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Overview of Phaco

Overview of Phaco. Dr. Anil Kulkarni, M.S. Miraj. Phacodynamics. Common Terms USG power Irrigation Aspiration/ Flow Vacuum. ACOUSTIC VIBRATOR. Two Types Magneto-restrictive-

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Overview of Phaco

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  1. Overview of Phaco Dr. Anil Kulkarni, M.S. Miraj

  2. Phacodynamics Common Terms • USG power • Irrigation • Aspiration/ Flow • Vacuum

  3. ACOUSTIC VIBRATOR Two Types • Magneto-restrictive- • Piezoelectric – electrical energy is used to reorient piezoelectric crystal which in turn is translated in to linear movement.

  4. ULTRASONIC POWER Vibration of tip – Energy release • Jackhammer effect • Cavitation : when tip retreats fluid cannot follow, void created produce tiny bubbles Bubbles implode amongst themselves creating shock waves. • Heat (By product)

  5. ULTRASONIC POWER Phaco Power : Power depends on – Amplitude (stroke length) of phaco tip • Continuous Power • Pulse Power • Burst Power

  6. ULTRASONIC POWER • Linear – On pressing the foot pedal there is gradual rise of parameters from “O” to preset values with a linear relation to foot pedal control. • Panel – On pressing foot pedal, the parameters reach to the preset panel values.

  7. ULTRASONIC POWER • Constant Mode – • Power is delivered continuously. • It can be linear or panel controlled. • Pulse mode – • Phaco power is delivered at preset intervals. • It can be varied. • It gives relative intervals, where there is absence of tip movement.

  8. ULTRASONIC POWER • Effective Phaco time – • It is the total phaco time at 100% phaco power. • It can be less than total foot pedal time. • Less EPT indicates less energy delivered to the eye.

  9. Irrigation • Gravity driven • IOP > 10 mm Hg • wound leak reduces pressure spikes • Bottle height 30-75 cm • double irrigation for high vacuum

  10. ASPIRATION SYSTEM • Aspiration – Evacuation of fluid through a closed system. • Flow Rate – Quantity of fluid pulled from the eye per minute through the instrument tip • Measured in CC/Min.

  11. PERISTALTIC PUMP • Principle – A pressure differential is created by compression of the aspiration tubing in a rotating motion. • Aspiration tube passes over the knobs. • When the drum rotates aspiration tube is successively compressed by the knobs over the drum to produce vacuum in the tubing.

  12. VENTURI PUMP • This uses compressed gas to create inverse pressure. • Vacuum generated is related to gas flow which is regulated by a valve. • The vacuum build up is almost instantaneous on pressing the foot pedal.

  13. Surge • Sudden increase in outflow uncompensated = A/C collapse • High IOP and negative pressure in aspiration tubing

  14. Surge Prevention • Decrease vacuum • decrease flow rate • non compliant tubes • tighter wound • raise bottle height • microprocessor • venting

  15. Venting • Safety mechanism to limit the vacuum to predetermined maximum level • bleeding air or fluid in aspiration line. • Balance IOP and negative pressure in aspiration line

  16. Rise time

  17. SUPERIOR INCISION • BETWEEN 11 & 1 O’CLOCK • Advantages : a. Maximum protection against infection b. Easy for beginners • Disadvantages : a. Difficult to construct & work in deep seated eyes b. Poor visibility - corneal folds c. Less Red Glow d. Difficult in cases of filtering surgery e. Maximum ATR

  18. TEMPORAL INCISION • BETWEEN 8 & 10 O’ Clock. • Advantages : a. Easy to make/manipulate in deep seated eyes b. Good tissue visibility c. Maximum red glow d. All types of cases e. Less foreign body sensation • Disadvantages : a. More chances of infection b. Sitting position difficult.

  19. CLEAR CORNEAL INCISION • SIMPLE & FAST • Diamond Blades • Single plane incision - single blade (No groove/No cautery/ No scleral tunnel) • Easy for topical anesthesia • DISADVANTAGES : a. More chances of Infection b. More endothelial damage c. Increased astigmatism (if >5 mm)

  20. ASTIGMATIC CONSIDERATIONS • Incision funnel : Bonded by two curved lines. Incisions made with in the funnel : • Curvilinear incision - Maximum ATR • Straight line incision - Less ATR • Frown /Cheveron incision - Least ATR • SITE OF INCISION • Superior incision - More ATR • Supero-temporal Incision - Moderate ATR • Temporal Incision - Least ATR

  21. Methods To Enlarge Pupil • Sphincter sparing 1. Synechiolysis – Old uveitis, Prior surgery, prolonged miotics 2. Membranectomy 3. Visco elastic – Cohesive eg. Na,Hyaluronate

  22. Methods To Enlarge Pupil B) Involving the sphincter • Pupil Stretching : By two instruments : By Prongs

  23. Methods To Enlarge Pupil • Mini sphincterotomies • Grieshaber Iris hooks • Pupil ring expanders • Iridotomy

  24. Gradual Enlargement of the Pupil is preferred over rapid, sudden tugging. • Stretching always performed under visco elastic • Intra cameral Lidocaine may be necessary • Aim for adequate pupil (Not very large)

  25. Large sphincter tears Atonic pupil, photophobia Deformed pupil / Aesthetic change Iris haematoma Iris damage – Mechanical, -- Thermal Cost involvement Post operative inflammation Undesirable effects

  26. Capsulorhexis • Posterior Zonular Fibres are inserted 1 to 1.5 mm. and Anterior Zonular Fibres about 2 mm. From Equator. • Central 6 mm. is Zonule free area of the anterior Capsule. • Krag by computer simulation showed that C.C.C. diameter needs only to be 1/2 to 2/3 diameter of IOL Optic diameter.

  27. Anterior chamber maintained : Visco elastic : Air : A/C maintainer. • Bent needle of 26 No. • Or Forceps can be used. • Shearing • Ripping • While tearing, always catch the cutting edge.

  28. CCC Advantages • In the Bag Phaco emulsification is possible. • Centering of IOL is possible. • In case of PCR, IOL can be implanted over the capsular rim. • Chances of posterior synechiae are reduced.

  29. Complications • Shrinkage of anterior capsular opening. • Capsular bag hyperdistension. • Epithelial cell hyperproliferation on the posterior capsule.

  30. Through side port : No escape of fluid & hence post capsular rupture (Always use main incision) Large Volume Fluid Trapped [ to avoid – ½ ml. at a time, at 2-3 places, after lifting the anterior capsule] Hydrodissection

  31. Nucleus Management • Soft cataract/ posterior subcapsular cataract • SPRING Technique • Hard Cataract : Cracking operations. 1. Divide & Conquer 2. Stop & Chop 3. Quick Chop.

  32. SPRING TECHNIQUE • Sequential Pulsed Removal of Inner Nuclear Girdle. • Central Sculpting - Broad & Deep • Relaxing Nucleotomies 7.30, 4.30, Center. • Aspiration of the collapsed wings. • Spring with crack hybrid technique.

  33. SPRING

  34. DIVIDE & CONQUER • 4 Basic steps : 1. Sculpting to a very thin posterior nuclear Plate. 2. Fracturing nuclear rim and posterior plate. 3. Fracturing again to break wedge shaped Section. 4. Rotating the nucleus, further fracturing followed by emulsification.

  35. TRENCH, DIVIDE & CONQUER • Trench should be small, central & vertical to leave enough firm nucleus for applying force of two instruments. • More nuclear density - fuller length of trenching. • Crack starts at the posterior pole and then extends to 6 & 12 o’clock. • Hemisections are then further divided.

  36. CRATER, DIVIDE & CONQUER • Deep Central Sculpting to produce large crater leaving dense peripheral rim, for fracturing. • Harder the nucleus – smaller the wedge shaped sections. • All sections are left in the bag: To keep it distended ; To keep ultrasonic turbulence in bag.

  37. Nagahara Chop • Advantage : Least phaco time. • Disadvantage: Pieces rejoin and prevent their removal Threat to the integrity of anterior capsule by chopper

  38. Stop & chop Koch’s modification : • Trench sculpted & nucleus is halved, • then stop and start chop.

  39. PHACO QUICK CHOP (PFIFER) • Main difference is placement of chopper. • It is placed on top of the buried phaco tip near centre of lens- away from anterior capsular rim.

  40. PHACO QUICK CHOP (PFIFER) • near vertical chopping. • Chopper pushed down, phaco tip moves up and then both are laterally separated. • Prepare all fragments before emulsifying to enable endo capsular phaco. • 2mm exposure of phaco tip.

  41. Coaxial MICS • Use of micro tip • Nano sleeves • Incision 2 – 2.2 mm • No change in surgeon’s technique • IOLs available for insertion • High vacuum and phaco aspiration possible

  42. P.C. Rent (INTRA-OP FACTORS) • Peripheral escape of rhexis • forceful hydrodissection • high vacuum and high power settings • one handed technique-chasing the fragments • sculpting too deep / too peripheral

  43. POSTERIOR CAPSULAR RENTsigns • Sudden deepening of the AC. • New found difficulty in emulsifying the nucleus… • mydriasis / pupil distortion • Visible vitreous in AC!!.. STOP!! EVALUATE…PLAN..!!

  44. RENT CONTROL ACTS..!!!The 10 commandments.. • FREEZE movements,reduce bottle height • inject visco from side port • stop irrigation • press reflux • withdraw phaco tip from AC Assess damage-site , extent of rent.

  45. Rent control acts..!! Contd.. 6. Mechanized bimanual vitrectomy 7. Removal of residual nuclear fragments 8. Dry cortex aspiration 9. Re-assess capsular support and insert IOL …PC / AC 10.Secure wound closure Post op care-antibiotics, steroids, NSAIDs

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