Power Modulation in Phacoemulsification
Liza Hemaid Sayed Awwad;
Abstract
The human lens consists of three main parts: Lens Capsule which completely envelops the lens, Lens Epithelium which consists of cuboidal cells and Lens Fibers.
During life time the lens may develop a kind of opacification that causes impaired vision, this opacification is known as Cataract; the lens is specially prone to the opacification due to its high proteins content and minimal replenishment of these proteins as the lens ages.
The cataract has many risk factors including chronic exposure to UV light, artificial UV radiation and the presence of oxygen reactive metabolites as well as smoking and tobacco chewing.
The cataract can be classified according to their cause and it includes: Age-related, secondary, drug induced, radiation and traumatic cataracts. However, the cataract lens itself is usually graded using “LOCs System”, the LOCs grading system depends on the “Photographs of slit lamp cross-section of the lens” as a reference for grading nuclear opalescence and nuclear color, it also depends on the “Photographs of the lens seen by retroillumination” as a reference for grading cortical and posterior subacapular cataract.
In 1967 Charles Kelmen introduced his invention “Phacoemulsification machine” to the world, it is a machine that can be used to remove the cataractous lens by the use of ultrasonic energy, early after that the clinical trial showed a promising results. Now the phacoemulsification surgery is considered of the most frequent surgery in the world, and it has a very high margin of safety, it is not life threatening surgery, however local complication such corneal endothelial cell loss is still one of the main problem of the surgery.
The phaco machine consists of four parts: Ultra sound system, Phaco hand piece, foot paddle and Irrigation/aspiration systems.
The ultrasound system is the part responsible for creating the power needed for the surgery, this power is created by the frequency by which the needle is moving (mainly 35.000 to 45.000 cycles per second HZ) and this frequency is mostly efficient for the nucleus emulsification.
One of the most important key aspects for the successful phacoemulsification is the machine fluidics, balanced fluidics during phaco surgery keeps the eye inflated; preventing collapse. The phaco fluidics consists of irrigation and aspirations system, the irrigation is responsible for inflow of liquids to the eye, and the aspiration is responsible for the outflow from the eye.
Many types of pumps are currently used in the irrigation systems e.g. peristaltic, venturi, and hybrid pumps.
For a long time power modulation in phacoemulsification has become one of the most challenging keys in the development of the phaco machines, factories engineers and even physicians have developed their own aspects trying to achieve the highest efficiency and safety.
The power modulation was achieved either by Directly decreasing the amount of power used during the surgery or by Indirectly by using adjuvant ways to decrease the harmful power reaching the cornea.
The first type of the Power modulation is the “Technique dependant methods” in which no modifications in the machine is conducted, however an innovative techniques is used to decrease the amount of ultrasound energy that needed to emulsify the lens and these techniques include:
• Divide and conquer technique: this is based on using U/S energy away from endothelium; it involves the creation of two deep grooves in the nucleus that intersect centrally, followed by the cracking of the nucleus into four separate quadrants. This cracking is accomplished by placing a spatula or chopping device at the base of one side of the groove and the phaco tip at the other side.
• Phaco Chop Techniques: and it relies on using lower amount of U/S energy, in this technique the phaco tip essentially performs a lamellar dissection of the nucleus as the central trough is sculpted. The chop can be classified generally to horizontal and vertical chopping techniques.
• Using barriers between endothelium and U/S energy; it involves the usage of Ophthalmic Viscosurgical Devices OVDs to protect the endothelium and deepen the anterior chamber to maintain ample surgical space during phacoemulsification. The OVDs may be either Cohesive OVDs that tend to be effective for maintaining space or Dispersive OVDs (or known as adhesive) which has become more prominent because they are superior coating agents, are better retained in the anterior chamber and along the endothelial layer, and provide greater protection.
During life time the lens may develop a kind of opacification that causes impaired vision, this opacification is known as Cataract; the lens is specially prone to the opacification due to its high proteins content and minimal replenishment of these proteins as the lens ages.
The cataract has many risk factors including chronic exposure to UV light, artificial UV radiation and the presence of oxygen reactive metabolites as well as smoking and tobacco chewing.
The cataract can be classified according to their cause and it includes: Age-related, secondary, drug induced, radiation and traumatic cataracts. However, the cataract lens itself is usually graded using “LOCs System”, the LOCs grading system depends on the “Photographs of slit lamp cross-section of the lens” as a reference for grading nuclear opalescence and nuclear color, it also depends on the “Photographs of the lens seen by retroillumination” as a reference for grading cortical and posterior subacapular cataract.
In 1967 Charles Kelmen introduced his invention “Phacoemulsification machine” to the world, it is a machine that can be used to remove the cataractous lens by the use of ultrasonic energy, early after that the clinical trial showed a promising results. Now the phacoemulsification surgery is considered of the most frequent surgery in the world, and it has a very high margin of safety, it is not life threatening surgery, however local complication such corneal endothelial cell loss is still one of the main problem of the surgery.
The phaco machine consists of four parts: Ultra sound system, Phaco hand piece, foot paddle and Irrigation/aspiration systems.
The ultrasound system is the part responsible for creating the power needed for the surgery, this power is created by the frequency by which the needle is moving (mainly 35.000 to 45.000 cycles per second HZ) and this frequency is mostly efficient for the nucleus emulsification.
One of the most important key aspects for the successful phacoemulsification is the machine fluidics, balanced fluidics during phaco surgery keeps the eye inflated; preventing collapse. The phaco fluidics consists of irrigation and aspirations system, the irrigation is responsible for inflow of liquids to the eye, and the aspiration is responsible for the outflow from the eye.
Many types of pumps are currently used in the irrigation systems e.g. peristaltic, venturi, and hybrid pumps.
For a long time power modulation in phacoemulsification has become one of the most challenging keys in the development of the phaco machines, factories engineers and even physicians have developed their own aspects trying to achieve the highest efficiency and safety.
The power modulation was achieved either by Directly decreasing the amount of power used during the surgery or by Indirectly by using adjuvant ways to decrease the harmful power reaching the cornea.
The first type of the Power modulation is the “Technique dependant methods” in which no modifications in the machine is conducted, however an innovative techniques is used to decrease the amount of ultrasound energy that needed to emulsify the lens and these techniques include:
• Divide and conquer technique: this is based on using U/S energy away from endothelium; it involves the creation of two deep grooves in the nucleus that intersect centrally, followed by the cracking of the nucleus into four separate quadrants. This cracking is accomplished by placing a spatula or chopping device at the base of one side of the groove and the phaco tip at the other side.
• Phaco Chop Techniques: and it relies on using lower amount of U/S energy, in this technique the phaco tip essentially performs a lamellar dissection of the nucleus as the central trough is sculpted. The chop can be classified generally to horizontal and vertical chopping techniques.
• Using barriers between endothelium and U/S energy; it involves the usage of Ophthalmic Viscosurgical Devices OVDs to protect the endothelium and deepen the anterior chamber to maintain ample surgical space during phacoemulsification. The OVDs may be either Cohesive OVDs that tend to be effective for maintaining space or Dispersive OVDs (or known as adhesive) which has become more prominent because they are superior coating agents, are better retained in the anterior chamber and along the endothelial layer, and provide greater protection.
Other data
| Title | Power Modulation in Phacoemulsification | Other Titles | تعديل القوة المستخدمة في تفتيت المياه البيضاء بالموجات فوق الصوتية | Authors | Liza Hemaid Sayed Awwad | Issue Date | 2015 |
Recommend this item
Similar Items from Core Recommender Database
Items in Ain Shams Scholar are protected by copyright, with all rights reserved, unless otherwise indicated.