INTRODUCTION
During the last decade, in industrialized countries phacoemulsification has largely replaced ab-externo extracapsular cataract extraction with posterior chamber intraocular lenses (ECCE/PC IOL) with sutures. The self-sealing incision provides rapid visual rehabilitation. However, in low income countries phacoemulsification plays only a very limited role in the reduction of cataract blindness, mainly due to the high cost of a phaco machine and the advanced cataracts with hard nuclei. Therefore, eye surgeons have been searching for alternatives to phacoemulsification.
During the last years, different sutureless non-phaco cataract surgical techniques were developed, where either the whole nucleus or the nucleus divided in parts, is removed through a self-sealing tunnel.1–7 Small incision sutureless cataract surgery is becoming increasingly popular and is slowly replacing sutured ECCE in developing countries. It provides fast visual recovery and good visual outcome at low cost, also in high volume cataract surgical centres.8–12
The surgical complication rate and visual outcome is comparable to phacoemulsification.13
These non-phaco cataract surgical techniques got different names, e.g. “Small Incision Cataract Surgery (SICS)”, “Manual SICS”, “Manual Phaco” and “Sutureless ECCE/PC IOL.
The Fishhook Technique
The Fishhook Technique is one of the small incision cataract surgical techniques. The speciality of the Fishhook Technique is that the whole nucleus is extracted out of the capsular bag and through the self-sealing tunnel with a small hook, made of a 30 G needle (Fig. 1.1).
The Fishhook Technique was developed at Sagarmatha Choudhary Eye Hospital in Lahan, Nepal in 1997, where since then it has become the routine cataract surgical procedure. Till October 2005 more than 280,000 sutureless cataract surgeries have been performed in Lahan by this technique and many more in other eye centres around the world.
Once the technique is mastered, sutureless cataract surgery with nucleus hook extraction has a very low complication rate and provides excellent immediate uncorrected postoperative visual acuity.14
The Fishhook Technique has also proved to be suitable for high volume surgery.8,9 An experienced eye surgeon, involving paramedical staff in pre- and postoperative steps, can perform 15-20 cataract surgeries per hour.
Tunnel Construction
A correct tunnel construction with a self-sealing wound is a prerequisite for a good visual outcome and requires a stepwise training and experience.
The tunnel can be done at 12 o'clock or temporal, ideally at the steepest corneal meridian to keep the postoperative astigmatism at a minimum.
The size of the tunnel depends on the age of the patient and the anticipated size of the nucleus. Very big brown nuclei in older patients may require an opening of 8 mm, whereas cataracts in younger patients need incisions only as large as the IOL optic.
The tunnel construction can be made with either conventional tunnel instruments (razor blade fragment, crescent knife, keratome) or with a diamond knife.
A good sclera holding forceps helps when performing the following three steps:
Frown Incision
A “frown” shaped scleral incision has proved to cause the least surgically induced astigmatism. At its closest point it should be at least 2 mm behind the limbus.
Sclerocorneal Tunnel
This is the most difficult part of the tunnel construction. The sclerocorneal tunnel should be done in half scleral thickness and needs to end at least 1 mm into the clear cornea to ensure a self-sealing effect (Fig. 1.2). If the tunnel is going too deep, it might come to a premature entry. This may result in an iris prolapse during surgery and requires suturing.
If the tunnel is prepared too shallow, the surgeon might perforate to the outside (“button hole”).
Opening of the Anterior Chamber (AC)
The opening of the AC is performed with a sharp pointed instrument (keratome or diamond knife) with cutting movements from outside to inside (Fig. 1.3).
All three steps (frown incision, sclerocorneal tunnel, opening of the anterior chamber) and even the linear capsulotomy can be done with only one instrument, using either a specially designed diamond knife (Fig. 1.4) or a modified keratome (Anil Kumar Singh, Fig. 1.5).
Capsulotomy
A linear capsulotomy can be performed with a cystitome, a keratome or a diamond knife.
Preferred but more difficult is a continuous curvilinear capsulorhexis (CCC), which guarantees the best possible IOL centration. It needs to be large enough for the nucleus to get through.
In case of mature white cataracts it is very helpful to stain the anterior capsule with “Trypan Blue”. First, air is injected into the AC through a side port incision before the anterior capsule is stained with “Trypan Blue”. Then the air is replaced with viscoelastic solution, like methyl cellulose, and the CCC performed with Utrata forceps (Fig. 1.6) or a cystitome.
Hydrodissection and Nucleus Extraction
In case of a linear capsulotomy, forceful hydrodissection is done to mobilize the nucleus. Then the nucleus is slightly lifted at the side of the tunnel.
In case of CCC, gentle hydrodissection is performed beneath the remaining anterior capsule. The fluid pressure pushes part of the nucleus out of the capsular bag. Then the elevated nucleus is rotated towards the tunnel (Fig. 1.7). After injection of viscoelastics in front and behind the nucleus, the fishhook is carefully inserted between nucleus and posterior capsule and the tip then turned so that it inserts into the central lower nucleus. Without lifting the nucleus into the AC, it is extracted out of the capsular bag and through the tunnel (Figs 1.8 to 1.10). Cortex will remain and act as a kind of “safety cushion”, protecting the corneal endothelium.
Completing the Surgery
Remaining cortex is removed by hydroexpression and with the help of a Simcoe cannula (Fig. 1.11). Cortex behind the iris at the tunnel side may be removed through a side port incision.
A PC IOL is inserted into the capsular bag (Fig. 1.12).
TRANSITION FROM SUTURED TO SUTURELESS CATARACT SURGERY
Sutureless cataract surgery is more difficult to learn than ab-externo sutured ECCE/PC IOL surgery. However, it is easier to learn and to perform than phacoemulsification.
A self-sealing wound with minimum induced astigmatism requires a very accurate tunnel construction as well as good surgical skills and experience to work inside the eye through a narrow tunnel.
Many surgeons are keen to convert from sutured to sutureless cataract surgery. It is best to wait until they feel entirely confident and have consistent good results with conventional ECCE/PC IOL surgery. Self-evaluation of the postoperative uncorrected visual acuity and surgical and postoperative complications is a reliable indicator.
While converting from sutured to sutureless cataract surgery, a stepwise approach is an important key to success. The surgeon should:
- First practice hydrodissection, nucleus mobilization and nucleus hook extraction during conventional ab-externo ECCE/PC IOL surgery;
- Select immature cataracts to start with so that the tip of the hook can be seen while inserting it into the nucleus;
- Start with a larger tunnel and smaller nuclei.
SUMMARY
Sutureless non-phaco cataract surgery has become increasingly popular in developing countries. It is an alternative to phacoemulsification in providing immediate good visual outcome. The surgical time is short and the cost for consumables reduced.
There are various techniques available. The Fishhook Technique, developed in Lahan, has proved to be very successful and cost-effective and is suitable for high volume cataract surgery.
Sutureless non-phaco cataract surgery is more difficult to learn than ab-externo cataract surgery with sutures. It requires additional training.
Once the Fishhook Technique or any other sutureless non-phaco cataract surgical technique is mastered, the immediate good outcome will motivate many cataract patients to go for surgery and therefore will play an important role in the reduction of worldwide cataract blindness.
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