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

Figure 24.19: The fragments are removed with the special recurved tank track forceps

Figure 24.22: IOL inserted. Here a silicone Strorz IOL is injected in

An adequate sized tunnel length is essential so that the wound subsequently self-seals itself. The anterior chamber is filled with viscoelastic. The ideal viscoelastic to use is Healon which can maintain the chamber depth, which is so essential in this procedure. A good sized capsulorhexis is essential. The minimum size is usually 7 mm. Following the rhexis, a good hydro-dissection is carried out the in such a manner that the edge of the nucleus tips forward. This tipping of the nucleus forward is also known as the ‘lens salute’.

The viscoelastic is again placed in the anterior chamber and a blunt rotator is placed on the opposite pole of the slightly prolapsed nucleus and swept around in a manner that the nucleus literally rolls over on itself into the anterior chamber. As a final maneuver, the lens is rotated using a blunt IOL rotator to be sure that it lies the anterior to the capsule.

The next step is the insertion of the wire loops, into the anterior chamber. Retract the loops in the cannula so that only the 2.00 mm of the narrow loops protrude forward of the cannula. Carefully insert the cannula into the anterior chamber until it goes in by about 3 mm. Let the wire loop expand themselves by pushing the round loop holder from behind. The loops in the anterior chamber are first inserted horizontally and then gradually turned till they sweep over the edge of the nucleus and then snugly hold it. The nucleus is gradually rotated utilizing the side report opening which we had remained at 2 o’clock position into the loops in such a manner that the loops straddle the nucleus equally . The cannula is supported and the wire loops smoothly pulled out.

Following the trisection of the nucleus, usually the middle part often simply slips out at the time of the wire loop removal. If it does not, it is of no consequence. Viscoelastic is re-injected and an iris repositor is introduced to separate the fragments apart making sure the fragments always remained vertical aligned to the incision.

A specially designed forceps which has special recurved tracks grooved into its substance of the jaws, with short square grooves virtually along the lines of a tank tracks. The force of fixing comfortably through a 4.0 mm incision and the individual fragments are held and simply removed. The harder to the nucleus they

easier it is to hold. In the advantage of the tracks is that once it is grasped the fragments come out in the single stroke.

A good cortical cleanout is done in and subsequently after polishing the capsule, in the intraocular lenses is inserted in the eye. If a foldable lens is to be used then it can be simply inserted utilizing a folder or injected. If a standard 5.5 mm PMMA lens is to be utilized for the opening would need to be widened by 1.5 mm. Utilizing and arcuate incision makes the opening self-sealing. The edges of the cut conjunctiva can be apposed utilizing a coaptation forceps. The viscoelastic to his washout, chamber is reformed.

SUMMARY

The eye is exceptionally quieter. Ironically, the harder to the nucleus the easier the trisector works and the hall mark of the procedure. It is an exceptional technique which is of great use, not only for one who does small incision nonphaco techniques, but also for the phaco surgeon, who is often faced with a hard cataracts usually coupled with the compromised endothelium, and for whom this would prove to be an ideal choice.

This technique is also very useful when the nucleus is hard, especially in the deep brown incompressible cataracts where trying to do a sandwich method causes undue stress on the corneal edges leading to sheer which will lead to an unstable astigmatism. The advantage of splitting the nucleus into three parts permits easier removal of the smaller fragments.

The other alternative methods utilize a back stop or a flat back blade, inserted under the nucleus and a vertical splitter designed, like a bread board, so that it cuts the nucleus into two or into three fragments. But in both these techniques it presupposes that the chamber depth is adequate. Indian cornea have smaller, steeper cornea’s and a shallower anterior chamber depth where, utilizing the back stop and cutter there is always the likelihood of corneal. Simply rotating the nucleus into the loops of the wire is a simpler, safer technique. As with all new techniques a certain element of practice is required to gain facility with this method. But the learning curve is short, and the results are gratifying.

INTRODUCTION

Small incision, non-phako techniques are very important to achieve consistent success in cataract surgery. There are many techniques available which permit it to be done with a high level of accuracy and competency. However, all techniques at present are dependent on the lens lying flat with the hard nucleus being sheared off, or chopped off, with the nucleus lying horizontally, flat abutting the posterior capsule. The risk factors with this techniques is that the dome of the cornea may be damaged with endothelial cell loss leading to corneal decompensation, or damage may occur to the iris if entrapped between the choppers or splitters, or the incision may be damaged leading to an non-occluding incision requiring sutures which enhance the astigmatism, or the posterior capsule is likely to be damaged often irretrievably with the result that a implant cannot be inserted and the with the added possibility of nuclear drop, either partial or total.

The obvious answer to prevent any possibility of damage is to handle the lens vertically. In an effort to analyze the technique in two consecutive eye camps, all cases were selected, to be done with the Slider pincer technique only.

THE INSTRUMENT

The “Jaws” slider pincer is a specially designed instrument to cut even the hardest cataract into longitudinal slices. It has its tip designed as a beak of a bird and properly rounded to permit its easy entry into the eye. The jaws of the slider pincer literally slide open thus placing no stress whatsoever on the 3.2 mm incision. The jaws are made of hardened tungsten steel

Keiki R Mehta, Cyres K Mehta (India)

to prevent any whiplash on handling hard cataracts. The tips of the pincer forceps are designed with the part placed at 12 o’clock being blunt with roughened edges to prevent slippage, while the 6 o’clock placement pincer is made curved and sharp to permit easy slicing through the substance of the lens.

THE TECHNIQUE

The standard technique utilized was to do a corneal tunnel entry with a 3.2 mm diamond knife, a good capsullorhexis followed by hydrodissection which is done in two parts. The first part is carried out using either BSS or ringer-lactate. The moment it is noticed that the fluid wave has spread below the lens, the cannula is removed and a specially designed cannula which is three-port attached to a viscoelastic cannula. The use of this cannula permits the easy rotation of the lens with no pressure on the posterior capsule.

Once the lens is made to rotate out of the capsular bag, the specially designed pincer forceps is introduced via the incision. Since it is curved it manages to easily enter the eye with no stress on the incision. It is introduced in its closed form, sideways and then 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. On an average, +2 or +3 density cataract, two pieces are adequate, as the pieces will compress when held with a forceps and come out easily enough from a 3.2 mm opening. However, if the density is higher, especially if it is grade +5 or over (suprahard) cataract it may be necessary to cut the cataract into three or even four slices. Thus the initial slice will be from 1 o’clock to 5 o’clock, while the middle piece will cut at 12 o’clock

Figure 25.1: The slider pincer instrument. Note the inner part of the upper slider is sharp while the lower part is flat to prevent it slipping off the nucleus when held

Figure 25.2: The slider pincer now being closed. Note the close approximation

Figure 25.4: The special designed forceps to remove the split nuclear remnants. The tips do not touch (like obstetrical forceps) so accidentally iris cannot be held

Figure 25.5: Straight square toothed forceps for removal of small nuclear pieces

Figure 25.3: With the slider pincer completely approximated. Note the smooth beaked head which can easily enter the 3.00 mm incision

Figure 25.6: Clear corneal initial entry made with a 3.00 mm diamond knife

Figure 25.7: Rhexis being made. Ideal is a 7.00 mm rhexis

Figure 25.8: Following hydrodissection the edge of the blunt repositor is placed at the edge of the nucleus to simply turn the nucleus over ( Supracapsular tumble)

Figure 25.9: The nucleus being tumbled over

Figure 25.10: Once the nucleus is in the anterior chamber, the ‘jaws’ is inserted via the 3.2 mm incision on the surface of the nucleus

Figure 25.11: The jaws is opened up fully until it encompasses the nucles. A repositor from the side may be used to properly position the lens

to 6 o’clock, while the last piece will be from 11 o’clock to 7 o’clock position. Thus these hard pieces will be easy to remove. Always remember to cut the pieces longitudinally as cross cutting a piece has no advantage and makes it more troublesome to remove.

Utilizing the specially designed non-apposing curved forceps the pieces can be easily removed in their entirety . The tips of the forceps do not appose and thus can never grasp iris accidentally. One of the biggest advantages of this procedure over the Sandwich technique of removing the nucleus is that there is no stress on the incision which does not shear and lead to troublesome irregular astigmatism.

Figure 25.12: As the slider is approximated it immediately slices through the nucleus. Literally with this instrument no resistance is noted even with the hardest nucleus

Figure 25.13: Using the special delivery forceps literally shaped like the obstetrical forceps and the tips do not meet to prevent accidental grasp age of the iris. The inner edges of the forceps blade are grooved to prevent slippage which prevent the fragment from slipping out

RESULTS

The results from the 200 cases done consecutively were exceptionally good. The complications were virtually negligible and well within the usual results as compared to phakoemulsification. On the other hand if the results were compared to phako done in grade+5 or suprahard cataracts (+6 or more) the results were significantly better. Even in the hardest cataracts in no case was the posterior capsule compromised.

In an effort to analyze the cases further, Endothelial cell studies were carried out. The results once again show that the results with the pincer forceps was

Figure 25.14: Individual pieces are grasped with the special forceps

Figure 25.15: Final fragment being held and removed

Figure 25.16: An simple I/A completes the procedure

Figure 25.17: I/A completed, final fragments of the cortex aspirated out

Figure 25.18: A foldable IOL is inserted via the small 3.2 incision

measurably better than with phako and the results were far superior if the very hard cataracts were selected where the ultrasound energy compromised the endothelium still further.

In addition 50 cases were done using the Sandwich technique. Surprisingly the endothelial cell loss with the Sandwich is quite high and more so if the cell count is done with the eye measured at 15 degree deflection. As compared to the pincer forceps it would seem virtually mandatory that if small incision non-phako be considered, then the pincer forceps is the answer to the problem and the Sandwich technique should be relegated to posterity.

Figure 25.19: Foldable silicone Allergan IOL (SI40) is injected in

Figure 25.20: IOL in the eye. Notice how quiet the eye is. Notice that the 3.2 mm tunneled openings always seal themselves. The final appearance, completely undistinguishable from a true phako by anyone

Variations

In a very hard cataract the split may not go through and through the nucleus. Spin the nucleus on its vertical axis and do it from the other side to complete the chop.

In thin hard cataracts typically associated with white hypermature cataract, spear the lens with a sharp instrument to support it against the splitter.

Perhaps the greatest advantage of the pincer slider technique is that it prevents the development of extensive endothelial cell loss which is, unfortunately,

Table 25.1: Complications n = 254

a common problem of the Non-phako Sandwich technique, or the vectis slide, in the hands of novices. Though per se, it is a very nice technique when done by a master, however when a novice tries the same techniques, especially in a grade 3+ in an effort to do it rapidly and with the fear that the nucleus may not come it or slip to the side, the novice tries to pull too hard and then abrades the cornea.

Why do these problems occur with the Sandwich technique ?

1.The corneal dome has inadequate space for gymnastics.

2.The perception of depth is often inadequate unless exceptional microscopes are used.

3.Multiple entry in and out of the eye will invariably lead to inadvertent corneal touch with grave results.

4.A panicky surgeon leads to a lost eye. Nothing panics a surgeon as much as a uncooperative lens in a small incision, non-phako surgery.

5.Subsequent often flat chambers due to traumatized wound entries lead to a further exacerbation of the problem.

All these problems are completely obviated using the ‘Jaws’ slider pincer technique with the lens in the ‘lens salute’ mode. It is a far safer technique and needs to be a part of the armamentarium of not only small incision non-phako surgeon but also with the phako surgeon for he can now do every had cataract with minimal energy and be assured of splitting the hard nucleus every time without any problems.

SUMMARY

A simple effective technique which can be done easily, under direct vision, with minimal risks, giving a literally 100% chance of splitting the lens . Easily applicable even to eye camp surgery with minimal complications .

NB: This jaws instrument was originally developed for me by Mr Malkeet Singh of Indo German Instruments Company, Mumbai, to whom I extend my grateful thanks.

TECHNIQUES OF OPHTHALMIC ANESTHESIA

The techniques of ophthalmic anesthesia have changed over the years. In the eighteenth century couching was done under cocaine topical anesthesia. Then came facial and retrobulbar anesthesia techniques followed by peribulbar anesthesia technique. Of late subtenons and topical anesthesia have evolved.

OCULAR COMPLICATIONS OF RETRO/ PERIBULBAR ANESTHESIA

The most common complication is retrobulbar hemorrhage due to which the surgery has to be postponed for few days.

Other complications are:

•Globe perforation

•Optic nerve injury

•Central retinal artery occlusion

•Intra-arterial injection

Optic nerve sheath injury all of which can lead to permanent damage in vision. The systemic toxicity of anaphylaxis due to injection in the vessel is another serious complication.

WHY IS TOPICAL ANESTHESIA POSSIBLE TODAY

This is due to self-sealing incision which causes a closed globe without iris prolapse and other serious attendant complications. The anterior maintainer keeps the pupil well-dilated and the intraocular structures in there normal positions with constant intraocular pressure in all stages of surgery which helps to minimize pain.

THE DISADVANTAGES OF TOPICAL ANESTHESIA

The eye is mobile eye with less profound anesthesia which is not necessary in cooperative patients. Eye lids and periorbital area is not anesthetized which again makes little differences to a cooperative patients. Discomfort from microscope light is felt by few patients compared to injection anesthesia. Potential epithelial toxicity can occur due to which it is advisable to put anesthetic two minutes before surgery.

ADVANTAGES OF TOPICAL ANESTHESIA

The advantages of topical anesthesia is manifold as there is no risk from needle injection with the complications already mentioned. No bridal suture is required to be taken which reduces the risk of superior rectus palsy and also reduces the risk of iris prolapse during delivery of lens. The return of vision is rapid and almost immediate compared to retrobulbar injection which numbs the optic nerve. The rapid return of vision contributes a lot to mental healing of the patients. The eye following topical anesthesia need not be patched contributing to greater postoperative comfort.

CASE SELECTION FOR TOPICAL ANESTHESIA

It is preferable to have the following patients for this procedure:

•Patients with uncomplicated cataracts

•Patients with well-dilated pupils

•Patients which are best avoided are anxious patients

•Patients with hearing problems

•Patients who are mentally handicapped