phacoemulsification some basic ideas…

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Khalid M. Al-Arfaj, MD. Phacoemulsification some Basic Ideas…. Dammam University . 1-Quiz …. 2- lecture …. 3-Vedio …. Case selection … Anesthesia …. Pre-operative Eyedrops. Antibiotics Control blepharitis well before surgery (endophthalmitis usually results from lid flora)! - PowerPoint PPT Presentation

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Slide 1

Phacoemulsification some Basic Ideas

Khalid M. Al-Arfaj, MDDammam University

13-Vedio

1-Quiz

2- lecture

2Case selection Anesthesia 3Antibiotics

Control blepharitis well before surgery (endophthalmitis usually results from lid flora)! Fluoroquinolones

Povidone-iodineinexpensiveextremely broad-spectrumirritating to eye in undiluted (10%) solution; dilute to 5%irrigate fornices with solutionpaint, do not scrub, eyelashes when prepping

Pre-operative Eyedrops4History of small incisions1977: Scleral tunnel1990: Sclerocorneal1991: Clear corneal1991-present: Variations in clear corneal5Conjunctival peritomyDissection through Tenons fasciaCauteryScleral groove 1-2 mm posterior to the limbusScleral tunnelKeratome to enter the AC

6Advantages:Wound can be safely enlarged for conversion to ECCEConjunctiva covers the woundPotentially less endothelial damageAstigmatically neutral

7Disdvantages:Surgical exposureSunken eyeballProminent browPotential damage to ciliary bodyIris prolapseFiltering blebs and scarring make it difficult8Keratome to tunnel and enter the eye .

Clear cornea

9Advantages:Can use topical anesthesiaFasterBetter surgical exposureFiltering blebs and scarring irrelevantNo subconjunctival hemorrhages

10Disadvantages:Pre-existing corneal problems a relative contraindication:FuchsPrevious PKPossible higher rate of endophthalmitis in unsutured casesBallooning of conjunctiva if incision too posteriorConversion to ECCE more problematic

11AstigmatismPre-existing ocular disease:PterygiaFiltering blebsTubesEndothelial disease

Wound location

12Tunnel lengthGoal to be self-sealingSquare incisionDepends on widthGenerally want at least 2.0-2.5 mm longSharp entry through Descemets membraneWound architecture13External incisionToo anterior or too posteriorInternal incisionToo anterior or too posteriorTunnelToo long or too shortIncision widthToo narrow or too wideProblems with the wound14

15Wound Final ThoughtsThe 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 same16CapsulorrhexisContinuous 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.17TechniqueCompletely 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.18TechniqueGrasp 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.19Hydrodissection & Hydrodelineation

Goals

Nucleus rotationEpinucleus rotationLoosen cortex

20Used to separate lens nucleus from surrounding cortex and capsule

Creates a freely mobile nucleusFacilitates nucleus rotation during phacoemulsification

Hydrodissection21Used to separate epinucleus from harder nuclear material

Creates an epinuclear bowl that protects lens capsule during phacoemulsification

Hydrodelineation22Hydrodissection cannula25- to 30- gauge

Flattened tip with angled or curved shaftFacilitates placement under anterior capsuleJ-shaped cannula may be used for sub-incisional area

Background

Technique 23Complete several fluid waves to ensure adhesions to capsule broken

Proceed to hydrodelineationInject fluid into edge of nucleusGolden ring sign indicates epinuclear separation

Confirm that nucleus rotates

24Lens nucleus occludes capsulorhexis Trapped BSS expands posterior capsule, AC shallowsPosterior capsule may rupture

Intraoperative Capsular Block Syndrome25PHACODYNAMICS

26Two Basic ElementsUS Emulsify the CataractFluid circuit cooling and remove the Emulsified Cataract

27Three Main Machine Functions USFlowIrrigation

28FluidicsIrrigationFlowVacuum29FluidicsFlow peristaltic vacuum only at occlusionVacuum venture continuous vacumBOTH millennium Flow control mode Vacuum control modeType of Pumps30IrrigationAmount of fluid that enters the eye Depend on:Bottle heightpressure on the eye

flow from the eyeTip diameterWound leak

31Flow 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 rateSurge Vacum riseSafety

32VacuumHolding power With occlusion No flow but pump will continue negative pressure at aspiration line vacum Stop pump at maximum preset vacum33Good Fluidics Irrigation Wound Leak

Aspiration (flow) Vacum34

35Surge Sudden of A/C pressure collapseDynamic of vacum by surgeon by deocclusionBottle height Machine complianceVacum and flow rateTip diameter resistance 36FlowFlow depends on pump speednot on bottle height37US Power mode of delivery38

39USSafest phaco is with appropriate power not with the lower power

40Mechanism of ActionJackhammer direct contactCavitation with cavitational bubblesSonic wave41Mode = US DeliveryContinuous Pulse Burst

42PulseFixed interval but linear power Fixed duty cycle43

44Burst ModeFixed power of linear intervalVariable duty cycle

45

46

47RepulsionChatter flaying of peace away from the PHACO tipMode - by Pulse , Burst and WS

48