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

Figure 16.11: Cortical clean-up

A little ‘tapping’ at the scleral incision at this stage will expel the remaining free epinucleus, part of which may have got stuck in the tunnel itself.

CORTICAL CLEAN-UP

This part is the most enjoyable in this technique. Because of the ACM, the irrigation aspect is automatically taken care of, and a deep, closed chamber ensures easy accessibility of cortical remnants. I prefer using a J-shaped, round tipped, top opening 23 G canula attached to a disposable 5 cc syringe for this job. It is introduced through one side port and cortex is sucked, drawn free, and aspirated by gentle movements and changes in aspiration pressure. Because of the ACM, the chamber remains constantly deepened, and even the equatorial cortex becomes easy to hold (Figure 16.11). If the freed cortex chunks appear difficult to aspirate, just release them in the AC. One tap at the outer lip of the incision will expel them in a second. This is the magic of ACM. One should not try to bring them out through the side port, as they’re sure to get stuck there, and you’ll be busy removing these from the second side port.

The two side ports together provide a complete 360degree reach for cortex extraction. One can use a sand blasted tip to polish the under-edge of the anterior capsule. Alternatively, just aspirating with the regular canula can also help denuding the remaining epithelial cells from the anterior capsule.

There are wonderful alternatives for polishing the posterior capsule in this technique. Attaching a J-shaped, round tipped, bottom opening canula to a glass syringe without the plunger, one gently moves it over the posterior capsule. The positive pressure in the AC created by the ACM combines with the negative pressure in the glass syringe (because of the absence of the plunger) to produce a 0-degree suction at the tip of the canula. This bottom opening of the tip, when it is gently moved over the posterior capsule, sucks up whatever debris may be remaining there. Alternatively, one can employ the technique of ‘Water-jetting’, wherein gentle puffs of water from a 26 G cannula are directed at different parts of the posterior capsule to effectively dissect out the adhering remnants, sometimes even plaques. Small leakages of BSS from the side port engaging the 26 G cannula prevent the pressure from rising to dangerous levels.

IOL INSERTION

The step now being described is specific to the Blumenthal’s technique where the lens is being implanted without the use of viscoelastic material, but may be equally beneficial in other modalities too. I like to describe this as “Pull and Dial”, in contrast to the “Push and Dial” step employed generally. The explanation being that as you try to ‘push’ an IOL through the tunnel into the AC, the BSS tends to gush out as the McPherson’s forceps is unable to block the tunnel effectively. This is likely to give you a capsular bag wherein the posterior capsule is convex, rather than concave. The likelihood of PC rent with the haptic becomes very high.

To prevent this, I insert the inferior haptic followed by the body of the optic into the tunnel, holding it with the forceps. At this point, the haptic and the lower dialing hole on the optic are visible in the chamber. I now release the optic, only using a plane forceps in the left hand to hold the superior haptic, preventing it from altering the angle of the IOL. With the right hand, I enter from the side port with a Sinsky hook and engage the lower dialing hole on the optic which is lying within the AC (Figure 16.12). This is now dragged down and towards 6 o’clock position till the lower haptic and lower part of the optic is safely in the capsular bag. As the optic gently slides in, the tunnel keeps closing over it, thereby preventing any shallowing of the AC. The upper dialing hole is now engaged with the same hook, and the upper haptic is dialed into the bag (Figure 16.13).

Figure 16.12: Implantation technique engaging lower dialing hole

Figure 16.13: Implantation technique drawing the lens downwards from upper hole

CLOSING UP

There isn’t much left to do in this. The wound is checked for leaks, i.e. the chamber of the IV set is viewed while gently pressing on the eye, near the 9 o’clock or 3 o’clock limbus. If there is excessive outflow of BSS, it suggests a leaking wound. The tunnel is checked for residual debris which may be the cause. Removing the ACM now will produce a slight shallowing of the anterior chamber and narrowing of the pupil (Figure 16.14). If

Figure 16.14: Checking for leaks

felt necessary, the chamber may be deepened by injecting some BSS from a side port. The side ports and the ACM port may be sealed tighter with stromal hydration if needed (more so for the surgeon’s sound sleep). The slight corneal haze that appears as a result is of no risk, and would vanish by the next morning.

The conjunctiva may be apposed with bipolar cautery, or simply drawn down over the wound and left there.

DO’S AND DON’TS

The advantages of the Blumenthal’s technique are the same as those of using an anterior chamber maintainer. I’d like to list them out systematically here:

1.The use of BSS exclusively maintains the normalcy of the AC to a larger extent throughout the surgery, thereby decreasing the release of Prostaglandins and such, which is evident in the lower inflammatory reaction in the anterior chamber the next day. The reduction in the chamber, depth fluctuation and turbulence are also contributory factors.

2.During all steps, as mentioned earlier with each step, the presence of the ACM eases the maneuvers, particularly for one converting from ECCE to MSICS.

3.In cases of PC rent, the ACM pressure prevents a break in the vitreous face, allowing you to convert the rent into a posterior capsulorrhexis. If vitreous face does break, it is still prevented from prolapsing much into the AC. If anterior vitrectomy is needed, the ACM provides the irrigation, leaving one hand

of the surgeon free to hold another instrument, like the light-pipe.

4.Playing with the height of the BSS bottle, you can control the pressure in the eye, making this technique a truly ‘Controlled’ surgery. For example, you can raise the height to 70 cm for CCC and nucleus expulsion, lowering it to about 45-50 cm for the other steps. It can be lowered even further, to 20 cm or so, in case of a break in the anterior vitreous face. It is known as to approximately what IOP can be expected at different heights of the BSS bottle.

In fact, for most of us who’ve adapted to this technique whole-heartedly, fitting the ACM becomes second nature, reflexly doing it like fitting the speculum before starting surgery.

From repairs, to repolishing of posterior capsule, to repositioning of an errant haptic (of another surgeon’s

case), we find the ACM an indispensable tool. It acts as a third hand for the surgeon, justifying the extra few seconds spent in fitting it, as well as creating an extra opening in the eye.

(Illustrations/photographs Courtesy Indian Journal of Ophthalmology and Jaypee)

REFERENCES

1.Thomas R, Kuriakose T, George R. Efficient Small Incision Cataract Surgery. Indian Journal of Ophthalmology 2000;48:145-51.

2.Blumenthal M, Askenazi I, Fogel R, et al. The Gliding Nucleus. J Cataract Refract Surg 1993;19:435-7.

3.Blumenthal M. Surgical principles and techniques for Small Incision ECCE. Mini Highlights of Ophthalmology 1993;21:5(1-8).

4.Trivedi N. The techniques of IOL Implantation in SICS, Small Incision Cataract Surgery 155-7 (K Singh; Jaypee).

INTRODUCTION

The suprahard Cataract pose distinct problems in Manual SICS.

1.The nucleus being hard will not mould through the incision.

2.The nucleus is sclerotic in nature and there is hardly any epinucleus.

3.Sometimes the nucleus is as big as 9 mm in diameter (which requires a 9 mm internal incision and an internal corneal valve to keep the incision self sealing).

4.The nucleus may also be 5 mm thick (which requires additional scleral pocket dissection to accommodate the nucleus in the tunnel).

5.This nuclear dimension (requires a big rhexis for safe prolapse).

6.The zonules are also weak which makes nucleus prolapse very tricky and any rhexis-to-nucleus size disproportion leads to zonular dehiscence.

7.The cataracts have capsular adhesions which makes nuculear rotation and prolapse more troublesome.

8.To complicate all these they also have small rigid pupils due to senility, previous surgery (glaucoma, vitreoretinal surgery, etc) or pseudoexfoliation.

9.The endothelium is also weak with age or existing disease or surgery.

10.The nuclear thickness results in a relatively shallow anterior chamber making anterior chamber maneuvers difficult.

This relatively shallow anterior chamber with the big nucleus filling up the whole anterior chamber coupled with zonular weakness, hardness of nucleus and weak

endothelium leaves very little scope for phacofracture techniques. On the other hand, the whole big nucleus to be delivered through the sclerocorneal flap valve incision requires the internal and the external incision to be big and roomy (adequate scleral pockets). However constructing such an incision with a intact self sealing internal valve is not easy. Delivering such a big hard nucleus by hydroexpression (Blumenthal’s technique) would require a still bigger incision. It is a passive process and the nucleus is expected to engage in the internal incision and expressed through the tunnel by opening the incision with posterior lip depression. Hydrostatic pressure is the only expression and guiding force. The irrigating vectis develops the hydrostatic force in the anterior chamber but more importantly it mechanically directs the nucleus through the internal incision and tunnel to the external incision by its movements and simultaneously opens the incision by posterior lip depression. Delivering the hard nucleus with irrigating vectis technique remains a safe method and some incisional considerations have to carefully incorporated to facilitate the process and keep the incision self-sealing in nature. However if the self seal is lost it can always be recovered by sutures. Keeping the endothelial and zonular considerations in mind, it is always important to give a bigger incision (to err on the safer side) rather than to concentrate on the sutureless self sealing issue of the incision.

THE OPERATION

The operation is described from the head end (the conventional position). A temporal approach can be done without much modifications to correct pre-existing ATR astigmatism or in postglaucoma surgery eyes.

Figure 17.1: White cataracts

Figure 17.2: Opening the rhexis

Anesthesia

The operation is performed under topical lignocaine 4% drops with intracameral lignocaine 1% . Peribulbar anesthesia is the perfered practise as age (elderly patients tending to be less cooperative) and the deep set eyes which these patients may have, arcus and corneal haze may make visualisation difficult with the epithelium becoming clouded by topical lignocaine.

Incisional Considerations

Conjunctiva and Tenon’s is lifted together at 10-0 Clock limbus by a 2 in 1 corneal forceps in the left hand and

Figure 17.3: Can opener capsulotomy

Figure 17.4: Irrigating vectis technique

cut. A rim of 1 mm conjunctiva is kept intact at the limbal end to preserve the stem cells which promote quick healing. The conjunctival cut is continued from the right to left 10° to 2° clock parallel to the limbus by a corneal scissor in the right hand. The conjunctiva is retracted back to the upper fornix by nudging with 15 no bard parker blade in the right hand. The globe is fixed by the corneal forceps in left hand (now gripping the sclera) at 2° clock away from the proposed site of external incision. A few blunt strokes of the BP blade on the sclera pushes back any Tenon’s which may adhere to the sclera. The bare sclera in the incision site is exposed. This gives a smooth external incision. Gentle

cauterisation is done with a wet field cautery along the vessels (incision site cautery is avoided as far as possible). A 7 mm frown external incision (centered at 11 o’ clock) is given 1.5 mm behind the limbus with a 15 no. BP blade from left to right, the globe being fixed with forceps in the left hand. The eyeball is curved like a globe so the depth of the incision in the beginning is shallow and deep in the centre with same pressure of the BP blade. Hence a conscious effort is directed to begin the incision boldly and gradually ease the pressure in the centre and the again gently press as the incision comes down from center to the right. A uniform halfthickness of the incision is important as this leads to the plane of tunnel dissection. A button holing of the roof of the tunnel occurs in the periphery (because the external incision tends to be shallow in the periphery) while a premature entry into anterior chamber occurs in the center (as the external incision tends to be deep in the center). The tunnel is dissected by a sclerocorneal splitter or crescent blade. The globe is fixed by the left hand forceps. The scleral grip of the forceps should be good because it gives counterforce to the sclerocorneal splitting. The splitting is started from the left by gentle swipes and wriggling action of the splitter forwards. The splitting to create the tunnel should start from the split area and carried to the right. A new plane should not be started at another site because then the tunnel becomes multiplanar. While approaching the cornea end the heel of splitter should be kept down as the cornea is more curved than the sclera and a premature entry may occur. Adequate 2 mm additional elliptical

scleral pockets must be dissected from either side of the 7 mm external incision. The scleral pockets are like pleats of our trousers which will accomodate the thickness of the nucleus (like the trouser pockets accommodate the fist of our hand) The scleral pockets can be continued down to 3 and 9 o’ clock till it reaches the biggest horizontal diameter of the cornea and the eye. Similarly the scleral tunnel dissection should also be carried down to 3-9 o’ clock area. Corneal valve has to be dissected 1.5 mm wide parallel to the limbus upto 3 and 9 o’ clock. This gives a large corneal valve and biggest internal incision can be given from 3-9 o’ clock. If the white-to-white diameter is 11 mm and a 1 mm corneal valve is kept on either side a 9 mm internal incision is possible with safe corneal valve on either side.

The internal incision is given by a bevel-down keratome, the globe being fixed by the left hand forceps. The keratome finds its plane in the tunnel and then it is guided up negotiating the corneal curvature and them dimpled down to enter the anterior chamber (AC). The entry must be parallel to the external incision. If the entry becomes slightly oblique (usually it is oblique in the left side which becomes closer to the limbus.) The corneal valve is lost on the left side as it crosses the limbus. Only corneal tissue is elastic scleral tissue is not. If the internal incision crosses the limbus and extends to the sclera the self sealing action of the whole incision complex is lost. AC is reformed tightly by viscoelastic.

The internal incision is enlarged first on the left as this is where the valve generally slips to the limbus. The

keratome cuts while entering and not while coming out. The keratome enlarges the internal incision tip guided centripetally towards the pupil. Care is taken to see that the valve does not slip into the limbus and the internal incision is carried to the 3 and 9 o’ clock to give the maximum internal incision. The anterior chamber is reconstituted with viscoelastic if it shallows at any point. Clear corneal triangular side ports are given in different corneal planes at 2 and 10 o’ clock region with their apex towards the AC. In all procedures the globe is fixed by the corneal forceps gripping the sclera at 2 o’ clock beyond the incision. The anterior chamber is reconstituted with viscoelastic tightly after the incision is over.

The Incision on the Lens (Capsulorhexis)

The forceps grip of the left hand acts as an X-Y of the microscope also centering the eye in the microscope field and making the eye co-axial with the scope. The rhexis is initiated by a linear cut from center to the periphery by a bent cystitome or a bent 26 gauge needle. The visco-reconstitution is done whenever necessary. The linear incision is now lifted by a capsulorhexis forceps and turned curvilinearly on itself. Small tears are made. The torn end should be folded on itself by viscopressure and the tearing edge should be grasped and regrasped frequently making small advances each time. The rhexis is completed outside in so that the rhexis does not run to the periphery. A big rhexis is mandatory to prolapse the big hard nucleus. A big rhexis is achieved if the fear of peripheral escape is

taken away from the mind (If the rhexis escapes it may be restarted from the other side or converted to a canopener capsulotomy. Manual SICS is a exocapsular technique and a rhexis is desirable but not mandatory). The shallowing of the AC can be prevented during rhexis by holding the rhexis forceps fulcrumed on the roof of the tunnel rather than pressing on the posterior lip (which becomes a unconscious practice). Posterior lip depression opens the AC allowing visco to escape while lifting the roof of the tunnel closes the eye. The capsulotomy can be done from the side ports also or after the initial entry into the AC but the space is limited, and the rhexis forceps can get oarlocked. It becomes difficult to go to peripheral extremes to grasp and regrasp the capsule. If the rhexis appears smaller on completion than as desired a cut is made in the rhexis margin with an angled long blade vannus scissors. A second larger rhexis can be done. Alternatively multiple (at least 8-16) radial cuts are given in the rhexis alround to open it. This method virtually maintains a rhexis configuration without sharp floating anterior capsular tags which may be dangerous during cortical cleaning. The multiple release of the rhexis distributes the stress on the rhexis at multiple points so that the release does not extend behind to the zonule and the posterior capsule during lens rotation or prolapse. This method is quite efficient in smaller pupils (commonly associated with these cases). In case a strong capsular adhesion comes in the way which cannot be torn it can be cut by a angular vannus scissors or a can opener conversion can be done from there on.

In a can opener technique multiple small nicks are made by a sharp bent 26 gauge needle where one nick joins another until the whole circle is completed. The cut capsule can be removed by capsulorhexis forcep. Uncut tag is noticed and is cut by a bent angled vannus scissors. Good Anterior chamber constitution with visco and using the side ports to advantage to attend any peripheral area comes handy.

Staining the capsule with trypan blue (0.5%) is a good practice as it improves visibility and starches the capsule which facilitates rehxis. An envelope capsulotomy is also very effective. The triangular stab is made in the anterior capsule with a keratome. The opening in the capsule is enlarged by two cuts or either side. This capsulotomy works well in hypermature morgagnian or sclerotic cataracts. The anterior capsular flap can be torn after nucleus removal.

The AC is slightly debulked of visco to create space in eye to accommodate hydrodissection fluid.

Hydrodissection

The tip of a 2 cc syringe with hydrodissection cannula is placed between the capsule and cortex. The capsule is lifted slightly upwards and small amount of fluid injected. This is repeated in multiple sites until the nucleus bulges anteriorly and the AC shallows.

Nucleus Rotation

AC is deepened by visco. Two blunt copeland hooks are introduced from the 10and 2- o’ clock side ports. The nucleus is engaged and rotated clockwise gently with equal torques in both hands. Any resistance would suggest incomplete hydrodissection or a capsular adhesion. A repeat hydrodissection can be done carefully. If still there is resistance the forces are slightly increased. However excessive forces may cause zonular dehiscence in already week zonules in these cases. If corticocapsular adhesion is seen in the anterior capsule a separation may be a attempted by a iris repositor. If this separation is not accomplished, multiple release of the rhexis may address the issue safely without taxing the zonules.

Prolapse of the Nucleus

The anterior chamber is reconstituted by viscoelactic, one Copeland hook through one side port is dipped to engage the nucleus to pull it away from the rhexis margin towards the center while another Copeland from the other side port pulls the rhexis at the same

Figure 17.9: Open and close chamber surgery

point towards the periphery till the equator of the lens comes clear of the rhexis. Now the Copeland engaging the nucleus is dipped further so that the equator of Lens prolapses from the rhexis margin while the other Copeland now goes behind the equator pushes the nucleus upwards further facilitating prolapse. Once a part of equator is prolapsed the two Copeland walk on the equator of the lens in tyre rolling fashion to bring the whole nucleus out of the bag. However great care must be executed in this maneuver. If this does not occur them the rhexis is smaller for the nuclear size. Undue force to accomplish prolapse may result in zonular dehiscence. If the resistance is not overcome with regular force the rhexis should be released with multiple incisions.

Nucleus Delivery

The irrigating vectis is a smart little instrument which is a vectis but has an irrigating line built in it. This is connected to the irrigating bottle and a continuous irrigation is achieved. Viscoelastic is given above and below the nucleus. The eye is aligned in downward gaze by the left hand forceps grip on the sclera to facilitate the introduction of the irrigating vectis. Once the irrigating vectis is negotiated behind the nucleus the eye is aligned in co axial or straight up position by the left hand forceps. The vectis should not press on the posterior lip as the hydrostatic pressure needs to build at this stage to facilitate the nucleus to engage in the internal incision. If this engagement does not happen

and nucleus moves in AC the vectis should be withdrawn and the internal incision enlarged. Once the engagement occurs the vectis presses the posterior lip of the incision thereby opening the incision and it is simultaneously withdrawn thereby facilitating nucleus removal. The left hand forceps also at the same time moves the eye from co-axial or straight gaze to upward gaze facilitating the process. This expression is a automatic process.

A common apprehensive mistake during this stage is to pull the vectis up towards the roof of the tunnel and not press on the posterior lip of tunnel which opens the incision. The pull up and lifting the roof of the incision actually closes the incision further and rubs the nucleus against the endothelium. In fact the whole trick lies in mastering this movement. The posterior lip depression is avoided because we think we will disturb the posterior capsule and vitreous which is not possible since the fluid from irrigation vectis always pushes the posterior capsule back. If the nucleus is trapped in the tunnel we must see if more than 1/3 of the nucleus is in the AC then the vectis is gently withdrawn by posterior lip depression and nucleus pushed back into the anterior chamber with a Copeland hook. The AC is firmly reconstituted by visco and the internal incision, scleral pockets and external incision carefully extended and the procedure repeated again. It is always better to err on the bigger side loose the self seal and give stitches then to damage the endothelium.

Another consideration is because of our forearm gets stuck in our belly our right arm operates from the side of our trunk the vectis (or any other instrument) moves in 5 to 11 o’ clock axis rather than a 6 o’ clock to 12 o’ clock vertical direction. So the right side of incision is more used where as the left side remains redundant. A incisional enlargement can be done more in the right side (if it is centered at 12). For the same season it is

important to centre the incision at 11 o’ Clock rather than at 12 o’ clock. If almost all the nucleus is stuck in the tunnel and a part of nucleus is prolapsed from external incision, the nucleus can be fractured in the tunnel safely and remaining piece pushed back into the AC realigned in the vertical direction and delivered. The synchrony of the left hand guiding the eye position, the irrigating vectis building hydrostatic pressure, engagement of nucleus to posterior lip depression and withdrawal of vectis and nucleus delivery is a one action procedure.

Cortical Cleaning

The cortical cleaning is done through the side port by a left hand suction simcoe cannula. The subincisional cortex can easily be accessed. The cortex under the side port can be cleaned through the main wound. It is important to clear the scleral tunnel of cortex or any nuclear debris because if they are trapped it may lead to persistent uveitis and an irritable eye.

The IOL is introduced as usual under viscoelastic cover. It is important to flush the visco between IOL and posterior capsule as retained visco is the main cause of TAS and raised IOP. Washing behind the IOL is a safe and essential practice.

The AC is reconstituted by hydration through the sideport and perfect apposition of the main wound assessed by pressing on the posterior lip of the incision. If there is leakage a stitch is given to close the incision properly. Incision integrity goes a long way in quick wound healing immediate visual recovery, less astigmatism and all above prevents any post operative spill from outside into the eye thereby preventing endophthalmitis. The conjunctiva is repositioned and cauterised. Good conjunctival apposition also prevents endophthalmitis and promotes quick wound healing.

STEP 1: ANESTHESIA

Material Required

i.Topical proparacaine 0.5%

ii.Lignocaine 2% 0.5 cc (preservative free)

iii.25 G curved cannula attached to 2 cc syringe.

Procedure

i.Topical proparacaine 0.5% is instilled in cul-de-sac. Conjunctiva two minutes before surgery and repeated whenever required.

Conjunctiva dissected at limbus of required length.

ii.Hemostasis achieved.

iii.Pocket is created in the superio-temporal region under conjunctiva.

iv.Curved canula 25 g. With blunt tip mounted on 2 cc. Syringe with 0.5 cc of lignocaine 2% is inserted behind the eyeball through the pocket created in the conjunctiva and anesthetics is injected

v.Wait for 30 seconds.

STEP 2: ANTERIOR CHAMBER

MAINTAINER (ACM)

Material Required

i.Olive type 20 G cannula attached to very thin silicon tube

ii.20 G MVR angled knife

iii.BSS with irrigation system attached to adjustable stand.

Procedure

i.1.5 to 2 mm size incision is made into the clear cornea at 6 o’clock position with 20 G. MVR knife

ii.With irrigation on and bevel up ACM is forced into the AC.

iii.Bevel turned down when ACM is in AC.

iv.BSS Bottle height 65 to 70 cm from the eye.

Advantages

i.Always positive pressure in the eye (i.e. 40 mm Hg) which facilitate the anterior lens surface to become flat upto some extent, enhances controlled CCC.

ii.ACM is put before making tunnel.

iii.Easy intraocular manipulations.

iv.More visibility of AC than viscoelastics.

Disadvantages

i.Mild AC turbulance due to irrigation jet-raised CCC flap of anterior capsule keeps on moving.

ii.Insertion of foldable IOL with holder forcepsdifficult.

STEP 3: SIDE PORT INCISION

Material Used

i. 20 G MVR knife.

Procedure

i.Stab incision is made with 20 G MVR knife at limbus at convenient site.