Saturday, October 01, 2005

Chapter 3 - Phacoemulsification Step-by-Step

Please read the following textbook for additional information- Koch, Paul S., Simplifying phacoemulsification safe and efficient methods for cataract surgery (5th ed), Thorofare, NJ Slack, 1997.


Phacoemuslifcation Step-by-Step

Indications: Most common method of cataract removal.

Contraindications: few, maybe: almost no zonular support or extremely hard lens.


Pre-op: orbital massage can be used to compress vitreous – use Honan balloon or super pinky to decrease intraocular pressure.

Anesthesia:

  • Topical /- intracameral non preserved lidocaine

  • Retrobulbar and lid block

  • Subtenon's block

  • Rarely general anesthesia, e.g.: claustrophobia, dementia, tremor


Complications of Anesthesia:



  • Retro-bulbar hemorrhage: If this occurs, then delay case and consider cantholysis.

  • Inject/perforate eye ball with needle during a retrobulbar block: If this occurs, then delay case and cryo/laser area, and pray. Call risk management.

  • Subconjunctival Hemorrhage: This is not serious, and forget about it.


STEPS



  1. Rarely superior bridle suture used (infraducts eye to allow superior exposure).


    • Potential complications: a) driving needle into vitreous – if this occurs then delay case and cryo/laser area.


  2. Paracentesis with #75 blade, or some other sharp knife, mark #75 with ink. Fixation with 0.12 forceps or with fixation ring helps to stabilize the eye.


    • Potential complications:

    • a) put in wrong place – if this occurs, then make another paracentesis;

    • b) too small – if this occurs, then make another wound;

    • c) too big – if this occurs, then suture later;

    • d) nick lens capsule – if this occurs, include nick during capsulorhexis;

    • e) nick iris – this is not serious and forget about it.


  3. If topical case, then instill lidocaine (1% non-preserved in TB syringe with Troutman 27 or 30 g). There is some debate about utility of instilling lidocaine in the anterior chamber.


    • Potential complications:

    • a) stings – this is normal and reassure the patient;

    • b) put in wrong medicine – if this occurs, then wash out anterior chamber and pray;

    • c) Cornea epithelial toxicity from anesthetic – I recommend coating the cornea with dispersive OVD [view video].


  4. Place ophthalmic viscoelastic device (OVD) into anterior chamber. One method is the Arshinoff shell technique: 1st dispersive (e.g. Viscoat), then cohesive (e.g. Healon). The Arshinoff shell technique provides two advantages: dispersive OVD coats corneal endothelium and protect from ultrasound energy and cohesive OVD maintains chamber during the first part of procedure. Alternatively, use just one type of OVD. Healon is the cheapest at the VA hospital.


    • Potential complications:

    • a) shoot loose cannula into anterior chamber – if this happens, then tighten it better next time;

    • b) Air bubbles – if this happens, then suck out the air with syringe or place OVD distal and force out.


  5. Wound -- Comes in three main types: limbal, scleral, and corneal.


    • Advantages of a limbal wound: Easy to convert to ECCE, Instruments don't distort cornea, and Great for greenhorns.

    • Disadvantages of a limbal wound: Induces astigmatism, Always requires suture, iris prolapse more common, Requires conjunctival manipulation & cautery, eye is red after surgery.

    • Advtanges of a scleral wound: Rarely induces astigmatism and seals nicely.

    • Disadvantages of a scleral wound: Hard to convert to ECCE, Technically difficult, Iris prolapse more common, Requires conjunctival manipulation & cautery, Instruments distort cornea, and Eye is red after surgery.

    • Advantages of a corneal wound: Rare astigmatism, No cautery or conjunctival manipulation, and Eye is white after surgery.

    • Disadvantages of a corneal wound: Hard to convert to ECCE, Technically difficult, Instruments distort cornea, and Possible increased risk of endophthalmitis. [VIEW VIDEO OF PERITOMY TO PREVENT CONJUNCTIVAL DONUT DUE TO TRAPPED FLUID]

    • Style

      Advantages

      Disadvantages

      Limbal

      Easy to convert to ECCE
      Instruments don't distort cornea
      Great for greenhorns

      Induces astigmatism
      Always requires suture
      iris prolapse more common
      conjunctival manipulation & cautery
      Eye is red after surgery

      Scleral

      Rarely induces astigmatism
      Seals nicely

      Hard to convert to ECCE
      Technically difficult
      Iris prolapse more common
      conjunctival manipulation & cautery
      Instruments distort cornea
      Eye is red after surgery

      Cornea

      Rare astigmatism
      No cautery or conjunctival manipulation
      Eye is white after surgery

      Hard to convert to ECCE
      Technically difficult
      Instruments distort cornea
      possible increased risk of endophthalmitis




  6. Capsulorhexis – most important step of this surgery. Anterior chamber must be filled with viscoelastic. There are two basic techniques: continuous curvilinear capsulorhexis (CCC) and can opener.


    • Advantages of the CCC: Less risk of vitreous loss, IOL is very stable, and Less risk of PCO.

    • Disadvantages of the CCC: Hard to do, May need capsular stain with poor red reflex, and Needs relaxing incisions for ECCE.

    • Advantages of Can Opener Technique: Easy to do, Red reflex not required, and Allows ECCE nucleus expression.

    • Disadvantages of Can Opener Technique: Increased risk of vitreous loss, IOL is less stable, and Increased risk of PCO. We will discuss the CCC because this is the preferred surgical technique. The goal of CCC is to produce a central circular opening slightly small than the optic diameter.

    • There are three basic techniques for CCC (only way to learn about this is to watch videos):

      • a) Cystitome - initial cut and control of tear with cystitome (best with cohesive OVD) [view video];

      • b) Combo - initial cut with cystitome, most of tear with forceps (most common technique) [view video];

      • c) Forceps - use sharp forceps to cut and then grab capsule to complete tear.



    • Potential complications:

      • a) Poor red reflex – if this occurs then, stain the lens capsule with Trypan Blue or ICG;

      • b) Tear starting to go radial – if this occurs then, add OVD;

      • c) Radial tear - Use scissors to restart in other direction, Relaxing tear 180 across, Can opener and conversion to ECCE, or Debulk lens by sculpting out bowl prior to hydrodissection;

      • d) if too small, then enlarge after placing IOL;

      • e) if too big, then forget about it because this is not a serious issue;

      • f) zonular laxity – if there is evidence of zonular laxity during the case, then consider placing iris hooks to stabilize the capsular bag.




  7. Hydrodissection - This is the second most important step of the procedure. Skip this step with posterior polar cataract, perforating lens trauma or early post vitrectomy cataract. Use balanced salt solution in 3 cc syringe with troutman 27 gauge or similar. Inject fluid just under capsule to cleave cortex from capsule. Look for a fluid wave. Don't stop till you get enough. Don't stop till you get enough! Rotate lens to ensure the job is done because if the lens does not rotate then you will not be able to perform the cataract extraction. May prolapse lens with a large capsulorhexis, which can be a good thing if you want to phacoemulsify the lens in the anterior chamber.


    • Potential complications:

    • a) No fluid waive – if this occurs, then try again in different spot, increase force, or use bursts and gently push on nucleus between bursts;

    • b) Iris Prolapse - Remove dispersive OVD. If using a clear cornea wound, then use sub-incisional iris hook [view video ];

    • c) Prolapse nucleus – if this occurs then, Brown technique or Pop n Chop, flip into ciliary sulcus, or push back into bag;

    • d) Blowout post capsule – too late, but was this because of s/p vitrectomy, trauma or posterior polar cataract? If this occurs and the lens drops, then clean up the vitreous in anterior chamber, place IOL, and call your retina surgeon.


  8. Phacoemulsification (phaco): The goal is to remove lens with the minimum ultrasound to reduce damage to the cornea. Trend is to use increasing vacuum and decreasing ultrasound power to remove nucleus. Phacoemulsification of the nucleus can be done by several techniques:


    1. There are numerous ways to disassemble a lens nucleus:

  9. Cortical Aspiration - Aspiration is used to grab and peel the cortex off not suck it up. Dangerous procedure and is the most common time for vitreous loss in experienced surgeon. Sub-incisional removal is the most difficult, especially with a small rhexis. Adequate hydrodissection makes this step easier.
    [view table of possible complications during cortical aspiration ].

  10. Fill Bag with OVD - Form the lens bag not the sulcus. Use cohesive OVD in the bag. Consider dispersive OVD adjacent to wound to seal – Arshinoff Shell -- this method uses two OVDs sold in a rather expensive kit. Place OVD ahead of the cannula -- don't pierce the post capsule with cannula.

  11. Wound may need to be extended to allow placement of the lens - PMMA IOL (doesn't fold) needs a wound that is slightly more than optic size. Many injected IOL's don't need extension from incision for phaco needle. Well constructed wound that is a bit bigger seals better than a stretched small wound.

  12. Lens is placed into capsular bag [ view video ]:

    1. A) PMMA IOL - Grasp IOL and trailing haptic with forceps (e.g. Kelman-McPherson), place leading haptic into bag; optic into AC; release forceps, place trailing haptic into bag with hook or forceps.

    2. B) Folded IOL - Folded and placed in special forceps. Incision size grows a bit with increased power of IOL – 3.5 mm range. Moustache style fold: wider incision but haptics flow into bag. Axial style fold: smaller incision but haptics need guidance.




    3. [click here for larger image]

    4. C) Injected IOL - Many different systems available. For instance, the single piece acrylic (Alcon SA 60) and plate IOL is most simple [view video]. Three piece IOL requires some haptic care and manipulation. Be careful of Descemet's membrane with IOL insertion (especially with injectors).





    [click here for larger image]

  13. Is the IOL right side up? - Correct side up looks like 7-O-L-even.



    [click here for larger image]

    IOL is designed for right handed surgeon to easily rotate it.






    When the IOL is upside down, the IOL looks like an S so Stop.







    • Upside down angulated 3 piece IOL creates myopic shift with anterior IOL shift



    • [click here for larger image]

    • Make sure that both Haptics are in the Bag


      • May need to add OVD - often some is lost during insertion of IOL

      • Most common cause of decentration: one haptic in bag; one in sulcus

      • Bag has less space than sulcus - ½ in IOL shifts toward sulcus haptic




        [click here for larger image]

    • Rotate IOL so that Haptics are 90 degrees from the wound

      • Set yourself up for the next step, which is irrigation and aspiration (I/A)

      • Allows I/A tip to get under IOL to remove OVD under IOL

      • Frees most common site of residual cortical material from haptic


    • Special IOL Placement Conditions


      • Anterior Capsular Tear


        • Single piece acrylic in the bag - creates little tension on the bag

        • 3 piece with both haptics in the sulcus


      • Zonular Dialysis


        • Capsular Tension Ring with any IOL

        • 3 piece IOL with PMMA haptic oriented toward weak area of zonules


      • Posterior Capsular Tear


        • Dispersive OVD in the post capsular hole -- gently place IOL into bag

        • Place 3 piece in sulcus /- capture of optic by centered anterior CCC [view video]


      • No Capsular Support


        • AC IOL: there are 3 sizes depending on white to white size

        • Iris Sutured PC IOL

        • Scleral Sutured PC IOL

    • Iris Clip IOL (Artisan™ - not approved by FDA for aphakia yet)

Potential Complications

What to do about it

Place IOL up-side down

Can leave as is - accept myopic shift, or
Take one haptic out of wound with Sinsky hook
Fill with OVD above and below IOL
One hook above and one below -- Flip IOL

Inadvertent sulcus placement

Fill with OVD -- Rotate into bag with hook
If a 3 piece can leave in sulcus with myopic shift
Do not leave single piece acrylic (Alcon SA60) in sulcus

IOL doesn't center

Usually one haptic in sulcus one in bag
dial both into bag or both into sulcus
Possible zonular dialysis
if nearly centered leave it alone
rotate IOL carefully for best centration
with 3 piece often haptics best at weak area
check wound for vitreous
consider placement of CTR
place miochol to help check for vitreous
Haptic damage (especially with 3 piece IOL)
may have to replace IOL

Tear in Descemet's

Use care to not extend tear
Place Air Bubble at end of case – post op
position wound up -- bubble seals Descemets

Marred IOL

If not central forget about it
If central replace IOL

Lens Material behind IOL

Rotate haptic 90 deg from wound
Toe down with I/A and get under IOL
With aspiration tip showing at all times aspirate



14. Sutures are preplaced

  • Pre-place sutures while OVD maintains chamber

  • Usually need 2 interrupted or one X suture with 6 mm scleral tunnel

  • Usually need 1 interrupted suture with 3 mm limbal wound

  • Usually need no sutures with proper 3 mm wound of cornea or sclera



15. OVD is removed with I/A device

  • As always keep tip opening up

  • Go under IOL to remove OVD, especially if you have been having IOP problems post op


Potential Complications

What to do about it

Chamber Instability

Increase bottle height

Check Tubing and fluid level

Wound too big? -- suture end of the wound

Decrease vacuum

Catch Iris [view video]

Reflux fluid Continue and maintain your bearings

Grab capsule and tear zonules

Capsular tension ring Place dispersive OVD in weak area


16. Sutures are tied

  • /1/1 for 10-O nylon in the sclera

  • 2/1/1 for 10-O in clear cornea to allow small knot to rotate and bury


17. Other


  • Give antibiotic ointment or drops, we rarely give subconjuntival antibiotics

  • Consider postoperative povidine iodine

  • Patch to protect cornea if retrobulbar or topically, if subtenons anesthesia was used


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