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

Figure 11.8: Visco aspiration after IOL insertion

Figure 11.9: Stable bubbles in HPMC

When you want to implement a change in your technique, do it one step at a time. Initially avoid Phacosection in very soft as well as very hard cataracts. Revisit your teacher or re-watch his surgery after 10 and than about 25 of your surgeries. Attend all cataract CMEs, whether it is SICS or phacoemulsification. There will be plenty of fine points to learn about and implement at any stage of your career!

If you can do a good extracapsular or phacoemulsification sugrery, you can perform a good phacosection. The learning curves are similar, but the concepts are different. With phacosection, you alone

Figure 11.10: First postoperative day

have the absolute control on the situation, at every single step and moment, and you remain the master. There are no surprises, no accidents and no gadgets. Everything happens as you dictate. All you need to do is to set your mind and enjoy the surgery! It is best for your health too, as you don’t need Adrenaline! Put on music, and enjoy every moment.

The technology dependent surgery of phacoemulsification has its benefits as well as disadvantages. Higher costs, higher risks, need for consumables which cannot be properly sterilised when reused, etc. are some of them. It is ever undergoing refinements, making one feel obsolete as soon as a new machine is bought or a new technique is learnt. The complications with phacoemulsification are less forgiving. They can be intraoperative or postoperative. Some of them like endophthalmitis and TASS are related to the equipment, consumables and flash autoclave. In SICS, you can have as many surgical sets as possible, which are adequately cleaned and sterilized with conventional autoclave. This avoids Endophthalmitis and TASS.

DO’S AND DON’TS FOR PHACOSECTION

Phacosection is s a safe and beautiful technique for any type of cataract. All types and grades of cataract can be managed atruamtically, as the nucleus is divided into two halves, facilitating removal through a 6 mm tunnel. Splitting the nucleus prevents damage to the tunnel. As the corneal topography remains stable Phacosection is compatible with multifocal IOLs. This technique is ideal for pediatric cataracts, where the lens is aspirated and CCC, PCCC and Vitrectomy

performed within the limited space. This technique offers maximal endothelial protection and is ideal for endothelial dystrophies and post-keratoplasty surgeries. In complicated intraoperative situations, the adequate tunnel size makes the maneuvers easy and safe, maximizing endothelial protection and minimizing tissue handling and postoperative uveitis. The tunnel is nonleaking, does not need hydration, and so this technique is ideal when posterior segment surgeries like RD and vitrectomy are contemplated along with. The tunnel remains sealed through out posterior segment surgery, unlike any other techni-

ques, and at any point of time it could be opened again, like while delivering a dislocated nucleus or an IOL. The low IOP during the entire procedure makes Phacosection an ideal technique for cataracts associated with trauma, uveitis and glaucoma. There are no contraindications for this technique. Never perform this technique with tunnels smaller than 6 mm. It is only in phacoemulsification that you need small and tight tunnels, and not in SICS. It is advantageous to have a 6 mm wide tunnel, and this minimises endothelial damage. Beginners need to avoid very soft and very hard nuclei during the learning phase.

INTRODUCTION

Scleral tunnel nonphako cataract surgery has evolved over the years. It started with the type of incision, then went on to the site of incision and now has progressed to include the size of the incision.

Type of Incision

It has been well established that the frown incision lends to the most astigmatic neutral tunnel. Also the shape of the incision allows maximum manipulation during intra ocular lens implantation.

Site of the Incision

Initially, it started with the superior position and subsequently the surgery has evolved and now you have surgeons routinely doing superotemporal and temporal approach.Though there is a risk of endophthalmitis with the temporal site with the routine 6 mm incisions, no studies have been done to document this hypothesis.

Size of the Incision

The square incisional geometry principle states that for a tunnel to be self sealing the length of the tunnel has to be greater than the length of the external incision. Most surgeons take a 6 mm incision. Now considering the above principle , it is theoretically impossible to form a self sealing scleral tunnel with a 6 mm scleral incision. At least one suture has to be taken to make the tunnel secure.

To summarise , most surgeons today do small incision cataract surgery using a 6 mm frown incision

at the superior position. The main concerns with this type of surgery are,

1.How secure is the wound if you leave it sutureless. Though most surgeons tend to leave the wound sutureless, the risk of endophthalmitis does exist.

2.The amount of astigmatism that is produced. The scleral incision lends to lesser astigmatism compared to the corneal, yet most surgeons do get a Astigmatism in the zone of 1 Diopter.

In order to overcome the above problems, at our institute we are routinely doing 3 mm SICS. In this chapter, we will describe the technique, the modifications that we have done and the studies that we have conducted.

INCISION

I prefer to give a peribulbar block using 3 cc of Lignocaine and 2 cc of Sensocaine mixed with Hynidase. After achieving adequate hypotony, I take the superior Rectus stitch if I am doing the superior approach, though many surgeons today forego this step, I prefer to use it as it gives more stability during wound construction using a 3 mm incision. After taking the conjunctival flap and applying minimal cautery, I plan the site of the incision depending on the preoperative Keratometry findings. If there is a greater than 1.5 D difference between the 2 K readings, I take my incision at the steeper axis; otherwise I routinely take the incision at the superior site.

I take a 3 mm frown incision 1.5 mm away from the limbus upto 0.25 mm deep using a 11 no blade. Then using the beveled crescent, I dissect the scleral tunnel; the corneal dissection is upto 1.25 mm at the superior

location and 1.5 mm at the temporal location. I make the scleral side-pockets. Then using a 3.2 Keratome, I enter the AC and extend the entry upto 7 mm. I reform the AC using viscoelastics. Contrary to conventional practice, I feel that making the entry big before starting the rhexis helps in the procedure. With the 3 mm external entry and the use of viscoelastics, collapsing of the AC is no longer an issue. As the entry is big and the AC slightly shallow, the bend 26 no needle remains in a more horizontal plane thereby helping in the smooth movement of the flap.

CAPSULORHEXIS

It is very important to get the size correct, the bigger the rhexis, the better it is, as it is easier to prolapse the nucleus from the bag. The adult lens has a diameter of around 9.5 mm, also the zonules arei inserted upto 2 mm from the equator posteriorly and 1.5-2 mm from the equator anteriorly. This leaves us with a 7 mm clear zone to work on. So when you attempt a big rrhexis, it is important to remember that the zonules are not far away. I start by first taking a 2-2.5 mm knick on the anterior capsule extending from the center to the 5 o’clock position . it is very important to follow this as the centre is the point of maximum convexity of the lens, so when you turn the flap on itself and start rotating it, you get better control on it. After taking the nick I take

another nick of 1-1.5 mm 60 to the above nick and by nudging the angle with the blunt end of the 26 no needle I turn the flap on itself. This initial step if well done is half the job well done. Most beginners will testify to the fact that when they fail to do a rrhexis it is either at this stage or when they try to rotate the flap at the 12 o’clock position.

After the initial flap is made, I press on the edge of the flap at the junction of the torn and the intact capsule and rotate towards the centre. At every stage ensure the AC is well formed and that the flap is rolled on itself. The next crucial step is when you join the flap to the place from where you started, do not bring the bent 26 no needle in towards the centre , keep moving in the periphery till the two ends meet.

HYDRODISSECTION

After extending the AC entry using the 3.2 Keratome, the general rule followed in conventional SICS is that the internal entry should be 1.5 times the external entry. But as the external entry here is just 3 mm, the same does not apply here. I generally make the internal entry around 7 mm. then using the 27 gauge cannula, I first go to the 5 o’clock position, just lift the capsule and inject saline and see the fluid wave pass. As I am doing this I apply minimal pressure with the cannula on the lens, so that the fluid wave reaches the opposite pole.

Remember that, you have to be very careful during this procedure, if you suddenly inject too much fluid the intra bag pressure suddenly rises and give rise to a rent. Another thing that you must pay attention to is that the fluid wave should reach each and every quadrant, otherwise during irrigation and aspiration, it gets

This is the most important step in the surgery. Here is where my modified vectis and modified viscoelastic cannula come into play.

The modifications that I have made include:

•Introduced serrations on the upper surface and introduced a transverse bar in one.

Figure 12.6: Modified viscoelastic cannula

What I do is that after I have adequately cushioned the nucleus with viscoelastic, I enter the AC with the modified vectis. This vectis has a transverse bar and serrations on it. Both these modifications make it easier to engage the nucleus. I make sure that the the forward end of the vectis lies above the iris diaphragm smoothly. Once the nucleus is engaged, inject viscoelastic above the nucleus to create space between the endothelium and the nucleus Then using the lmodified viscoelastic cannula which has a pointed bend (< 0.5 mm) at the end, I press on the nucleus while it is lying on the vectis, simultaneously pushing visco into the AC, all the while applying the pressure downwards. As a result of this, the nucleus breaks into multiple pieces and the visco being pushed separates the two pieces. Then using the vectis I remove the pieces out of the AC.

After this I perform irrigation and aspiration. Then using the injector I inject the lens in the bag using an injector.

Figure 12.8

CONCLUSIONS

The 3 mm SICS is routinely being performed at our center.

The results of the first 50 cases performed at our center were presented at the AIOS 2005 at Bhubaneshwar

and another paper comparing the superior to the temporal site using the 3 mm scleral tunnel has got accepted for the AIOS 2006 at Bhopal.

The postoperative rehabilitation of the patient is much faster compared using the 6 mm tunnel. The incidence of postoperative keratitis though higher is not statistically significant. The surgically induced astigmatism is in the range of 0.75 D ATR with the number stabilizing around 2 months postoperative.

IMPORTANT POINTS TO NOTE (Do’s and Don’ts)

•A beginner should not attempt 3 mm MSICS. It can be tried by a surgeon who is adept in MSICS.

•One who is planning to go for 3 mm MSICS gradually reduce the size of incision, start with 6 mm incision.

•Dr Sahu modified instruments are a must.

•Only try temporal 3 mm msics after mastering 12 o’clock and upper temporal MSICS

•For controlled incision fix the eye by a plain forceps, hold both end of cut conjunctiva, right handed surgeon fix left side, left handed surgeon vice versa. Don’t pull the conjunctiva push forcep lightly against the sclera to stabilize the eye ball.

Incision

I use 11 no BP knife with the holder. Blade is kept at 70 degree to the surface of the sclera. Blade is entered 1/3 through sclera thickness. There is no way to measure it except the feel at your finger tip. I prefer frown incision.

1 mm back cut on either end of the incision is a must in my technique. If it is a straight line than back cut is slightly slanted outward. If it is a frown incision then back cut is straight back ward.

Always use good instrument not cheap instrument even if it is disposable. It may be comparatively costly but you will enjoy your surgery. 2.8 keratome, tunnel knife and mvr knife all can be autoclaved used at least 3 times. Don’t use instrument that makes you struggle.

Rhexis

If you plan to do rhexis through side port first complete tunneling, stop before entering a/c then make side port with mvr knife. Infuse dispersible viscoelastic, complete rhexis with 26 no bent needle. Use Tryphan blue as and when required to stain the anterior capsule.

If I want to do rhexis through main port and Planning a foldable IOL implant I do not extend internal

lip till the periphery, keep it 5 mm as close to square incision as possible. Internal lip is more than the external just to facilitate to delivery of divided nucleus. If I am planning a PMMA lens (5.25 mm) then I make pocketing (separating sclera by the side of back cut incision) this provides space for the movement of PMMA lens while the frown incision stays 3 mm. Internal lip is extended to the periphery (7 mm) by forward movement of 2.8 keratome making the tunnel look like funnel.

Hydroprocedure

I use a cannula with a oval cut edge on the surface at the tip. Introduce the cannula between the posterior surface of anterior capsule and anterior surface of the nucleus inject BSS slowly. Solution hits back of anterior capsule, spreads uniformly behind, between posterior capsule and cortex. You will see fluid wave and golden ring if it is grade1 or grade 2 cataract. If you don’t see wave or ring do not worry. I prefer to do hydration at multiple sites. While infusing solution I go on compressing the nucleus, which helps spread of solution behind. Then I dial the nucleus clock and anti clockwise 3 times each, this maneuver loosens cells in the periphery which are subsequently are removed by simco cannula during cortex removal procedure.

Nucleus Delivery

I have devised my own technique for which I have modified the dialer, vectis and visco cannula. I pull the anterior capsule rhexis margin towards myself then go behind the nucleus with my dialer and nudge the nucleus out. One word of caution do not try to bring out the nucleus if the rhexis is small (less than 5 mm), either make it big or give two relaxing incision at 11 and 1 o’clock with bend 26 no needle which is being used for rhexis.

Never try to bring out the nucleus without making it freely mobile, move it 3 to 4 time in circular fashion, it reduces chance of PCO in future and help delivery of nucleus easy.

Dr Sahu’s MSICS Stop and Chop

Nucleus is brought on the surface of iris after nudging then clock and anticlockwise movement.

Inflate AC by infusing dispersible viscose behind the nucleus see all parts of iris going behind, position Dr. Sahu’s modified vectis behind the lens above the iris diaphragm. By your left hand hold the vectis behind

the nucleus and above the iris diapram it there, see to it that you don’t capture iris in the opposite site otherwise iris disinsertion will happen along with bleeding clouding of anterior chamber. Once lens is stabilized with the vectis behind, (don’t lift the lens otherwise lens will rub against endothelium) create space between the lens and endothelium by infusing viscoelastic through Dr. Sahu’s modified cannula. Infuse viscos at the margin of internal lip of tunnel above the lens below endothelium see space being created, move the cannula in the space while constantly compressing the nucleus down ward, constantly infusing visco, while left hand keeps vectis steady. Against lens gets compressed against the vectis and through pressure breaks in to two pieces. Constant viscoinfusion separates two broken pieces.

By the vectis broken pieces are glided out of the a/c through the tunnel piece by piece. Once lens piece is engaged in the inner mouth of the funnel compress the floor of the tunnel with the vectis while gliding out the divided nucleus piece. During this procedure do not rub lens against endothelium.

Cortical Cleaning

Cortical cleaning is done through side port and main port by simco cannula

Lens Implant

Lens implant is done by injector.

i.e. the external incision is kept 1-1.5 mm from the limbus (Figure 13.4).

The tunnel is dissected, starting from the 6 mm groove, using a crescent knife until the blade is 2 mm inside the clear cornea. The tunnel is fan shaped so that the internal incision is about 20% wider than the external incision. Scleral side pockets are also made with the crescent knife (Figure 13.5).

A 3.2 mm keratome is then used to enter the anterior chamber (Figure 13.6).

After this Trypan blue is injected into the anterior chamber, under an air bubble. The air bubble protects the endothelium from being stained with the dye. The Trypan blue is then washed out of the eye with balance salt solution leaving the anterior capsule of the mature cataract stained blue.

The anterior chamber is then reformed with the viscoelastic (Figure 13.7).

A 26-gauge needle fashioned into an irrigating cystitome is used to create the continuous curvilinear capsulorhexis (Figure 13.8).

In case of a swollen white cataract, the rhexis is deliberately kept very small in the beginning as the rhexis edge tends to go towards the periphery. When the capsulorhexis is nearly complete, the corneal end of the tunnel is extended on either side with the keratome or the crescent knife (Figure 13.9). The anterior chamber is maintained with the viscoelastic throughout this procedure. The Utrata forces are used to complete the rhexis, making it wider at the same time.

A forceful hydrodissection makes the nucleus tilt up on one side (Figure 13.10). If the nucleus is very hard and rigid, it is not flipped upside down, but is instead, gently cart-wheeled out of the capsular bag by dialling, using the bimanual technique (Figure 13.11). A smaller or a softer nucleus flipped upside down and brought