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

Ophthalmologists working within developing countries are currently exploring possible alternatives to phacoemulsification in order to obtain the advantages of a self-sealing sutureless incision at a significantly lower cost.1-12

At Prapokklao hospital (Chanthaburi,Thailand), several techniques have now been used to perform extracapsular cataract extraction (ECCE) without phacoemulsification. These include the modified Blumenthal technique, Ruit technique, the nylon loop technique, prechop manual phacofragmentation and the Kongsap technique.1,6-12

The Kongsap technique is a manual small incision cataract surgery in which the lens nucleus is divided into two to four fragments prior to manual removal through a relatively small incision, using inexpensive instrumentation.11-12 The foldable intraocular lens (IOL) is placed in the capsular bag and the wound is closed with a no stitch suture.

INSTRUMENTATION

Essentially, the instruments for the Kongsap technique are similar to the standard ECCE.

Additional instruments used are:

—A nuclear supporter. This is crafted from a crescent knife. Its sharpness being reduced by the use of a grindstone (Figure 27.1A). The top surface is roughened in order to ensure easier manipulation of the nucleus.

—A nuclear cutter is made from a Sinskey hook. Its sharpness is located inferiorly (Figure 27.1B).

—A 3.0 mm angled keratome.

—A 15 degree stab knife.

Local anesthesia; retrobulbar anesthesia or peribulbar anesthesia are the primary methods used in the Kongsap technique cataract surgery. Lidocaine (2%) is administered to achieve local anesthesia. Sub-Tenon anesthesia or topical anesthesia may also be used depending upon the condition of the patient’s status and the surgeon’s experience.

SURGICAL TECHNIQUE

Incision

A 4-mm temporal clear corneal wound is made using a 3.0 mm keratome (Figure 27.2). However, the scleral tunnel incision may also be used in this technique. In cases of performing the scleral tunnel incision, a partial thickness 6.0-6.5 mm scleral tunnel incision is made 2 mm behind the limbus and the scleral tunnel is extended 1 mm into clear cornea.

Side Ports

One side port, at the 12 o’clock position is performed with a 15 degree stab knife (Figure 27.3). The capsulorhexis and cortical debris aspiration is performed via this side-port incision. The side port is initially smaller whilst undertaking the capsulorhexis and is then enlarged during the cortex aspiration.

Capsulorhexis

A 6-7 mm continuous curvilinear capsulorhexis (CCC) is performed with a 27 G bent needle when the anterior chamber is filled with a balanced salt solution. The

Figure 27.1A: The nuclear supporter

Figure 27.1B: The nuclear cutter

cystotome is connected to an insulin syringe and a bottle of balanced salt solution (BSS) which is introduced through the 12 o’clock side port. The first puncture is located in the center of the anterior capsule followed by the creation of the anterior capsular flap (Figure 27.4). The anterior capsule is torn in a curved manner by either pushing or pulling the flap. Alternatively, this step may be undertaken whilst the anterior chamber is being filled with a viscoelastic material.

Figure 27.2: The corneal incision

Figure 27.3: Side-port incision at 12 o’ clock position

Figure 27.4: The capsulorhexis

Figure 27.5: Hydrodissection and hydrodelineation

Hydrodissection/Hydrodelineation

A 26 G blunt tipped cannula mounted on a 2 cc syringe filled with BSS is guided behind the rhexis margin in the subcapsular plane (Figure 27.5). The cannula is slightly lifted and the BSS is injected slowly and smoothly until a fluid wave can be seen. The cannula may also be inserted through the temporal corneal incision allowing injection of the fluid to the right and left of a 9 o’clock meridian. Hydrodelineation is performed to separate the nucleus from the epinucleus. The fluid is injected between the nucleus and epinucleus until the golden ring can be seen.

Anterior Cortical Debris Removal

Anterior cortical debris should be removed as much as possible in order to manipulate the hard core nuclear with greater ease (Figure 27.6). Aspiration can be better controlled using a Simcoe cannula passed through the side-port incision.

Nuclear Fragmentation

The viscoelastic is injected into anterior chamber. The nucleus is dislocated out of the bag to the anterior chamber using a spatula and a Sinskey hook (Figure 27.7). Viscoelastic is injected below and above the nucleus facilitating this maneuver. The nuclear supporter is held by the left hand and the Sinskey hook or nuclear cutter by the right hand. The platform of the nuclear supporter is passed under the nucleus with the nuclear cutter being placed over the nucleus. The nucleus is slightly manipulated allowing nuclear fragmentation to occur by gently pushing the nuclear

Figure 27.6: Anterior cortical debris removal

Figure 27.7: Lens prolapse into anterior chamber

supporter and the nuclear cutter against each other (Figures 27.8 and 27.9). The nucleus is now divided into three fragments with each fragment being approximately 3.0-3.5 mm in size.

Nuclear Removal

Viscoelastic materials are injected below and above the nucleus. The nuclear supporter is passed under the first fragment and the nuclear cutter is placed over it. The fragment can then be removed with a pulling motion (Figure 27.10). The second and third fragments are extracted using the same technique. Remain aware that the viscoelastics should be injected into the anterior chamber once it is shallow in order to protect the corneal

Figure 27.8: Nuclear fragmentation

Figure 27.9: Nuclear fragmentation into three fragments

endothelium and allow safe manipulation during the process.

Cortical Aspiration

Once the nuclear fragments have been extracted, the epinucleus and lens cortex are flushed out by gentle pressure on the sclera posterior to the main incision. The residual cortex is removed through the side-port incision by a Simcoe cannula (Figure 27.11).

IOL Implantation

The viscoelastic materials are injected into the anterior chamber and a foldable IOL is implanted in the capsular bag using the forceps or the injector (Figures 27.12A and

Figure 27.10: Nuclear extraction through a clear corneal incision

Figure 27.11: Epinucleus and lens cortex aspiration

B). Both the side-port and the corneal incision will be hydrated by injection of a few drops of BSS into the stroma (Figure 27.13).

For ophthalmologists new to this technique, a 5-mm temporal clear corneal incision should be undertaken and a 5.0 mm polymethyl methacrylate posterior chamber intraocular lens (PCIOL) can be implanted into the capsular bag.

SURGICAL RESULTS

The Kongsap technique has been successfully performed on more than 1,000 eyes. Outcomes of the first 95 eyes in terms of the postoperative visual acuity can be seen in Table 27.1. Good visual outcomes were

Figure 27.12A: Foldable intraocular lens implantation

Figure 27.12B: Foldable intraocular lens implantation

achieved for the majority of the cataract patients operated on with the Kongsap technique. Visual acuity of 20/40 or better was achieved in 83 eyes (87.37%) at the end of first postoperative week and this result remained stable for 85 eyes (89.48%) at the end of six

Figure 27.13: The wound closure with no suture

months. When making the comparison to phacoemulsification, the postoperative visual acuity of this technique showed no statistically significant difference between the groups (Table 27.2).

The complications arising from cataract surgery using the Kongsap technique are shown in Table 27.3.

Prolapse of the iris (7.37%) remained the most frequent intraoperative complication. This occurred during the removal of the nucleus and was due to early perforation into the anterior chamber of the wound.

The most significant postoperative complication was transient corneal edema, which developed in seven eyes (7.37%).

All cases of iris prolapse and corneal edema were observed in the first 30 eyes of the surgery using this technique.

Regarding the safety of the operation, the mean corneal endothelial cell loss is detected in 5.3 ± 6.5% at one month after surgery and 7.1 ± 6.6 % at three months postoperatively.12 The comparative study for the corneal endothelial cell loss after cataract surgery with the Kongsap technique is equivalent to those of phacoemulsification.13

Table 27.2: Postoperative Snellen best-corrected visual acuity (n = 102)13

KMPF = The Kongsap Manual Phacofragmentation (n = 52) PE = Phacoemulsification (n = 50)

Table 27.3: Intraoperative and postoperative complications12

RECOMMENDATIONS

As this technique is performed mostly in the anterior chamber, corneal endothelial damage may occur during nuclear luxation, nuclear fragmentation and also during nuclear removal through the clear corneal incision. Such damage can be avoided if a high-density viscoelastic agent is frequently injected into the anterior chamber together with the surgeon holding the nuclear supporter and the nuclear cutter as still as possible. It has also been noted that progression in the learning curve can lower the incidence of endothelial-related complications.

Patient selection is important to the success of this surgery. The guidelines are similar to the ones used for phacoemulsification. A nuclear hardness of 2+ to 3+ according to Lens Opacities Classification System II,14 ensures that it is easier to perform nuclear fragmentation using this technique.

The Kongsap technique enables cataract surgery in the hard cataract having a large nucleus but there is narrow space for manipulation in the anterior chamber; thus, the nucleus is hard for nuclear fragmentation and the central fragment is thick. Therefore, for good visual

Figure 27.14: The half-thickness scleral groove 2 mm from the limbus

Figure 27.15: The 6-7 mm scleral tunnel incision

results and safety to the patients, the scleral tunnel incision is highly recommended (Figures 27.14 and 27.15). The nucleus is divided into two fragments in order to decrease the chance of corneal endothelial damage and the incision should be enlarged to approximately 6-7 mm to make the the nuclear removal and implantation of a 5.0 mm PMMA intraocular lens (Figures 27.16 to 27.18) more easy.

If a nuclear cutter is not available in the operation theater, the Sinskey hook may be used during the stage of nuclear fragmentation. However, nuclear fragmentation with the Sinskey hook is more difficult to carry out than when using a nuclear cutter, especially with regards to the hard cataract.

Figure 27.16: Nuclear fragmentation through the scleral tunnel incision

Figure 27.17: Nuclear extraction through the scleral tunnel incision

The other alternative method, the anterior chamber maintaining system may be used in the stage of capsulorhexis and cortex extraction. The anterior chamber maintainer (ACM) is connected to a bottle of BSS and elevated to the required height providing a comfortably formed anterior chamber. The ACM is introduced into the nasal side-port incision and a CCC is performed with a 27 G bent needle when the anterior chamber is filled with BSS.12 With the ACM, the quantity of viscoelastic material used in one case is reduced, diminishing the financial outlay. The viscoelastics are used only

Figure 27.18: The intraocular lens implantation

during the nuclear fragmentation and nuclear extraction stages.

CONTRAINDICATIONS (PRECAUTIONS)

A very hard black or brown cataract is contraindicated for cataract surgery using the Kongsap technique. Generally, the Modified Blumenthal technique6 or the nylon loop technique10 is preferred when dealing with very hard black or brown cataracts. Patients with weak zonule or zonule dehiscence are also contraindicated for this surgical technique.

Very low viscosity, dispersive viscoelastics such as methylcellulose should be avoided in this surgical technique as they do not maintain or stabilize the anterior chamber and provide a low ability to protect the corneal endothelium.

CONCLUSION

Cataract surgery using the Kongsap technique provides self-sealing incision, rapid visual recovery and low complications. It can be used as alternative to phacoemulsification in the developing countries.

REFERENCES

1.Garg A, Fry LL, Tabin G, Gutierrez-Carmona FJ, Pandey SK. Clinical practice in small incision cataract surgery (Phaco Manual). Jaypee Brothers, New Delhi, 2004.

2.Gerald T, Keener Jr. The nuclear division technique for small incision cataract extraction. In: Rozakis Cataract Surgery: Alternative small incision techniques, NJ Slack 1990;163-91.

3.Kansas PG, Sax R. Small incision cataract extraction and implantation surgery using a manual phacofragmentation technique. J Cataract Refract Surg 1988;14:328-30.

4.Gutierrez-Carmona FJ. Manual multiphacofragmentation through a 3.2 mm clear corneal incision. J Cataract Refract Surg 2000;26:1523-8.

5.Akura J, Kaneda S, Ishihara M. Quarters extraction technique for manual phacofragmentation. J Cataract Refract Surg 2000;26:1281-7.

6.Blumenthal M, Moisseiev J. Anterior chamber maintainer for extracapsular cataract extraction and intraocular lens implantation. J Cataract Refract Surg 1987; 13(2):204-6.

7.Ruit S, Tabin GC, Nissman SA, Paudyal G, Gurung R. Low-cost high-volume extracapsular cataract extraction with posterior chamber intraocular lens implantation in Nepal. Ophthalmology 1999;106(10):1887-92.

8.Kongsap P, Wiriyaluppa C. Prechop manual phacofragmentation: Cataract surgery without a phacoemulsification machine. Asian J Ophthalmol 2002;4:7-9.

9.Kongsap P, Wiriyaluppa C. Manual prechop allows cataract removal through relatively small incision. Ocular Surgery News (Internat ed) 2003;21(20):48-9.

10.Kongsap K. Manual small incision cataract surgery: Nylon loop technique. Asian J Ophthalmol 2006;8:135- 8.

11.Kongsap P. Sutureless ECCE with foldable IOL: the Kongsap technique. Ocular Surgery News 2006;24:7880.

12.Kongsap P. Manual sutureless cataract surgery with the foldable intraocular lens using the Kongsap technique: the results of 95 cases. J Med Assoc Thai 2007;90(8):162732.

13.Kongsap P. Corneal endothelial cell loss between the Kongsap manual phacofragmentation and phacoemulsification. J Med Assoc Thai 2008;91(7):1059-65.

14.Chylack LT Jr, Leske MC, McCarthy D, et al. Lens Opacities Classification System II (LOCS II ). Arch Ophthalmol 1989;107:991-7.

INTRODUCTION

Trabeculectomy is a filtering procedure which lowers the intraocular pressure by creating a new channel for aqueous outflow between the anterior chamber and sub-conjunctival/ sub-Tenon space. Cataract surgery is frequently combined with this procedure, in patients with vision impairing cataract and uncontrolled or marginally controlled glaucoma with maximum tolerated medical therapy or patients with medically uncontrolled glaucoma and a cataract which is likely to become visually significant in the near future. It is also indicated in patients with vision impairing cataract and glaucoma controlled with multiple medications.

There are many advantages of a combined procedure vis-a-vis, a staged procedure, in respect that, there is decreased exposure to drugs like anesthetic medications, is more cost-effective, promotes early visual rehabilitation and there is decreased incidence of early postoperative pressure spikes.

As the cataract surgery has evolved spectacularly, from a sutured procedure to a sutureless one, so has the patient’s demands for a combined surgery which is hassle free and provides the best visual outcome. There are various methods described in the literature to perform this surgery, but one of the main concerns that still remain for both surgeon and the patient is the unsatisfactory visual outcome. The causes may be many ranging from the most obvious, viz optic nerve damage, to the most practical, i.e. postsurgical astigmatism. Surgically induced astigmatism is becoming an important issue because it delays visual rehabilitation and exerts a negative effect on the final visual outcome. As more and more people are being diagnosed at an early stage because of tremendous advancement in

CS Dhull, Sumit Sachdeva (India)

technology, more people are being operated early while they are still active in their daily lifestyle, so the demand for a surgery which is comfortable, yet provides the best visual outcome is on the anvil.

The conventional cataract surgery with trabeculectomy involves, creating a triangular or rectangular partial thickness scleral flap before cataract surgery and performing trabeculectomy with a scleral punch or vannas scissors, then closing the flap with the help of sutures. This procedure has been the gold standard since long and all other procedures are compared with this one.

But there are certain limitations of this conventional surgery. First of all, it is quite time consuming. Secondly, sutures applied in this procedure cause a significant amount of astigmatism.

We describe a procedure here which is similar in efficacy to conventional trabeculectomy in terms of reducing the intraocular pressure but is quite a breakthrough in reducing postoperative astigmatism.

PROCEDURE

1.After giving a peribulbar anesthesia, we clean and drape the patient’s eye.

2.A superior rectus bridle suture is passed and eyespeculum applied.

3.A fornix-based conjunctival flap (Figure 28.1A) is made and wetfield cautery (Figure 28.1B) is done to coagulate bleeders.

4.We prefer to make a side-port entry with 15° disposable keratome about 90° away from main incision site, and perform continuous curvilinear capsulorhexis (CCC) after forming the anterior chamber with viscoelastic.