Residency · Residency · Ophthalmology

Cataract Surgery Fundamentals: Phacoemulsification Technique

Preoperative Assessment

A thorough preoperative evaluation is essential for successful cataract surgery. Visual acuity should be measured with best correction, and glare testing can help quantify the functional impact of the cataract. Slit lamp examination characterizes the cataract type and density -- nuclear sclerotic, cortical, or posterior subcapsular -- and evaluates for pseudoexfoliation, phacodonesis (lens instability), pupil dilation capacity, and anterior chamber depth. Fundoscopy is performed to rule out posterior segment pathology that might limit visual potential after surgery, such as macular degeneration, diabetic retinopathy, or optic neuropathy. Intraocular pressure and gonioscopy are measured when clinically indicated.

Biometry for IOL power calculation is performed using optical biometry (IOLMaster or Lenstar), with A-scan ultrasonography reserved for eyes with dense media that prevent optical measurement. Keratometry and topography assess corneal astigmatism for toric IOL planning and screen for irregular astigmatism. The ocular surface should be optimized by treating any dry eye or blepharitis before surgery, as a compromised tear film degrades biometric accuracy and surgical outcomes. Zonular integrity is assessed, particularly in patients with pseudoexfoliation, a history of trauma, or prior vitrectomy. The pupil is evaluated for risk of intraoperative floppy iris syndrome (IFIS), which is associated with alpha-blocker use, and for small pupil size that may require pharmacologic or mechanical dilation. Informed consent should address the key risks including endophthalmitis, retinal detachment, posterior capsule rupture, cystoid macular edema, and refractive surprise.

Anesthesia

Topical anesthesia using proparacaine or tetracaine drops, with or without intracameral preservative-free lidocaine 1%, is the most common approach for routine phacoemulsification. It requires a cooperative patient and provides no akinesia. Peribulbar block involves injection of a lidocaine/bupivacaine mixture into the peribulbar space, providing both akinesia and anesthesia, though it carries risks of retrobulbar hemorrhage, globe perforation, and brainstem anesthesia. Retrobulbar block places the injection within the muscle cone, offering reliable akinesia but with a greater risk of hemorrhage and optic nerve injury; it is less commonly used today. Sub-Tenon (parabulbar) block, in which a blunt cannula is placed in the sub-Tenon space, provides a safer alternative with good anesthesia and some akinesia. General anesthesia is reserved for pediatric cataracts and uncooperative patients.

Surgical Steps of Phacoemulsification

1. Wound Construction

The clear corneal incision (CCI) is the most commonly used approach, typically measuring 2.2-2.8 mm and placed temporally or superiorly. The incision has a self-sealing triplanar architecture consisting of an external groove, a lamellar tunnel through the stroma, and an internal entry into the anterior chamber. A temporal approach offers the advantages of inducing minimal against-the-rule astigmatism and remaining away from the superior limbus should future glaucoma filtering surgery be needed. A paracentesis (side-port incision) of 1.0-1.2 mm is created to provide access for a second instrument and for OVD injection.

2. Viscoelastic (OVD) Injection

Ophthalmic viscosurgical devices serve two main purposes: maintaining anterior chamber space and protecting the corneal endothelium. Cohesive OVDs such as Healon and Provisc (sodium hyaluronate) are high-molecular-weight substances that effectively maintain space and are easily removed; they are used for chamber maintenance and IOL insertion. Dispersive OVDs such as Viscoat (chondroitin sulfate/sodium hyaluronate) coat and protect the endothelium but do not evacuate easily. Viscoadaptive OVDs like Healon5 behave as both types, remaining in the eye during phacoemulsification due to a fracture threshold but becoming removable at higher vacuum settings. The soft-shell technique combines the benefits of both: a dispersive OVD is applied first to coat the endothelium, then a cohesive OVD is layered on top to maintain anterior chamber space.

3. Capsulorrhexis (Continuous Curvilinear Capsulorhexis -- CCC)

The capsulorrhexis is the single most critical step in phacoemulsification, as it controls every subsequent maneuver. The ideal capsulorrhexis is approximately 5.0-5.5 mm in diameter, centered, circular, and slightly smaller than the IOL optic (typically 6.0 mm). This ensures 360-degree overlap of the capsulorrhexis edge on the IOL optic, which is essential for stable capsular fixation and prevention of posterior capsule opacification. The technique uses either a cystotome or capsulorrhexis forceps, beginning with a central puncture and then tearing in a continuous curvilinear fashion. Challenges include poor red reflex (managed with retro-illumination or trypan blue capsule staining) and intumescent or white cataracts, which carry the risk of the "Argentinian flag sign" -- a runaway capsulorrhexis caused by equatorial lens pressure. If a radial tear occurs, rescue maneuvers include redirecting the tear or converting to a can-opener capsulotomy.

4. Hydrodissection and Hydrodelineation

Hydrodissection involves injecting balanced salt solution between the capsule and cortex using a flat cannula. This creates a fluid wave that separates the cortex from the capsular bag through 360 degrees, allowing free rotation of the nucleus within the bag. Care must be taken to watch for posterior capsule distension, which is particularly dangerous in posterior polar cataracts where a pre-existing capsule defect may exist; aggressive hydrodissection can cause fluid misdirection and capsule blowout. Hydrodelineation involves injecting BSS within the lens substance itself to separate the harder endonucleus from the softer epinucleus. The visible demarcation between these two zones is termed the "golden ring sign." The epinucleus serves as a protective shell during phacoemulsification, cushioning the posterior capsule from the phaco tip.

5. Nucleofractis Techniques

Divide and Conquer

In the divide and conquer technique, the surgeon sculpts a deep central groove in the nucleus using the phaco tip, then rotates the lens 90 degrees and sculpts a second groove to create a cross pattern. The nucleus is then cracked into four quadrants using a bimanual technique with the phaco tip and a second instrument. Each quadrant is emulsified and aspirated sequentially. This technique is well-suited for beginners because it provides a systematic, step-by-step approach.

Phaco Chop

Phaco chop is a more efficient technique preferred by experienced surgeons, particularly for dense cataracts. In horizontal chop, the phaco tip is embedded centrally in the nucleus while a chopper is placed at the lens equator and brought centrally to split the nucleus. In vertical chop, the phaco tip is buried in the nucleus and the chopper is placed adjacent to it and pushed downward to create a vertical split. The key advantages of chopping are less phaco energy, shorter ultrasound time, and reduced endothelial damage. The technique requires sufficient nuclear density to allow the chopper to gain purchase.

Stop and Chop

Stop and chop is a hybrid technique in which an initial groove is sculpted (as in divide and conquer), and the nucleus is then chopped into segments. It serves as an excellent transitional technique for surgeons moving from divide and conquer to pure phaco chop.

6. Phacoemulsification Parameters

Phaco power can be delivered as longitudinal, torsional (OZil), or transversal tip movement. Torsional phaco is generally more efficient, producing less chatter and reduced energy delivery and heat generation compared with longitudinal ultrasound. The key machine parameters include power (the percentage of ultrasound energy, which should be kept as low as effective), vacuum (the holding force on nuclear fragments, with higher vacuum providing better grip), aspiration flow rate (determining the speed of cortical removal), and bottle height or infusion pressure (which controls anterior chamber stability). Effective phaco time (EPT) or cumulative dissipated energy (CDE) quantifies the total ultrasound energy delivered during the case; lower values indicate better endothelial protection. Phaco tip occlusion must be managed carefully, as a surge can occur when occlusion suddenly breaks, destabilizing the anterior chamber.

7. Irrigation/Aspiration (I/A) of Cortex

Cortical removal is performed with bimanual or coaxial irrigation/aspiration. The subincisional cortex is the most challenging to access and may require rotating the eye or using bimanual I/A. Gentle aspiration is essential to avoid capsule rupture; the cortex is stripped centripetally from the capsular fornix toward the center. Polishing the posterior capsule at this stage can reduce subsequent posterior capsule opacification.

8. IOL Implantation

Modern foldable IOLs are made of acrylic (hydrophobic or hydrophilic) or silicone and are inserted through the main 2.2-2.8 mm incision using an injector cartridge. The IOL is placed in the capsular bag, and both haptics must be confirmed to be within the bag. Hydrophobic acrylic is the most commonly used material because of its lower PCO rate, though glistenings (fluid-filled microvacuoles) may develop over time. Hydrophilic acrylic produces fewer glistenings but has a higher PCO rate and a risk of calcification. Proper IOL centration is verified by confirming capsulorrhexis overlap on the optic edge.

9. Wound Closure

The corneal incision is sealed by stromal hydration -- injecting BSS into the wound walls to swell the stroma and appose the wound edges. Wound integrity is confirmed by ensuring a negative Seidel test (no aqueous leak with fluorescein). If the wound is not self-sealing, a 10-0 nylon suture is placed. All viscoelastic must be removed thoroughly from the anterior chamber to prevent a postoperative IOP spike.

Postoperative Care

Postoperative medications include a topical fluoroquinolone (moxifloxacin or gatifloxacin) for one to two weeks, a topical corticosteroid (prednisolone acetate 1%) tapered over four to six weeks, and a topical NSAID (ketorolac, nepafenac, or bromfenac) to reduce the risk of cystoid macular edema. Intracameral antibiotics (cefuroxime or moxifloxacin) injected at the conclusion of surgery provide strong prophylaxis against endophthalmitis, with the ESCRS study demonstrating approximately a five-fold reduction in risk. Follow-up visits are scheduled for postoperative day 1, one week, and one month, with additional visits as needed. Refraction for a spectacle prescription is typically performed at three to four weeks, once the eye has stabilized.

Common Complications

Posterior capsule rupture is the most feared intraoperative complication and is managed with anterior vitrectomy, with consideration of sulcus IOL placement or a secondary IOL. Postoperative endophthalmitis occurs at a rate of approximately 0.03-0.1%; it can be acute (within six weeks) or chronic, and the Endophthalmitis Vitrectomy Study (EVS) guides management decisions. Cystoid macular edema (Irvine-Gass syndrome) peaks at four to six weeks postoperatively and is treated with topical NSAIDs and steroids. Retained lens fragments in the vitreous require referral for vitrectomy. Toxic anterior segment syndrome (TASS) is a sterile, non-infectious inflammatory reaction that occurs within 24 hours and responds to aggressive topical steroids. Posterior capsule opacification (the "after cataract") is the most common long-term complication, affecting 20-40% of patients at five years, and is treated with Nd:YAG laser capsulotomy. Other complications include transient corneal edema from endothelial damage, IOL decentration or dislocation, and refractive surprise (unexpected postoperative refraction).

<image>Step-by-step surgical illustration of phacoemulsification. Eight panels in sequence: (1) Clear corneal incision construction showing the triplanar tunnel architecture in cross-section; (2) Capsulorrhexis being performed with a cystotome creating a continuous curvilinear tear in the anterior capsule, viewed from the surgeon's microscope perspective; (3) Hydrodissection showing a flat cannula injecting BSS under the capsule with a fluid wave propagating across the lens; (4) Nucleus sculpting in a cross-groove pattern (divide and conquer); (5) Bimanual cracking of the nucleus into quadrants; (6) Phaco chop technique with the chopper engaging the equator while the phaco tip holds the nucleus centrally; (7) I/A cortical removal with stripping of cortical material from the capsule; (8) Foldable IOL being injected from the cartridge into the capsular bag. Label each step clearly.</image>

<image>Anterior segment cross-section diagram showing ideal capsulorrhexis geometry. The continuous curvilinear capsulorrhexis shown as a circular opening in the anterior capsule, slightly smaller than the IOL optic diameter (5.0-5.5 mm CCC vs. 6.0 mm optic). The IOL is seated in the capsular bag with the capsulorrhexis edge overlapping the optic 360 degrees. Annotations show why this overlap matters: prevents IOL tilt/decentration, provides barrier to lens epithelial cell migration (reducing PCO), and ensures stable effective lens position. A second panel shows a too-large capsulorrhexis with no optic overlap and resulting IOL subluxation risk.</image>

<image>Comparison diagram of phacoemulsification nucleofractis techniques. Three panels with surgeon's view: (1) Divide and conquer — cross-groove pattern sculpted into the nucleus with four quadrants being cracked apart; (2) Horizontal phaco chop — phaco tip embedded in the nucleus centrally with the chopper approaching from the equator and bringing toward center to split; (3) Vertical chop — phaco tip buried vertically with chopper placed adjacent and pushed downward to create a vertical split. Include arrows showing direction of instrument movement and force vectors in each technique.</image>

Key Clinical Pearls

The capsulorrhexis is the single most important step in phacoemulsification -- a well-constructed CCC determines the success of every subsequent maneuver. In intumescent white cataracts, trypan blue capsule staining and a slow, controlled capsulorrhexis are essential to prevent the Argentinian flag sign. Hydrodissection must be gentle in posterior polar cataracts because a pre-existing posterior capsule defect means that fluid misdirection can cause capsule blowout. Lower phaco energy translates directly to less endothelial damage, so torsional phaco, high vacuum settings, and efficient chopping techniques should be employed. Intracameral antibiotics (cefuroxime or moxifloxacin) at the end of surgery reduce endophthalmitis risk approximately five-fold, as demonstrated by the ESCRS study. Alpha-blocker use (particularly tamsulosin) should always be elicited in the history, as IFIS can cause significant intraoperative complications. All OVD must be removed at the conclusion of surgery to prevent IOP spikes, which are a common cause of postoperative day 1 pain and corneal edema. PCO prevention relies on square-edge optic design, hydrophobic acrylic material, and capsulorrhexis-optic overlap, all of which reduce lens epithelial cell migration behind the IOL.

References

• Lundstrom M, et al. Risk factors for refractive error after cataract surgery. J Cataract Refract Surg. 2012;38(10):1709-1713.
• ESCRS Endophthalmitis Study Group. Prophylaxis of postoperative endophthalmitis following cataract surgery. J Cataract Refract Surg. 2007;33(6):978-988.
• Endophthalmitis Vitrectomy Study Group. Results of the EVS. Arch Ophthalmol. 1995;113(12):1479-1496.
• Vasavada AR, Raj SM. Step-by-step phacoemulsification. In: Cataract Surgery. Jaypee Brothers, 2018.
• AAO BCSC Section 11: Lens and Cataract. 2023-2024.

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