Everything you should know about a phacoemulsifier
A cataract is a kind of eye disease arising from the clouding of the eye lens, which is usually clear. The gold standard treatment for worsening symptoms involves extracapsular cataract extraction surgery performed with a phacoemulsifier. Phacoemulsifiers are microsurgical devices that work by delivering ultrasonic vibrations through an ultrasound probe to the cloudy lens. The vibrations destroy/emulsify the nucleus of the cloudy crystalline lens (phacoemulsification), and the particles are removed through a hollow center on the probe. Phacoemulsification is quickly followed by inserting an artificial intraocular lens.
Phacoemulsifiers guarantee safety and ensure the rapid destruction of cataracts. They are a product of technological advancements, away from large incision extracapsular extractions and archaic manual nuclear expression methods that are harmful and stressful.
History of phacoemulsifiers
The oldest surgical technique for cataract management is couching. This procedure was recorded as far back as 2000 BC. Ancient Egyptians reportedly performed it, but the procedure continued for so long before developing modern techniques. Couching is a lens depression technique that involves pushing a cloudy lens to the distal part of the eye with a sharp instrument.
Modern surgical procedures for cataracts include intracapsular and extracapsular extraction surgeries. The first extracapsular cataract extraction was performed in 1747 by Jacques Daviel, a European ophthalmologist. It was a significant advancement in ophthalmology. Phacoemulsifiers, an extracapsular extraction surgery, was developed by Charles Kelman in the late 1960s. He had always wondered why cataract extraction surgeries had to require large incisions. At that time, the procedure involved intact removal of the lens material, which is very painful with a long and stressful recovery process. Dr. Kelman went ahead to develop the phacoemulsification methodology and consequent device. He initially thought of using dissolving enzymes on the lens material before developing the first handpiece phacoemulsifier device. The modified device got developed in collaboration with Cavitron Corporation.
Indications to use a phacoemulsifier
- Very cloudy vision, progressive loss of vision
- Poor vision in sunlight and well-lit room
- Low or total loss of central vision
- Frequent need to change prescription eyeglasses
- Difficulty in performing normal daily activities
However, other indications can point towards a need for cataract surgery:
- Presence of other eye conditions such as an age-related macular degeneration
- Comorbidities such as diabetes hasten the progression of cataracts
- Inability to perform full eye examination due to the cloudy lens
- Younger patients as they also experience fast progression of the disease
Another critical determinant of the use of a phacoemulsifier is the state of the cataract. Denser cloudiness will likely require the old method of extracapsular extraction surgery. This is to avoid a gamble of whether the phacoemulsifier will destroy the cataract or not. Very dense lenses are removed intact through larger incisions. Hence, phacoemulsifiers are not preferred in such cases. They are also not preferred when the patient has certain corneal diseases.
Phacoemulsifier utilizes small incisions of about 2-3 mm to deliver ultrasound vibrational waves that destroy cataracts, starting from its denser nucleus. The particles are aspirated through a hollow space at the tip of the device. The lens capsule is left intact to allow the easy insertion of the artificial intraocular lens (IOL), a procedure that immediately follows the phacoemulsification process. Phacoemulsifiers also perform anterior vitrectomy, which is an adjunct procedure that allows the placement of intraocular lenses after phacoemulsification. Anterior vitrectomy is simply the removal of vitreous humor from the anterior part of the eye cavity. This is necessary to avoid any obstruction by the vitreous gel to the insertion of IOL. Anterior vitrectomy is also indicated for some other ophthalmic repair procedures.
Complications of using a phacoemulsifier
Several complications can arise from using this device or the phacoemulsification process as a whole. Serious general complications may include bleeding, post-operative inflammation, and double vision. Complications such as endophthalmitis also can occur. Endophthalmitis is an infection of the eyeball, which is not very common as there are effective antibiotics to prevent and combat it.
Cystoid macular edema (CME) is another complication resulting from problems from the viscoelastic fluid or other infusion fluids injected into the eye. It could also be a sub-clinical manifestation of toxic anterior segment syndrome (TASS). Cystoid macular edema is treated with some specific NSAIDs such as nepafenac.
The dislocation of the intraocular lens is also common. The lens should be handled by the optic and repositioned. Another solution to this is sutured IOL; however, it increases the chances of complications like CME.
Retinal detachment may also occur during the surgery or long after. The common cause of material dislocations and detachment is the bad handling technique of the phacoemulsifier. The equipment should not be placed into the vitreous, and appropriate vitrectomy should be done for every surgery scenario present. The intraocular pressure should be well managed and kept in check too.
Phacoemulsifier has no alternatives regarding small-incision extracapsular cataract extraction surgery. However, other devices can be helpful to get the same job done through other surgical procedures, including:
- Non-phaco extracapsular extraction. Incisions are more prominent, and a phacoemulsifier is not used with this extraction. However, the same manipulations as performed in phacoemulsification occur.
- Intracapsular extraction. Incisions here are larger too. The entire lens material and capsule are removed intact. It is effortless but also painful and riskier.
Procedures of lesser similarity to phacoemulsification include manual small-incision cataract surgery and laser-assisted surgery.
Specifications of a phacoemulsifier
A phacoemulsifier has facilities for phacoemulsification, aspiration, anterior vitrectomy, and bipolar coagulation. It typically has two handpieces that house four piezo crystals, a digital LCD panel display for surgical parameters, excellent audio, and a multifunctional footswitch.
Technical specifications are:
- Ultrasonic tip frequency of 29 – 60 Hz
- An ultrasonic pulse rate of 1-14 p/secs
- Aspiration is 0-500 mmHg linear vacuum
- Anterior vitrectomy of 30-600 cuts/min
- Bipolar coagulation is 2 – 6 watts, foot-controlled
- Input power is 220-240 volts and 50-60 Hz
- Environmental working conditions are a temperature of 20 - 30℃ and humidity of less than 70>#/p###
- Storage temperature is below 50 ℃ while humidity is 15-90 >#/p###
Other vital features are extensive programmability – auto priming, auto tuning, auto fluidic, reflux switch, and so on.
How the equipment works
A phacoemulsifier delivers vibrational energy that drives the emulsification of cloudy lenses through an ultrasound probe. The machine vibrates at a fixed frequency, up to 40,000 cycles per second. This occurs when the foot pedal is lowered to position 3. The vibrations can be longitudinal or lateral (seen in recent advanced models). Equipment that can vibrate in both directions is more efficient, as it enables the lens to be cut/destroyed in multiple ways.
The phaco needle creates some mechanical energy as it hits the cataract. It also transfers some particle and fluid wave energy to the lens material, and the residual of all these is heat energy. Thus, it is essential to select or regulate the phaco power to heat the cornea and damage it. The phaco power and total energy expelled are parameters accessible from the digital supply. Both parameters are related to the time of power to the "on" setting. Thus, a knowledge of these parameters is needed to control the phacoemulsifier. An inappropriate power or energy will damage the cornea and predispose the patient to many complications. Only a licensed ophthalmologist is permitted to operate this machine.
If such modifications are not enough, there are other advanced ways to control the phacoemulsification process technically.
The following medical equipment brands produce excellent phacoemulsifiers:
- MEDA- This brand is produced by a giant Chinese company, Meda co, Ltd. The design is from the Institute of Biomedical Engineering, Chinese Academy of Medical Sciences.
- ZEISS VISALIS – This is another fantastic range of phacoemulsifiers from a German giant manufacturer, Carl-Zeiss.
- Centurion® from Alcon®- This is an amazing product range. The federal (USA) law restricts this brand's sale to be performed only by a physician or on order by a physician.
- The popular NIDEK company also produces another top brand of phacoemulsifiers known as FORTAS™
Phacoemulsifiers have successfully revolutionized surgical procedures in cataract treatment. It is entirely out-patient, less painful, and the recovery is faster and well tolerable. These are impressive attributes not associated with other surgical methods, which has influenced the gradual domination of phacoemulsification. Things get back to normal sooner after a phaco procedure than any other cataract surgery. However, patients receive a shield or, subsequently, eyeglasses to prevent any trauma to the eyes, even during sleep. The patients also use prescription eye drops for up to a month after surgery to help prevent inflammation, infections, and harmful intraocular pressure.