Phacoemulsification
Encyclopedia
Phacoemulsification refers to modern cataract surgery
in which the eye
's internal lens
is emulsified
with an ultrasonic
handpiece and aspirated from the eye. Aspirated fluids are replaced with irrigation of balanced salt solution
, thus maintaining the anterior chamber, as well as cooling the handpiece.
must diagnose a cataract
and conduct or appropriately supervise the conduction of the operation. University programs typically allow patients to specify if they want to be operated upon by the consultant or the resident or fellow.
Proper anesthesia is a must for ocular surgery. Topical anesthesia
is most commonly employed, typically by the instillation of a local anesthetic
such as tetracaine
or lidocaine
. Alternatively, lidocaine and/or longer-acting bupivacaine
anesthestic may be injected into the area surrounding (peribulbar block
) or behind (retrobulbar block
) the eye muscle cone to more fully immobilize the extraocular muscles
and minimize pain sensation. A facial nerve
block using lidocaine and bupivacaine may occasionally be performed to reduce lid squeezing. General anesthesia
is recommended for children, traumatic eye injuries with cataract, for very apprehensive or uncooperative patients and animals. Cardiovascular monitoring is preferable in local anesthesia
and is mandatory in the setting of general anesthesia. Proper sterile precautions are taken to prepare the area for surgery, including use of antiseptics like povidone-iodine. Sterile drapes, gowns and gloves are employed. A plastic sheet with a receptacle helps collect the fluids during phacoemulsification. An eye speculum
is inserted to keep the eyelids open.
. These can be based on peristaltic
or a venturi
type of pump.
The phaco probe is an ultrasonic handpiece with a titanium
or steel
needle. The tip of the needle vibrates at ultrasonic frequency to sculpt and emulsify the cataract while the pump aspirates particles through the tip. In some techniques, a second fine steel instrument called a "chopper" is used from a side port to help with chopping the nucleus into smaller pieces. The cataract is usually broken into two or four pieces and each piece is emulsified and aspirated out with suction. The nucleus emulsification makes it easier to aspirate the particles. After removing all hard central lens nucleus with phacoemulsification, the softer outer lens cortex is removed with suction only.
An irrigation-aspiration probe or a bimanual system is used to aspirate out the remaining peripheral cortical matter, while leaving the posterior capsule intact. As with other cataract extraction procedures, an intraocular lens implant
(IOL), is placed into the remaining lens capsule. For implanting a PMMA IOL, the incision has to be enlarged. For implanting a foldable IOL, the incision does not have to be enlarged. The foldable IOL, made of silicone
or acrylic of appropriate power is folded either using a holder/folder, or a proprietary insertion device provided along with the IOL.
It is then inserted and placed in the posterior chamber in the capsular bag (in-the-bag implantation). Sometimes, a sulcus implantation may be required because of posterior capsular tears or because of zonular dialysis. Because a smaller incision is required, few or no stitches are needed and the patient's recovery time is usually shorter when using a foldable IOL.
introduced phacoemulsification in 1967 after being inspired by his dentist's ultrasonic probe.
Cataract surgery
Cataract surgery is the removal of the natural lens of the eye that has developed an opacification, which is referred to as a cataract. Metabolic changes of the crystalline lens fibers over time lead to the development of the cataract and loss of transparency, causing impairment or loss of vision...
in which the eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
's internal lens
Lens (anatomy)
The crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a...
is emulsified
Emulsion
An emulsion is a mixture of two or more liquids that are normally immiscible . Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion is used when both the dispersed and the...
with an ultrasonic
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
handpiece and aspirated from the eye. Aspirated fluids are replaced with irrigation of balanced salt solution
Balanced salt solution
A balanced salt solution is a solution made to a physiological pH and salt concentration. Solutions most commonly include sodium, potassium, calcium, magnesium, and chloride. Balanced salt solutions are used for washing tissues and cells and are usually combined with other agents to treat the...
, thus maintaining the anterior chamber, as well as cooling the handpiece.
Preparation and precautions
Being a delicate organ, the eye requires extreme care before, during and after a surgical procedure. An ophthalmologistOphthalmology
Ophthalmology is the branch of medicine that deals with the anatomy, physiology and diseases of the eye. An ophthalmologist is a specialist in medical and surgical eye problems...
must diagnose a cataract
Cataract
A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light...
and conduct or appropriately supervise the conduction of the operation. University programs typically allow patients to specify if they want to be operated upon by the consultant or the resident or fellow.
Proper anesthesia is a must for ocular surgery. Topical anesthesia
Topical anesthetic
A topical anesthetic is a local anesthetic that is used to numb the surface of a body part. They can be used to numb any area of the skin as well as the front of the eyeball, the inside of the nose, ear or throat, the anus and the genital area. Topical anesthetics are available in creams,...
is most commonly employed, typically by the instillation of a local anesthetic
Local anesthetic
A local anesthetic is a drug that causes reversible local anesthesia, generally for the aim of having local analgesic effect, that is, inducing absence of pain sensation, although other local senses are often affected as well...
such as tetracaine
Tetracaine
Tetracaine is a potent local anesthetic of the ester group...
or lidocaine
Lidocaine
Lidocaine , Xylocaine, or lignocaine is a common local anesthetic and antiarrhythmic drug. Lidocaine is used topically to relieve itching, burning and pain from skin inflammations, injected as a dental anesthetic or as a local anesthetic for minor surgery.- History :Lidocaine, the first amino...
. Alternatively, lidocaine and/or longer-acting bupivacaine
Bupivacaine
Bupivacaine is a local anaesthetic drug belonging to the amino amide group. AstraZeneca commonly markets it under various trade names, including Marcain, Marcaine, Sensorcaine and Vivacaine.-Indications:...
anesthestic may be injected into the area surrounding (peribulbar block
Nerve block
Regional nerve blockade, or more commonly nerve block, is a general term used to refer to the injection of local anesthetic onto or near nerves for temporary control of pain. It can also be used as a diagnostic tool to identify specific nerves as pain generators...
) or behind (retrobulbar block
Retrobulbar block
A retrobulbar block is a regional anesthetic nerve block into the retrobulbar space, the area located behind the globe of the eye. Injection of local anesthetic into this space constitutes the retrobulbar block. This injection provides akinesia of the extraocular muscles by blocking cranial nerves...
) the eye muscle cone to more fully immobilize the extraocular muscles
Extraocular muscles
The extraocular muscles are the six muscles that control the movements of the eye . The actions of the extraocular muscles depend on the position of the eye at the time of muscle contraction.-List of muscles:-Importance:...
and minimize pain sensation. A facial nerve
Facial nerve
The facial nerve is the seventh of twelve paired cranial nerves. It emerges from the brainstem between the pons and the medulla, and controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity...
block using lidocaine and bupivacaine may occasionally be performed to reduce lid squeezing. General anesthesia
General anaesthesia
General anaesthesia is a state of unconsciousness and loss of protective reflexes resulting from the administration of one or more general anaesthetic agents...
is recommended for children, traumatic eye injuries with cataract, for very apprehensive or uncooperative patients and animals. Cardiovascular monitoring is preferable in local anesthesia
Local anesthesia
Local anesthesia is any technique to induce the absence of sensation in part of the body, generally for the aim of inducing local analgesia, that is, local insensitivity to pain, although other local senses may be affected as well. It allows patients to undergo surgical and dental procedures with...
and is mandatory in the setting of general anesthesia. Proper sterile precautions are taken to prepare the area for surgery, including use of antiseptics like povidone-iodine. Sterile drapes, gowns and gloves are employed. A plastic sheet with a receptacle helps collect the fluids during phacoemulsification. An eye speculum
Speculum (medical)
A speculum is a medical tool for investigating body cavities, with a form dependent on the body cavity for which it is designed. In old texts, the speculum may also be referred to as a diopter or dioptra...
is inserted to keep the eyelids open.
Surgical technique
Before the phacoemulsification can be performed, one or more incisions are made in the eye to allow the introduction of surgical instruments. The surgeon then removes the anterior face of the capsule that contains the lens inside the eye. Phacoemulsification surgery involves the use of a machine with microprocessor-controlled fluid dynamicsFluid dynamics
In physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics and hydrodynamics...
. These can be based on peristaltic
Peristalsis
Peristalsis is a radially symmetrical contraction and relaxation of muscles which propagates in a wave down the muscular tube, in an anterograde fashion. In humans, peristalsis is found in the contraction of smooth muscles to propel contents through the digestive tract. Earthworms use a similar...
or a venturi
Aspirator
An aspirator, also called an eductor-jet pump or filter pump, is a device that produces vacuum by means of the Venturi effect. In an aspirator, fluid flows through a tube which then narrows. When the tube narrows, the fluid's speed increases, and because of the Venturi effect, its pressure...
type of pump.
The phaco probe is an ultrasonic handpiece with a titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
or steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
needle. The tip of the needle vibrates at ultrasonic frequency to sculpt and emulsify the cataract while the pump aspirates particles through the tip. In some techniques, a second fine steel instrument called a "chopper" is used from a side port to help with chopping the nucleus into smaller pieces. The cataract is usually broken into two or four pieces and each piece is emulsified and aspirated out with suction. The nucleus emulsification makes it easier to aspirate the particles. After removing all hard central lens nucleus with phacoemulsification, the softer outer lens cortex is removed with suction only.
An irrigation-aspiration probe or a bimanual system is used to aspirate out the remaining peripheral cortical matter, while leaving the posterior capsule intact. As with other cataract extraction procedures, an intraocular lens implant
Intraocular lens
An intraocular lens is an implanted lens in the eye, usually replacing the existing crystalline lens because it has been clouded over by a cataract, or as a form of refractive surgery to change the eye's optical power. It usually consists of a small plastic lens with plastic side struts, called...
(IOL), is placed into the remaining lens capsule. For implanting a PMMA IOL, the incision has to be enlarged. For implanting a foldable IOL, the incision does not have to be enlarged. The foldable IOL, made of silicone
Silicone
Silicones are inert, synthetic compounds with a variety of forms and uses. Typically heat-resistant and rubber-like, they are used in sealants, adhesives, lubricants, medical applications , cookware, and insulation....
or acrylic of appropriate power is folded either using a holder/folder, or a proprietary insertion device provided along with the IOL.
It is then inserted and placed in the posterior chamber in the capsular bag (in-the-bag implantation). Sometimes, a sulcus implantation may be required because of posterior capsular tears or because of zonular dialysis. Because a smaller incision is required, few or no stitches are needed and the patient's recovery time is usually shorter when using a foldable IOL.
History
Charles KelmanCharles Kelman
Charles D. Kelman was an ophthalmologist and a pioneer in cataract surgery.Kelman was born in Brooklyn, New York to David and Eva Kelman. He grew up in Queens where he attended Forest Hills High School. After graduation, he attended Boston's Tufts University, where he earned a B.S...
introduced phacoemulsification in 1967 after being inspired by his dentist's ultrasonic probe.