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Phacoemulsification

Phacoemulsification is a minimally invasive surgical technique for removal that employs ultrasonic energy to emulsify the clouded crystalline lens of the eye, allowing its fragments to be aspirated through a small incision typically measuring 2 to 3 millimeters in diameter, after which an artificial is implanted to restore vision. This procedure, which revolutionized by replacing older, more invasive methods like extracapsular , was pioneered by American ophthalmologist D. Kelman in 1967, who drew inspiration from ultrasonic dental tools to develop the emulsification concept. Initially met with skepticism due to the fragility of early equipment, phacoemulsification gained widespread adoption in the 1980s following advancements in phacoemulsification machines, irrigation systems, and the introduction of foldable intraocular lenses that could be inserted through the same small incision. Today, it represents the gold standard for worldwide and is the most common surgical procedure globally, performed on over 20 million patients annually with high success rates and rapid recovery times. The technique is indicated primarily for cataracts—opacifications of the that impair , cause glare, or hinder daily activities—particularly in cases involving , cortical, or posterior subcapsular cataracts. Phacoemulsification's advantages include reduced surgical trauma, lower risk of induced , and enhanced patient outcomes compared to traditional methods, with most individuals experiencing improved vision within days and minimal postoperative care. Although complications such as posterior capsule rupture, corneal , or can occur, their incidence is low—typically 1-2% for posterior capsule rupture—due to refined techniques and equipment. Ongoing innovations, including advanced phaco machines with torsional or pulse modes, continue to optimize efficiency and safety, particularly for complex cases like dense brunescent cataracts.

Background

Etymology

The term "phacoemulsification" derives from the Greek word phakos (φάκος), meaning "" or "" (referring to the shape and function of the eye's crystalline lens), combined with "," which denotes of breaking down a substance into a fine emulsion, here achieved through ultrasonic energy to fragment the lens material. This nomenclature was coined by American ophthalmologist Charles D. Kelman during the 1960s as he developed the technique, with the term first appearing in his landmark 1967 paper describing the procedure's application in .

History

Phacoemulsification was invented by American ophthalmologist Charles D. Kelman in 1967, revolutionizing by using ultrasonic vibrations to emulsify and aspirate the clouded through a small incision. The concept originated from Kelman's 1964 experience in a dentist's chair, where he observed an ultrasonic dental probe's high-frequency vibrations creating a cooling mist, inspiring him to adapt similar technology for breaking down the without large cuts. Kelman initially tested the mechanism on animal models and enucleated eyes before performing the first human procedure that year on a patient with absolute . By 1969, he had treated 12 patients, marking the technique's early clinical application. In the , phacoemulsification faced significant adoption challenges, including technical difficulties with early equipment and strong resistance from the ophthalmic community, which favored the established intracapsular method. The first commercial phacoemulsification machine, the Kelman-Cavitron device, became available in 1970, but the procedure's steep and concerns over safety led to a temporary decline in use by the mid-decade. Despite these hurdles, pioneers like Kelman persisted, performing 500 procedures by 1973, contributing to a cumulative total of about 3,500 in the United States between 1967 and 1973. By the 1980s, advancements in phacoemulsification machines, including increased tip power and better systems, facilitated wider acceptance and improved outcomes, making the technique more reliable for routine removal. The 1990s saw a pivotal shift toward small-incision phacoemulsification, enabled by the introduction of foldable intraocular lenses that allowed implantation through incisions as small as 3 mm, reducing and accelerating patient recovery. These developments solidified phacoemulsification's role as the preferred method. Entering the early 2000s, phacoemulsification had evolved into the gold standard for , with adoption rates exceeding 97% of procedures in the United States by 1996 and becoming the dominant global technique in developed regions due to its minimally invasive nature and high success rates.

Indications and Contraindications

Indications

Phacoemulsification is primarily indicated for the removal of mature that cause significant , such as a best-corrected of less than 20/40, which interferes with daily activities like reading, driving, or recognizing faces. This procedure is recommended when the leads to symptoms including , glare sensitivity, halos around lights, or reduced sensitivity, particularly in cases of , cortical, or posterior subcapsular . For traumatic or hypermature , phacoemulsification restores vision by emulsifying and aspirating the opacified lens while preserving capsular integrity for implantation. Phacoemulsification is also indicated in primary angle-closure glaucoma to deepen the anterior chamber and reduce the risk of acute attacks, often combined with goniosynechialysis or iridotomy. Additional indications include combined procedures for patients with coexisting conditions, such as open-angle glaucoma where phacoemulsification is paired with minimally invasive glaucoma surgery (MIGS) to enhance reduction and decrease medication reliance in mild to moderate cases. It is also suitable for lens subluxation with adequate capsular support, allowing stabilization techniques like capsular hooks during surgery to manage zonular weakness. Patient selection criteria emphasize age-related cataracts in adults typically over 50 years, with stable ocular anatomy including sufficient corneal clarity, adequate anterior chamber depth, and no uncontrolled systemic comorbidities like or that could complicate recovery. Candidates must be suitable for under , with assessments confirming that is primarily cataract-related rather than due to other pathologies like . Professions demanding high , such as piloting or , may prompt earlier intervention even if impairment is moderate.

Contraindications

Phacoemulsification is contraindicated in patients with active ocular infections, such as , as surgery can exacerbate the condition and lead to severe complications like vision loss. Uncontrolled accompanied by a shallow anterior chamber represents a relative due to the heightened risk of prolapse, chamber collapse, and postoperative intraocular pressure elevation during the procedure. Severe corneal , often indicated by a low endothelial count (typically below 1000 cells/mm²), is also an absolute , as the ultrasonic energy and irrigation-aspiration can cause irreversible corneal and . Relative contraindications include very dense brunescent cataracts, which may necessitate high ultrasound energy levels, increasing the risk of thermal injury to the cornea and Descemet's membrane. Pediatric cases, particularly in patients under 1 year old, present anatomical challenges, such as a softer lens nucleus and higher complication rates including vitreous loss and capsular tears, requiring specialized surgical techniques. Similarly, patients with bleeding disorders, such as hemophilia or those on anticoagulant therapy without proper management, pose a relative contraindication due to the potential for intraoperative or postoperative hemorrhage. Preoperative assessment is essential to identify these contraindications and ensure . This includes a comprehensive slit-lamp examination to evaluate for signs of , endothelial status, and anterior chamber depth, as well as biometry to measure axial length and chamber parameters for surgical planning. Specular microscopy may be performed to quantify endothelial cell density in at-risk cases.

Mechanism of Action

Ultrasound Emulsification

The ultrasonic probe tip in phacoemulsification vibrates longitudinally at frequencies typically ranging from 35,000 to 45,000 Hz, with 40,000 Hz being the most common setting for efficient emulsification. This high-frequency generates that fragments the cataractous nucleus primarily through a effect, where the tip's rapid forward-backward motion (stroke length of 20–50 μm) directly shears and breaks the lens material into micro-particles, often aided by bubbles that form and implode to produce shock waves up to 75,000 . Although some studies question the dominant role of cavitation, suggesting it may be negligible compared to direct mechanical action, the combined effects enable precise emulsification of the into aspirable fragments. Energy delivery is controlled through various modes to optimize fragmentation while minimizing damage. Continuous mode provides steady , suitable for softer es, whereas and burst modes deliver intermittent — at rates of 10–120 per second with off periods, or bursts of 40–80 ms followed by longer pauses—to reduce overall heat generation and repulsion of material. settings, expressed as percentages from 20% to 100%, are adjusted based on density; lower (e.g., 20–40%) suffice for soft nuclei, while higher levels (up to 100%) are used for brunescent or dense, hard cataracts to ensure effective cutting without excessive . Thermal safety is paramount, as prolonged can cause buildup at the probe tip, potentially leading to corneal burns or endothelial damage. Coaxial irrigation fluid, flowing at rates of 20–30 mL/min, continuously cools the tip and surrounding tissues during . Typical energy application per lens quadrant lasts 1–10 seconds, depending on nuclear hardness and , allowing for controlled emulsification integrated with for immediate removal of fragments.

Irrigation and Aspiration

Irrigation in phacoemulsification involves the continuous inflow of (BSS) through a sleeve surrounding the ultrasonic or via a separate line, which serves to maintain anterior chamber depth, stabilize , and cool the to prevent thermal injury to ocular tissues. The BSS, typically delivered from an elevated infusion bottle (70-110 cm above the eye), creates a hydrostatic of approximately 50-80 mmHg to counteract surgical manipulation and ensure chamber stability during fragmentation. This system supports ultrasound-based emulsification by providing a medium that facilitates movement and dissipates heat generated by ultrasonic vibrations. Aspiration removes the emulsified fragments and excess through the probe's port, utilizing controlled levels typically ranging from 200 to 500 mmHg to draw material toward the tip without compromising chamber integrity. Modern phacoemulsification machines employ either peristaltic pumps, which generate indirectly through roller compression of tubing for precise ( rates of 20-60 /min), or Venturi pumps, which create directly via gas for rapid response and higher holdability of fragments. Peristaltic systems offer smoother, more predictable buildup, reducing risks during breaks, while Venturi systems provide immediate adjustment for efficient fragment capture, with surgeon preference guiding selection based on case complexity. Following emulsification, cleanup is performed using a dedicated low-flow / (I/A) handpiece, often or bimanual, operating at reduced (100-300 mmHg) and flow rates (15-30 mL/min) to gently remove residual cortical material from the capsular bag while minimizing the risk of posterior capsule rupture or bag distortion. This step polishes the capsule and evacuates viscoelastic remnants, ensuring a clear visual axis and stable placement, with techniques like viscodissection employed for adherent to enhance safety.

Preoperative Preparation

Anesthesia Options

Phacoemulsification cataract surgery typically requires to ensure comfort, globe immobility, and surgeon precision while minimizing risks associated with more invasive techniques. The choice of anesthesia depends on factors such as anxiety level, , and , as well as procedural complexity. Topical anesthesia is the most commonly employed method, used in the majority of procedures worldwide and increasing over time (e.g., from 30% to 76% in large European registries from 2000 to 2018), involving the application of numbing eye drops such as proparacaine or tetracaine to the conjunctiva and eyelids. This approach is often supplemented with intracameral injection of preservative-free 1% lidocaine into the anterior chamber, providing effective analgesia without the need for needles penetrating the orbit. Advantages include rapid onset, minimal systemic absorption, avoidance of injection-related complications like hemorrhage or globe perforation, and quick postoperative recovery, allowing patients to resume normal activities shortly after surgery. For patients who are particularly anxious or require greater akinesia of the , options such as peribulbar or retrobulbar blocks may be selected. These involve injecting a combination of 2% lidocaine and 0.75% bupivacaine into the extraconal (peribulbar) or intraconal (retrobulbar) space around the eye to achieve both and muscle . While effective for ensuring immobility, these techniques are less favored today due to potential risks including retrobulbar hemorrhage, optic nerve damage, or central spread of anesthetic, and they are reserved for cases where topical methods prove insufficient. General is rarely utilized in phacoemulsification, comprising approximately 2-4% of cases as of 2017-2019 data, and is primarily indicated for pediatric patients, uncooperative adults with cognitive impairments, or those with contraindications to such as severe orbital pathology. It involves systemic induction to render the patient unconscious, ensuring complete immobility but carrying higher risks of cardiovascular and respiratory complications compared to local options. Adjunctive sedation, such as intravenous or oral at doses of 0.5–2 mg titrated to effect, is frequently combined with topical or to alleviate anxiety and enhance patient tolerance without compromising respiratory drive. This conscious sedation approach promotes hemodynamic stability and patient satisfaction while allowing real-time monitoring of akinesia and analgesia levels during .

Patient and Site Preparation

Prior to phacoemulsification, the patient is positioned on the surgical table to facilitate optimal access to the eye and alignment with the operating . The head is stabilized in a neutral position, typically flat and centered under the to maximize the and surgical exposure, with the approaching from the temporal or superior side depending on the incision . This positioning ensures during the procedure and minimizes movement risks. To achieve adequate pupillary dilation, mydriatic agents such as tropicamide 1% are instilled topically 30 to 60 minutes preoperatively, often in combination with 2.5% or 10%, administered in multiple drops at intervals to reach maximum dilation of approximately 7-8 mm. This step is crucial for visualizing and manipulating the during . Anesthesia administration, such as topical proparacaine, is timed shortly before positioning to coincide with site preparation. The surgical site is prepared to minimize infection risk through meticulous sterile techniques. The periocular skin and eyelids are scrubbed with 10% solution using sterile applicators, followed by instillation of 5% directly into the conjunctival fornices for at least 3 minutes to reduce ocular surface flora. The area is then dried, and sterile adhesive drapes are applied to isolate the eye, excluding eyelashes from the field via a fenestrated or slit drape secured around the eyelids. An eyelid speculum is inserted post-draping to maintain exposure. Instrumentation setup involves calibrating the phacoemulsification machine by priming the and system with to remove air bubbles and ensure proper function, including insertion and testing of the disposable cassette. Ophthalmic viscosurgical devices (OVDs), such as , are prepared in sterile syringes for intraoperative use to maintain anterior chamber depth and protect endothelial cells during lens manipulation. These steps confirm equipment readiness and chamber stability prior to incision.

Surgical Technique

Incision and Access

The incision and access phase of phacoemulsification establishes entry into the anterior chamber while minimizing trauma to the and maintaining stability. Initial access is achieved through a , a small side-port incision created in the peripheral , typically positioned 2 to 3 clock hours from the intended main incision site. This incision is made parallel to the plane using a 15-degree blade or microvitreoretinal (MVR) blade, allowing for the introduction of a to inject viscoelastic substance into the anterior chamber; the viscoelastic maintains chamber depth, protects the , and facilitates subsequent instrument insertion. The primary entry is then formed via a clear corneal incision, a self-sealing measuring 2.2 to 2.8 mm in width, commonly positioned at the 12 o'clock superior location to align with the surgeon's dominant hand and reduce against-the-rule . This incision is crafted in a multiplanar —starting with a partial-thickness groove, followed by a deeper lamellar , and culminating in entry to the anterior chamber—using a or metal keratome , which ensures precise, beveled edges for watertight closure without sutures. The clear corneal approach revolutionized by enabling smaller, sutureless wounds that promote rapid visual rehabilitation and lower induced compared to earlier scleral techniques. Access during phacoemulsification incorporates either a or bimanual configuration, each tailored to density and surgical needs. The approach, standard for most routine cases, integrates and within a single phacoemulsification probe sleeve inserted through the 2.2- to 2.8-mm main incision, providing balanced but requiring careful management to avoid chamber collapse. In contrast, the bimanual approach is favored for dense cataracts (e.g., grade 3-4 ), employing a narrower main incision (1.2 to 1.4 mm) for the sleeveless phaco probe and directing separate through the via a second instrument, which enhances chamber stability, reduces fluid usage, and allows superior nuclear manipulation with lower energy. Both methods rely on the initial incisions to ensure secure, leak-proof entry, directly influencing the efficiency of emulsification and overall procedural safety.

Capsulorhexis and Lens Manipulation

The continuous curvilinear capsulorhexis () is the standard technique for creating an opening in the anterior lens capsule during phacoemulsification, involving a controlled, circular tear that maintains capsule integrity. Developed independently by Howard V. Gimbel and Thomas Neuhann in the late 1980s, CCC typically measures 5 to 6 mm in diameter to overlap the optic edge of the implanted (IOL), thereby ensuring capsular bag stability and reducing the risk of postoperative IOL decentration or tilt. To perform CCC, the surgeon first injects an ophthalmic viscosurgical device (OVD), such as , into the anterior chamber to maintain space and protect endothelial cells, followed by initiating the tear with a cystotome (a bent 27- or 30-gauge needle) or . The cystotome punctures the capsule peripherally, and the tear is propagated in a curvilinear fashion by countering the natural radial propagation tendency through controlled , resulting in a self-sealing, tear-resistant edge. This method's precision facilitates subsequent lens manipulation and IOL centration, minimizing complications like capsule tears that could extend to the . Following , hydrodissection separates the from the capsule, enabling rotation and reducing zonular stress during extraction. Introduced by in as cortical cleaving hydrodissection, the procedure involves injecting () via a under the capsulorhexis edge, creating a fluid wave that cleaves corticocapsular adhesions while preserving cortical attachment to the epinucleus. The tents the capsule rim to direct the peripherally, with gentle injection in multiple aliquots to avoid pressure spikes that could damage the zonules or . Hydrodelineation complements hydrodissection by delineating the from surrounding layers, specifically separating the inner endonucleus from the softer epinucleus to form a protective cushion during emulsification. Performed by inserting the into the lens substance and injecting to induce a golden ring sign indicating epinuclear hydration, this step enhances nucleus mobility and facilitates safer phacoemulsification probe access. Pre-chopping techniques further loosen the prior to emulsification, dividing it into smaller segments using specialized chopper instruments to lower energy requirements. Horizontal chopping, pioneered by Kunihiro Nagahara in , employs a horizontally oriented chopper that engages the under the capsulorhexis, fracturing it against the phaco tip in a centripetal motion to create initial cleavage planes. Vertical chopping, described by Hiroko Fukasaku, uses a vertically oriented chopper to impale and split the central downward while the phaco probe stabilizes it upward, particularly effective for dense cataracts. These methods prepare the lens for probe insertion by promoting controlled disassembly without excessive manipulation.

Emulsification and Removal

The emulsification and removal phase of phacoemulsification involves the systematic fragmentation and extraction of the using an ultrasonic phacoemulsification , typically performed by to ensure controlled removal and minimize and mechanical on ocular structures. After initial lens mobilization, the is inserted through the capsulorhexis into the anterior chamber, where it is positioned to embed into the central for sculpting a deep groove, often extending from approximately 11 to 7 o'clock, reaching depths of over 80% of the nuclear thickness while staying within the capsulorhexis margin to avoid capsular damage. This sculpting creates a trench that facilitates subsequent division, with multiple passes used to widen it if necessary for denser material. To divide the nucleus, the probe tip and a second instrument, such as a , apply lateral forces within the sculpted trenches to crack the into four , often after rotating the 90 degrees to form a second trench. Each is then rotated or ed anteriorly—using techniques like the "split and " method where a elevates the sharp apex for centralization—and emulsified sequentially by embedding the tip into the posterior edge while draws the fragment toward the tip for ultrasonic breakdown and vacuum-assisted removal. Higher and vacuum settings are employed during removal to facilitate efficient extraction with reduced energy, promoting safer emulsification at the plane or centrally. For hard or brunescent cataracts, specialized nucleofractis techniques like divide-and-conquer and stop-and-chop are employed to minimize cumulative ultrasound energy delivery and endothelial cell loss. The divide-and-conquer method, originally developed for phacoemulsification, involves deep central sculpting followed by cracking into quadrants, allowing extension to challenging cases such as hypermature lenses while maintaining a well-centered . In contrast, the stop-and-chop technique begins with a trough sculpted to bisect the into two heminuclei, which are then rotated 180 degrees for further division; chopping is performed by briefly activating (foot pedal 3) to embed the tip, followed by 2 for holding, with the cleaving fragments laterally toward the , enabling efficient disassembly of dense nuclei through pulsed or burst modes to limit energy use. Both approaches prioritize mechanical fragmentation over prolonged phacoemulsification, reducing the risk of posterior capsule complications in firm cataracts. Following nuclear removal, the residual lens cortex is cleared using irrigation and (I&A) handpieces to polish the capsular bag without causing tears or opacification. A bimanual or I&A system is introduced, with low vacuum and flow rates applied to gently aspirate cortical strands, starting from the and progressing equatorially to avoid bag distension or zonular . Polishing maneuvers involve rotating the tip along the capsular surface to remove any adhering viscoelastic or cortical material, ensuring a clean posterior capsule while preserving bag integrity for subsequent steps. This meticulous cortex evacuation is essential, as incomplete removal can lead to postoperative inflammation or posterior capsule opacification.

Intraocular Lens Implantation

Following the emulsification and removal of the cataractous lens, the empty capsular bag provides the site for (IOL) implantation to restore visual function. Various types of IOLs are selected based on patient needs and surgical goals in phacoemulsification procedures. Monofocal IOLs, the most commonly used, provide clear vision at a single distance, typically distance, requiring for near tasks. Multifocal IOLs incorporate multiple focal zones to enable vision at near, intermediate, and distance ranges, reducing dependence on spectacles. Toric IOLs address preexisting by incorporating cylindrical power to correct corneal irregularities. Accommodating IOLs mimic natural lens movement to adjust focus dynamically. For small-incision phacoemulsification, foldable IOLs made from hydrophobic or materials are preferred, as they can be compressed and inserted through incisions under 3 mm without requiring enlargement. IOL power is determined preoperatively through biometry to target , the refractive state where parallel light rays focus on the without . Measurements of axial length, corneal curvature, and anterior chamber depth are obtained using optical or biometry devices. The SRK , an early empirical model, calculates power as P = A - 2.5L - 0.9K (where P is IOL power in diopters, A is the lens constant, L is axial length in mm, and K is average keratometry in diopters); more advanced formulas like SRK/T refine this approach with theoretical adjustments for effective lens position to enhance accuracy, particularly in eyes with extreme axial lengths. During surgery, the selected foldable IOL is loaded into an injector for insertion. The capsular bag and anterior chamber are reformed with viscoelastic material to maintain space and protect ocular structures. The is advanced through the clear corneal incision, and the IOL is slowly injected into the capsular bag, with the leading haptic unfolding first. Once partially deployed, the injector is withdrawn, and a Sinskey hook or is used to center the optic and position the trailing haptic beneath the capsulorhexis edge, ensuring stable fixation and alignment. This minimizes trauma and promotes rapid visual rehabilitation.

Wound Closure and Final Steps

Following the implantation of the intraocular lens (IOL), the ophthalmic viscosurgical device (OVD) is meticulously removed to mitigate the risk of postoperative (IOP) elevation and subsequent complications such as secondary . This step involves using an irrigation and aspiration (I/A) handpiece to gently aspirate the OVD from both behind the IOL and the anterior chamber, ensuring complete evacuation while maintaining anterior chamber stability; cohesive OVDs facilitate easier removal due to their tendency to extrude as a cohesive mass, whereas dispersive types may require additional techniques like the soft-shell method for thorough clearance. Incomplete OVD removal can obstruct outflow, leading to IOP spikes exceeding 30 mmHg in the early postoperative period if left unaddressed. Wound sealing then ensures the of the surgical site, primarily relying on the self-sealing properties of the clear corneal incision, which is typically 2.2–3.2 mm wide and designed to naturally upon withdrawal of instruments. To enhance sealing, the incision edges are hydrated with () using a , promoting stromal swelling and a watertight closure without inducing significant ; for larger or compromised , 10-0 nylon sutures may be placed to secure the site. is verified via the Seidel test, wherein a or fluid injection checks for aqueous leakage—positive if fluorescein staining reveals a stream of diluted —prompting further or suturing if necessary. In cases of vitreous prolapse through a posterior capsular tear, an anterior is performed as a measure using a vitrectomy cutter to excise prolapsed vitreous, thereby preventing traction on the and restoring anterior segment architecture before final closure.

Complications

Intraoperative Complications

Intraoperative complications during phacoemulsification, though relatively uncommon with modern techniques, can arise from challenges in maintaining anterior chamber stability, precise instrumentation, or thermal management, potentially requiring immediate intervention to preserve visual outcomes. These events occur in approximately 2-5% of cases overall, influenced by factors such as surgeon experience and patient . Posterior capsule rupture (PCR) represents one of the most frequent and serious intraoperative complications, with an incidence ranging from 1% to 3.5% in routine phacoemulsification procedures. This occurs when the posterior capsule tears during manipulation or emulsification, often due to excessive phacoemulsification energy, vitreous pressure, or incomplete hydrodissection, leading to vitreous into the anterior chamber. Management typically involves halting phacoemulsification, performing an anterior to remove prolapsed vitreous using a vitrectomy cutter, and adjusting intraocular (IOL) placement to the sulcus or anterior chamber if the capsular bag is compromised. In experienced hands, timely recognition and intervention can limit progression, with studies showing that 84% of cases achieve favorable visual recovery when addressed promptly. Iris prolapse or trauma, occurring in 0.1% to 1.2% of surgeries, often results from sudden anterior chamber during phacoemulsification, particularly when irrigation-aspiration is unbalanced or during instrument exchange. This can manifest as iris tissue herniation through the incision or mechanical injury from the phaco tip, exacerbated in cases of or poor pupillary dilation. Prevention focuses on maintaining stable (IOP) through continuous irrigation, proper viscoelastic use, and controlled fluid dynamics to avoid chamber shallowing. If occurs, gentle repositioning with instruments like iris hooks or a is employed, minimizing further to preserve iris integrity and reduce risks of hemorrhage or pigment dispersion. Phaco burn, a thermal injury to the corneal endothelium and incision site, arises from frictional heat generated by the ultrasound probe when irrigation flow is impeded, such as by a dislodged sleeve or excessive phaco power in dense cataracts. Its incidence is low, less than 0.1%, but can lead to localized opacification, endothelial cell loss, and potential wound contracture if severe. Mitigation strategies include using pulse or burst ultrasound modes to reduce cumulative energy delivery, ensuring sleeve integrity, and optimizing irrigation rates to dissipate heat effectively. Intraoperatively, recognition involves monitoring for steam or tissue whitening at the incision; treatment may require cooling with balanced salt solution and, in rare cases, incision revision to prevent long-term corneal decompensation. Variations in surgical techniques, such as chop versus stop-and-chop methods, can influence the likelihood of these complications by altering energy use and chamber stability.

Postoperative Complications

Postoperative complications of phacoemulsification, while relatively uncommon, can impact visual recovery and require prompt management to preserve outcomes. These issues arise due to inflammatory responses, infections, or lens capsule changes following the procedure. Key complications include , posterior capsule opacification (PCO), and (CME), each with distinct incidences, symptoms, and preventive or therapeutic strategies. Endophthalmitis is a severe intraocular that occurs rarely after phacoemulsification, with an incidence typically less than 0.1% in modern settings. Symptoms often include ocular pain, decreased vision, redness, and potentially or lid swelling, manifesting within days to weeks postoperatively. Prevention focuses on strict aseptic techniques and prophylactic measures such as intracameral antibiotics, which have been shown to significantly reduce the risk. Early recognition and treatment with intravitreal antibiotics are essential to mitigate vision loss. Posterior capsule opacification (PCO), the most frequent long-term complication, involves proliferation of lens epithelial cells on the posterior capsule, leading to visual blurring. The incidence of clinically significant PCO requiring intervention is approximately 20% at 5 years post-surgery, varying by design. It typically develops months to years after the procedure and is managed effectively with :yttrium-aluminum-garnet (:YAG) capsulotomy, a quick outpatient procedure that creates an opening in the opacified capsule without . Advances in materials have helped lower PCO rates, but it remains a common reason for subsequent interventions. Cystoid macular edema (CME) results from postoperative inflammation causing fluid accumulation in the , with an incidence of 1–3% in uncomplicated cases. It presents as reduced central vision, often peaking 4–12 weeks after surgery, and is more prevalent in patients with risk factors like or . Management involves topical nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids to resolve the , with most cases improving within months. Prophylactic use of NSAIDs perioperatively can further minimize its occurrence.

Recovery and Outcomes

Recovery Process

Following phacoemulsification, patients receive immediate postoperative care to protect the eye and promote healing. On the first day, an eye shield is typically placed over the operated eye to prevent accidental , and it is worn continuously for the initial 24-48 hours, then at night for at least one week. Patients are advised to avoid rubbing or pressing on the eye, as well as heavy lifting or strenuous activities, to minimize the risk of increased or wound displacement. Topical medications form a of early recovery, with eye drops prescribed to prevent and drops to control , both administered for approximately 4 weeks post-surgery. These drops are instilled as directed, often starting the day after surgery, with patients instructed to wait at least 5 minutes between different types to ensure . Non-steroidal drops may also be used for 4 weeks to further reduce the risk of cystoid . Routine follow-up visits are scheduled to monitor , , and , typically occurring the day after , at one week, and at one month. These appointments allow for early detection and management of any issues, such as elevated pressure or residual . Driving may resume around one week postoperatively if is stable and approved by the , though patients should avoid it until cleared to ensure . Lifestyle adjustments support a smooth recovery, including wearing sunglasses outdoors to alleviate and protect against irritants like wind or bright light. Patients should gradually return to normal activities, avoiding swimming, hot tubs, or dusty environments for 4-6 weeks, with full recovery generally achieved within this timeframe as the eye stabilizes.

Clinical Outcomes

Phacoemulsification yields high rates of visual improvement, with over 95% of patients achieving a best-corrected (BCVA) of 20/40 or better postoperatively as of , and patient satisfaction exceeding 98% in uncomplicated cases. In uncomplicated cases without comorbidities, this figure exceeds 98%, typically assessed at 3 months following surgery. The procedure's small incisions, often 2.2 to 3 mm, contribute to low surgically induced , generally under 1 diopter, facilitating rapid and stable refractive recovery. The safety profile of phacoemulsification is favorable, with overall complication rates below 5% in experienced settings, including rare sight-threatening events such as (approximately 0.01-0.05%, further reduced by routine intracameral antibiotic use) and (approximately 0.5-1% cumulative over 5 years, with most occurring within 1 year). This low incidence supports rapid patient rehabilitation, often within 1-2 weeks, compared to several weeks to months for traditional extracapsular (ECCE). Compared to ECCE, phacoemulsification demonstrates superiority in recovery time and visual outcomes, with faster of postoperative and earlier achievement of functional . Long-term intraocular lens (IOL) stability remains high, exceeding 95% in uncomplicated cases, as evidenced by sustained BCVA over years without significant decentration or opacification requiring intervention beyond routine capsulotomy in approximately 10-20% within 2-5 years, depending on IOL type.

Recent Advances and Research

Technological Advancements

Since the , femtosecond laser assistance has emerged as a key technological advancement in phacoemulsification, enabling automated creation of precise anterior capsulorhexis and softening or fragmentation of the cataractous lens prior to ultrasonic emulsification. This laser pretreatment performs corneal incisions, capsulorhexis, and lens fragmentation in a controlled, automated manner, minimizing manual variability and enhancing reproducibility compared to traditional techniques. By pre-softening the lens nucleus, femtosecond laser assistance significantly reduces the cumulative energy required for phacoemulsification, with studies reporting reductions in effective phacoemulsification time and energy by up to 30% or more, particularly beneficial in moderate to dense cataracts. This decrease in energy use also correlates with lower endothelial cell loss and reduced risk of thermal injury to surrounding ocular tissues. Integration of phacoemulsification with microinvasive surgery (MIGS) represents another established innovation, allowing simultaneous cataract removal and targeted management through minimally invasive implants or procedures during the same operation. Common MIGS approaches, such as trabecular micro-bypass stents (e.g., iStent) or gonioscopy-assisted transluminal trabeculotomy, are performed alongside phacoemulsification to enhance aqueous outflow via the . Clinical outcomes demonstrate that these combined procedures achieve (IOP) reductions of 20–30% postoperatively, often with decreased reliance on topical medications, making them suitable for patients with mild to moderate open-angle . This synergy improves overall surgical efficiency and patient satisfaction by addressing both and in a single session, with success rates defined as IOP ≤21 mmHg and ≥20% reduction from baseline. Advancements in phacoemulsification machines have further refined procedural control, particularly through torsional and active fluidics systems, which offer superior performance in handling dense cataracts. Torsional employs a rotational oscillation of the phaco tip to emulsify the lens nucleus more efficiently than traditional longitudinal , reducing repulsion of nuclear fragments and allowing higher levels for faster in hard-grade cataracts. When combined with active fluidics—pressurized infusion systems that maintain stable by proactively replenishing fluids—these machines minimize pressure fluctuations and , enhancing chamber stability during surgery. In dense cataracts, this integration has been shown to improve surgical efficiency, shorten operative times, and reduce postoperative corneal , contributing to better visual recovery. Recent platforms, including the Alcon and J&J (as of October 2025), exemplify these features, providing advanced active fluidics, real-time thermal monitoring, and customizable tips for optimized control in complex cases.

Ongoing Research

Recent clinical trials from 2024 to 2025 have focused on the integration of phacoemulsification with minimally invasive surgery (MIGS) to address both and mild-to-moderate , emphasizing reductions in postoperative medication burden. A and of patients with normal-tension reported that MIGS combined with phacoemulsification resulted in a mean reduction of 0.95 IOP-lowering medications at 12 months, equating to approximately 50% fewer drops from a typical baseline of two medications, with sustained effects observed up to 24 months (mean reduction of 1.32 medications). These findings underscore the procedure's potential to improve patient compliance and by minimizing topical therapy needs without increasing complication rates. Advancements in (AI)-assisted biometry are under active investigation to refine (IOL) power calculations for phacoemulsification, particularly in complex cases. A 2025 study evaluating seven AI-based formulas demonstrated that the Karmona formula achieved prediction errors within ±0.5 D in 89.67% of eyes, while Hill-RBF 3.0, LSF AI, and Pearl-DGS reached 87.50%, surpassing many traditional methods in medium-long eyes and reducing refractive errors overall. Another analysis in highly myopic eyes confirmed AI formulas like Pearl-DGS yielding 69.57% accuracy within ±0.5 D, highlighting their role in enhancing precision for diverse axial lengths. These developments aim to minimize postoperative and enhance visual outcomes, with ongoing trials assessing integration into routine preoperative workflows. Comparative studies between phacoemulsification and small-incision (MSICS) continue to evaluate cost-effectiveness, especially in developing countries where resource constraints limit access. A review noted that MSICS enables surgeries at costs as low as $20 USD, supporting high-volume delivery in low- and middle-income settings while achieving comparable to phacoemulsification. In parallel, research on techniques blending phacoemulsification and MSICS elements is advancing; for instance, a cost-utility of mobile programs in resource-limited areas advocated approaches incorporating with phacoemulsification for improved feasibility and reduced equipment dependency. These efforts prioritize scalable solutions to address global backlogs, with trials measuring long-term outcomes in high-density surgical environments.