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Phacoemulsification some Basic Ideas…
Khalid M. Al-Arfaj, MDDammam University
3-Vedio …
1-Quiz …
2- lecture …
Case selection …
Anesthesia …
Antibiotics
• Control blepharitis well before surgery (endophthalmitis usually results from lid flora)!
• Fluoroquinolones
Povidone-iodine• inexpensive• extremely broad-spectrum• irritating to eye in undiluted (10%)
solution; dilute to 5%• irrigate fornices with solution• paint, do not scrub, eyelashes
when prepping
Pre-operative Eyedrops
History of small incisions
1977: Scleral tunnel1990: Sclerocorneal1991: Clear corneal1991-present: Variations in clear corneal
Conjunctival peritomyDissection through Tenon’s fasciaCauteryScleral groove 1-2 mm posterior to the limbusScleral tunnelKeratome to enter the AC
Advantages:Wound can be safely enlarged for conversion to ECCEConjunctiva covers the woundPotentially less endothelial damageAstigmatically neutral
Disdvantages:Surgical exposure
Sunken eyeballProminent brow
Potential damage to ciliary bodyIris prolapseFiltering blebs and scarring make it difficult
Keratome to tunnel and enter the eye .
Clear cornea
Advantages:Can use topical anesthesiaFasterBetter surgical exposureFiltering blebs and scarring irrelevantNo subconjunctival hemorrhages
Disadvantages:Pre-existing corneal problems a relative contraindication:
FuchsPrevious PK
Possible higher rate of endophthalmitis in unsutured casesBallooning of conjunctiva if incision too posteriorConversion to ECCE more problematic
AstigmatismPre-existing ocular disease:
PterygiaFiltering blebsTubesEndothelial disease
Wound location
Tunnel lengthGoal to be self-sealing“Square” incision
Depends on widthGenerally want at least 2.0-2.5 mm long
Sharp entry through Descemet’s membrane
Wound architecture
External incisionToo anterior or too posterior
Internal incisionToo anterior or too posterior
TunnelToo long or too short
Incision widthToo narrow or too wide
Problems with the wound
Wound Final Thoughts
The wound may be one of the easiest steps of cataract surgery, but it sets the stage for the entire caseEveryone may have a different phaco woundPrinciples the same
Capsulorrhexis
Continuous curvilinear capsulorrhexis (CCC)It is a continuous tear capsulotomy.It can be made in the anterior capsule or both anterior and posterior capsules.It confines the IOL to the capsular bag.It assures long-term centration of the IOL.
Technique
Completely fill the anterior chamber with viscoelastic agent.Flatten the dome of the anterior lens capsulePuncture the anterior capsule with a bent 30-gauge needle or sharp-tipped capsulorhexis forceps.Start a flap that flops over toward the incision.
Technique
Grasp the flap with capsulorrhexis forceps (Utrata forceps).Spiral out to the desired diameter.Tear tangentially all the way around (no radial forces).Regrasp the flap as necessary.Keep an equal distance from the pupil margin while tearing.
Hydrodissection & Hydrodelineation
Goals
Nucleus rotation
Epinucleus rotation
Loosen cortex
Used to separate lens nucleus from surrounding cortex and capsule
Creates a freely mobile nucleusFacilitates nucleus rotation during phacoemulsification
Hydrodissection
Used to separate epinucleus from harder nuclear material
Creates an epinuclear bowl that protects lens capsule during phacoemulsification
Hydrodelineation
Hydrodissection cannula25- to 30- gauge
Flattened tip with angled or curved shaft
Facilitates placement under anterior capsule
J-shaped cannula may be used for sub-incisional area
Background
Technique …
Complete several fluid waves to ensure adhesions to capsule broken
Proceed to hydrodelineationInject fluid into edge of nucleus“Golden ring” sign indicates epinuclear separation
Confirm that nucleus rotates
Lens nucleus occludes capsulorhexis
Trapped BSS expands posterior capsule, AC shallows
Posterior capsule may rupture
Intraoperative Capsular Block Syndrome
PHACODYNAMICS
Two Basic Elements
US → Emulsify the CataractFluid circuit → cooling and remove the Emulsified Cataract
Three Main Machine
Functions USFlowIrrigation
Fluidics
IrrigationFlowVacuum
Fluidics
Flow → peristaltic → vacuum only at occlusionVacuum → venture → continuous vacumBOTH → millennium
Flow control mode Vacuum control
mode
Type of Pumps
Irrigation
Amount of fluid that enters the eye Depend on: Bottle
height pressure on
the eye
flow from the eye
Tip diameterWound leak
Flow
Fluid leaving the eye ml/minSpeed with which the material is sucked to the tipControl pump speedNo-occlusion → current and attraction forceWith occlusion → rise time (time for maximum preset vacum)Flow rate
Surge Vacum riseSafety
Vacuum
Holding power With occlusion → No flow
but pump will continue → negative pressure at aspiration line → vacum → Stop pump at maximum preset vacum
Good Fluidics
Irrigation Wound Leak
Aspiration (flow)
Vacum
Surge
Sudden ↓ of A/C pressure → collapse
Dynamic ↓ of vacum by surgeon by deocclusion
Bottle height Machine complianceVacum and flow rateTip diameter → resistance
Flow
Flow depends on pump speed
not on bottle height
US Power
mode of delivery
USSafest phaco is with appropriate power not with the lower power
Mechanism of Action
Jackhammer → direct contactCavitation → with cavitational bubblesSonic wave
Mode = US Delivery
Continuous Pulse Burst
Pulse
Fixed interval but linear power Fixed duty cycle
Burst Mode
Fixed power of linear intervalVariable duty cycle
Repulsion
Chatter → flaying of peace away from the PHACO tip
Mode - ↓ by Pulse , Burst and WS
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