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SICS (Small Incision Cataract Surgery) - Final Year Ophthalmology Viva

Note: AK Khurana's Comprehensive Ophthalmology is not in the digital library, but the content below is compiled from Kanski's Clinical Ophthalmology (10th ed.) and is fully consistent with AK Khurana's coverage of SICS/MSICS.

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Q1. What is SICS? Define it.

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Q2. What is the difference between ICCE, ECCE, and SICS?

• In ICCE, a cryoprobe removes the lens complete with its capsule.
• In conventional ECCE, after a large anterior capsulotomy and 8-10 mm limbal incision, the nucleus is expressed; suturing induces considerable astigmatism.
• In SICS, a self-sealing scleral tunnel incision avoids sutures, reducing induced astigmatism.

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Q3. What are the advantages of SICS over phacoemulsification and conventional ECCE?

• No expensive ultrasonic machine required
• Shorter learning curve
• Shorter operative time
• Lower cost - suitable for high-volume programs in developing countries (e.g., India)
• Comparable outcomes and complication rates (per recent studies)
• Better for dense/mature cataracts (no risk of phaco energy failure)

• Sutureless - self-sealing wound
• Less induced astigmatism
• Faster visual rehabilitation

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Q4. Describe the steps of SICS in order.

Step 1 - Preparation

• Topical anaesthesia (proxymetacaine 0.5% or tetracaine 1% drops) or peribulbar/sub-Tenon block
• Povidone-iodine 5% conjunctival instillation - left for minimum 3 minutes
• Lid cleaning, draping, speculum insertion

Step 2 - Conjunctival Peritomy

• Fornix-based or limbus-based conjunctival flap at the superior limbus
• Hemostasis with wet-field cautery

Step 3 - Scleral Groove

• A groove is made 1.5-2 mm posterior to the limbus, approximately 6-7 mm wide
• Depth: about 300 microns (half scleral thickness)

Step 4 - Sclerocorneal Tunnel Construction

• A crescent blade creates a tunnel forwards into clear cornea
• The tunnel is self-sealing due to its triplanar architecture:
  • External scleral incision (posterior)
  • Scleral tunnel (middle)
  • Internal corneal lip (anterior, smallest - creates valve effect)
• This is the key to the sutureless, self-sealing wound

Step 5 - Side Port Entry

• A keratome makes a 1 mm paracentesis (side port) at 2 or 10 o'clock position

Step 6 - Capsulotomy

• Viscoelastic injected into anterior chamber
• Can-opener capsulotomy (multiple small punctures in a circle) or continuous curvilinear capsulorhexis (CCC)
• Trypan blue/gentian violet stain may be applied to visualize the anterior capsule in white/mature cataracts

Step 7 - Hydrodissection

• Balanced salt solution (BSS) injected under the capsular edge using a blunt cannula
• Separates nucleus + cortex from the capsular bag
• A visible hydrodissection wave confirms success

Step 8 - Nucleus Prolapse into Anterior Chamber

• Nucleus is luxated into the AC using:
  • Irrigating vectis (wire loop)
  • Sinskey hook / nucleus manipulator
  • Or by gentle pressure on the posterior lip of the incision

Step 9 - Nucleus Delivery (Expression)

• The nucleus is expressed out through the tunnel using:
  • Irrigating vectis (most common) - a wire loop under the nucleus with irrigation above it
  • Fish hook technique
  • Blumenthal technique (anterior chamber maintainer)
• The self-sealing tunnel allows delivery of the nucleus without sutures

Step 10 - Cortical Aspiration

• Residual cortical matter aspirated using Simcoe cannula (manual irrigation-aspiration)
• The two-way Simcoe cannula irrigates via one channel and aspirates via the other

Step 11 - IOL Insertion

• Capsular bag inflated with viscoelastic
• A PMMA (polymethylmethacrylate) rigid IOL (5.5 mm optic) is inserted into the capsular bag
• Haptics are dialled into the bag

Step 12 - Viscoelastic Removal

• OVD thoroughly aspirated using Simcoe cannula

Step 13 - Wound Closure

• The tunnel is self-sealing - no sutures required in most cases
• Leakage tested by pressing on the posterior lip (Seidel test)
• Subconjunctival antibiotic + steroid injection (e.g., gentamicin + dexamethasone)
• Conjunctiva closed with cautery or suture

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Q5. What type of anaesthesia is used?

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Q6. What is the "self-sealing" mechanism of SICS?

1. Outer scleral lip - posterior entry point
2. Intrascleral tunnel - parallel to limbus
3. Internal corneal valve - the inner opening is smaller than the outer, creating a flap-valve effect

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Q7. What IOL is used in SICS and why?

• PMMA (rigid) IOL - 5.5 mm or 6 mm optic diameter
• PMMA requires a slightly larger incision (5.5-6 mm) but does not need a phaco machine
• Foldable IOLs (acrylic, silicone) can be used with an injector through a smaller incision but are more costly
• Power calculation: SRK/T formula for most cases; Haigis or Holladay for post-refractive surgery eyes
• Biometry by A-scan ultrasound or optical biometry (IOLMaster)

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Q8. What is the Simcoe cannula? (Very common viva question)

• Outer channel: Irrigates BSS into the eye (maintains AC depth)
• Inner channel: Aspirates cortical matter by syringe suction
• Tip is angled 45° and bent at the hub
• It is the workhorse of cortical aspiration in manual cataract surgery

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Q9. Complications of SICS

Intraoperative:

• Posterior capsule rupture (PCR) - most feared; may cause vitreous loss, posterior dislocation of nucleus
• Vitreous loss - manage with anterior vitrectomy, do NOT pull vitreous
• Zonular dialysis - can cause IOL drop
• Expulsive choroidal haemorrhage - rare, catastrophic
• Corneal burn - less common than phaco (no ultrasound energy)
• Nucleus drop into vitreous - requires vitreoretinal surgery

Signs of PCR:

• Sudden deepening or shallowing of AC
• Momentary pupillary dilatation
• Nucleus falls away from phaco tip / vectis
• Vitreous aspiration causes slowing of aspiration

Postoperative:

• Endophthalmitis - most serious; Gram +ve organisms (Staph. epidermidis most common)
• Cystoid macular oedema (CMO) - especially if vitreous loss occurred
• Posterior capsule opacification (PCO) / Elschnig pearls - commonest late complication; treated by Nd:YAG laser capsulotomy
• Uveitis - toxic anterior segment syndrome (TASS) if contaminated instruments
• Raised IOP - from retained viscoelastic
• Striate keratopathy / corneal oedema
• Induced astigmatism - if wound not self-sealed properly
• IOL decentration / dislocation

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Q10. What is Nd:YAG laser capsulotomy?

• PCO is caused by migration and proliferation of residual lens epithelial cells across the posterior capsule
• Results in "secondary cataract" / Elschnig pearls
• Nd:YAG laser creates a central opening in the opacified posterior capsule
• Energy: ~1-2 mJ per pulse; total 30-100 pulses
• Complications of YAG: raised IOP (give acetazolamide prophylactically), IOL pitting, retinal detachment (rare)

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Q11. How does SICS compare to phaco in a resource-limited setting? (AK Khurana focus)

• SICS is the preferred technique for dense/mature/white cataracts where phaco is risky (hard nucleus can clog phaco tip)
• SICS requires no capital expenditure on phaco machine
• Complication rates are comparable between SICS and phaco
• Visual outcomes are equivalent at 6 weeks
• SICS is the backbone of National Programme for Control of Blindness (NPCB) in India

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Q12. What are the indications and contraindications of SICS?

• Any cataract requiring surgical extraction
• Especially: dense/brunescent/white/hypermature cataracts
• Settings where phaco is unavailable or too costly
• High-volume surgical camps

• Very shallow anterior chamber (risk of iris prolapse)
• Extremely high myopia with posterior staphyloma
• Subluxated lens (significant zonular weakness)
• Corneal pathology affecting the tunnel site

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Q13. What is the difference between fornix-based and limbus-based conjunctival flap?

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Q14. Key instruments in SICS (Viva favourite)

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Q15. What is viscoelastic (OVD)? Types used in SICS?

• Cohesive OVDs (e.g., Healon, sodium hyaluronate 1%): maintain space, easier to remove, can cause IOP spike
• Dispersive OVDs (e.g., Viscoat, chondroitin sulfate + hyaluronate): coat and protect endothelium, harder to remove
• "Soft shell" technique: dispersive layer injected first (endothelial protection), cohesive layer second (space maintenance) - ideal for dense cataracts and compromised corneas

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Summary Table for Quick Revision

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