (about 0.6 mm × 0.6 mm) with a curved cutting edge (Figure 14.9).

Figure 14.1: Diagram showing the axe chopper positioned in front of the nucleus and iris repositor behind it

The iris repositor and the axe chopper are moved in a continuous curvilinear fashion, first to fragment the nucleus and then to push the fragments away from each other (Figures 14.1, 14.2 and 14.12). Figures 14.3 to 14.5 schematically show the cross-sectional view of the maneuver (as if viewed from 12 o’clock). The instruments should be moved in the direction of the green arrows shown in Figure 14.3. Although the movements are continuous curvilinear, initially the instruments are brought closer to each other so as to fragment the nucleus and in the later part they move away from each other to separate the fragments. This is ‘Closed chamber manual phacofragmentation’. The fragmentation need not be necessarily equal. For the fragmentation, the instruments should not be straightway opposed to each other (Figure 14.6). This can cause a sudden hazardous tumbling of the nucleus, the posterior capsule may rupture and the corneal endothelium may get damaged.

The internal incision of the tunnel is now completed using a keratome knife parallel to iris plane and cutting the tissue during ‘out to in’ movements (Figure 14.13). The fragments are extracted out over Sheet’s glide as in Blumenthal’s mini nuc technique utilizing the positive pressure created in the anterior chamber due to continuous infusion through the ACM (Figure 14.15). A surgeon may employ other methods like viscoexpression, forceps extraction after closing the infusion

Figure 14.2: Diagram showing the axe chopper and the iris repositor pushing apart the nuclear fragments

Figure 14.3: Cross-sectional view of the maneuver (as if viewed From 12 O’clock). The chopper and the repositor should be moved in the direction of the green arrows. Although the movements are continuous curvilinear, the instruments are brought closer to each other initially so as to fragment the nucleus and then moved away from each other to separate the fragments

Figure 14.4: The initial crack when the axe chopper gets buried into the nucleus

Figure 14.5: The completion of phacofragmentation

Figure 14.6: Incorrect manipulations: If the instruments are straightway opposed to each other, a sudden hazardous tumbling of nucleus can occur

Figure 14.7: It may be difficult to express out a fragmented nucleus due to egress of fluid from sides. A sinskey hook passed through the side port can push the fragment out

Figure 14.8: The axe chopper

Figure 14.9: The tip of the axe chopper

Figure 14.10: The initial 0.9 mm entry into the anterior chamber about 1.5 to 2.00 to the left of the midline

line temporarily. Hydroexpression using a Sheet’s glide is not always easy for nuclear fragments. A round undivided nucleus can effectively block the scleral tunnel, allowing build up of pressure in the anterior chamber to facilitate hydroexpression. A fragmented nucleus can be ineffective, allowing the egress of fluid from sides. If such a difficulty is encountered, a Sinskey hook passed through the side port can push the fragment out (Figures 14.7 and 14.14). The epinuclear mass is delivered out using Sheet’s glide. Water jetting of the bag is done through a fine canula passed through the side port (Figure 14.16). The cortex is aspirated manually using a single port aspiration canula, passed through the side port (Figure 14.17). This canula is attached to a syringe through a silicon tube. An

Figure 14.11: The axe chopper positioned in front of the nucleus and iris repositor behind it

Figure 14.12: The completion of phacofragmentation

intraocular lens is implanted in the bag (Figure 14.18). While implanting the lens, once the inferior haptic is placed in the lower bag, it is advisable to support the superior haptic with the forceps in the left hand before releasing the optic. Otherwise the lens can recede behind due to continuous flow of the BSS, the optic stays in the tunnel and the inferior haptic may touch the corneal endothelium. If necessary the ports are hydrated, the eyeball is pressurized with BSS and the conjunctiva is sealed with wet field coagulator.

The major advantage of this technique is that the phacofragmentation is done in a closed, deep chamber using very fine instruments, thus making it safer.

Figure 14.13: The internal incision is completed only after phacofragmentation

Figure 14.14: A Sinskey hook passed through the side port can push the fragment out

DO’S AND DON’TS OF THE PROCEDURE

1.The corneal tunnel for anterior chamber maintainer should always be almost tangential and not radial. This tunnel is usually near lower limbus. Hence a radial short tunnel is more risky compared to a tangential one as far as endophthalmitis is concerned.

2.Introduction of ACM should be the first step of surgery and its withdrawal the last one. This keeps the globe pressurised throughout surgery; one can operate with normal internal architecture and any predetermined maneuver can be executed as planned.

Figure 14.15: Delivery of nuclear fragment over sheet’s glide

Figure 14.16: Water jetting of the capsular bag is done through a fine canula passed through side port

3.The ACM should preferably be kept ‘on’ throughout procedure. This provides enormous space to work. The one way flow prevents organisms from entering AC. The inside out flow of fluid washes out debris, blood, pigment, cortex, etc. Low turbulence and low fluctuation of AC depth due instantaneous fluid recovery results in less discharge of prostaglandins and leucotriens; hence there are less chances of postoperative inflammation as well. Maintained pressure minimizes risk of expulsive hemorrhage, keeps the pupil dilated. The capsular bag is kept distended, hence I/A is safe with less chances of capsular capture. In the event of PC rupture positive pressure pushes back the vitreous face and further hazards

Figure 14.17: Aspiration of cortex through side port

Figure 14.18: The implantation of an IOL

are minimized. Positive pressure also acts as tamponade in case of bleeding.

4.Phacofragmentation should be done before the tunnel is opened up internally in this technique. This ensures an almost closed chamber maneuvering of the nucleus.

5.The nucleus should preferably be prolapsed only partially out of the capsular bag (with major portion out of the bag). This ensures corneal protection.

6.As the fragmentation is done with very fine instruments, the details of movements of the instruments mentioned in this chapter should be strictly followed. Otherwise one can end up in sudden hazardous tumbling of the nucleus.

7.Making capsulorhexis through side port with ACM is not very easy. The egress of fluid through side port causes lot of movements of capsular flap during the procedure. Hence a proper side port is not prepared in the first instance. Instead a very small entry sufficient to introduce capsulorhexis needle is made with MVR blade. This ensures a good closed chamber capsulorhexis with minimal turbulence in AC. The side port is completed using the MVR blade again only after capsulorhexis.

BIBLIOGRAPHY

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