Cataract Surgery Techniques & Complications

Cataract surgery is the most commonly performed intraocular operation worldwide and a perennial NEET PG favourite. This note compares phacoemulsification, SICS and ECCE, walks through IOL power calculation, and gives you the full spectrum of intra-operative and post-operative complications with their management.

Overview & evolution of techniques

The basic principle of every cataract operation is removal of the opacified crystalline lens and replacement with an intraocular lens (IOL). What has changed over the decades is the size of the wound, the method of nucleus removal, and whether the posterior capsule is preserved.

High-yield: The two modern surgeries (Phaco and SICS) are extracapsular techniques — they preserve the posterior capsule, which supports the IOL and acts as a barrier against vitreous prolapse. Intracapsular cataract extraction (ICCE), which removes the lens with its entire capsule, is now largely obsolete except for grossly subluxated lenses (e.g., Marfan, homocystinuria).

Classification of extraction methods

Technique	Wound size	Sutures	Nucleus handling	Capsule preserved	Typical use
ICCE (intracapsular)	10–12 mm	Multiple	Whole lens + capsule removed (cryo)	No	Markedly subluxated lens
ECCE (conventional extracapsular)	10–11 mm	6–8 (10-0 nylon)	Nucleus expressed whole	Yes (posterior)	Hard/brown cataract, training
SICS (manual small-incision)	6–7 mm (self-sealing)	Usually none	Nucleus prolapsed & delivered	Yes (posterior)	High-volume, hard cataracts, camps
Phaco (phacoemulsification)	2.2–3.2 mm	None	Nucleus emulsified by ultrasound	Yes (posterior)	Standard of care, soft–moderate cataract
FLACS (femtosecond-laser-assisted)	2.2–2.8 mm	None	Laser fragments + capsulotomy	Yes	Premium/refractive surgery

High-yield: A continuous curvilinear capsulorrhexis (CCC) — a smooth circular tear in the anterior capsule — is the defining step of modern phaco and is essential for "in-the-bag" IOL placement. A can-opener capsulotomy (old ECCE) predisposes to radial tears and capsular instability.

Phacoemulsification — stepwise approach

Phaco uses a titanium tip vibrating at ultrasonic frequency (≈40 kHz) to emulsify the nucleus, which is then aspirated. The procedure is performed under topical or peribulbar anaesthesia.

Steps (in order):

1. Clear corneal / scleral tunnel incision (2.2–2.8 mm) plus a side-port paracentesis.
2. Viscoelastic (OVD) injected to maintain the anterior chamber.
3. Continuous curvilinear capsulorrhexis (CCC) — 5–5.5 mm.
4. Hydrodissection (fluid wave to separate cortex from capsule) → and hydrodelineation (separating the hard endonucleus from epinucleus).
5. Nucleus emulsification — using a chosen technique.
6. Cortical aspiration (irrigation–aspiration).
7. IOL implantation in the bag (foldable acrylic through the small wound).
8. Wound hydration / closure — stromal hydration makes the tunnel self-sealing.

Flow of nucleus disassembly techniques: Divide-and-conquer → Phaco chop → Stop-and-chop → Pre-chop. Phaco chop uses less ultrasound energy and is gentler on the corneal endothelium.

High-yield: Total ultrasound time and energy correlate directly with post-operative corneal endothelial cell loss and corneal oedema. This is why phaco-chop (less energy) is preferred in dense nuclei and why a very hard brown/black cataract may be better served by SICS.

SICS vs Phaco vs ECCE — the comparison that gets asked

Parameter	Phaco	SICS	ECCE
Incision	2.2–3.2 mm	6–7 mm	10–11 mm
Equipment cost	High (machine)	Low	Low
Surgical time	Short	Very short	Longer
Suture-induced astigmatism	Minimal	Minimal (none)	Significant
Visual rehabilitation	Fastest	Fast	Slow
Best for hard/brown cataract	Less suited (high energy)	Excellent	Good
Cost-effectiveness (developing world)	Lower	Highest	Moderate
Endothelial cell loss	Energy-dependent	Low	Moderate

High-yield: SICS gives visual and astigmatic outcomes comparable to phaco but at far lower cost and is faster for very hard cataracts — making it the workhorse of Indian high-volume settings and eye camps. ECCE is now reserved for cases unsuitable for both.

Types of IOL & the capsular bag

• Material: PMMA (rigid, needs larger wound), silicone, hydrophobic/hydrophilic acrylic (foldable — used in phaco/SICS).
• Placement: In-the-bag (ideal) > sulcus-fixated (if posterior capsule rupture but anterior capsule intact) > anterior chamber IOL / iris-claw / scleral-fixated IOL (no capsular support).
• Designs: monofocal (standard), toric (corrects astigmatism), multifocal/EDOF (presbyopia correction — "premium" lenses).

High-yield: If there is posterior capsule rupture (PCR) without vitreous loss and anterior capsule rim is intact → place a 3-piece IOL in the ciliary sulcus. If there is inadequate capsular support → AC IOL, iris-claw, or scleral-fixated IOL.

IOL power calculation

The power of the implant is computed from two measured variables: keratometry (K, corneal curvature) and axial length (AL).

• Axial length is measured by A-scan ultrasound biometry or, more accurately, optical biometry (IOLMaster — partial coherence interferometry).
• Keratometry measures corneal power.

SRK formula (regression):

P = A − 2.5L − 0.9K

where P = IOL power, A = A-constant (lens-specific), L = axial length (mm), K = average keratometry (D).

SRK-II modifies the A-constant for very short and very long eyes (adds correction factors for AL <20 mm and >24.5 mm). Modern practice uses theoretical formulae (SRK/T, Hoffer Q, Holladay, Haigis, Barrett Universal II) which are more accurate, especially at extremes of axial length.

High-yield: Axial length is the single greatest source of IOL power error — a 1 mm error in AL ≈ 2.5–3 D of refractive error. Always confirm biometry, especially in long myopic or short hypermetropic eyes. Optical biometry (IOLMaster) is the gold standard where media are clear.

Choose appropriate formula by axial length: short eye → Hoffer Q / Barrett; average → SRK/T or Barrett; long eye → SRK/T / Barrett / Haigis.

Intra-operative complications

Posterior capsule rupture (PCR) ± vitreous loss

The most important intra-operative complication. It may occur during emulsification, cortical aspiration, or IOL insertion.

Signs: sudden deepening of the anterior chamber, pupillary "snap", nucleus tilt, inability to rotate nucleus, lateralisation of pupil margin.

Management flow: Stop phaco → inject dispersive viscoelastic to tamponade vitreous and keep nuclear fragments anterior → perform anterior vitrectomy if vitreous presents → remove residual cortex → place IOL in sulcus if rim adequate, or AC/scleral-fixated IOL otherwise.

High-yield: Vitreous loss is a major risk factor for downstream cystoid macular oedema, retinal detachment, and endophthalmitis. Never use a simple irrigation–aspiration on prolapsed vitreous; a vitrectomy cutter is required.

Dropped nucleus / nucleus drop

A nuclear fragment falls into the vitreous cavity through a PCR → requires pars plana vitrectomy (PPV) by a vitreoretinal surgeon. Do not chase fragments into the vitreous with the phaco probe.

Suprachoroidal haemorrhage (expulsive)

Sudden severe pain, shallowing of AC, red reflex loss, prolapse of intraocular contents — a dreaded, sight-threatening event during open-globe surgery. Immediate wound closure is mandatory. Risk factors: hypertension, advanced age, high myopia, glaucoma, anticoagulation.

Other intra-operative events

• Descemet's membrane detachment — air/viscoelastic tamponade.
• Iris prolapse / floppy iris syndrome (IFIS) — associated with tamsulosin (alpha-1A antagonist) used for BPH; managed with iris hooks, pupil expansion rings, intracameral phenylephrine.
• Capsulorrhexis run-out (radial tear) — risk of extension to posterior capsule.

High-yield mnemonic — IFIS triad: "BFP" — Billowing iris, Floppy iris prolapse to incisions, Progressive intra-operative miosis. Always ask about tamsulosin history.

Early post-operative complications

Complication	Onset	Key feature	Management
Acute endophthalmitis	1–7 days	Pain, ↓vision, hypopyon, vitritis	Vitreous tap + intravitreal antibiotics
Striate keratopathy	Day 1–2	Corneal oedema (endothelial trauma)	Usually self-limiting; hypertonic saline
Wound leak / shallow AC	Days	Seidel positive	Resuture / bandage CL
Iris prolapse	Days	Pigmented tissue at wound	Surgical repositioning
Raised IOP	Days	Retained viscoelastic	Topical anti-glaucoma
Toxic anterior segment syndrome (TASS)	12–48 h	Sterile inflammation, no pain/vitritis	Intensive topical steroids

Acute post-operative endophthalmitis — must know

• Commonest organism: coagulase-negative Staphylococcus (Staphylococcus epidermidis); more virulent: Staph aureus, Streptococcus, Pseudomonas.
• Presentation: pain, decreased vision, lid oedema, hypopyon, vitritis, loss of red reflex — typically 2–5 days post-op.
• Investigation of choice: vitreous tap (and aqueous tap) for Gram stain & culture; B-scan if no fundal view.
• Management: intravitreal antibiotics — vancomycin (gram-positive cover) + ceftazidime (gram-negative cover). Per the Endophthalmitis Vitrectomy Study (EVS): if vision is only light perception, perform pars plana vitrectomy; if vision is hand movements or better, intravitreal antibiotics alone suffice.

High-yield: TASS vs infectious endophthalmitis — TASS is sterile, appears in 12–48 h, is painless, limited to the anterior segment (no vitritis), and responds dramatically to steroids. Endophthalmitis is infective, presents after 2–7 days, is painful, with vitritis/hypopyon. Confusing these is a classic exam trap.

Late post-operative complications

Posterior capsule opacification (PCO) — "after-cataract"

The most common late complication of extracapsular surgery. Residual lens epithelial cells proliferate and migrate onto the posterior capsule.

• Elschnig pearls (bladder cells) and Soemmering's ring are the morphological forms.
• Presentation: gradual painless decline of vision months–years after an initially good result, glare.
• Treatment of choice: Nd:YAG laser posterior capsulotomy — a non-invasive laser creates a central opening in the capsule.

High-yield: Nd:YAG laser posterior capsulotomy is the definitive treatment of PCO. Its main complications are transient rise in IOP, IOL pitting, and cystoid macular oedema; rarely it predisposes to retinal detachment. A sharp-edged (square-edge) hydrophobic acrylic IOL reduces PCO incidence.

Cystoid macular oedema (CMO) — Irvine–Gass syndrome

• Accumulation of fluid in the outer plexiform layer of the macula post-cataract surgery, typically peaking 6–10 weeks post-op.
• Investigation of choice: OCT (petaloid pattern); fundus fluorescein angiography shows a classic "flower-petal" / petaloid leakage at the macula and disc leakage.
• Risk factors: vitreous loss, PCR, diabetic retinopathy, retained lens fragments.
• Management: topical NSAID + steroid; refractory cases → intravitreal steroids/anti-VEGF.

Other late complications

• Pseudophakic bullous keratopathy — endothelial decompensation → corneal oedema; needs endothelial keratoplasty (DSEK/DMEK).
• Retinal detachment — higher in myopes, after PCR/vitreous loss, post Nd:YAG.
• IOL decentration / subluxation ("sunset/sunrise syndrome"), UGH syndrome (Uveitis–Glaucoma–Hyphaema, classically with poorly positioned AC IOLs).
• Late chronic endophthalmitis — classically Propionibacterium acnes (now Cutibacterium acnes) — indolent, granulomatous, with a white capsular plaque.

High-yield: Chronic / delayed endophthalmitis = Cutibacterium (Propionibacterium) acnes or fungi; presents weeks–months later with low-grade granulomatous uveitis and a characteristic white plaque on the capsule, often partially steroid-responsive.

Key differentials

• Causes of decreased vision after "successful" cataract surgery: refractive surprise (biometry error), corneal oedema (early), CMO (weeks), PCO (months–years), endophthalmitis (pain + inflammation), retinal detachment (field loss + floaters).
• Painful red eye post-op: endophthalmitis vs TASS vs raised IOP vs wound infection — distinguish by timing, pain, vitritis, and steroid response (see table above).
• Sudden vision loss in theatre: suprachoroidal haemorrhage vs vitreous loss with dropped nucleus.

Recently asked / exam angle

• SRK / SRK-II formula and its components (A − 2.5L − 0.9K) — direct recall.
• Investigation of choice for axial length: A-scan biometry / optical biometry (IOLMaster).
• Commonest organism in acute post-op endophthalmitis: Staph. epidermidis (coagulase-negative staph).
• EVS guidelines: when to do vitrectomy (vision = light perception) vs intravitreal antibiotics.
• Treatment of after-cataract (PCO): Nd:YAG laser capsulotomy — and its complications.
• Irvine–Gass syndrome — CMO after cataract surgery; petaloid pattern on FFA, diagnosed on OCT.
• IFIS and tamsulosin association — repeatedly tested image/clinical vignette.
• Most common intra-operative complication: posterior capsule rupture; management with anterior vitrectomy and sulcus IOL.
• TASS vs endophthalmitis differentiation — high-frequency one-liner question.
• Best surgery for a hard brown cataract in a camp setting: manual SICS.

Rapid revision

1. Phaco, SICS and ECCE are all extracapsular — posterior capsule preserved; ICCE removes the whole lens.
2. CCC (capsulorrhexis) enables in-the-bag IOL placement.
3. Phaco wound 2.2–3.2 mm; SICS 6–7 mm self-sealing; ECCE 10–11 mm sutured.
4. Ultrasound energy ↑ → endothelial cell loss ↑ → corneal oedema; use phaco-chop for hard nuclei.
5. SICS = best cost-effective, fast surgery for hard cataracts in high-volume Indian settings.
6. SRK formula: P = A − 2.5L − 0.9K; SRK-II adjusts for short/long eyes.
7. Axial length error of 1 mm ≈ 2.5–3 D refractive error; optical biometry (IOLMaster) is gold standard.
8. PCR ± vitreous loss = commonest intra-op complication → anterior vitrectomy + sulcus IOL.
9. Acute endophthalmitis: Staph epidermidis; treat with intravitreal vancomycin + ceftazidime; EVS — vitrectomy if vision = light perception.
10. TASS = sterile, painless, 12–48 h, steroid-responsive, no vitritis (vs infective endophthalmitis).
11. PCO (after-cataract) = commonest late complication → Nd:YAG laser posterior capsulotomy; Elschnig pearls, Soemmering's ring.
12. Irvine–Gass CMO peaks ~6 weeks, petaloid FFA pattern, diagnosed on OCT; chronic endophthalmitis = Cutibacterium acnes with capsular plaque.