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

Figure 2.14: Second corneal side port at 2:00

Figure 2.15: Standard ECCE approach

cannulae while cleaning the main subincision wound area from cortical materials while the latter is for the second instrument during phacoemulsification (Figure 2.14).

ECCE After an adequate fornix based peritomy with a temporal relaxing incision, cauterization of superficial blood vessels follows. A standard ECCE approach then follows (Figure 2.15).

Lens Delivery Phase (Figures 2.16 to 2.18)

MSICS Two blunt instruments is used, the first is engaged lifting the nucleus edge towards outside the capsular bag while the other instrument holds the nucleus under it to avoid sinking back into the bag. An adequate amount of viscoelastic gel introduced into the AC and beneath the lens nucleus helps push it outside the capsular bag into the anterior chamber at the same time protects endothelium from trauma while lens nucleus is prolapsed using the cartwheel maneuver (make sure not to put so much tension enough to break the zonules). Complete prolapse of lens nucleus is achieved as it floats freely into the anterior chamber. With the lens loop inserted between the nucleus and the posterior capsule, the “Sinolinding” hook is placed on top of the lens 1 mm beyond the center (without touching the endothelium). After slight pressure exerted by the two instruments sandwiching the lens nucleus, a gentle traction engages the tip of the hook with the nucleus while the lens loop holds the lens nucleus from below until completely extracted through the sclerocorneal tunnel.

Figure 2.18: Sinolinding hook is a specially designed instrument with a 45 degrees curved tip in reference with the handle

Care must be observed not to trap the iris during the process of extraction to avoid iridodialysis.

Hints

1.To avoid splitting the nucleus into small chunks, insert the hook until the tip is 1 mm beyond middle portion of the nucleus before tilting the handle upright. This maneuver engages the sharp tip of the hook right in the middle of the nucleus where it is most resistant to breakage.

2.When nucleus gets fractured and stuck in the tunnel, remove fractured fragment. Gently push back the remaining nucleus into the AC after injecting viscoelastic gel between the nucleus and endothelium. Reposition the nucleus with its fractured side parallel to the tunnel.

3.Inject copious amount of viscoelastic gel into the “space” between the posterior surface of the lens and the capsuleiris plane to push the posterior capsuleiris plane down as the nucleus floats.

4.During extraction under the TSI anesthesia, ask the patient to look down as you gently pull the hook and loop towards you. It acts like as a counter force.

Phaco Using a keratome, an initial incision is done before creating a 3-plane 2-3 mm wound. A phaco tip is then inserted while a second instrument (preferably nagahara chopper) is used to assist during the procedure (Figure 2.19).

IOL Insertion

MSICS Insertion of IOL in MSICS follows the standard ECCE technique. With the leading haptic directed

towards the capsular bag, lens is secured and pushed slowly through the tunnel until the IOL optic is halfway in the bag. The trailing haptic is then insinuated inside the bag. IOL is positioned properly by gentle manipulation until the desired position is achieved. Simcoe cannula is used to aspirate remaining VEGs inside the AC and under the lens (Figure 2.20).

Phaco With injector loaded with foldable IOL, carefully insinuate the tip through the main paracentesis and slowly inject the IOL into the AC. Lens dialer is used to manipulate until all of the IOL is inside the capsular bag. Simcoe cannula clears the remaining VEG in the AC and under the lens (Figure 2.21).

THE RESULT (Figures 2.22A to 2.23C

MSICS (Hook Sandwich)

COMPLICATIONS

a.During paracentesis

•Too large/tight side port causes leakage and difficulty of inserting instruments, respectively.

b.During capsulotomy/capsulorrhexis

•Too small/too wide capsulorrhexis/capsulotomy

•Extension of capsulorrhexis

•Posterior capsular tear

c.During wound construction

•Hyphema

•Astigmatism

•Button hole incision

•Premature corneal entry

•Iridodialysis

•Wound leak for large incision

•Difficulty of lens extraction for small incision

d.During anterior dislocation of lens nucleus

•Rupture of lens zonules causing lens dislocation

•Injury to the endothelium

•Injury to the iris

e.During nucleus extraction

•Descemet’s membrane separation

•Injury to the endothelium by the hook

•Posterior capsule tear caused by the lens loop

•Corneal edema at incision site

•Iridodialysis

f.During aspiration of cortical materials

•Retained cortex specially at subincision area

•Tear at posterior capsule

g.During lens implantation

•Decentered or tilted IOL

•Dropped IOL.

BIBLIOGRAPHY

1.Jacob S, Agarwal A, Agarwal A, Agarwal S, Chowdhary S, Chowdhary R, et al. Trypan blue as an adjunct for safe phacoemulsification in eyes with white cataract. J Cataract Refract Surg 2002;28:1819-25.

2.Kansas P. Phacofracture. In: Rozakis GW (Ed): Cataract surgery—alternative small incision techniques. New Jersey: Slack Inc, 1990:45-70.

3.Kothari K, Jain SS, Shah NJ. Anterior capsular staining with Trypan blue for Capsulorhexis in mature and hypermature cataracts. A preliminary study. Indian J Ophthalmol 2001;49:177-80.

4.Lam DS, Tano Y, Ritch R, Rao SK. Cataract IV, Sutureless Large Incision Manual Cataract Extraction (SLIMCE), 2008.

5.Malik Krishan PS, Goel R. Nucleus management with Blumenthal technique—anterior chamber maintainer. Indian J Ophthalmol 2008.

6.Natchiar G. Manual small incision cataract surgery: An alternative technique to instrumental phacoemulsification. Madurai: Aravind Publications 2004.

7.Ruit S, Tabin GC, Nissman SA, et al. Low cost high volume extracapsular cataract extraction with posterior chamber intraocular lens implantation in Nepal. Ophthalmology 1999;106:1887-92.

8.Santos EO, et al. Philippine National Survey on Blindness. 2004:6-9.

9.Srinivasan A. Nucleus management with irrigating vectis. Indian J Ophthalmology 2008.

10.Thomas R, Kuriakose T, George R. Towards achieving small-incision cataract surgery 99.8% of the time. Indian J Ophthalmol 2000;48:145.

11.Thylefors B, Negrel AD, Pararajasegram R, et al. Global data on blindness. Bull World Health Organ 1996;74: 319-24.

INTRODUCTION

SICS is a closed chamber, high turbulence cataract surgery with postoperative results comparable to phacoemulsification surgery. Many different techniques of SICS have been developed over the past many years, each with its own advantages and disadvantages. As with cataract surgery by phacoemulsification technique, wherein, knowing the machine parameters is of paramount importance for a successful outcome, ditto in SICS, a thorough knowledge of the physical forces at play during the surgery helps in maximizing the results of the surgery. Let us now consider the evolution of the various steps in cataract surgery and how it affected the final outcome of the surgery.

Pressure plays an important role in the conduct of cataract surgery. With ICCE and ECCE the emphasis was on low intraocular pressure. The success or failure of surgery depends to a large extent on the pressure play across the cornea and across the various intraocular structures. The structures of the eye being very delicate, respond rapidly to pressure changes during the surgical procedure. Too much of turbulence inside the eye can result in postoperative iritis, irregular pupil, zonular dehisence, endothelial cell loss, etc. Each step in cataract surgery, whether ECCE, SICS or phacoemulsification, depends to a large extent on delicate pressure modulations for a successful visual outcome.

HISTORICAL ASPECT

During the days of cataract surgery with corneal loupe or with naked eye, most of the surgeries used to be intracapsular cataract extractions or extracapsular

surgeries. In these surgeries, achieving hypotony before the start of the surgery was the main objective—whether by means of oral acetazolamide or intravenous mannitol or by applying prolonged pressure over the eyeball subsequent to retrobulbar injections. The pressure differential achieved in this case across the cornea was such that the atmospheric pressure was always higher than the intraocular pressure, so that in spite of a large wound, the intraocular contents remained inside the eye. Any external pressure on the globe like that from speculum blades or bridle sutures or tight lateral canthus would try to push out the intraocular con- tents—sometimes even leading to expulsive hemorrhage. The wound in all such cases had to be secured

Figure 3.1: Pressures in ECCE – Higher