Manual Small Incision Cataract Surgery

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Continuing Education Activity

The most common cause of curable blindness worldwide is cataract. It accounts for nearly 75% of blindness in the developing world. Every year about 1 to 2 million cataract cases are added to the global burden, and the number of cataract surgeries performed worldwide accounts for approximately 10 to 12 million. To address this global concern, numerous efforts are underway to reduce the cataract backlog by performing cost-effective manual small incision cataract surgery on the poor and the needy. This has helped in making cataract services available to all. The transition from intracapsular cataract extraction to extracapsular cataract extraction and the manual small incision cataract surgery has transformed outcomes of cataract surgery in terms of visual outcomes, quality of life, and increased surgical acceptance by the patients. Cataract surgery has undergone a massive revolution and technical advancements, and now MSICS has become the surgery of choice in the developing world and phacoemulsification in the developed world. Today is the rollable and accommodative IOL era, which can be implanted through an incision as small as 2 mm. MSICS offers the advantages of being a high-quality surgery, comfort for the patients, less surgical induced astigmatism than extracapsular cataract extraction, no suture-related problems, early rehabilitation, and reduced postoperative visits. MSICS has a short learning curve, is cost-effective, and simple with various indications in nearly all types of cataracts. This activity deals with the anatomy, indications, contraindications, instruments, personnel, technique, complications, and clinical significance of MSICS for the interprofessional team.

Objectives:

  • Describe the indications of manual small incision cataract surgery.
  • Outline the potential complications of manual small incision cataract surgery.
  • Summarize the technique of manual small incision cataract surgery.
  • Review the equipment required for manual small incision cataract surgery.

Introduction

Cataracts are one of the most common causes of reversible blindness worldwide, and cataract surgery is one of the most common ocular surgery performed globally for visual rehabilitation. Vision-related quality of life and visual rehabilitation are essential parameters to determine the success of cataract surgery.[1]

Cataract surgery has evolved over the years, and due to advances in surgical technique, instrumentation, and availability of newer drugs, the surgical procedure involves less risk and excellent outcomes.[2] As per the report by WHO, nearly 20 million people are bilaterally blind worldwide.[3]

The introduction of phacoemulsification by Kelman in 1967 revolutionized the clear corneal self-sealing incisional surgery.[4] Manual SICS became famous from 1980 onwards, especially in developing countries, due to comparable surgical outcomes in contrast to phacoemulsification, less costly equipment needed,  less time-consuming procedure, and fewer complications in complex cases.[5]

Cataract surgery evolved from ECCE to MSICS and then to phacoemulsification. The most significant advantage of MSICS over ECCE is that it is a sutureless surgery with a self-sealing tunnel.[6]

An average SICS takes approximately 7 to 10 minutes in expert hands. The surgery steps are detailed below in the activity, along with indications and contraindications.[7] Here we have also described the intraoperative and postoperative complications associated with MSICS. MSICS is still the surgery of choice in high volume cataract settings, developing and underdeveloped countries, and complex cataract cases. However, a lot of modifications have been described like the Mininuc technique (anterior chamber maintainer technique), Ruit technique (V-shaped capsulotomy), Malik technique (anterior chamber maintainer with continuous infusion of viscoelastic), and double nylon loop technique (nucleus trisection technique), but the basic technique remains the same.[6]

Anatomy and Physiology

Anatomical Limbus

The anatomical limbus is a transition zone between the conjunctivocorneal and corneoscleral junction.[8]

Conjunctivocorneal Junction

  • At this junction, the bulbar conjunctiva is densely adherent to the underlying structures.
  • The conjunctival substantia propria ends here, but the epithelium is in continuity with the cornea.
  • The epithelium at the limbus is several layers thick and is arranged irregularly.[8]

Sclerocorneal Junction

At this junction, the corneal lamella is transparent and is continuous with the oblique, circular, and opaque scleral fibers.[7]

Transitions at the Limbus

  • Corneal epithelium becomes continuous with bulbar conjunctival epithelium
  • Bowman's membrane becomes continuous with the lamina propria of the conjunctiva and the tenon's
  • Corneal stroma becomes sclera
  • Descemet membrane gives rise to Schwalbe's line
  • Endothelium lines the trabecular meshwork and becomes continuous with the anterior surface of the epithelium.[9]

Surgical Limbus

This is a 2 mm wide transition zone with a clear cornea and the opaque sclera on the other side.[10]

Anterior Limbal Border

This overlies the termination of the Bowman's membrane. This is the anterior boundary of the surgical limbus. It appears as a ridge formed by the insertion of the conjunctiva and tenons capsule of the conjunctiva. The blue limbal zone varies in each quadrant. This is 1 mm in the superior quadrant, 0.8 mm in the inferior quadrant, and 0.4 mm in the nasal and temporal quadrant.[11]

Blue Limbal Zone

It is a transparent zone between the anterior and limbal posterior borders. Beyond the blue zone, there is a white sclera.[8]

Mid Limbal Line

This is at the junction of the blue zone with the white sclera. This zone covers the Descemet membrane Schwalbe's line); it is one of the important landmarks.[12]

Posterior Limbal Border

This zone lies 1 mm posterior to the mid-limbal line, overlying the scleral spur. This forms the posterior border of the surgical limbus and is seen with sclerotic scatter.[10]

White Limbal Zone

This 1 mm wide zone between the mid-limbal line and posterior limbal border overlies the trabecular meshwork. The importance of limbus in cataract incisions.[13]

Clear Corneal Incision

This is located in front of the anterior limbal border and is associated with high induced astigmatism. It may result in Descemet stripping.[14]

Anterior Limbal Incision

This incision is located in the blue limbal zone, traverses the Descemet membrane, and may cause DM detachment or stripping.[15]

Mid Limbal Incision

This is externally located on the mid-limbal line and traverses Schwalbe's line internally, and is the preferred site for incision in the eye.[15]

Posterior Limbal Incision

This is located at the white limbal zone. This is the junction of the mid-limbal line and posterior limbal border. The underlying trabecular meshwork may be injured while performing an incision here.[15]

Scleral Incision

This is located posterior to the posterior limbal border. It results in hyphema and bleeding.[16]

Indications

The indications of MSICS depend on the surgeon's experience, skill, and expertise in managing the cases.

For Beginners

  • Nuclear sclerosis grade 2-3
  • Posterior subcapsular cataract
  • Cortical cataracts [7]

For Experienced Surgeons

  • Nuclear sclerosis grade 4
  • Nuclear sclerosis grade 5
  • Hard mature cataract
  • Brown cataract
  • Intumescent cataract
  • Morgagnian cataract
  • Traumatic cataract
  • Temporal SICS in glaucoma cases
  • Posterior polar cataract
  • Complicated cataract
  • Pseudoexfoliation
  • Subluxated cataract
  • Dislocated cataract
  • Small pupil cases
  • Phacolytic glaucoma
  • Phacomorphic glaucoma
  • High myopia
  • High axial length
  • Deep socket
  • Nanophthalmos
  • Pediatric cataract
  • IOL exchange
  • Secondary IOL cases
  • Post vitrectomy[17]

Contraindications

The major contraindication is the surgeon's skill, expertise, and experience. Other contraindications include those listed below:

  • Subluxated or dislocated cataract with weak capsular support
  • Microcornea
  • Scleral thinning
  • Peripheral corneal thinning
  • Low endothelial cell count cases
  • Ciliary staphyloma
  • Scleral ectasia
  • Conjunctival scarring
  • Bleeding diathesis[18]

Equipment

For Tunnel Construction

  • Bridle suture
  • McPherson- Westcott conjunctival scissors
  • Bonaccolto conjunctival forceps
  • Calliper
  • Conjunctival bipolar/ unipolar cautery
  • Razorblade and holder/15-degree blade
  • Crescent knife
  • Keratome 3.2 mm[6]

Paracentesis

  • Side port blade 15 degrees[19]

Capsulotomy

  • 26- 30 G disposable needle/cystitome
  • Capsulorhexis forceps[20]

Hydro-Dissection

  • 25 G hydro dissection cannula[7]

Nucleus Prolapse

  • Hydrodissection cannula
  • Sinskey hook[21]
  • Cyclodialysis spatulaKuglen'ss hook[22]

Nucleus Dissection

  • Nucleus dissection
  • Nucleus bi-sector
  • Nucleus tri-sector
  • Miloop[23]

Nucleus Extraction

  • Sinskey hook
  • Irrigating wire vectis[24]

Cortex Aspiration

  • Simcoe cannula
  • J-shaped
  • Hydrodissection cannula[21]

IOL Implantation

  • Sinskey hook
  • Lens holding forceps[25]

Conjunctival Closure

  • Bonaccolto conjunctival forceps
  • Unipolar/ bipolar cautery[16]

Personnel

A successful manual small incision cataract surgery involves the interplay of an Ophthalmologist, mid-level ophthalmic personnel in the OPD helping in taking IOP, nursing staff in the ophthalmic theater, and nursing staff performing the A-scan, and IOL master and counseling staff assisting in IOL choice.[26]

Preparation

The patient preparation begins with the preoperative installation of NSAIDs, and antibiotic eye drops 3-7 days before the surgery. The eye should be blocked to facilitate a smooth and safe surgery. The preferred block modalities are peribulbar, retrobulbar, and sub tenons anesthesia. Topical anesthesia has also been tried in MSICS with limited success.

The patient is given anesthesia in the block room and then taken to the operating theater. Once the patient is supine on the table, the right eye is identified, and the eye is cleaned with 10% povidone-iodine, and topical povidone-iodine is put in the eye. The eye is then draped, and a speculum is applied to keep the eye open for performing surgery.[27]

Technique

Bridle Suture

In superior tunnel MSICS, the 4-0 prolene suture is passed through the superior rectus and lateral rectus in case of a temporal tunnel. Bridle sutures help to stabilize the globe during sclerocorneal tunneling and provide counter traction for nucleus and epinucleus delivery. A bridle suture is placed by holding the muscle and tilting the globe downwards to expose the globe. Care should be taken to prevent perforation of the globe.[7]

Conjunctival Peritomy

The conjunctiva is opened by grasping with a forceps and putting a small buttonhole incision with a sharp scissor at the limbus. The conjunctiva with the tenons is opened up from 10 to 2 o clock position, and a small relaxing inward incision is given at two o clock. Then gentle cautery is done to cauterize the vessels.[28]

Sclerocorneal Tunnel Construction

The concept of a sclerocorneal tunnel is based on three planar tunnel. The first is a perpendicular scleral incision, the second is a horizontal incision through the sclera and cornea, and the third is a beveled incision in the anterior chamber. The inner corneal has the self-sealing property.[16]

Paul Ernest first proposed the concept of the inner corneal lip. The inner corneal lip has the advantage that it saves the eye in case of expulsive choroidal hemorrhage and patients with respiratory and cardiac comorbidities. The benefits of the self-sealing sclerocorneal tunnel are low incidence of hyphema, iris prolapse, hypotony, no sutures needed, and early resumption of day-to-day activities.

The tunnel has a trapezoid configuration with the peripheral triangular tunnel. The incision configuration can be straight, frown incision, chevron, or inverted V-shaped and Blumenthal side cuts.[6] The incision should be placed in Koch" s incisional funnel to minimize astigmatism.[16]

Temporal Sclerocorneal Tunnel

This is indicated in cases with against-the-rule astigmatism, superior bleb, glaucoma patients, the superior graft was taken for pterygium surgery, deep socket, scarred conjunctiva, etc. The tunnel technique is the same as described for the superior scleral tunnel. The advantages can be good working space, less astigmatism, the globe is parallel to the axis of the microscope, good preparation for temporal phacoemulsification, and help in deep sockets. The disadvantages of the temporal tunnel being it takes time to get adjusted to the temporal view and a high incidence of endophthalmitis.[29]

Paracentesis (Side Port Incision)

The paracentesis incision is placed at 9 or 8 o clock with a 15-degree blade. Paracentesis is used to put adrenaline for pupillary dilatation, trypan blue for capsular staining, viscoelastic for anterior chamber formation, and while performing capsulorhexis. Paracentesis also helps in cortex aspiration, an anterior chamber after the surgery, and nucleus prolapse, dialing, IOL dialing, and Implantation with the help of a sinskey hook.[30]

Anterior Chamber Entry

This approach is made with the help of a 3.2 mm angled keratome. While entering the scleral lip, the heel of the keratome should be parallel to the tunnel, and then the heel is rotated 90 degrees to make it perpendicular to the tunnel. Then the heel of the keratome is raised parallel to the iris until a dimple is seen on the corneal surface. The keratome is advanced till the anterior chamber entry is done. Then the entry is extended on either side till the limbus so that the nucleus can be delivered after prolapse into the anterior chamber.[31]

Capsulotomy

A large capsulotomy of 7 to 8 mm is desired for MSICS in contrast to 5 to 6 mm for curvilinear capsulorhexis in cases with phacoemulsification.[20]

Can Opener Capsulotomy

Can opener capsulotomy is ideal in extracapsular cataract extraction and beneficial under challenging cases of MSICS such as mature cataract, small pupil, fibrosed and calcified ALC, brown cataract, as a savior in cases of rhexis extension, and for beginners doing MSICS.[20] Can-opener is performed with a bent 26 G needle by performing multiple radial cuts of punctures quadrant-wise. Between 15 and 20 punctures are desired in each quadrant.

The tears are made circumferentially to avoid damage to the zonular insertions. The significant advantage of CCC is that it is easier to learn and helpful in small pupil cases, mature, hyper mature, brown cataract, and traumatic cataract cases. The limitations are a high risk of radial tear extending to the posterior capsule, zonular stress during prolapse, chances of PCR and ZD during cortex aspiration, and chances of IOL decentration.[32]

Continuous Curvilinear Capsulorhexis

CCC is the ideal type of capsulotomy. The CCC offers various advantages.

  • A good hydro dissection can be performed with full confidence
  • Nucleus prolapse and delivery will be safe and easier
  • In the bag, IOL implantation with good centration- Effective Lens Position (ELP)
  • Cortex removal is safe and easy with minimal risk of ZD or PCR
  • In the case of PCR, sulcus support is present for IOL implantation[33]

Disadvantages

  • Difficult learning curve
  • Small rhexis may pose difficulty in nucleus prolapse
  • Difficult in small pupil cases
  • Small rhexis may cause capsular bag distension syndrome or capsular contraction syndrome
  • Difficult to remove the sub incisional cortex[22]

Prerequisites for Performing Safe Capsulorhexis

  • Good ocular anesthesia
  • Clear and transparent cornea
  • Good pupillary dilatation
  • Good anterior chamber depth
  • Elastic capsule
  • Intact zonular fibers
  • Nuclear sclerosis of moderate to good hardness
  • No positive vitreous pressure[34]

Instruments Required

  • 26G cystitome
  • Converging forceps- Utrata forceps
  • Forceps with coaxial arms- Caporessi and Possi

Capsulorhexis with forceps is performed using either a shearing force or a ripping force. The capsulorhexis is facilitated with the help of staining the anterior lens capsule with trypan blue dye. The capsule is stained with 0.1% trypan blue, and this is very helpful in white cataracts. The advantages of dye being non-toxic to endothelium and doesn't leak into vitreous. 0.5% indocyanine green can also be used, but the cost is very high.

The other dye available is 0.2% sodium fluorescein, but this is toxic to endothelium and leaks into the vitreous. A blue filter can be used to enhance visualization. The capsular staining technique can be suprascapular and subcapsular, of which suprascapular is more commonly employed.[35]

Staining Technique

After injecting the air bubble, the dye is injected with a tuberculin syringe from the paracentesis or main port. The air bubble prevents the dye from getting diluted and prevents endothelial staining. The air bubble is then replaced with the help of viscoelastic.

A good capsulorhexis is performed in a formed anterior chamber with viscoelastic. The capsulorhexis is initiated slowly, and the vector force is directed towards the center to prevent extension. In pediatric cataracts, the capsule is very elastic; hence the rhexis is completed with the help of forceps. Posterior capsulorhexis is also done in cases with pediatric cataracts, thick posterior capsular plaque, and posterior capsular rupture.[35]

Envelope Capsulotomy  

This is done in cases with hypermature cataracts or with weak capsular support. The capsule is punctured with the help of keratome, and milky fluid is egressed. Then the capsule is cut on either side with the help of a vannas scissor and extended till six o clock.[20]

Hydroprocedures

This is the technique of nucleus prolapse from the capsular bag with the help of a balanced salt solution without excess stress on the zonules, which can be hydrodissection and hydrodelineation.[22]

Hydrodissection

This is the separation of the cortex from the anterior lens capsule. After performing the rhexis, the viscoelastic should be washed from the anterior chamber. If hydrodissection is performed in the chamber pressurized with viscoelastic, it can result in posterior capsular rupture. The hydrodissection is performed with the help of a 27 gauge bent tip hydrodissection cannula in a syringe filled with BSS.

Cortical cleavage hydrodissection is achieved by passing the cannula under the anterior lens capsule and advancing to the equator, and a jet of fluid is passed under the nucleus. This separates the cortex with epi and endonucleus from the anterior lens capsule. The advantage is no cortex is left in the capsular bag, and it produces no stress on the zonule and the capsular bag during cortex aspiration.

The phenomenon to look for while hydrodissection is fluid wave passage from one end of the equator to the other, anterior movement of the nucleus, shallowing of the anterior chamber, and stretching of the anterior lens capsule.

The capsular bag distension syndrome can be observed while hydrodissection in the small pupil. This is prevented by performing double rhexis or multiple mini-hydro dissections. A pupil snap sign is seen when sudden hydrodissection is performed in the small pupil, indicating a posterior capsular rupture.[7]

Hydrodilineation or Hydrodelamination

This is the separation of the endonucleus from the epinucleus. Aziz Anis first described this. In hydrodilneation, the cannula is embedded 45 degrees in the substance of the nucleus at the paracentral zone, and a fluid wave is passed. The fluid movement separates the nucleus from the endonucleus, and a golden ring sign is seen. Hydrodilineation is helpful in the posterior polar cataract.[36]

Nucleus Prolapse in Anterior Chamber

The nucleus prolapse in the anterior chamber is performed with the help of a Sinskey hook or cystitome or with the use of a hydrodissection cannula. The surgeon should learn to prolapse the nucleus through a can opener, and continuous curvilinear capsulorhexis as in can opener capsulotomy hydrodissection is contraindicated; hence the surgeon should know how to prolapse with a Sinskey hook.

After hydrodissection, when one of the poles of the nucleus has prolapsed out of the bag, the nucleus is dialed or wheeled in the anterior chamber under viscoelastic cover. The viscoelastic should coat under the nucleus's surface to protect the posterior capsule and the above surface to protect the endothelium.[22]

Nucleus prolapse is difficult in the case of soft cataracts, small rhexis, brown cataracts, dense cortical adhesions, inadequate hydrodissection, and small pupil cases. The nucleus can be mechanically hooked with a Sinskey hook or cystitome or can be prolapsed with hydro jet during hydrodissection.

Nucleus prolapse can also be done by a bimanual technique using a Sinskey hook and a spatula. This technique is helpful in small pupil cases and cases where repeated attempts have failed to prolapse the nucleus. Another technique is the tumbling technique which is useful in soft cataracts where the nucleus is flipped in the posterior chamber and prolapses up with the help of the hydro cannula. The prerequisites are adequately sized rhexis and a deep anterior chamber.[22]

Nucleus Extraction

Irrigating Wire Vectis

Steinert described this technique using irrigation wire Vectis using mechanical and hydrostatic forces. The wire Vectis is 4 mm in width and 8 mm in length. It has three irrigating ports on its anterior surface, each having a 0.3 mm opening in size. The posterior end is the main body of the Vectis, which is connected to the syringe containing ringer lactate or BSS.

Once the nucleus is prolapsed in the anterior chamber, the Vectis is introduced below the nucleus under viscoelastic cover. The nucleus prolapses by synchronous movements of the bridle suture, the mechanical movement of Vectis, and the hydrostatic jet from the fluid through the syringe. In this way, the nucleus is prolapsed out of the tunnel.

If the technique is not followed correctly, various complications can be encountered like corneal endothelial damage, nucleus trap in the tunnel, iridodialysis, zonular dialysis, posterior capsular rupture, and vitreous loss.[37]

Phacosandwich

This was described by Luther. L. Fry in 1985. Initially, he tried to bisect the nucleus in the anterior chamber by using a lens loop and iris spatula. He noticed that the lens could be squeezed through the tunnel by sandwiching it between two instruments. The two most commonly used instruments are Sinskey hook and wire Vectis.[38]

Phacofracture

  • Nucleus Bisection
  • Nucleus Trisection
  • Phacosalute and fracture
  • Wire-loop technique
  • Phacofracture at exit[39]

Modified Blumenthal Technique

This technique is not used frequently; however, some surgeons still perform this technique using an anterior chamber maintainer. This is a hollow tube of 0.9 mm outer diameter and 0.65 mm inner diameter. The tube is attached to the BSS bottle and suspended 50 to 60 cm above the patient's eye. The surgery steps are the same, except for an anterior chamber maintainer attached through the side port. Another side port is made for instrument manipulation. This technique is also called the Mininuc technique.[24]

Fish Hook Technique

In this technique, a 30 G needle is bent and used as a fish hook for nucleus extraction. The needle is maneuvered behind the nucleus to hook it under the surface, and under viscoelastic cover, the nucleus is gently hooked out of the bag.[40]

Cortex Aspiration

Once the nucleus is delivered, the capsular bag is cleaned of the cortex for IOL implantation. This is done with the help of two-way irrigation and aspiration Simcoe cannula. The cortical fibers are engaged with the use of Simcoe under a vacuum created by aspiration. Once the fibers are caught in Simcoe, they are slowly aspirated and mechanically pulled towards the center. In this way, the cortex is removed clockwise till the 360-degree capsular bag is free of the cortex. The epinucleus can be removed using Simcoe cannula, hydro cannula, or viscodissection.[21]

Management of Subincisional Cortex

  • Through side port using Simcoe cannula
  • Using bimanual irrigation and aspiration
  • J shaped Simcoe cannula
  • Dialing the IOL in the bag[41]

IOL Implantation

The optic of PMMA IOL is around 6 mm, which can be passed through the 6 to 7 mm SICS tunnel and dialed in the capsular bag. Small diameter IOL like 5 to 5.5 mm can also be placed in the capsular bag in soft and traumatic cataract cases.[25]

The Technique of IOL Implantation

The IOL implantation is done with the help of lens holding forceps, conjunctival forceps, and a Sinskey hook. The IOL is first passed through the tunnel parallel to the iris plane until it reaches the anterior chamber's central part. After that, the IOL haptic is tilted towards the capsular bag, so the haptic is placed below the rhexis margin.

Then the IOL is dialed through the hole till the optic haptic junction reaches around four o clock. The IOL is depressed and dragged towards the capsular bag, and the lagging haptic is placed below the rhexis margin. In case of a can opener capsulotomy or a posterior capsular rent, the IOL is implanted in the sulcus. All the steps are performed under adequate viscoelastic cover. After surgery, the capsular bag is thoroughly washed with viscoelastic to prevent secondary glaucoma.[42]

Wound Closure

After the surgery, the anterior chamber is reformed through a side port with the help of BSS, and the conjunctiva is cauterized with a bipolar cautery to close the incision and prevent the risk of endophthalmitis. At the completion, 0.1 ml intracameral moxifloxacin is injected through the side port to minimize the risk of endophthalmitis.[16]

Complications

Intraoperative

Wound Related

Incision Position

Anteriorly placed incisions have a poor self-sealing mechanism, resulting in wound leak and, against the rule, astigmatism. This is managed by placing 10-0 nylon tunnel sutures. Posteriorly placed incisions lead to a broader tunnel, risk of hyphema due to bleed and premature entry, and difficulty in delivering the nucleus through the tunnel. This is again managed by placing 10-0 nylon tunnel sutures.[43]

Incision Length

Shorter incisions less than 6 mm are related to nucleus engagement in the tunnel and difficulty in nucleus delivery. Tunnel compression during nucleus delivery can aggravate endothelial trauma, iridodialysis, zonular dialysis, and posterior capsular rent. Large incisions are related to the rule astigmatism and wound leak, which sutures can manage.[43]

Incision Depth

The incision depth should ideally be one-third of the scleral depth. In highly myopic eyes, with scleral scarring or deep socket, the surgeon may find it challenging to find the correct depth of the incision.[43]

Scleral Disinsertion

A deep incision may result in separating the upper sclera from the lower sclera and result in disinsertion. If there is no tissue bridge, there is no support for the sclera from the groove to the limbus. This complication is managed with radial sutures to secure the edges of the scleral groove. Scleral disinsertion is prevented by making a partial thickness groove, freehand incision, or a guarded blade. The scleral tunnel roof or floor may also be torn.[17]

Button Hole

There occurs superficial dissection of the sclera flap. The dissection should be terminated, and then a groove should be made at a deeper plane, and then the tunnel should be continued.

Premature Entry

This results in from incision at a deeper plane. Once a premature entry is noted, dissection should be stopped as a groove should be made at a correct plane, and then the tunnel should be continued.[7]

Descemet Membrane Detachment

Any iatrogenic or traumatic injury to the DM may result in DM detachment. Sometimes DM stripping may occur when fluid from the cannula or viscoelastic from the paracentesis passes into the corneal stroma and DM and separates the DM. Sometimes the DMD appears as a free-floating membrane and is mistaken as a remnant of the anterior capsule and is aspirated in the Simcoe cannula. This results in DM loss and leaves a permanent corneal opacity. The DMD is managed with the help of air tamponade, and if needed, the tunnel is sutured to prevent the leak of air bubbles.[44]

Conjunctival Ballooning

Sometimes during block or while hydrating the corneal stroma, the fluid may egress through the stroma into the conjunctiva and result in hooding or ballooning of the conjunctiva. This may impair the anterior chamber visualization and may mask the surgical steps. This is managed by placing a small incision 1-2 mm posterior to the conjunctiva and allowing the fluid to egress.[45]

Paracentesis

The configuration of the paracentesis is essential as a too anterior paracentesis in the cornea may lead to DM stripping, too far in the sclera will result in bleeding, too small instruments may result in DM stripping, and too large may result in leakage.

Capsulorhexis

Runaway Rhexis

There can be a peripheral extension of the tear and may result in a posterior capsular tear.[46]

Capsulorhexis Size

A small capsulorhexis may result in difficulty in nucleus prolapse. Difficulty in prolapse may lead to PCR, zonular dialysis, or nucleus drop. A large capsulorhexis may cause a problem with the placement of an IOL. If the rhexis margin is not seen on one side,  the IOL placement will be difficult and may even result in decentration.[22]

Hydrodissection

  • Inadequate cortical capsular bag dissection
  • Fluid misdirection syndrome
  • Zonular dialysis
  • PCR
  • Nucleus drop
  • Capsular block syndrome

Nucleus Prolapse

Difficulty prolapsing the nucleus may result from the small pupil, incomplete hydro dissection, the small size of the rhexis, synechiae, brown cataract, and soft nucleus. This may result in endothelial damage, iridodialysis, zonular dialysis, posterior capsular rent, or nucleus drop.[43]

Nucleus Delivery

While nucleus delivery, if the tunnel is of inadequate size, it can result in Descemet membrane detachment, endothelial damage, iridodialysis, PCR, and ZD. These complications arise due to small tunnel, ragged tunnel, incomplete hydro dissection, anterior chamber leak, premature entry, or vitreous in the anterior chamber.

Hyphema

The significant reasons for hyphema can be deeper tunnel incision, iridodialysis, and microbleeds from conjunctival vessels seeping into the anterior chamber. This can be prevented by correct surgical technique and an excellent viscoelastic cover.[43]

Iris Damage

Injury to the iris can cause a tear, sphincter damage, iridodialysis, and iris prolapse. Sphincter tears can occur in cases with PXF and complications during nucleus delivery.

  • Iridodialysis
  • Iris prolapse
  • Pupillary constriction
  • Zonular dialysis
  • Posterior capsular rupture
  • Retained cortex
  • Nucleus drop
  • Positive pressure
  • Expulsive choroidal hemorrhage

Postoperative

Immediate

  • Wound leak
  • Descemet membrane detachment
  • Corneal edema
  • Endothelial damage
  • Uveitis
  • Secondary glaucoma
  • Toxic anterior segment syndrome

Delayed

  • Corneal decompensation
  • Uveitis
  • Capsular contraction syndrome
  • IOL dislocation
  • IOL subluxation
  • Posterior capsular opacification
  • Irvin Gass syndrome
  • Endophthalmitis
  • Pan ophthalmitis

Complications Unique to MSICS

Tunnel and Scleral Complications

  • Surgically induced necrotizing scleritis
  • Buttonhole
  • Premature entry
  • Nucleus in tunnel
  • Cortex in the anterior chamber
  • Wound leak
  • Paracentesis leak
  • Exposed suture knots
  • Incorrect suture placement

Corneal Complications

  • Corneal edema
  • DMD
  • Striate keratopathy
  • Pseudophakic bullous keratopathy
  • Epithelial defect
  • Recurrent erosions[43]

Clinical Significance

MSICS has revolutionized cataract surgery in today's era, especially in low-income and developing countries. Large-scale studies have quoted similar long results of MSICS and phacoemulsification considering visual acuity and astigmatism.

MSICS offers the advantage under challenging cases where an excellent outcome can be achieved without complication. MSICS has served as a stepping stone for performing good phacoemulsification as the majority of steps of both the surgeries are similar except for the trenching and emulsification in phacoemulsification. MSICS is more of a skill-based surgery that improves surgeons' tissue handling.[47]

Enhancing Healthcare Team Outcomes

To achieve a good outcome in cataract surgery following MSICS, the ophthalmic surgeon, the mid-level ophthalmic personnel, the optometrists, the OT staff, and the nurses assisting with IOL power calculation and counseling play a crucial role. A perfect outcome following MSICS is a result of good teamwork.[48]

Nursing, Allied Health, and Interprofessional Team Interventions

The nursing staff helps in documenting visual acuity, refraction, lacrimal syringing, intraocular pressure, IOL power calculation, counseling, and assisting in OT. The allied health professionals also help shift patients with systemic comorbidities and play a vital role during any emergency.[48]

Nursing, Allied Health, and Interprofessional Team Monitoring

The nursing, the allied health staff, and the interprofessional team help in monitoring high-risk patients with systemic comorbidities, monitoring pediatric patients under general anesthesias, intubation, extubation, and vitals of physically ill patients requiring urgent cataract surgery.[48]



(Click Image to Enlarge)
Digital image depicting postoperative SICS image of the patient depicting stable IOL.
Digital image depicting postoperative SICS image of the patient depicting stable IOL.
Contributed by Dr Bharat Gurnani, MBBS, DNB, FCRS, FICO, MRCS Ed, MNAMS

Contributed by Dr Bharat Gurnani, MBBS, DNB, FCRS, FICO, MRCS Ed, MNAMS
Article Details

Article Author

Bharat Gurnani

Article Editor:

Kirandeep Kaur

Updated:

6/6/2022 1:42:21 AM

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