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

Figure 30.2: Scleral pocket being fashioned

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 when the surgeon reaches close to limbus his movement should be very gentle. Otherwise, it may lead to early entry into the anterior chamber causing formation of a leaky corneal valve. The corneal tunnel should extend up to 1.5 mm from the limbus and the corneal incision should be 2 mm wider than the scleral incision. Entry into the anterior chamber is made with a 3.2 mm angled keratome. It should be sharpblunt keratome leads to Descemet’s detachment. A dimple on the anterior surface of cornea is seen when pressure of the keratome is applied towards the anterior chamber (Figure 30.3). Then entry into the anterior chamber is made (Figure 30.4). This movement should

Figure 30.4: Entry into anterior chamber with 3.2 keratome

be well controlled otherwise it may hit the anterior capsule causing rupture of the anterior capsule, which may jeopardizes the fashioning of capsulorhexis.

Capsulotomy

Viscoelastic is injected into the anterior chamber. Here, the care should be taken to slightly press the scleral side so that the aqueous leaks out and the viscoelastic takes it place. It will make the anterior chamber deep and capsulotomy becomes easier. Any type of capsulotomy can be fashioned in SICS—can-opener, envelope or capsulorhexis, all are useful. In fact author suggests canopener and envelope technique in initial few cases, because the prolapse of the nucleus in AC is much easier than when a capsulorhexis has been fashioned. Size is important in case one prefers to make capsulorhexis (Figure 30.5). It should be not less than 6.5 mm and slightly eccentric on the upper side. Both these things will help in prolapse of the nucleus in the AC. In case the capsulorhexis is small, whole nucleus with capsular

Figure 30.6: Extension of incision

bag may come in the AC. Then it would be intracapsular rather than extra-capsular surgery. In this case two relaxing incisions on the edge of capsulorhexis at 11 and 2 o’clock may facilitate the prolapse of nucleus in anterior chamber. Once the rhexis is complete the incision is extended to desired size of 6-6.5 mm (Figure 30.6).

Hydrodissection-Hydrodelineation

Aim of hydrodissection is to break all the adhesions between cortex and capsule. This results in a freely rotating nucleus within the bag. The technique of hydrodissection has been described elsewhere. Two points need to be mentioned here. Don’t try to strain the zonules by pushing your rotating instrument too hard. If hydrodissection is complete there will be no difficulty in rotating the nucleus. If it is difficult, it means incomplete hydrodissection. In this event more fluid should be injected beneath the anterior capsule and retry the rotation. Secondly, fluid injection should be slow and only small amount should be injected. Hydrodelineation is not a must in SICS. It helps in debulking the nucleus and delivery of nucleus through smaller incision becomes easier. But presently, the author does the expression of nucleus without hydrodelineation because the epinucleus is a soft structure. Its accidental touch to the endothelium causes less damage to it than the touch of the nucleus.

Nuclear Luxation

This is single important step in a successful SICS. Nuclear luxation or prolapse in anterior chamber is easier, if the pupil is widely dilated and a good rotation of the nucleus is achieved after hydrodissection. In initial few cases, prolapsing the nucleus in anterior

Figure 30.7: Nucleus prolapsed in AC

chamber is easy if can-opener or envelope type of capsulotomy has been performed. The nucleus is prolapsed by rotating the nucleus after filling the chamber with viscoelastic. The moment, rim of nucleus is visualized, the cannula is brought below the rim of nucleus; and again viscoelastic is injected in between the nucleus and capsule. The upper pole of nucleus will prolapse in the AC (Figure 30.7). In small pupils one can depress the nucleus at 5 O’clock with the cannula. The upper pole tilts anteriorly at 11 o’clock. Now the nucleus is rotated toward 12 o’clock. Thus achieving the aim of prolapse of upper pole of nucleus. Once you are sure about prolapse of nucleus in AC, inject more viscoelastic between the cornea and anterior surface of nucleus and also behind the nucleus. This maneuver requires copious use of viscoelastic to prevent injury to the corneal endothelial cells. Once this is achieved the nucleus is now ready for delivery.

Nuclear Delivery

The author uses irrigating vectis and a Sinskey type of dialer but the difference here is that it is like a hammer at the end and much thicker than the dialer. Thus it has blunt end, which prevents injury to posterior capsule. The author calls it a dumbbell. Fluid flow through the vectis is checked. First thing is to enter anterior chamber through the incision with the dumbbell in your left hand. This is kept at the center of nucleus (Figure 30.8). No pressure is applied. Then the irrigating vectis is passed behind the nucleus in such a way that the nucleus is sandwiched between these two instruments (Figure 30.9). Now pressure is applied from below the nucleus and also on the anterior surface of lens. Pressure should be more from the top than from beneath. Once you are sure about the hold, the sandwiched nucleus is

Figure 30.8: The Sinskey or dumbbell goes first in the anterior chamber; the vectis follows afterwards

Figure 30.9: Nucleus is sandwiched between two instruments

brought out of the wound taking care that the sandwiched nucleus does not touch the corneal endothelium. In this process two things may result. If the lens is soft, it will come out in one go. If it is hard, it may break into several pieces. A part of that will come out sandwiched between two instruments. Remaining pieces of nucleus are taken out by either viscoexpression. One needs to be very cautious here. The anterior surface of nucleus or its pieces should always have viscoelastic in front of them. In case one finds difficulty in delivering out the nucleus, the incision length should be increased. This problem is normally encountered in brown hard cataracts. Rarely in very big nucleus the tunnel has to be abandoned and a routine ECCE is performed.

Cortical Clean-up

Remaining debris is perinucleus and cortical matter. This is removed by two way Simcoe cannula, which is attached to a bottle. Cannula is opened with full flow.

Figure 30.10: IOL is implanted after thorough wash

Take this free flowing cannula to 6 o’clock and slight pressure with the cannula on tunnel will cause perinucleus to come out. Remaining material is cortex. A part of this will come out with perinucleus by hydroexpression. Cortical fibers are then aspirated with the cannula.

IOL Implantation

After the posterior capsule has been washed and no fibers are left, intraocular lens is implanted. The technique of IOL implantation is simple. First viscoelastic is injected in the anterior chamber within the bag. All PMMA nonfoldable IOL is then held with the IOL holder forceps. Then keeping the direction of haptic downwards it is pushed into the lower capsular bag. The optic goes in the anterior chamber with the same push (Figure 30.10). Now the trailing haptic is inserted in the bag by dialing it with the Sinskey hook if IOL has holes, or with the Y shaped dialer, if there is no hole in the IOL.

Wound Closure

Conjunctiva is reposited back by holding the conjunctiva with two forceps. Cautery is then applied at two ends. Sutures are usually not applied in the section. They are needed only when the valve is compromised. A figure of eight suture usually suffices in that case. Then gentamycin and dexamethasone injection is instilled on the top of conjunctiva. There is no need of giving any sub-conjunctival injection.

Complications

The complications of phaco sandwich technique per se are few. Intraoperative complications include damage to corneal endothelium, iridodialysis, and posterior

capsule rupture postoperatively transient corneal edema may be frequent, if too much handling has been done within the chamber.

Recommendation

Before contemplating the manual small incision cataract surgery by the phacosandwich technique the surgeon should thoroughly examine the cataract for its hardness. Initially one should not try this technique in very hard cataracts. This surgery is fine for up to grade 3 and 4 hardness. The wound should be enlarged to 6.5 mm. 1 mm larger than this is recommended for harder nuclei. The nuclear luxation into the anterior chamber, at least of the upper pole is must. Before sandwiching the nucleus copious amount of viscoelastic has to be

used on the top of nucleus and behind the nucleus. The lens should come out without much of fuss. There is no problem in enlarging the incision, which gives you shining cornea the next day. In slightest doubt always apply suture.

BIBLIOGRAPHY

1.Luther F. The phacosandwich technique in George W Rozakis et al (Ed). Cataract Surgery: Alternative Small Incision Techniques. Thorofare Inc. 71-110; 1995 Indian edn.

2.Singh Kamaljeet. The Phacosandwich technique in Kamaljeet Singh (Ed). Small Incision Cataract Surgery (Manual Phaco). Jaypee Brothers, India 2002;101-7.

INTRODUCTION

Hydroexpression with an irrigating vectis is a simple technique of Manual SICS using a combination of mechanical and hydrostatic forces to express out the nucleus.1 A simple irrigating vectis is all that is needed to perform the procedure. The technique is specially suited for softer cataracts, which will easily mould through smaller incisions; even harder cataracts can be tackled just by increasing the size of the scleral tunnel. The surgery can be performed either through a superior or temporal scleral tunnel incision. With temporal approach, even with larger incisions the amount of resultant astigmatism will be less and consequently the uncorrected vision will be better.

SURGICAL PROCEDURE

Peritomy

The conjunctiva and the Tenon’s layer are dissected separately. This helps to minimize the amount of cautery applied, as there are no tags of Tenon’s left, which may cover the bleeders requiring excessive cautery. If the surface is smooth without any episcleral tissue then the scleral dissection also becomes easier. The amount of conjunctival dissection should be minimal and preferably 8 to 10 mm.

Scleral Tunnel and Side Port Incision

It consists of a 6 mm - scleral incision placed 1.5 to 2 mm from the limbus either superiorly or temporally. The incision may be straight or frown shaped. The scleral tunnel is constructed by carrying forward the scleral dissection using a bevel up crescent blade. A side

port entry is made at 9 o’ clock (75 to 90 degrees to the right side of the tunnel) and preferably it should be 1 mm in size. Viscoelastic is injected into the anterior chamber through the sideport incision to make the eye firm. This is to facilitate entry of the main wound with the keratome for creation of the corneal valve and completion of the internal wound in one stretch. The sideport entry also helps to form the anterior chamber at the end of the procedure as well as for the removal of subincisional cortex.

The entry into the anterior chamber is made with a sharp 3.2 mm bevel down keratome taking care to create a corneal valve of atleast 1.5 mm, which provides the self-sealing valve. A broader corneal valve of 2 mm is even acceptable as the maneuver performed through the wound is limited and the chance of distortion of corneal dome is minimal. The internal wound is then enlarged to 6 or 6.5 mm using a 5.2 mm blunt tipped bevel down blade. The internal opening should be slightly larger than the external incision to facilitate the delivery of nucleus.

Capsulotomy

Additional viscoelastic is injected and the capsulotomy is performed. Capsulorhexis is preferred except in advanced nuclear cataracts and in patients with small pupil associated with hard cataracts.

Flipping the nucleus into anterior chamber: With a rhexis, a forceful hydrodissection is done until a part of the nucleus prolapses into the anterior chamber. Then with the help of a Sinskey hook or lens dialler or the cannula itself, the nucleus is rotated either clockwise or anticlockwise and delivered into the anterior chamber.

Following can-opener capsulotomy, with Sinskey hook engage the superior pole of the nucleus and tip the pole up into the iris pupillary plane. Then the nucleus is rotated with the same instrument in clockwise or anticlockwise direction until it is completely in the AC, so that it is clearly loosened from its attachments to the equatorial and posterior cortex.

In cases with small pupil, can-opener capsulotomy is preferred. Iris and anterior capsule is retracted with Sinskey hook towards 12 o’ clock, superior pole of the nucleus is tipped up. Partially prolapse the nucleus through the pupil, such that Iris will support the superior pole of the nucleus. Place the viscoelastic between the nucleus and the iris and manipulate the iris with the viscoelastic or iris spatula until the iris is entirely behind the nucleus.

If the capsulorhexis is too small, or the nucleus too large, it may be necessary to make more than two relaxing incisions in the capsulorhexis rim to tip-up the nucleus to distribute the forces present during the tipup maneuver and thus minimize the risk of tearing past zonules.

Nucleus Removal

Prior to nucleus removal, it is necessary to make sure that the whole nucleus lies in front of the iris. The nucleus can be removed using an irrigating vectis. This technique basically uses a combination of mechanical and hydrostatic forces to express out the nucleus. The irrigating vectis is available in various shapes and sizes.2 We prefer a 5 mm wide vectis, with one to three 0.3 mm forward irrigating ports with a gentle superior concavity. This vectis is attached to a 5 cc syringe containing ringer lactate when in use (Figure 31.1).

After prolapsing the nucleus into the anterior chamber viscoelastics are liberally injected both above and below the nucleus. The upper layer shields the endothelium while the lower layer pushes the posterior capsule and iris diaphragm posteriorly. This creates space for the atraumatic insertion of the vectis. A proper superior rectus bridle suture, which helps in fixating the globe, is crucial for the success of this step. The superior rectus suture is loosely held in the left hand or the assistant is asked to hold it. The vectis is now tested outside for the patency of the ports (Figure 31.2). After confirming the patency the vectis is insinuated, concave side up, under the nucleus. Try to see the margins of the vectis through the nucleus to avoid pinching of the iris and consequent iridodialysis. It is possible to visualize the vectis border in most cataracts except in very white and black nuclei (Figure 31.3).

Figure 31.1: Irrigating vectis connected to a 5 ml syringe

Figure 31.2: Checking the patency of three port vectis

Now the following movements should occur in synchrony. The irrigating vectis is withdrawn out slowly without irrigating till the superior pole of the nucleus is engaged in the tunnel. At this point the superior rectus is pulled tight and with the globe thus fixed, the irrigating fluid is injected slowly to build up the hydrostatic pressure inside the chamber and the vectis is slowly pulled out while pressing down on the scleral lip. These steps are crucial in protecting the endothelium. The irrigation keeps the anterior chamber well formed whereas the downward pressure helps to open up the wound and prevent the nucleus rubbing on the endothelium. The nucleus moulds through the tunnel and comes out (Figure 31.4).

The irrigation has to be reduced when the maximal diameter of the nucleus just clears the tunnel. This step

Figure 31.3: Nucleus engaged with the irrigating vectis

Figure 31.4: Nucleus moulding out through the tunnel

prevents the nucleus being thrown out forcefully with a consequent sudden decompression and shallowing of the anterior chamber.

MANAGEMENT OF HARD CATARACTS

By increasing the incision size to 7.0 mm, one can probably manage any size of nucleus. Brunescent nuclei can be removed through a smaller wound by purposely breaking the nucleus into two pieces, if it gets locked in the wound during the removal process (Fragmentation at the scleral pocket).3 There are two techniques for doing this. The first technique involves lifting the heel of the vectis when the nucleus gets locked in the

tunnel. This usually breaks off the superior 1/3 to 1/2 of the lens nucleus. Alternatively one can remove the vectis as the nucleus gets locked in the wound and chop off a part of the nucleus outside the tunnel with a sinskey hook. The remainder can be pushed back into the anterior chamber with the longitudinal axis oriented towards 6-12 o’clock position and removed using the vectis. These techniques offer the surgeon the opportunity to reduce the size of most, if not all cataract incisions.

Irrigation-aspiration of the Cortex

It is done using the Simcoe cannula. If there is problem in the removal of subincisional cortex, then it can be approached through the sideport using the same cannula. The IOL is implanted preferably in the bag. Injecting fluid through the side-port incision forms the anterior chamber. The wound is checked for any leak. Normally no sutures are required, as the tunnel is selfsealing.

DO’S AND DON’TS

It is a time-tested technique and practiced by most surgeons in our institute with excellent results. It is safe and probably the best method to start learning Manual SICS. Only a single instrument is used inside the anterior chamber and with a good cover of viscoelastics, the procedure is very safe to the endothelium. With the use of irrigation the anterior chamber remains formed throughout the procedure. With adequate sized wound and capsulotomy, any cataract can be safely managed without any complications.

Unlike instrumental phacoemulsification, Manual SICS using an irrigating vectis is universally applicable to nearly all cataract extraction procedures. It can also be performed following RD surgery or vitrectomy, patients with colobomas and even traumatic cataracts more safely than phacoemulsification.

REFERENCES

1.Manual small incision cataract surgery: An alternative technique to instrumental phacoemulsification. Aravind publications 2000;25-32.

2.Akura J, Kaneda S, Hatta S, Matsuura K. Manual sutureless cataract surgery using a claw vectis. J Cataract Refract Surg 2000;26:491-6.

3.Barrov E, Isakov I, Rock T. Nucleus fragmentation in a scleral pocket for small incision extracapsular cataract extraction. J Cataract Refract Surg 1998;24:160-5.

INTRODUCTION

Certain difficult situations co-existing with visually significant cataract warrants special techniques and special considerations during cataract extraction surgery. If appropriate technique and precautions are taken up, the result of surgery can be excellent even in these difficult situations. Some of the difficult situations that may be encountered during cataract extraction are:

1.Small pupil

2.White cataract

3.Hard black cataract

4.Subluxated cataract

5.Cataract with pseudoexfoliation

6.Cataract with existing filtration bleb.

The significance of a systematic preoperative evaluation is to be emphasized in every case of cataract surgery. A good preoperative evaluation of a case is very important to foresee certain difficulties or problems that may crop up during the surgery. If the surgeon and the assistant are aware and geared up before hand for the difficult situations that could be encountered during the surgery, then it can be dealt in an efficient way. The surgeon must be well trained and competent enough to deal with such situations and should be aware of all the complications of the technique used to deal with the difficult situations.

SMALL PUPIL

It is preferred to have a widely dilating pupil throughout the surgery especially when performing capsulorhexis, nucleus prolapse and cortical cleanup. Small pupil is the most common problem encountered

by most of the surgeons during cataract extraction surgery. Some of the causes of non dilating pupil are

a.Chronic use of miotics

b.Diabetes

c.Posterior synechiae

d.Previous intraocular surgery

e.Intra operative trauma

f.Idiopathic

g.Pseudoexfoliation.

The management of non dilating small pupil starts preoperatively. A good preoperative examination can give an idea if the particular pupil is going to dilate or not. Presence of posterior synechiae or presence of amorphous deposition of flakes on the pupillary margin should make the surgeon cautious and a preoperative trial of pupillary dilatation should be given to know the extent of pupillary dilatation and various surgical options should be considered. If the patient is on chronic miotic therapy then it should be stopped before surgery and IOP controlled with alternative drugs.

Cycloplegics and mydriatics along with non steroidal anti inflammatory drugs (NSAID) should be used to dilate the pupil and for maintaining pupillary dilatation during surgery. Use of topical ketorolac 0.5% has been found to have effective inhibition of surgically induced miosis and it provides a more stable mydriatic effect during surgery.1,2

Managing Intraoperative Miosis

Prolapsing out nucleus into the anterior chamber and the maneuvers to prolapse the nucleus out through the tunnel can lead to surgical trauma to the iris if the surgeon is not careful. This surgical trauma can lead to

miosis of the pupil. A pupil which was dilated at the start of surgery but has now become small due to surgical trauma is best managed with intracameral adrenaline. A 0.5 ml of Injection Adrenaline 1:10,000 without preservative is used and is diluted in 4.5 ml of ringer lactate. The anterior chamber is then flushed with 0.1 to 0.2 ml of this fluid. The pupillary dilatation starts immediately after flushing the anterior chamber with this fluid and the pupillary dilatation is well maintained after dilatation with adrenaline. Intracameral adrenaline should be used with caution especially in hypertensive patients and patients with cardiac problem. A permission of the anesthetist should be asked for prior to injecting intracameral adrenaline.

Managing Nondilating Pupil

Non dilating pupil is a relative term. The extent of pupillary dilatation should be assessed keeping in mind the experience of the surgeon, the type and hardness of the cataract. Even if after maximal dilatation with pharmacological agents the surgeon feels that the pupil is not dilated enough for smooth and uncomplicated completion of surgery then the surgeon should consider surgical methods of pupillary dilatation. Surgical methods of pupillary dilatation are to be achieved depending on the cause of non dilatation of the pupil. If the pupil is not dilating due to posterior synechiae or if a pupillary membrane is restricting the pupil to dilate, then releasing posterior synechiae or performing membrenectomy will dilate the pupil.

If the pupil is not dilating due to restriction at the sphincter pupillae then sphincter needs to be tackled. The sphincter can be stretched either by using two instruments which can engage the pupillary margins such as Lester lens manipulator or by using special instruments such as Keuch small pupil dilator.

Technique of Stretching Small Pupil

Bimanual stretching of the pupil is the easiest method of achieving pupillary dilatation.3,4 The pupil is stretched right in the beginning of the surgery. Once the anterior chamber has been entered it is filled with viscoelastic to create enough space. Two Lester manipulators are introduced either through the main tunnel or through the side ports and the pupil is stretched in two opposite direction. Both the manipulators are pushed gently fully across the chamber without damaging the anterior chamber structures. Gentle stretching of pupil will cause multiple tiny partial tears in the sphincter which do not have any detrimental effect on the shape of the pupil. Pupil can be stretched

Figure 32.1: Pupil being stretched by pull and push of lens manipulator

Figure 32.2: Pupil being stretched by pushing lens manipulators with cross over action

in two or many meridians as required. If the pupil is being stretched in the vertical meridian that is at 12 and 6 o’clock position then one manipulator is pushed towards 6 o’clock and the other manipulator is pulled towards 12 o’clock position (Figure 32.1). If the pupil is being stretched in horizontal meridian that is at 3 and 9 o’clock then both the manipulators are pushed in opposite direction with cross over action (Figure 32.2). Pulling, instead of pushing the pupillary margin in this meridian will not result in good stretching.

Instead of stretching the pupil, multiple small fine sphincterectomies can be made with the help of Vannas scissors. These small fine sphincterectomies usually do not interfere with normal functioning of the pupil.

Iris hooks can also be used to dilate the pupil, but they are really not required during small incision non phacoemulsification cataract surgery and most of the cases can be managed by pupil stretching. They add to the cost and time of the surgery.

The Graether pupil expander, a device for mechanically dilating the pupil is also available. It is a soft silicone ring grooved to engage the iris sphincter and maintains pupil dilation during cataract surgery and intraocular lens implantation.5

If proper technique is employed to stretch the pupil a reasonable pupillary dilatation can be achieved and the complications due to small pupil can be avoided, however the techniques of pupillary stretching themselves require some practice before they can be performed smoothly.

WHITE CATARACT

In the developing countries the problem of mature and hyper mature white cataracts still exist in a large section of population. Managing white cataracts requires certain alterations in the technique of the surgery as white cataract has certain peculiarities. The capsule is more fragile in cases of white cataract and poses a problem of visibility during capsulorhexis. The intra lenticular pressure is more and there are more chances of capsulorhexis extending into the periphery. In cases of hypermature white cataracts the zonules may be compromised. The problem of capsulorhexis is managed to a greater extent by the use of dyes such as trypan blue6 or indocyanine green.7,8

Trypan blue is used to stain the capsule. First of all, the aqueous in the anterior chamber is replaced with an air bubble. Now a few drops of trypan blue are placed on to the anterior lens capsule under the air bubble. Due to capillary action the dye spreads over the capsule, if it does not spreads then it can be painted over the anterior capsule with the help of cannula. The dye stains the capsule immediately; however it can be left over the capsule for 10 seconds to get a better contrast. Once the dye has been injected it can be washed out with BSS and can be replaced with viscoelastic.

Performing capsulorhexis in case of white cataract requires great skill. The problem of non visualization of the anterior capsule is taken care of by staining the capsule as just mentioned. This is eases the procedure

of capsulorhexis. However there is one more glitch in performing capsulorhexis and that is the raised intra lenticular pressure. The anterior capsule is flattened with a good amount of viscoelastic, preferably with sodium hyaluronate 2.3% and the capsulorhexis is performed through a side port to prevent leakage. Frequent replenishing of the viscoelastic should be done if there is leakage of viscoelastic. The capsulorhexis should be of adequate size to let out the nucleus out without much of a struggle.

In cases of hypermature Morgagnian type of cataract a small nick in the anterior capsule will let the milky fluid come out, there by decreasing the intra lenticular pressure, but it should be performed in a very controlled manner as sudden expulsion of milky fluid from the lens can extend the capsular opening to the periphery.

In cases of white cataract even though the size of the lens is large but the size of the nucleus is usually small. The large size of the lens is due to the hydrated lens fibers so in most of the cases the capsulorhexis need not be very large.

In cases of white cataracts the posterior pole is not visible and hence any preexisting rent in the posterior pole cannot be appreciated before prolapse of nucleus. In all cases of white cataract, hydrodissection should be carried out with great caution and with minimum of fluid. If possible it is best to avoid hydrodissection, if the nucleus can be made mobile by just rotating it with the help of Sinskey’s hook.

White cataracts are most often associated with white plaques adherent to the posterior capsule. The plaques present in the visual axis should be gently peeled off from the posterior capsule with the help of bent 30 G needle and/or with the help of Utrata forceps under high magnification. These plaques generally come out very easily.

If proper technique is used and proper precautions are followed an excellent visual results can be obtained in cases of white cataract.

HARD BLACK CATARACT

The hard brown to black cataracts are more common in the developing countries. They pose a problem because their nucleus is very big in size and they are hard and non mouldable. Hard cataracts can be easily recognized preoperatively on slit lamp examination. The surgeon should be ready to make some alterations in the surgical steps to deal with hard cataracts.

If the surgeon is planning to take out whole of the nucleus through the tunnel, then a wide tunnel