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

Figure 19.4: A long table with surgeon in the middle facilitates high volume temporal

Figure 19.5:

Figure 19.6: A modified table that slides to allow both temporal and superior incisions

Figure 19.7: Results of temporal section

Figure 19.8: Results of superior section

surgery with posterior chamber intraocular lens surgery as an efficacious surgical technique to address the backlog of cataracts in developing nations. A temporal incision can reduce postoperative astigmatism among patients often lost to follow-up, allowing them to maximize their long-term visual function.

Figure 19.11: Diagram of our sutureless ECCE/IOL techniques sclerocorneal tunnel and capsulotomy from the surgeon’s perspective

REFERENCES

1.WHO Fact Sheet No 213. Global Initiative for the Elimination of Avoidable Blindness. Feb 2000.

2.Thylefors B. A global initiative for the elimination of avoidable blindness [editorial]. Am J Ophthalmol 1998;125:90-3.

3.Ruit S, Tabin GC, Nissman SA, et al. Low-cost highvolume extracapsular cataract extraction with posterior chamber intraocular lens implantation in Nepal. Ophthalmology 1999;106(10):1887-92.

4.Ruit S, Paudyal G, Gurung R, et al. An innovation in developing world cataract surgery: sutureless extracapsular cataract extraction with intraocular lens implantation. Clinical and Experimental Ophthalmology 2000;28:274-9.

5.Chitkara DK, Smerdon DL. Risk factors, complications, and results in extracapsular cataract extraction. J Cataract Refract Surg 1997;23:570-4.

6.Cockerman GC, Hettinger ME, Azar DT. Astigmatism and Cataract Surgery. In Albert DM, Jakobiec FA, (Eds): Principles and Practice of Ophthalmology, 2nd ed. Philadelphia: Saunders, 2000:1538-50.

7.Flaxel JT, Swan KC. Limbal wound healing after cataract surgery: a histologic study. Arch Ophthalmol 1969;81:653-9.

8.Stainer GA, Binder PS, Parker WT, Perl T. Modulation of post cataract astigmatism by suturing techniques. Int Opthalmol Clin 1983;23:57-67.

9.Steinert RF, Brint SF, White SM, Fine IH. Astigmatism after small incision cataract surgery. Opthalmology 1991;98:417-24.

10.Neumann AC, McCarty GR, Sanders DR, Raanan MG. Small incisions to control astigmatism during cataract surgery. J Cataract Refract Surg 1989;15:78-84.

11.Oshika T, Tsuboi S. Astigmatic and refractive stabilization after cataract surgery. Ophthalmic Surg 1995;26:30915.

12.Gills JP, Sanders DR. Use of small incisions to control induced astigmatism and inflammation following cataract surgery. J Cataract Refract Surg 1991;17(Suppl): 740-4.

13.Azar DT, Stark WJ, Dodick J, et al. Prospective, randomized, vector analysis of astigmatism after three, one, and no-suture phacoemulsification. J Cataract Refract Surg 1997;23:1164-73.

14.Levy JH, Pisacano AM, Chadwick K. Astigmatic changes after cataract surgery with 5.1 and 3.5 mm sutureless incisions. J Cataract Refract Surg 1994;20:630-3.

15.Gimbel HV, Sun R. Postoperative astigmatism following phacoemulsification with sutured versus unsutured wounds. Can J Ophthalmol 1993;28:259-62.

16.Mueller-Jensen K, Barlinn B. Long-term astigmatic changes after clear corneal cataract surgery. J Cataract Refract Surg 1997;23:354-7.

17.Long DA, Monica ML. A prospective evaluation of corneal curvature changes with 3.0 to 3.5 mm corneal tunnel phacoemulsification. Ophthalmology 1996;103: 226-32.

18.Anders N, Pahm DT, Antoni HJ, Wollensak J. Postoperative astigmatism and relative strength of tunnel incisions: A prospective clinical trial. J Cataract Refract Surg 1997;23:332-6.

19.Oshima Y, Tsujikawa K, Oh A, Harino S. Comparative study of intraocular lens implantation through 3.0 mm temporal clear corneal and superior scleral tunnel selfsealing incisions. J Cataract Refract Surg 1997;23:347-53.

20.Gross RH, Miller KM. Corneal astigmatism after phacoemulsification and lens implantation through unsutured scleral and corneal tunnel incisions. Am J Ophthalmol 1996;121:57-64.

21.Cravy TV. Routine use of a lateral approach to cataract extraction to achieve rapid and sustained stabilization of postoperative astigmatism. J Cataract Refract Surg 1991;17:415-23.

22.Wong HC, Davis G, Della N. Corneal astigmatism induced by superior vs. temporal corneal incisions for extracapsular cataract extraction. Australian and New Zealand J of Ophthalmology 1994;22(4):237-41.

23.Axt JC, McCaffery JM. <outbind://3/das/journal/ view/29716525/O/2403719?sid=192075220&source= MI> Reduction of postoperative against-the-rule astigmatism by lateral incision technique. J Cataract Refract Surg 1993;19(3):380-6.

BACKGROUND

In 1997, I met Prof. Michael Bluementhal during a conference in Nepal and learnt about his mini-nuc technique, which I introduced in our Lahan Eye Hospital in southeast Nepal. Being a busy eye hospital with often 300-350 cataract surgeries per day, performed by four surgeons, there was need for a different, more simplified technique. Instead of anterior chamber maintainer and hydroexpression of the nucleus we use a small hook for nucleus extraction. From 1998 till August 2003, more than 160,000 sutureless cataract operations with nucleus extraction have been performed at Lahan. In the meantime, this technique has spread to many Asian and African countries and even some surgeons in Germany use it when phacoemulsification is not appropriate. It is named “Lahan Technique”, “Hennig Technique” or more often “Fishhook Technique”. In 2000, a video of this technique was honoured with a Special Award during the Annual Meeting of German Ophthalmic Surgeons (DOC).

THE HOOK

The hook is made of a 30 G ½ inch needle, bending it with fine pliers or a needle holder. There are two bends:

1.The tip of the needle (Figure 20.1), which will insert into the central nucleus.

2.A slight bend between the tip and the plastic mount (Figure 20.2) to assure an easy insertion between the lower part of the nucleus and the posterior capsule.

The hook is mounted on a 1 ml tuberculine syringe and can be re-autoclaved and used for hundreds of nucleus extractions.

Albrecht Hennig (Nepal)

Figure 20.1: “Fishhook”, showing the bent tip of the 30 G ½ inch needle

Figure 20.2: “Fishhook”, side view

Figure 20.3: Frown incision

Figure 20.4: Sclero-corneal tunnel

THE TECHNIQUE

Tunnel Construction

After fornix-based conjunctival preparation and scleral cauterisation, the sclero-corneal tunnel can be done at 12 o’clock or temporal, ideally at the steepest corneal meridian to keep the post-operative astigmatism at a minimum. Scleral fixation with a good catching forceps, e.g. Pierse or Paufique, helps to perform a controlled corneo-scleral tunnel with a minimum of 1 mm into the clear cornea. We start with a scleral Frown incision (Figure 20.3) with a central distance of at least 2 mm behind the limbus (Figure 20.4). The width of the tunnel depends on the age of the patient and the size of the nucleus. Very big brown nuclei may require an inner

Figure 20.5: Opening of the anterior chamber

Figure 20.6: Continuous curvilinear capsulorhexis

opening to the anterior chamber of at least 8 mm (Figure 20.5).

For beginners we recommend conventional tunnel instruments. Experienced surgeons may use a diamond knife (double lancet with sharp sides), which enables them to perform the three tunnel steps as well as a linear capsulotomy with the same instrument.

Capsular Opening

A linear capsulotomy is either done with the keratome after preparing the inner corneal opening, or with a diamond knife. Preferred is a continuous curvilinear capsulorhexis (CCC) of 6-7 mm diameter (Figure 20.6). However, CCC may be difficult in various advanced cataracts.

Figure 20.7: Hydrodissection and nucleus mobilization

Hydrodissection and Nucleus Mobilization

After linear capsulotomy a forceful hydrodissection separates the capsule from the rest of the crystalline lens. Using the same irrigating cannula, the nucleus plus cortex is mobilized and slightly lifted up at the tunnel opening site.

In case of CCC, a careful hydrodissection is done on one side. If the CCC is large enough the cortex plus nucleus will tilt and partly prolapse mostly contralateral to the hydrodissection side. Then the elevated cortex-nucleus part is rotated towards the tunnel opening position (Figure 20.7).

Nucleus Hook Extraction

After placing some viscoelastics between nucleus and posterior capsule and into the anterior chamber, the bent 30G needle hook (Figure 20.8) is inserted between nucleus and posterior capsule with the sharp needle tip pointing to the right side. Then the hook is turned and slightly pulled back, so that the needle tip is engaged into the central lower portion of the nucleus (Figure 20.9).

Without lifting, the nucleus is pulled out of the capsular bag and through the tunnel (Figure 20.10). 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, nor does the nucleus rotate or tilt while being extracted (Figures 20.11 and 20.12).

Figure 20.8: The hook before insertion

Figure 20.9: Insertion of the hook between nucleus and posterior capsule

Completing the Surgery

After hydroexpression of remaining cortex and removal with a Simcoe cannula, a 6 mm optic PMMA IOL is inserted into the capsular bag (Figures 20.13 and 20.14).

In case of linear capsulotomy, two small cuts are done with fine scissors on both sides of the anterior capsule, and the anterior capsule removed.

OUTCOME

In the hands of experienced surgeons sutureless cataract surgery with nucleus hook extraction has a very low

Figure 20.10: Hook extraction of the nucleus out of the capsular bag

Figure 20.11: Extracted nucleus, top view

surgical complication rate and provides excellent immediate uncorrected postoperative visual acuity.1

This is underlined by another outcome study on high volume surgery where six surgeons performed 2,111 sutureless cataract surgeries within six days.2

LEARNING CURVE

Sutureless tunnel surgery is more difficult to learn than ab-externo ECCE/PC IOL with sutures. Ophthalmologists without surgical experience may start with sutured ab-externo ECCE/PC IOL. Once they achieve consistent good results with a low surgical complication rate, a step-wise conversion to sutureless surgery is advised.

Figure 20.12: Extracted nucleus, side view

Figure 20.13: Insertion of IOL

Figure 20.14: IOL placed in capsular bag

There is a much shorter learning curve for experienced phaco surgeons. They just need to learn the preparation of a larger tunnel and have to get familiar with the nucleus hook extraction. Once this technique is mastered, experienced eye surgeons at our hospital are able to perform 15-20 sutureless cataract operations per hour.

DO’S AND DON’TS

The sutureless cataract surgery with nucleus hook extraction is a safe, fast and inexpensive technique, which provides immediate good visual outcome.

The only additional instrument needed is a 30G needle, bent to a hook.

Among all other sutureless cataract surgical techniques, our technique is the only one where the nucleus is extracted straight from the capsular bag

through the tunnel, avoiding corneal endothelium touch.

Nucleus extraction requires a smaller tunnel size than nucleus removal by hydroexpression.

With more than 160,000 sutureless cataract surgeries performed in Lahan and many more in other eye centres around the world, the nucleus hook extraction is one of the techniques most often used in sutureless nonphaco cataract surgery.

REFERENCES

1.Hennig A, Kumar J, Yorston D, Foster A. Sutureless cataract surgery with nucleus extraction: Outcome of a prospective study in Nepal. Br J Ophthalmol 2003;87(3): 266-70.

2.Hennig A, Kumar J, Singh AK, Singh S, Gurung R, Foster A. World Sight Day and cataract blindness. Br J Ophthalmol 2002;86:830-1.

INTRODUCTION

The simplicity, safety, wider applicability and cost effectiveness of non phaco Small Incision Cataract Surgery (SICS) has inundated the present day cataract surgeon with various techniques of SICS. Every innovation is aimed at achieving a procedure, which is bereft of complications.

SICS, using ACM was introduced by Professor M Blumenthal. We started practicing his technique with some modifications. We soon realized that the property of ACM to maintain a deep anterior chamber could be utilized in phacosection and phacosandwich techniques also. Both the methods involve greater instrumentation inside the chamber endangering the corneal endothelium. ACM can also be used in phacoemulsification whenever a higher vacuum is required. It prevents chamber collapse and allows emulsification of hard nuclei with considerable ease. In micro-incisional surgery it provides as an additional source of fluid and allows the use of lower end phacomachine.

It can also be used for chamber maintenance in secondary cortical aspiration, anterior vitrectomy, lens aspiration in pediatric cataract, scleral fixation and Descemet’s stripping endothelial keratoplasty.

MODIFIED BLUEMENTHAL TECHNIQUE

Professor M Bluementhal, performed all the maneuvers under fluid without using viscoelastics. We have modified his technique and advocate copious use of viscoelastics to safeguard the corneal endothelium.

We prefer to use a frown shaped external incision of 5.5 to 6.5 mm length. A self-sealing corneo-scleral tunnel is dissected using crescent knife. The inner

wound diameter should be approximately 8 mm long with well made side pockets. The details of tunnel making have been described in other chapters. Prior to entry with a slit knife two side ports are made at 10 o’clock and 7 o’clock for capsulorhexis and ACM entry respectively.

Insertion of ACM

For making the 7 o’clock opening a 20 G MVR blade is held tangential to the 6 o’clock limbus and is entered from the temporal side, away from the vascular arcade, creating a valvular opening for insertion of ACM. The blade should be held in such a manner that its widest portion is parallel to the surface of iris. The opening should be of adequate size to snugly fit the ACM. Too small an opening results in struggle during insertion. If it becomes larger than the required size, there can be repeated slipping of the ACM, which will prevent building up of sufficient hydropressure to push the nucleus out.

The ACM is a hollow steel tube with 0.9 mm outer diameter and 0.65 mm inner diameter. While inserting, it is held firmly from the steel portion with the thumb and the index finger and entered with bevel up and then turned 180 degrees so that the bevel faces the iris. If part of the bevel remains in the corneal stroma, corneal haziness can occur due to stromal hydration. Prior to insertion, it should be flushed with BSS not only to check its patency but also to remove any air column in the tubing. The tube of ACM is attached to the BSS bottle suspended 50 to 60 cm above the patient’s eye.

The capsulotomy is performed through the opening at 10 o’clock position. Without going into the details, we would like to emphasize that the capsular opening

which is preferably but not necessarily a capsulorhexis should be more than 6 mm in size and the capsular rim at 12 o’clock area should be narrow to facilitate passage of Sinskey’s hook behind the upper pole during nuclear prolapse from the bag. It also assists in aspiration of the 12 o’clock cortex. If the size of CCC is small, relaxing cuts at 7 and 11 o’clock should be given. Nuclear prolapse if attempted through a small capsular opening can result in zonular dialysis.

In hypermature milky white cataracts, flow from ACM clears the chamber of the milky fluid released by the puncture of the anterior capsule. After the capsulotomy, the anterior chamber is entered with a slit knife. Hydroprocedures are then performed to reduce the size of the nucleus and free the nucleus from the capsular bag. Once the nucleus starts rotating freely within the bag, the chamber is filled with viscoelastics and the nucleus is prolapsed out of its bag with the help of Sinskey’s hook. Free nucleus in deep AC is then ready for being propelled out by the hydropressure generated by the ACM.

Principle of the Technique

•Engage the nucleus into the sclerocorneal pocket tunnel with the help of a lens glide/iris repositor

•Push the nucleus out by hydropressure

•Pull the nucleus out by a needle if required.

For engaging the nucleus into the corneo-scleral tunnel, after injecting viscoelastic both in front and behind the nucleus, a lens glide/iris repositor is passed behind the nucleus one third or half the nucleus width distance. Once the iris repositor is in position, ACM is opened and slight pressure is applied on the scleral side. Intermittent pressure, engages more and more nucleus out of the tunnel’s mouth. Subsequent taps enable the epinucleus and cortex to flow out of the anterior chamber.

At times, a free nucleus fails to engage in the section. This could be due to the following reasons:

•Small internal wound diameter

•Irregular/incompletely dissected tunnel

•Leaking anterior chamber

•Premature entry into anterior chamber

•Vitreous in anterior chamber.

The tunnel should be revisited with the slit knife. If the nucleus still fails to engage and there is no vitreous in anterior chamber, ACM is disconnected from the BSS and attached to a syringe containing viscoelastics. Viscoelastic, is then injected through the ACM by the

Figure 21.1: Assisted delivery in Modified Blumenthal technique

assistant while the surgeon keeps a watch on the progress of the nucleus and the intraocular tension. The pressure created by the viscoelastic pushes the nucleus towards the section. Once the nucleus is engaged, the ACM is reconnected to the BSS bottle and the nucleus is delivered in the usual manner. At times, if the nucleus is engaged but fails to deliver due to hypotony, the bottle height may be increased.

Assisted Delivery

If a small portion of the nucleus shows out of the section but further progress is stalled even with full flow of ACM, nuclear delivery can be assisted by 23 G needle held in the other hand. The nucleus is engaged at right angle to its axis with a 23 G needle and while the ACM generated hydropressure pushes it out, the needle assists by pulling it and intermittent pressure on the iris repositor guides the nucleus out (Figure 21.1).

If the nucleus is very large and hard, a bit of it may be sheared off, remaining nucleus is pushed back into the anterior chamber and the smaller diameter may be allowed to flow out.

A bimanual irrigation aspiration is carried out using an olive tipped cannula and ACM. In case of inadvertent posterior capsular rupture, flow through ACM pushes the vitreous back and facilitates cortical aspiration (Figure 21.2). Cortical clean up is followed by placement of posterior chamber intra ocular lens in the bag and hydration of the side ports.