Ординатура / Офтальмология / Английские материалы / Small Incision Cataract Surgery (Manual Phaco)_Singh_2002

Fig.15.18: Showing initiation and progression of capsulorhexis with forceps

Fig.15.19a: Showing capsulorhexis through one quadrant

Fig.15.19b: Showing near completion of the capsulorhexis with forceps

Capsulorhexis in Difficult Situations

Performing a capsulorhexis in eye with white cataract and/or small pupils can occasionally present a challenging task to the operating phaco surgeon. Absence of glow or small pupil compromises the visualisation of the capsule and the capsulotomy edge. However, certain modifications can be performed to perform a safe capsulorhexis in these cases.

Capsulorhexis in Mature Cataracts

The basic principle of capsulorhexis remains the same, however certain modifications can be made in technique.

Visualisation of the capsule can be increased by maintaining a deep anterior chamber using the viscoelastic material and also use of viscoelastic material for elevation and manipulation of the flap torn edge after initiation of capsulorhexis. An external light source (Fig. 15.16) can be used on an oblique angle to help us increase visualisation of the capsular flap. Progression of capsulorhexis in these cases should be very slow and steady and no attempts should be made to complete capsulorhexis rapidly.

Capsulorhexis in Hypermature Cataracts

In a hypermature cataract, puncturing the capsule leads to leakage of the cortical matter obscuring the view. This fluid matter should be aspirated or flushed from the anterior chamber with a viscoelastic such as methyl cellulose to clear the anterior chamber. A viscoelastic is then injected into the lens bag to increase its volume and the capsulotomy is performed.

A very valuable tool in improving visualisation of the capsule has been produced by staining with dyes.

Trypan Blue Staining

Inadequate visualisation of the capsule as in mature and hypermature cataract can be obviated by temporarily staining the anterior capsule with any contrasting dye for, e.g. 0.1% Trypan Blue. Staining of the anterior capsule simplifies capsulorhexis.

Technique

Through the side port incision, anterior chamber is completely filled with air. The air in the anterior chamber causes the dye to spread over the anterior capsule, bordered by the pupillary rim of the iris, it prevents a direct endothelial contact. The air also prevents dilution of the dye by the aqueous. It is observed that a large single air bubble is essential for staining of anterior

capsule. Multiple small air bubbles cause irregular staining of the anterior capsule.

After air is injected into the anterior chamber, with 27 G cannula, 0.2 ml of 0.1% Trypan Blue is injected. After 5 to 10 secs, the anterior chamber is thoroughly irrigated with Balanced Salt Solution (BSS) to wash out excess of dye. Because of blue stain of anterior capsule, the outline of the capsulorhexis is clearly visible. This is easily distinguished from the underlying grayish white lenticular tissue thus simplifying capsulorhexis.

Capsulorhexis in Small Pupils

In cataracts with small pupils, the pupils can be enlarged using either the stretching technique or using iris hooks or by multiple sphincterotomies. Capsulotomy is performed as usual making the size of capsulorhexis equal to just smaller to the pupillary diameter. The edge of the capsulorhexis should be visible. Once phacoemulsifica-

tion is completed, the capsulotomy size can be increased for safe introduction of the lens.

New Developments in Capsulorhexis

With technological advances a number of new aids are now available to ensure a safe capsulorhexis. Use of a radiofrequency probe or Erbium Yag laser are some examples of the same.

FURTHER READING

1.Barrett Sible Phacodynamkics, Mastering the two techniques of phacoemulsification, Second edition, Slack Incorporation, Los Angeles California.

2.Cook Davidson, Advanced phacoemulsification technique, Slack Incorporation California USA.

3.Paul H Cock: Mastering phacoemulsification, 4th ed, Jaypee Brothers, New Delhi, India.

4.William F Mallony: Textbook of phacoemulsification, 1st ed, 1998.

INTRODUCTION

Hydroprocedures are equally important in both the modalities of small incision surgery-manual non-ultra- sonic small incision cataract surgery as well as ultrasonic small cincision cataract surgery or phacoemulsification.

In this chapter, when I am going to deal with hydroprocedures at length it will be in the fitness of things that we address the subject in both its applications, i.e. manual small incision cataract surgery and phacoemulsification.

When you have gone through this chapter you should be armed with a wider, broad based perspective of the subject. That day is not far off when all cataract surgeons will have mastery over both the methods of small incision surgery-manual and ultrasonic.

CONCENTRIC ANATOMY OF THE LENS

The epithelial cells of the human crystalline lens are constantly proliferating to create lens fibres. The new fibres formed at the periphery compress the old and deeper layers. Thus the inner core constitutes the hardest part of the nucleus because it has been subjected to maximum pressure for the longest duration.

The lens in cross-section comprises of a concentric series of elliptical rings. Each ring represents laying down of additional lens material from the epithelial cells located on the underside of the anterior capsule.

For a cataract surgeon it is useful to consider the crystalline lens as having three zones.

Hard Core Nucleus

The innermost central core is known as the endonucleus. The hardcore nucleus cannot be aspirated; it can be (a) Expressed as in ECCE or (b) Fractured as in phacoemulsification or (c) Fragmented as in manual small incision surgery.

Epinucleus

This is the “semi-soft” intervening zone between the soft superficial cortex and the hard endonucleus. It can either be expressed or aspirated.

Superficial Cortex

This is comprised of the soft lamellae lying just beneath the capsular bag. The cortex can only be aspirated.

HISTORY

Hydrodissection was devised or “invented” by Michael Blumenthal of Israel who is the father of “Non-ultrasonic manual small incision cataract surgery.” Its initial aim was to reduce the size of the nucleus to the smallest possible hardcore endonucleus. This small endonucleus could then easily be tipped out of the capsular bag and then conveniently expressed out via a small self-sealing scleral incision.

Ironically this procedure has been used as a stepping stone in the evolution of ultrasonic small incision surgery or modern phacoemulsification.

Terminology and Classification

Hydroprocedures

HYDRODISSECTION

Conventional Hydrodissection

This is hydroseparation of the superficial cortex from the epinucleus. The cardinal reason to perform hydrodissection is to enable us to rotate the nucleus. The cortical

Fig. 16.1a

adhesions are broken so that the nucleus becomes freefloating in the capsular bag. We can rotate and bring different parts of the nucleus in front of the phaco tip so that they can be emulsified.

Basically hydrodissection is the injection of BSS under the anterior capsular flap so that the fluid dissects around the equator, goes below the nucleus and separates it from its cortical attachments. If you do not see the posterior fluid wave and the nucleus does not move anteriorly then you have not achieved hydrodissection. The endeavour is to create a definite plane of separation between the nucleus and cortical debris that remains attached to the capsular bag (Figs 16.1a and b).

Technique

First of all a good continuous curvilinear capsulorhexis is performed. A 27 G blunt cannula is taken on a 2 ml syringe filled with BSS (Figs 16.2 and 16.3). The cannula

Figs 16.1a and b: Hydrodissection. Courtesy: Alcon (India)

Fig. 16.3: Conventional hydrodissection

enters the eye through the 2.8 mm phaco incision or the larger incision of manual small incision surgery and the tip is passed under the anterior capsular rim. A sufficient amount of fluid is injected so that a posterior fluid wave is created. Injection of excessive fluid should be avoided. The acid test of having performed a good and complete hydrodissection is that you should be able to rotate the nucleus easily.

In white cataracts and in very dense cataracts the fluid wave will not be seen but slight forward movement of the nucleus is a good indication that a complete hydrodissection has been achieved.

Cortical Cleavage Hydrodissection

Fig. 16.4: Cortical cleavage hydrodissection

years that the cortex is naturally adherent to the capsule. Fine observed that after doing capsulorhexis when he removed the anterior capsule there were no adhesions between the cortex and capsule.

In cortical cleavage hydrodissection the cannula is lifted up, tenting the anterior capsule and then the BSS is pushed in. This technique produces a clear cut cleavage plane that separates all of the cortex from the capsular bag. Some fluid gets trapped at the equator because of dense cortical adhesions. So after the fluid wave is completed, the nucleus is depressed with the cannula to release all the trapped fluid into the anterior chamber. After doing cortical cleavage hydrodissection when phacoemulsification is performed all of the cotex comes out with the nucleus. There is hardly any cortex left to be removed by I/A.

Hydro-free Dissection

This is more or less the same as cortical cleavage hydrodissection. Gimbel has refined this technique-after lifting and tenting the anterior capsule the tip of the cannula is swept along the potential plane of cleavage; then the fluid is injected as usual creating a cleaner cortical cleavage.

HYDRODELINEATION OR HYDRODEMARCATION

This term stands for separation of the inner hardcore endonucleus from the overlying epinucleus by fluid injection (Figs 16.5 and 16.6).

Manual

There are two methods:

A.The cannula is pushed right into the body of the nucleus. The tip passes through the soft outer nucleus and meets with resistance when it hits the hard part of

Fig. 16.5: Hydrodelineation feel the resistance

Fig. 16.6: Hydrodelineation completed

the cataract. When fluid is injected at this point a golden ring is formed which signals the true separation of the nuclear layers.

B.Aspirate the superficial cortex and the epinucleus to reach the hardcore endonucleus which cannot be aspirated further. Hydrodelineation can now be performed by negotiating the tip of the cannula between the endonucleus and epinucleus and then injecting a

small amount of BSS.

Separation of the inner and outer nucleus is extremely helpful both in manual small incision surgery and in phacoemulsification.

In manual small incision surgery a small inner nucleus is isolated and can be more easily tipped out of the bag and then removed out via the self-sealing incision. In phacoemulsification the shell of soft outer nucleus acts as a very effective protective barrier for the posterior capsule. It saves the posterior capsule from damage by the razor sharp edges of the hard endonucleus as well as by the sharp phaco tip.

Hydrosonic Hydrodelineation

Aziz Anis (USA) devised a special hydrosonics handpiece by which he used small bursts of ultrasound to bury the tip deep into the hard endonucleus. Then BSS is injected at various depths to decompact and hydrate a very hard nucleus. This helps in easier phacoemulsification of very hard nuclei.

COMPLICATIONS OF HYDROPROCEDURES

A.Pressure generated by the fluid may lead to extension of an irregular capsulorhexis or a can opener capsulotomy upto the equator and even beyond it. The need for a good CCC cannot be cover emphasised both for manual small incision surgery and phacoemulsification.

B.Injection of excessive fluid during hydroprocedures may raise the intralenticular pressure to such a high level that the posterior capsule may give way and the nucleus may sink into the vitreous cavity.

C.In posterior polar cataracts even gentle hydrodissection may lead to dehiscence of the posterior capsule in the centre. In such cases only hydrodelineation should be attempted

D.At times the nucleus or even the entire lens may prolapse out of the bag into the anterior chamber. This is a welcome development if manual small incision surgery is attempted. If phacoemulsification is planned, the nucleus may gently be patted back into the capsular bag.

DISCUSSION

The nomenclature of inner and outer nucleus or endonucleus and epinucleus is not important. The all important point is appreciation of the concept that within the cataract there is a point where a fluid dissection can be made isolating an inner nucleus from an outer nucleus.

The endonucleus is hard in both ways (a) Physically the hardest part of the cataract (b) It represents the hardest or most difficult part of cataract removal.

Hydrodissection and hydrodelineation should be performed in every cataract procedure as far as possible. In young and soft cataracts it is better to do hydrodissection alone. Performing hydrodelineation in such cases leaves us with a thick outer nuclear shell which is stickly and very difficult to manipulate. In posterior polar cataracts it is better to do hydrodelineation alone; performing hydrodissection in such cases is catastrophic.

We should realise that mastering the techniques of hydroprocedures should be the endeavour of all cataract surgeons.

FURTHER READING

1.Eisner G: Eye Surgery: An Introduction to Operative Technique (2nd ed). Springer-Verlag, Berlin: 288-95, 1990.

2.Koch, Davidson: Advanced Phacoemulsification Techniques

Slack Inc, New Jersey, 1991.

3.Seibel BS: Phacodynamics: Mastering the Tools and Techniques of Phacoemulsification Surgery (Ist ed) Jaypee Brothers, New Delhi, 1995.

4.Sunita Agarwal et al: Phacoemulsification, Laser Cataract Surgery and Foldable IOL’s. Jaypee Brothers, New Delhi: 1998.

Small incision cataract surgery differs from conventional ECCE and phacoemulsification cataract surgery in that the nucleus needs to be essentially prolapsed into the anterior chamber from the

capsular bag before delivering it through the incision. Hence prolapse of nucleus in the anterior chamber is

the most important and sometimes a difficult step in manual phaco, taking into consideration the integrity of the capsular bag the vitreous face and corneal endothelial damage. However, in envelope technique the nucleus is not fully taken out of the capsular bag but is rotated in the bag and the upper pole is brought above the iris plane out of the capsular bag.

For prolapsing the nucleus in anterior chamber, hydrodissection and hydrodelination are very essential steps. Hydrodissection separates the peripheral cortex from the capsule and makes the nucleus free in the capsular bag, while hydrodelination separates the nucleus from cortex and peri-nucleus thus reducing the size of nucleus making its delivery possible through smaller incision.

For hydrodissection the Balanced Salt Solution (BSS) is injected through 27G cannula. The cannula is placed about 2 mm distal to the edge of capsulotomy or capsulorhexis and BSS injected. If red reflex is visible the fluid wave is seen passing along the posterior capsule all around. The visualisation of fluid wave ensures that hydrodissection is complete. The BSS is injected in different directions. Every time the BSS is injected the lens should be slightly tapped posteriorly so that the fluid does not collect posteriorly leading to posterior capsule rupture. A good hydrodissection makes the nucleus rotation and nucleus prolapse very easy.

After hydrodissection, hydrodelination is performed separating the nucleus from epinucleus. For hydrodelination the cannula is introduced deeply into the mid-periphery of the lenticular nucleus until the hard core of nucleus is reached. The cannula is withdrawn

slightly and BSS injected creating a cleavage between the soft fibre of the epinuclear shell and more dense portions of the central nucleus. When a complete hydrodelination is performed a golden ring is sometimes observed. Hydrodelination not only reduces the size of the nucleus but also facilitates nucleus rotation and nucleus prolapse into AC from the capsular bag.

Nucleus Rotation and Prolapse of Nucleus

Without nucleus rotation and nucleus prolapse, manual phaco cataract surgery can never reach its culmination. There are various techniques described and practiced. The few preferred ones are discussed below:

Tipping up Technique

The key to this procedure is proper tipping up of the nucleus out of the capsular rim and above the iris plane. The iris is retracted with a collar stud hook. Then the capsule and iris are held with a 1.0 mm iris spatula and the nucleus is nudged towards six O’clock with the collar stud hook. This lowers the superior pole of the nucleus and the equatorial rim becomes visible away from the iris margin. The superior pole of nucleus is tipped up with iris spatula. The viscoelastic is injected between the nucleus and post capsule. The nucleus is then rotated with iris spatula and is eventually prolapsed into anterior chamber (Fig. 17.1).

Tyre Levering Technique

If the nucleus is larger than the capsulorhexis or capsulotomy, prolapsing the nucleus is quite difficult. Tyre levering technique is useful in this difficult situation. A 7.0 mm nucleus can be removed out of 5.0 mm capsulorhexis. First of all the free rotation of nucleus is ensured after good hydrodissection and hydrodelination. The nucleus can be rotated with iris spatula or 30G irrigating cannula.

Fig. 17.1: Nucleus prolapse with the help of lens loop/irrigating vectis

The nucleus is nudged posteriorly towards the posterior capsule at nine O’clock equator so that the three O’clock equator comes out of the capsular rim slightly. The nucleus is then lifted up at three O’clock with iris spatula and rotated out of the capsular bag as tyre is taken out of its rim (Fig. 17.2).

Fig. 17.2: Tipping technique to nucleus prolapse

endothelium. The lens lies upside down in the anterior chamber. Ample amount of visco-elastic is now put above and below the nucleus suspending it in a pool of viscoelastic. This separates the nucleus from the corneal endothelium and prevents endothelial damage (Figs 17.3 and 17.4).

Tumbling of the Lens

In this technique the freely rotating nucleus is tumbled along the vertical meridian by using the visco-elastic cannula. The viscoelastic or BSS is injected under the anterior capsular rim at nine O’clock. The viscoelastic or BSS travel along the equator over the posterior capsule towards the opposite side. The pooling of viscoelastic or BSS behind the nucleus pushes the nucleus out of the rim at three O’clock. The nucleus is further pressed at nine O’clock, which pops the nucleus at three O’clock. The cannula is now sweeped from nine to three O’clock along the posterior capsule. This tumbles the lens and brings the posterior lens surface towards the corneal

Other Methods

There are other methods with slight modifications, which various surgeons are using according to their choice and size of the nucleus, capsulotomy/capsulorhexis and pupillary aperture.

A.In this method, a 20G irrigating cannula attached to BSS bottle is used. The cannula is inserted facing downward under the capsule at different places, i.e. three O’clock, six O’clock or nine O’clock positions. The cannula is positioned deep upto the equator. The fluid passes between the nucleus and posterior capsule and pressure builds up in the capsular bag. The pressure of the fluid pushes the pole of the nucleus out of

Fig. 17.3: Nucleus prolapse by visco-expression

the capsular rim and pupillary border. Viscoelastic is injected under the pole of the nucleus, which further pushes it out of the capsular rim. The nucleus is rotated with the viscoelastic cannula and this brings whole of the nucleus in anterior chamber.

B.This method is utilised in complicated cases where nucleus is large or pupil is small and it is difficult to prolapse the nucleus. With an iris retractor in the dominant hand the iris and capsule is retracted at twelve O’clock position and simultaneously the posterior rim of the scleral incision is pushed slightly downward. With the other hand, hydrodissection cannula on an empty 2 ml syringe is passed through two O’clock side port incision towards six O’clock position under the rim of anterior capsule.The six O’clock pole is pressed downward, which tumbles up the twelve O’clock pole out of the capsule rim. The retractor is removed and visco-elastic is injected between the nucleus and posterior capsule at twelve

Fig. 17.4: Nucleus prolapse by using iris retractor and hydrodissection cannula

O’clock. With the viscoelastic cannula the nucleus is rotated out of the capsular bag in the anterior chamber. All the above mentioned methods of nucleus prolapse have only small differences and they are used according to the situation. The basic principle is taking the nucleus out at anyone of the poles and then prolapsing the rest of the nucleus out of the capsular bag by various

methods.

Apart from incision construction, prolapse of the nucleus in anterior chamber is the most unique and important step of manual phaco surgery and needs to be done meticulously and carefully, otherwise, there is always a possibility of posterior capsular rupture and damage to corneal endothelium.

FURTHER READING

1.Shah Anil: In Small Incision Cataract Surgery (Manual Phaco)

Bhalani Pub: India 62-67, 2000.

2.Natchiar G: Manual Small Incision Cataract Surgery. Arvind Publications: India 21-24, 2000.

Fry is credited with the phaco sandwich technique. This technique is simple, allows removal of lens through a 6.0–6.5 mm self-sealing scleral tunnel incision, produces much less astigmatism compared to extracapsular cataract surgery and is sutureless. The author has adopted this technique for over 5 years and

results have been gratifying.

Instruments

Essentially the instruments required are similar to what an ECCE surgeon requires. Additional instruments are.

•Crescent knife

•3.2 mm angled keratome

•5.2 mm keratome

•Irrigating vectis

•Sinskey type dialer, iris repositor

•AC maintainer

Preoperative Preparation

The essential thing in this surgery is wide dilatation of pupil, which allows easy prolapse of the nucleus in anterior chamber and prevents iris entrapment during delivery of nucleus. Pupil dilatation and its maintenance in dilated status is achieved by instilling tropicamide and phenyle-

Fig. 18.1:Size of the conjunctival flap

phrine combination and flurbiprofen eye drops. These are instilled 1 hour before the surgery. Author suggests a conventional ECCE if the pupil is less than 5 mm in diameter at least in initial 50 cases. Acetazolamide one tablet is given 2 hours prior to surgery. Some surgeons avoid acetazolamide as it causes hypotony.

Anaesthesia

A peribulbar anaesthesia with a cocktail of 3 ml of xylocaine with adrenaline and 3 ml bupivacaine mixed with hylase is used. Superpinky ball or ocular massage for long is not recommended as it produces hypotony.

Surgical Steps

1.After applying speculum and holding superior rectus fornix based conjunctival flap is made (Fig. 18.1). Careful bipolar cautery should be carried out. It gives a bloodless field to operate and there is no inadvertent bleeding during the making of scleral tunnel, but overenthusiastic cautery should be avoided as it causes astigmatism.

2.6 to 7.5 mm partial thickness scleral tunnel incision is made 2 mm behind limbus. Harder the nucleus longer is the incision. In initial 25 patients longer incision is recommended to avoid unnecessary touch to the corneal endothelium. The scleral pocket is made with crescent knife (Fig. 18.2). Disposable crescent blades are the best. Their reuse might lead to a poor tunnel. This is the single most important step in this surgery. Therefore, no compromise should be accepted. Scleral pocket is extended in the corneal stroma. While making scleral tunnel sclera induces greater resistance than the cornea. Therefore, the surgeon should become very gentle while entering the cornea. Otherwise it may lead to early entry into the anterior chamber causing poor corneal valve. The corneal tunnel should be up to 1.5 mm from the limbus and as suggested by