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

Technique: Fish Hook is made of a 30 G ½ inch needle, bending it with fine pliers or a needle older. There are two bends:

1.The tip of the needle which wil insert in the central nucleus.

2.A slight bend between the tip and the plastic mount to assure an easy insertion between the lower part of the nucleus and the posterior capsule.

The hook is mounted on a 1 ml tuberculin syringe and can be reautoclaved.

After completing the rhexis and hydroprocedures, viscoelatic is injected between nuclues and posterior capsule and into the anterior chamber. The bent 30 G needle hook is inserted between nucleus and posterior capsule with the sharp needle tip pointing to the right slide. Then hook is turned and slightly pulled back so that the neelde tip is engaged into the central lower portion of the nucleus.

Without lifting, the nuclues is pulled out of the capsualr bag and through the tunnel. Cortex remains in the anterior chamber, acts as a cushion and thus protects the endothelium from any contact with the nucleus. Once the tip of the hook is correctly inserted into the nucleus, there is no risk to damage any part of the eye.

Advantage

•It is less expensive

•Sophisticated instruments are not required

•Easy to learn

•It can be widely used in case of high volume camps where large numbers of cataract surgery are to be done in short time.

Disadvantage

•Insertion of Fish hook is important. The tip should not touch the corneal endothelium or the Descemet’s membrane should not get detached.

•May not be useful in all cases of hard cataract.

Phaco-punch Technique

This technique requires the use of phaco-punch which was designed by Dr Bidaye.

Instruments: It consists of irrigating vectis with a plate in the base and ridge at its distal rim. The three irrigating ports allows viscoexpression, the ridge allow fracture of nucleus and plate help in sandwiching the nucleus between it and scleral corneal lip.

Technique: The irrigating phaco-punch is connected to HPMC syringe and is passed below the nucleus. Corneal endothelium is protected by cushion of HPMC.

Figure 35.19: Technique showing the use of Bidayes Phaco Punch (Courtesy: Dr Vilas Bidaye)

By injecting HPMC pressure is slowly built into the anterior chamber. The increased pressure will push the nucleus out of the wound gape, along the path guide by the punch by depressing the scleral wound with the punch.

The small ridge at distal end prevents the nucleus sliding back into the eye and creates cleavage line for short bite of nucleus. The plate prevents iris prolapse and serves as sandwich plate.

The combined effect removes small bit of the nucleus and converts the round nucleus into bean shaped nucleus. The nucleus is then rotated to align it in vertical direction along its long axis and is removed by injecting viscoelastic material

Hybrid Technique18

In the hybrid technique the nucleus is first sculpted with the phacoemulsification. The nucleus is then prolapsed into the anterior chamber and removed by any methods of nucleus delivery.

This technique is mainly useful for beginners who have started learning phacoemulsification. The technique of phacoemulsification is practiced step by step till the surgeon gain confidence in emulsifying the entire nucleus.

Advantages of nucleus division over phacoemulsification

•It is easier to learn

•It is not machine dependent

•It is less expensive

•The time for removal of nucleus is not time dependent. In phaco the removal of nucleus depends on grade of nucleus

•High learning curve in phacoemulsification.

Figure 35.20: The slider pincer instrument. Note the inner part of the upper slider is sharp while the lowr part is flat to prevent it shipping off the nucleus held

Figure 35.21: Once the nucleus is in the anterior chamber, the jaws is insetedvia the 3.2 mm incision on the surface of the nucleus

Figure 35.22: As the slider is approximated it immediately slices through the nucleus. Literlaly with this instrument no resistance is noted even with the hardesh nucleus

Precaution to be taken in nucleus division

a.Initially always attempt the procedures on widely dilated eyes.

b.Approach each care with a mindset that will allow ready conversion to standard extracapsular cataract extraction, if there is difficulty in prolapsing the nucleus in the AC.

Jaws Slider Pincer Technique

This technique has been developed by Dr Keiki Mehta (India) for small incision, Non-phaco Cataract Surgery. All existing techniques at present are dependent on the lens lying flat with a hard nucleus being sheared off or chopped off with the nucleus lying horizontally flat abutting the posterior capsule. Risk factors involved with these techniques is that the dome of the cornea may be damaged with endothelial cell loss leading to corneal decompensation.

Instrument: The jaw slider Pincer forcep is a specially designed instrument to cut even the hardest cataract into the longitudinal slices. It has a tip designed as a beak of a bird and properly rounded to permit its easy entry into the eye. The jaws are made of hardened tungsten steel to prevent any whiplash on handling hard cataracts. The tips of the pincer forceps are designed with the part placed at 12O’ clock being blunt while the 6 O’ clock placement is made curved and sharp to permit easy slicing.

Technique: A good capsulorhexis and hydrodissection is done. Once the lens is made to rotate out. Out of the capsular bag, pincer forcep is introduced via the incision. It is introduced in its closed form, sideways and than gradually opened up to encompass the width of the nucleus. Once it is properly positioned, the jaws are closed which automatically sections the nucleus into two parts. In case of suprahard cataracts, it is necessary to cut the cataract into three or four slices. Always remember to cut the pieces longitudinally as cross cutting makes it more troublesome to remove. With the help of non-apposing curved forceps, the pieces can be easily removed in their entirety.

Advantages

•There is no stress on the incision which does not shear and lead to troublesome irregular astigmatism.

•It prevents the development of extensive endothelial cell loss.

•Simple effective technique which can be done easily with minimal risks.

The Double Wire Snare Splitter Technique

This technique has also been developed by Dr Keiki Mehta (India) for small incision nonphaco cataract surgery. Many splitting techniques are being used by Ophthalmologists to guillotine the nucleus. Single strands of wire, nylon or polypropylene have been used but the problem is that using a single looped snare does not efficiently work as holding the lens eccentrically leads invariably to the nucleus being irregular cut.

Instrument

A disposable splitter was designed using two strands of wire and a disposable needle. A 20 gauge needle is cut off at the tip and the edges are rounded but maintaining a slight bevel as it permits easier entry into the eye. It is made by using two strands of 28 gauge flexible stainless steel wire threaded through a 20 gauge blunted Disposable needle. Of the two loops of wire, one leg of each is entwined around the other. Thus the two loops are now converted to three strands. Such a dual splitter work simultaneously leaving three fragments of nucleus, each of which is smaller than 4.00 mm (Figure 35.23).

Surgical Technique

After excellent workup of Sclero-corneal tunnel incision, wound construction and capsulorhexis, Viscoelastic is placed in the anterior chamber and a blunt rotator is placed on the opposite pole of the slightly prolapsed nucleus to get it rolls over on itself into the anterior chamber. Now wire loop is inserted into the anterior chamber first horizontally and then gradually turned till they sweep over the edge of the nucleus and then snugly hold it. Following the trisection of the nucleus, usually the middle portion often simply slips out at the time of the wire loop removal. With the specially designed forceps which has special recurved tracks grooved into the jaws through a 4.00 mm incision individual fragments are held and simply removed in the single stroke (Figures 35.24 to 35.26).

Advantages

•The eye is exceptionally quieter.

•Harder the nucleus, the easier the trisector works which is the hallmark of this procedure.

•It is an exceptional technique not only for MSICS but also for the phaco surgeon who often face Hard cataracts usually coupled with compromised endothelium.

Figures 35.23A to C: Dual splitter: Manner of construction:

(A)Standard 20 gauge, 1” length disposable needle selected

(B)Loops extended. Note divergence (C) The four wires are knotted together and made into a small loop

•The advantage of splitting the nucleus into three parts permits easier removal of the smaller fragments through small incisions hence less iatrogenic Astigmatism.

Figure 35.24: Pull the loops snug to hold the nucleus. Note the spread of the wire loops

Figure 35.25: Note how snuggly the nucleus is held. It remains immobile

Figure 35.26: The nucleus is sliced into three parts

CONCLUSION

Thus there are different techniques for the removal of nucleus out of the wound. Each method has its advantages and disadvantages, which depends on the experience of the operating surgeon. The technique followed should be comfortable to the doctor and should give good postoperative visual results.

REFERENCES

1.Beirouty ZA, Barker NH, Shanmugam NS. Sutureless one-handed small incision cataract surgery by manual nucleosuction: A new technique for cataract extraction. Eur J Implant Ref Surg 1995;7:295-8.

2.Bucher P. Manual Phaco Fragmentation. A small incision cataract operation technique. Basel: University Eye Hospital; 1992.

3.Peter Kansas. Phacofracture. In: Rozakis cataract surgery:Alternative small incision techniques. NJ Slack 1990;45-70.

4.Luther L, Fry. The Phacosandwich Technique. In: Rozakis Cataract Surgery: Alternative Small Incision Techniques. NJ Slack 1990;71-110.

5.Gerald T, Keener Jr. The Nuclear Division Technique for Small Incision Cataract Extraction. In: Rozakis cataract surgery: Alternative small incision techniques NJ Slack 1990;163-91.

6.KPS Malik, Ruchi Goel. Nuclear Management. Manual of Small Incision Cataract Surgery 2002;39-58.

7.Samas Basak. My Technique of SICS using Irrigating Vectis. Manual of Small Incision Cataract Surgery 2001; 138-45.

8.B P Guliani, OP Ag. Our Technique of SICS, Fish Hook method. Manual of Small Incision Cataract Surgery 2003;1153-6.

9.Junsuke Akkura, Shuzo Kaneda, M Ishihara, K Matsura. Quarters extraction technique for Manual Phaco Fragmentation. JCRS 2000;26.

10.Junsuke Akkura, Shuzo Kaneda, Shiro Hatta, Kazuki Matsura. Manual Sutureless Cataract Surgery using Claw Vectis. JCRS 2000;26.

11.Bayramlar H, Cekic O, Totan Y. Manual Tunnel Incision Extra Capsular Cataract Extraction using Sandwich Technique. JCRS 1999;25(3):312-5.

12.P Kongrap. Pre Chop Manual Phaco Fragmentation; Cataract Surgery without a Phacoemulsification Machine. Asian Journal of Ophthalmology 2002;4(4):7- 9.

13.Hepsen IF, Cekic O, Bayramlar H, Totan Y. Small Incision Extra Capsular Cataract Surgery with Phacotrisection. JCRS 2000;26(7);1048-51.

14.Kansas PG. Phacosection.Manual Small Incision Cataract Surgery. Albany : International Ophthalmology Seminar 1994;1-158.

No surgical technique is exempt from complications which can occur at any step in the surgical procedure. Obviously, surgical skill is a very important factor in avoiding such complications, but equally important is the surgeon’s experience in dealing with these complications which only comes after performing a significant number of cataract surgeries.

One important factor in the frequency of complications is dependent on surgical preparation and the clinical status of the patient. From the point of view of a patient’s preparation, it is important that the type of surgical procedure to be performed, and the type of anesthesia to be used be explained to him thoroughly before the operation.

This psychological preparation will serve to increase the patient’s collaboration during the surgery whether with local or topical anesthesia.

On the other hand, before and during surgery, we need to maintain the patient in optimum condition with regard to blood pressure, heart rate, etc. as with any other patient pathologies (diabetes, hypertension, etc.).

Concerning the eye to be operated on, it is important to do a meticulous study of the anterior and posterior segment and intraocular pressure before surgery.

This will help in planning the surgery and diminish the frequency of complications.

INTRAOPERATIVE COMPLICATIONS AND THEIR AVOIDANCE

Wound Construction

The clear corneal tunnel incision or scleral tunnel incision both present the distinct advantage of allowing cataract surgery in a closed system. The location and

construction of the wound are factors in avoiding later complications during surgery. The location of the scleral tunnel incision should be between approximately 1.5 and 2.0 mm away from the limbus and the clear corneal incision should be made inside the limbus with an intrastromal tunnel between 1.0 and 1.5 mm. This will avoid a premature entrance into the anterior chamber and the iris prolapse during hydrodissection, capsulorhexis, etc., at the same time reducing the risk of Descemet’s membrane detachment.

In the scleral tunnel incision a frequent complication is during undermining, a buttonhole may occur in the scleral flap. This may be caused by a groove that is too shallow, either throughout or only in some areas. If the dissection is too deep this can produce scleral disinsertion. To avoid this it is necessary to make a tunnel of 0.30 mm thickness (Figure 36.1).

Figure 36.1: When underminig the wound the dissection should be carried into clear cornea at least half-way into the blue zone, within 0.5 mm or less of the conjunctival attachment line

Figure 36.2: In a small capsulorhexis several cuts should be made with a cystotome on the margin in order to facilitate an easier luxation of the nucleus

Bleeding from the incision into the anterior chamber is more frequent with scleral tunnel incision. Davis B. Davis, MD has pointed out that the most important consideration in the prevention of hyphemas is to undermine well into a vascular, clear corneal limbus before entering the anterior chamber. Bleeding can be managed by means of careful bipolar cautery.

Capsulotomy

The capsulorhexis should be sufficiently wide not less than 6 mm to allow an easy luxation of the nucleus into the anterior chamber. If the capsulorhexis is small we will encounter great difficulties in the luxation of the nucleus into the anterior chamber resulting in a zonular rupture. As such, we should enlarge the capsulorhexis by means of making various cuts on its margins with capsulotomy scissors and forceps or with the help of a cystitome (Figure 36.2).

Nuclear Luxation

Difficulty in nuclear luxation occurs primarily under two circumstances; when the pupil is small and when the nucleus is soft. Before surgery any pupil must be examined with respect to its size and rigidity. If the pupil is small and fibrotic, it is best to simply perform sphincterotomies (Figure 36.3), sector iridectomy or to stretch the pupil with two Kuglin hooks.

Soft nuclei may also present a problem with luxation. For the very soft ones, simple aspiration can

Figure 36.3: When the pupil is small and fibrotic several sphincterotomies should be made with capsulotomy scissors to allow an easy luxation of the nucleus

be used. However, there are some nuclei that tend to fracture when an attempt is made to luxate them. In this case, hydrodissection and the sub-nucleus injection of viscoelastic material will facilitate luxation.

Dialysis or Rupture of the Posterior Capsule

Dialysis of the posterior capsule can occur in an effort to luxate the nucleus. The use of viscoelastic material as an aid in luxating the nucleus will avoid this problem in the case of medium-dilated pupils; in the case of very small pupils, it is avoided by sphincterotomies, sector iridectomy or mechanical enlargement of the pupil with two Kuglin hooks (Figure 36.4).

Rupture of the posterior capsule may occur during hydrodissection or nuclear fragmentation while trying to push the spatula or vectis between the nucleus and posterior capsule. It can be avoided by hydroexpressing the nucleus out of the capsular bag and then pushing the posterior capsule away from the nucleus by the injection of viscoelastic material.

Iris Trauma

It may occur if the superior leaf of the iris is captured on the spatula or vectis and the nucleus. It can be avoided by the injection of viscoelastic material at 12 o’ clock out of the plane of insertion of the spatula or vectis to retrodisplace the iris prior to introducing the instruments.