Phacoemulsification With Intraocular Lens (IOL) Implantation Technique

A lid speculum is used to hold the eyelids apart. Surgeons may choose from wire or screw, nasal or temporal, or self-retaining eyelid speculums.

Topical antibiotics or a diluted mixture of antiseptic is used to wash out debris and particulates from the conjunctival fornices. Exposure varies from 30-60 seconds and is followed by generous washing with a balanced salt solution to remove all traces of antiseptic solution from the surgical field.

A 1.2-mm or 15º stab knife is used to fashion a small paracentesis at the peripheral cornea, usually 3-4 clock hours away from the primary surgical incision. This is made along the iris plane and usually is a single-plane stab into the peripheral cornea. Other surgeons who perform phacoemulsification advocate a multiplane approach to enhance self-sealing. With a 1.2-mm stab knife, most second instruments, including bimanual aspirating handpieces, fit snuggly and do not make the wound gape, preventing wound leakage. Intracameral anesthetic injections, vital dye, and viscoelastic injections are performed after the side ports are created.

Scleral tunnel incisions most likely are performed by beginning phacoemulsification surgeons because of the ease of conversion to manual expression extracapsular cataract extraction. The initial advantage presented by a scleral tunnel incision is the avoidance of surgically induced astigmatism. The cumbersome nature of fashioning a scleral tunnel incision has made it fall out of fashion with most phacoemulsification surgeons.

A progressive reduction in incision size and related morbidity has marked the recent history of cataract surgery via phacoemulsification. Increased operating efficiency, improved astigmatism control, and foldable intraocular lens technology have led to increasing use of self-sealing, clear corneal incisions for cataract surgery. Pre-existing corneal astigmatism may be effectively treated during cataract surgery using incisional keratorefractive techniques (limbal relaxing incisions, peripheral penetrating corneal incisions). Additional steps, such as the creation of­­ a supra-incisional penetrating non-perforating corneal incision (Wong incision), have decreased the possibility of wound leaks. Femtosecond lasers that create precise corneal incisions now are available for all phacoemulsification surgeons. They have a unique ability to create a discrete photodisruption of tissue with minimal collateral effects.

The cataract surgery incision is illustrated in the image below.

Femtosecond Laser-Assisted Corneal Incisions

Femtosecond laser–assisted corneal incisions before cataract surgery are used to improve the incision location, length, creation, and closure. A single-, double-, or three-plane main corneal incision may be fashioned. One or two side ports may be made. Single or paired limbal relaxing incisions may be created.

A special forceps creates a continuous curvilinear capsulorhexis (CCC, see the image below). CCC has improved intraocular lens stability and centration, which helped reduce posterior capsular opacification and spurred the development of endolenticular nucleofractis techniques. Critical elements of technique for constructing continuous curvilinear capsulorhexis include operating in a deep and stable chamber, initiating the tear in the capsule's center, and grasping the flap to maintain control of the vector of the tear at all times. Using vital dyes has extended the application of continuous curvilinear capsulorhexis to cases with a reduced or absent red reflex. Femtosecond lasers that create precise continuous curvilinear capsulorhexis are now available for all phacoemulsification surgeons.

Femtosecond Laser-Assisted Capsulotomies

Femtosecond laser–assisted capsulotomies, when performed correctly, are almost always free floating. The risk of losing a capsulorhexis edge is eliminated. Capsulotomy size and location may be programmed. When used in white cataracts, incomplete capsulotomy may occur, although the risk of a capsule tear is less. ^[6]

Cortical cleaving hydrodissection has reduced the need for irrigation and aspiration of cortical material and the rate of posterior capsular opacification. Critical steps of cortical cleaving hydrodissection include injection of a balanced salt solution under the anterior capsule such that a fluid wave traverses the posterior aspect of the lens and decompression of the capsule by depression of the central portion of the lens.

Hydrodelineation means the separation of the epinucleus from the endonucleus to allow the epinucleus to serve as a protective cushion during the manipulation and extraction of the endonucleus.

Nuclear rotation with a second instrument ensures the nucleus is entirely mobile and reduces the possibility of transferring stress to the posterior capsule and zonules during nuclear disassembly.

Most phacoemulsification machines have parameters for power, vacuum, pulse, burst, oscillation levels, and bottle height. These may be set to allow specific phaco procedures to proceed during different steps of phacoemulsification surgery.

Phacoemulsification may be performed in various locations within the eye.

Anterior chamber phacoemulsification affords protection of the capsular bag, zonules, and iris. When a posterior capsular break is present, prolapsing the remaining nucleus into the anterior chamber may be necessary. Since it is nearer to the corneal endothelium, the risk for corneal endothelial loss is higher, despite using viscoelastic for protection.

Iris plane phacoemulsification affords protection of the capsular bag and the corneal endothelium; however, potential injury to the iris may occur if it is inadvertently pulled into the phacoemulsification handpiece.

Posterior chamber phacoemulsification currently is the most common location where surgeons perform phacoemulsification. The increased understanding of proper nucleus rotation and subsequent nuclear disassembly and efficient phacoemulsification machine parameters has increased the safety of phacoemulsification surgery and decreased morbidity, such as posterior capsular rupture (shown below) and endothelial cell loss.

Phacoemulsification is illustrated in the images below.

One-handed technique

This technique allows the creation of a single corneal incision and the use of a single phacoemulsification handpiece in shaving off each layer of the nucleus and the epinuclear envelope. This is performed with adequate capsulorhexis and nuclear rotation.

Two-handed techniques

Chop techniques substitute mechanical forces for ultrasound energy to disassemble the nucleus, use a high vacuum as an extractive technique to remove nuclear material, and facilitate the achievement of minimally invasive surgery and rapid visual rehabilitation. Bimanual, ultra-small incision cataract surgery and companion IOL technology now are a reality via laser and new ultrasound power modulations.

The divide and conquer technique uses ultrasonic sculpting of a deep central crater and fracturing of segments of a peripheral rim.

Phaco fracture involves ultrasonic sculpting of grooves and bimanual nucleus cracking into four separate quadrants.

Chip and flip mean sculpting a central bowl until a thin chip of endonucleus remains, whereas crack and flip is a modification of phaco fracture, including hydrodelineation.

Phaco chop requires a firm hold with a high vacuum and a second sharp instrument to divide the nucleus horizontally or vertically.

Investigation of the choo-choo chop and flip technique led to the conclusion that reduction of ultrasound energy is correlated with improvement of visual acuity on the first postoperative day.

Phacoemulsification with laser systems allows a reduction of incision size to 1.5mm.

Surgeons using bimanual microincision phacoemulsification have described improved chamber stability, ability to follow, and greater ease of irrigation and aspiration.

Femtosecond laser-assisted lens fragmentation techniques

Femtosecond laser–assisted lens fragmentation before cataract surgery aims to decrease or eliminate the need for ultrasound energy during nuclear disassembly. For softer nuclei, aspiration techniques may be sufficient. In harder nuclei, ultrasound emulsification still is required. ^[7] Numerous cutting patterns and algorithms (ie, energy, shot placement, pulse repetition frequency) influence the efficiency of nucleus softening fragmentation.

Cortical material remains attached to the capsular bag after nuclear disassembly and phacoemulsification. A straight irrigation/aspiration handpiece or a bimanual irrigation/aspiration set may be used to remove residual cortex (see the images below). The sub-incisional cortex usually is removed first, followed by superior cortical remnants. The rest are removed in a clock-hour fashion. The capsule is polished with the lowest allowable settings possible. Proper removal of lens epithelial cells prevents posterior capsular opacification and capsular phimosis.

The capsular bag and anterior chamber is reformed with viscoelastic. Preloaded foldable IOLs are now on the market. Most foldable IOLs are loaded onto a cartridge before injection into the capsular bag. They usually go through a sub 2.75 mm corneal slot. Preloaded IOLs decrease surgical time and decrease handling of the lens, thereby theoretically decreasing the risk of introducing contaminants into the eye. IOL lens insertion is illustrated in the images below.

Intracameral injection

Intracameral antibiotics at the end of surgery now are commonplace due to the statistically significant decrease in morbidity due to postoperative infections.

Test for leaks

Testing for wound leaks at the end of each surgery is essential. Neglecting a leaking wound may lead to a flat chamber and endophthalmitis. A properly constructed corneal incision will be self-sealing. Corneal incision hydration with a balanced salt solution usually provides a tight seal on most corneal incisions. A surgical sponge may be used to check for the egress of anterior chamber fluid. Using fluorescein dye may enhance the visualization of leaks from all incision sites.

Potential postoperative complications include the following conditions:

• Corneal edema

• Descemet's membrane detachment

• Induced astigmatism

• Corneal melting

• Conjunctival ballooning

• Epithelial downgrowth

• Toxic anterior segment syndrome (TASS)

• Flat chamber

• Elevated intraocular pressure

• Intraoperative floppy iris syndrome (IFIS)

• Iridodialysis

• Cyclodialysis

• Ciliary block glaucoma

• Chronic postoperative uveitis

• Retained lens material

• Capsular rupture

• Vitreous prolapse

• Dropped nucleus

• IOL complications (decentration and dislocation, pupillary capture, capsular block syndrome, uveitis-glaucoma-hyphema syndrome, pseudophakic bullous keratopathy, incorrect IOL power, IOL glare, IOL opacification)

• Anterior capsular fibrosis and phimosis

• Posterior capsular opacification

• Hemorrhage (retrobulbar hemorrhage, suprachoroidal effusion, expulsive suprachoroidal hemorrhage, hyphema)

• Endophthalmitis

• Cystoid macular edema

• Uretts Zavala syndrome

• Retinal light toxicity

• Macular infarction

• Retinal detachment