converting to ECCE

Conversion to ECCE often comes at a difficult time. The lens is about to fall south, the vitreous has prolapsed and the surgeon is stressed. 

Understanding the steps and process of conversion to ECCE is essential and study before the crisis will help soothe the stress when this inevitable process occurs. We will cover several areas: identifying patients at risk for the need for conversion to ECCE, indications for conversion, conversion from topical to sub-tenon’s, wound preparation, expressing the lens material, closure of the wound, placement of the IOL, post operative issues and a brief section on anterior vitrectomy. For more detailed instructions please refer to: http://webeye.ophth.uiowa.edu/eyeforum/tutorials/Cataract-ECCE/Cataract-Surgery-Complex-Conversion-Extracaps-ECCE.htm

One of the most important parts of the pre-operative process for cataract patients is to assess the difficulty factors that may lead to conversion to ECCE or otherwise complicate the procedure. You may want to add operative time to your schedule or ask for additional equipment. You may want to change to a superior limbal wound which facilitates conversion to an ECCE rather than a temporal clear corneal incision. You may want to do a retrobulbar block rather than topical anesthesia as the case may last longer or is more likely to become complicated. Or you may want someone more experienced to do the case. for more detail on dkifficulty factors please see: http://www.medrounds.org/cataract-surgery-greenhorns/2005/09/chapter-1-assessment-difficulty.html

Conversion to ECCE is indicated when phacoemulsification is failing. Sometimes this is due to a very hard lens which does not submit to ultrasound or a lens that is hard enough that the surgeon is concerned that the required ultrasound energy will harm a tentative cornea, e.g. Fuchs’ endothelial dystrophy or posterior polymorphous dystrophy (PPMD). Sometimes one will convert to ECCE when an errant capsulorhexis goes radial especially with a hard crystalline lens when the surgeon is concerned that the risk of dropping the lens is too great with continued phacoemulsification. Rarely now with Trypan Blue dye, a surgeon will choose to convert to ECCE when the anterior capsule is hard to see and capsulorhexis must be completed with the can opener technique. More often the conversion is indicated when the crystalline lens is loose from weak zonules or a posterior capsule tear which make phacoemulsification less safe than extending the wound and removing the residual lens material. Indications for conversion to ECCE include: Hard crystalline lens or unstable endothelium, Radial tear in anterior capsule with hard lens, Poor visualization despite Trypan dye,

Posterior capsular tear, and Zonular dialysis.

Converting to subtenon’s anesthesia. Often we convert cases from topical clear corneal to ECCE. While the ECCE can be done under topical it is usually more comfortable and safer to give additional anesthetic which is typically a sub tenon’s injection of bupivicaine and lidocaine. This will provide some akinesia and additional anesthesia. There is usually subconjunctival hemorrhage and if the injection is made too anterior it can cause chemoisis and ballooning of the conjunctiva. The steps of the sub tenon’s injection are shown in the video below(1):

A major decision step when converting to ECCE is to either extend the existing wound or close and make another. The ECCE will require a large incision of from 9-12 mm which is closed with suture. The decision to extend the existing wound or make a new wound hinges on several factors: location of the original wound, size of the brow, past surgical history, and possible need for future surgery.

Making a new incision during conversion is identical to that for a planned ECCE. The original incision is closed with a 10-O nylon suture. The surgeon and microscope are rotated as the surgeon should sit superior. The steps to make a new superior incision are:

• Conjunctival peritomy of about 170 degrees
• Use 64 or crescent blade to make limbal groove with a chord length of 11mm
• Bipolar cautery for hemostasis
• Use keratome to make initial incision starting in groove into AC
• Extend initial incision to full length of groove (with scissors or knife)
• Safety sutures are preplaced usually 7-O vicryl

Extending an existing incision can be tricky and the technique is different for scleral tunnels compared to clear corneal incisions. However in both cases the original extension is brought to the limbus. In the case of an original scleral incision the incision is brought anterior to join the limbus on either end before extending along the limbus for a chordlength of about 11mm. In the case of an existing corneal incision the corneal incision is brought posterior toward the limbus before extending the wound along the limbus for a chord length of about 11mm. When iris hooks are being used in a diamond configuration the wound can be extended to preserve the sub-incisional hook and the large pupil(2). The steps include:

• Conjunctival peritomy of about 170 degrees,
• Use 64 or crescent blade on either side of the existing wound to make a limbal groove with a chord length of 11mm
• Bipolar cautery for hemostasis
• Use Crescent to bring existing scleral wound anterior or existing corneal wound posterior to join limbus
• Extend initial incision to full length of groove (with scissors or knife)
• Safety sutures are preplaced usually 7-O vicryl.

One has to be far more careful when removing the nucleus during the typical conversion to ECCE which comes along with vitreous loss. First the anterior capsule must be large enough to allow the nucleus to express which may require relaxing incisions in some cases. When the zonules are weak or the posterior capsule is torn the lens cannot be expressed with fluid or external pressure as is often done with a planned ECCE with intact capsule/zonlules. After any vitreous is removed, the lens must be carefully looped out of the anterior chamber with minimal pressure on the globe. If the posterior capsule and zonlues are in tact than the lens can be expressed as described with a planned ECCE.

Placement of the IOL IOL selection with ECCE conversion depends on the residual capsular complex(3,4). The key to IOL centration is to get both of the haptics in the same place: either both in the bag or both in the sulcus.

When the posterior capsule is intact following a conversion to ECCE the anterior capsular opening is usually poorly defined which can make bag placement difficult. If the anterior capsule and thus the bag is well defined, then place a single piece acrylic IOL without folding it directly and gently into the bag using kelman forceps.

When the posterior capsule is intact and the anterior capsule is poorly defined then place a 3 piece IOL in the sulcus such as a large silicone IOL or the MA50 acrylic by placing these directly and unfolded into the sulcus with kelman forceps. Make sure that both haptics are in the sulcus.

When the posterior capsule is damaged, if enough anterior capsule and posterior capsule is left to support the IOL, define the sulcus with viscoat and place the IOL directly in the sulcus. Make sure both haptics are in the sulcus. If the IOL does not seem stable then place McCannel sutures to secure the IOL to the iris or remove and replace with an AC IOL (don’t forget to place a PI with vitrector).

When the capsule is severly damaged and cannot support an IOL then place the IOL in the anterior chamber. Use kelman forceps to place the IOL, then secure the chamber, and use a sinsky hook to place the AC IOL into its final position. (don’t forget to place a PI with vitrector).

Postoperative care for patients following conversion from phaco to ECCE is a bit more complicated and focuses on preventing cyctoid macular edema and limiting induced astigmatism. Often the care is very similar to that of a planned ECCE with about 3 post operative visits one the same day or next, one a week later, and one about 5-6 weeks later. Depending on the amount of astigmatism the patient may require several visits to sequentially remove sutures to eliminate induced astigmatism.

References

1. Oetting, TA, Cataract Surgery for Greenhorns, Available at http://medrounds.org/cataract-surgery-greenhorns.%20accessed%20September%209, 2007

2. Dupps WJ Oetting TA, Diamond iris retractor configuration for small-pupil extracapsular or intracapsular cataract surgery. J Cataract Refract Surg Vol 30(12):2473-2475

3. Chang DF, Oetting TA, Kim T, Curbside Consultations in Anterior Segment Surgery, Slack Inc, Thorofare NJ, 2007

4. Henderson BA, Essentials of Cataract Surgery, Slack Inc, Thorofare NJ, 2007

Using the eye simulator

Cataract surgery is difficult to learn, often both for the surgeon and patient. The holy grail for educators in this area has been a simulator that would allow practice without placing patients or attending coronary arteries at risk. The first versions of simulators are rolling off the lines now and we were fortunate that the VAMC in Iowa City purchased one of the EyeSi devices from VR Magic for our residents. Here we will describe how this fits into our curriculum and show a few videos that demonstrate its capabilities.

The first step for, I suppose any educational project is to establish stages of development and objectives for each stage. Much like the boy scouts have cub scouts, boy scouts, eagle...; we developed stages for our program using Dreyfus stages of novice, beginner, advanced beginner, proficient, and expert. We assumed that almost no resident will make expert in only 3 short years and that almost all will make the proficient stage. The objectives for each stage are measurable and we established resources to allow stage progression http://webeye.ophth.uiowa.edu/eyeforum/pdf/580oett.pdf .

Our objectives for the beginner (typically a first year at iowa) include the use of the wet lab and the simulator with a focus on developing a facilty with instruments within the eye. Our residents begin to do the easier parts of cases which we call "backing in" where residents do the last steps of a perfect case started by a senior resident. The might just fold the lens the first week, then fold and inset the lens, then fold and insert and also remove the OVD.. The simulator in this phase requires a set of tasks simulating the use of instruments within the eye, the capsulorhexis, and some basic steps of phacoemulsification.

Our objectives for the advanced beginner (typically a second year at iowa) is to use the simulator for more advanced practice and to begin to do whole cases. Our goal during this year is for the resident to be able to do whole cases in less than 45 minutes but do not expect them to be able to use both hands and the attending will typically control the paracentesis instrument.

The objectives for the proficient stage (third year at iowa) are more difficult and involve increasingly efficient and complex surgical tasks. The simulator has been less imortant so far for us in this regard however it does at times prompt discussion. The video below shows a simulator case where the lens fell due to zonular stress which prompts a discussion on what to do next and what are the risk factors for droppin the nucleus.

While we are thinking about it what are the risks for dropping the nucleus? Zonular issues such as pseudoexfoliation, RP, h/o uveitis, h/o trauma, and marfans are certainly important. Other risky situations where you must be very careful with hydrodissection include radial tear, posterior polar cataract, penetrating lens trauma, and early cataract after vitrectomy. This reminds me of the following video:

operating microscope basics

It is very important to learn how to operate the microscope before your first day in the OR.

Basics of the Microscope pedal.  While there are some subtle variations among models and manufacturers the basics of the microscope footpedal and operation of the micropscope are similar.  The microscope has a starting XY position which is centered at the start of the case and then small variations in this initial position are made using the foot pedal which makes small XY adjustments of the microscope.  The scope also has a starting focal point (i suppose this is the Z position) which is set up at the start of the cases and small variations from this are made during the case using the foot pedal which moves the focal point of the scope up and down.  Often the intensity of the light can be also be controlled with the foot pedal.

All of your extremities will be busy:  one foot for the microscope pedal, one foot for phaco pedal, one hand for the phaco handpiece, and the other hand for the chopper.  Most surgeons use non dominant foot to control the microscope pedal.  unless you are a soccer player your left foot is probably not that coordinated.  as such you should practice using the pedal way before your first case.  most people take off their shoes so that they can feel the microscope pedal better.

Foot pedal switches.  The typical positions of the microscopes foot switch controls are shown below.  The foot pedal is designed so that the foot can sit on a rasied foot rest.  A rocker swith in front of the foot rest is most important and moves the scope up and down to make small changes in focus.    a rocker switch behind the foot rest controls the zoom or magnification.  the magnification is typically low during wound construction and is increased during steps such as capsulorhexis which require more magnification.  Several inches in front of the foot rest is the joy stick which controls the XY position of the scope.  both the XY position and the focus shuold be centered prior to the case (usually a switch on the scope) and manually put into optimal initial position to allow maximal excursion of these functions during the case.


When you arrive in the OR ask yourself: “where will I be sitting?   Are you operating from a superior approach -- Superior approach is preferred when you may have a large incision with lots of sutures (eg. ICCE, ECCE, tough phaco when you may convert) and/or when you may have iris trauma (tolerated better under the lid) and when you are doing a trabeculectomy and want the bleb under the lid. Typical phaco is from a temporal approach to avoid the brow. i usually do rights eyes a bit inferior and temporal (eg 8 oclock) and left eyes superior andtemporal (eg 2 oclock); however. some surgeons like Dr Tim Johnson are always true temporal whether operating on the right or left eye. 

  

Proper Sequence to adjust Equipment to your body

1.     Place retrobulbar block first (give it time to work while setting up scope)

2.     Put assistant’s eyepiece and camera on proper side of microscope

3.     Push center focus and center XY position buttons on microscope (may be same button)

4.     Adjust ocular inter-pupillary distance and zero both objectives

5.     Lower surgeons chair

6.     Raise bed height to just allow both feet under bed onto both pedals

a.     Dominant foot – phaco pedal

b.     Non dominant foot microscope footswitch

c.     Take off shoes (wear white Nike crew length socks)

7.     Manually move entire microscope (not footswitch) so that you are in focus

8.     Raise surgeon chair height enough to allow surgeon to see comfortably into oculars

9.     Prep and Drape

 

placing the capsular tension ring (CTR)

The capsular tension ring (CTR) is very useful.  Here I will discuss the use of the standard, unsutured CTR. 

Indications  The CTR is most commonly used when the zonules are weak in a limited area or together with a capsular tension segment (CTS) with more generalized zonular weakness.  The CTR can also be used to help prevent capsular phimosis or to allow suturing of the ring and capsule later in patients with progressive or more generalized zonular weakness.  Some surgeons have also suggested that the ring will help prevent posterior capsular opacification but I think that has not been proven.  

CTR variations  The CTR comes in many varieties that include standard rings in various sizes, CTR with one or two eyelets that allow one to suture them to the sclera (Cionni modification), and the Henderson CTR with waves that allow one to place the ring early and still remove cortical material (distributed by FCI in the US).  A close cousin of the CTR is the Ahmed capsular tension segment (CTS) which has a partial ring and an eyelet that can be used temporarly to hold the capsule with a hook or sutured permanently to the sclera.    The standard CTR comes in a variety of diameters -- in general i would suggest using the larger ring (eg 13 mm in the AMO/Ophtec ring).  

Injecting the CTR.    Several techniques that have been described to place the CTR.  The most simple and the technique that i use most often is to use an injector.  The injector is simply a cylinder which has a spring loaded hook that pulls the ring into the cylinder with a plunger to push it back out.   Here is a video showing how to load the CTR into the injector and inserting the CTR into the capsular bag filled with OVD. 



Here are is a video showing an example of a traumatic case using a CTR placed with an injector. 



Here is a video showing the use of an injected CTR in a patient with RP to help prevent phimosis.





Injecting the CTR does place some tension on the existing zonules and sometimes too much stress.  Here is a video showing a case where the placement of the CTR with the injector created too much stress on the zonules and actually made the situation worse. 



Little fish tail placement of the CTR. Angunawela and Little described a nice CTR insertion technique to use when the zonules are very weak.  In this fish tail technique the center of the ring is pushed through the wound and the eyelets remain outside the ring which looked to Little like a fish tail.  This insertion technique allows for much less tension on the zonules as the ring is inserted. The ring is bent a bit as it is placed through the 2.75mm wound, but it seems to snap back into position nicely.   Here is a video showing this technique.




Alternative fish tail #1.  Getting the central portion of the ring into the eye with the Little Fishtail technique is the trickiest part.  A variation of this technique is to use Duet micro forceps to place the central portion of the ring into the wound and the CTR into the capsular bag.  The remainder of the ring is then placed using forceps as described by Angunawela and Little.  This seems like a very nice way to place a ring to minimize the stress on the zonules during placement but it does seem to stress the central portion of the ring a bit.   Here is a video showing this technique.



Alternative Fishtail #2.  This fish tail modified technique uses a suture like a fish on a line to pull the injected eyelet back out of the eye to form the fish tail confguration. One of the issues with the little fish tail technique is getting the loop of the CTR into the eye without damaging the elasticity of the CTR.   In this modified technique you first insert the leading eyelet of the CTR into the anterior chamber with a suture through the eyelet and leave the trailing eyelet out of the eye.   You then use the suture and a hook to bring the leading eyelet back out of the eye keeping the loop in the anterior chamber which places the CTR into the familiar fish tail configuration.  Then use forceps to place the CTR as described by little.   Here is a video showing this technique.


References:
 

1. Price FW Jr, Mackool RJ, Miller KM, Koch P, Oetting TA, Johnson AT. Interim results of the United States investigational device study of the Ophtec capsular tension ring. Ophthalmology. 2005 Mar;112(3):460-5.
2. Angunawela RI, Little B. Fish-tail technique for capsular tension ring insertion. J Cataract Refract Surg. 2007 May;33(5):767-9.

Pearls for Small Pupils

I use three techniques to manage small pupils:  stretching, iris hooks, and the Malyugin ring.

Pupil stretching used to be one of the main ways that I would force mydriasis.  This is really a good technique if you have posterior synechiae or if the patient has been on Pilocarpine chronically.  However, more and more I am avoiding using pupil stretching techniques because it is contraindicated in patients that are on Flomax (or other alpha blockers) as it can lead to even more problems with iris prolapse.  Compounding this problem is the reality that so often patients cannot remember having been on Flomax (or their other medications).  Because my practice is concentrated at our VA Hospital here in Iowa City, I have a lot of patients who have been on either Flomax or junior varsity versions of this alpha blocker in the past (Hytrin, Cardura, saw palmetto…) and so if they have a small pupil I just assume that have had Flomax.  I also think pupil stretching should be avoided in patients with shallow chambers, as there is a tendency for iris prolapse in those patients as well.  

The technique that I use for pupil stretching is to use two Kuglen hooks -- one through the paracentesis and the other through the main wound.  The hook through the paracentesis grabs the pupil and pulls it towards the paracentesis and then the other hook pushes 180 degrees across from the paracentesis to stretch the pupil.  The stretch is held for a few seconds and it is not uncommon that you will notice some hemorrhage along the pupil.  This is a good thing as it shows that there has been some change in the pupillary sphincter.  Following stretching of the pupil, you need to use a dispersive viscoelastic which is highly viscous to help push the pupil open.  There is really only one highly cohesive dispersing viscoelastic for me -- Viscoat; although others, such as Healon D and Vitrax, may be available in your area.  I like to place the Viscoat in a circular pattern, around and around, to gently push the pupil out.  You often find that at first you didn’t think there was much effect from the pupil stretch, and then after adding the Viscoat in this fashion, you gain enough mydriasis to safely proceed with surgery.    

I will also caution you that during hydrodissection, the fluid wave can catch the dispersive viscoelastic, pulling the iris with it out of the eye, producing prolapse of the iris.  As such, I recommend that you remove the viscoelastic over the lens, before hydrodissection, either using the automated irrigation/aspiration unit or use a syringe with BSS to wash out some Viscoat.  This will reduce the likelihood of iris prolapse during hydrodissection.  However, you just need to be careful during hydrodissection to avoid iris prolapse. 

Iris hooks are a great technique for the small pupil and I use them often, although I don’t use them as often as I used to as I am transitioning some to the Malyugin ring, which I will discuss below.  Iris hooks are great for shallow chambers, they are great for complex cases where you might have to convert to a large incision extracapsular procedure or if you have to use complicated suturing of IOLs or Cionni rings during the case which would make an internal device such as a Malyugin ring more difficult.  I usually avoid iris hooks if there is a bleb present, because it is sometimes hard to work around the bleb and you have to be very careful not to damage the bleb.  They are also harder when there are narrow lid fissures because the hooks get in the way of the lids, and so I tend to avoid them in that situation.  

The way I like to use iris hooks, I described in a paper with Louis Omphroy.¹ In this technique, we use a diamond configuration of the hooks such that there is one hook under the main incision, one across, and then one hook 90 degrees to either side of the wound.  This creates, relative to the incision, a diamond configuration of the iris.  I like to use a 27 gauge needle, a Grieshaber knife, or a 75 blade to make the four paracenteses for the iris hooks.  You want to make these as posterior as possible and you want to make them short and angled slightly down, such that the hook, when it is placed in the eye, is aimed towards the iris.  I like to place the hooks before I add viscoelastic so that the chamber is not so deep that it makes it very difficult to grab a hold of the iris.  After placing the hooks, then I add viscoelastic and make the incision just anterior to one of the hooks.  I tend to use a Kelman McPherson and a straight tie to place the hooks as shown in the video below.

I like the Malyugin ring and use it most of the time now for small pupils.  The Malyugin ring comes in two sizes; one with an internal diameter of 6.2 mm and the other with an internal diameter of about 7 mm.  The Malyugin ring is great in patients that are on alpha blockers such as Flomax².  It is great in patients that have narrow lid fissures because it does not involve any external manipulation to the eye and so you don’t have to have proptosis or great exposure.  I would recommend avoiding the Malyugin ring if you think you are going to convert to an extracap as this is very difficult with the ring as opposed to being relatively easy when using iris hooks.  I would avoid the Malyugin ring when using other intraocular hardware such as Cionni rings or suturing inside the eye, as the Malyugin ring can get in the way (relative to iris hooks) when doing these complex procedures.   

The Malyugin ring is placed with a special inserter into the eye and the leading eyelet is engaged onto the iris and then one toes down a bit as the ring is pushed further in, trying to engage the lateral eyelets as well.  Very often, only one of the two lateral eyelets is also engaged in the initial insertion process.  The trailing eyelet often is very difficult to disengage from the inserter without introducing a hook through the paracentesis to push the ring slightly to the side to allow the inserter to exit the eye.  I tend to use a Kuglen hook to subsequently place the eyelets that were not initially engaged with the inserter; a Lester hook can also be used or Sinskey hook.  

Retraction of the Malyugin ring is probably the trickiest thing.  You want to first disengage the leading eyelet which is across from the wound and then you want to disengage the leading eyelet and T it up slightly to the side and anterior.  Use plenty of viscoelastic so that you don’t engage the IOL during this process and that so that the cornea is safe.  The inserter is then placed in the eye slightly to the side of the eyelet, but over the ring, and then is turned such that the hook is over the entire eyelet and then pulled back and engaged onto the eyelet and pulled back into the inserter.  It is most important that you not completely retract the ring into the inserter, as funny things happen when you do this.  As shown in the video below, odd things will happen if you try to totally retract the ring, so just pull it back so that it is just thin enough to come back through the wound and pull it out of the eye. 

There are two choices for the Malyugin ring; one which is 6.2 mm in internal diameter which is useful for most cases, but if the pupil starts off big or if you are going to use a particularly large IOL, then I would recommend using the 7.0 mm Malyugin ring.  We tend to stock both in the operating room here, and use the smallest ring that you can to get the job done.  The advantage of the smaller ring is that it is easier to insert and easier to retract, and the advantage of the larger ring is that you can use it when the pupil starts off bigger.  

 

References: 

1.  Oetting TA, Omphroy LC.  Modified technique using flexible iris retractors in clear corneal cataract surgery, Cataract Refract Surg 2002;28(4):596-8.

2.  Chang DF.  Use of Malyugin pupil expansion device for intraoperative floppy-iris syndrome: results in 30 consecutive cases, Cataract Refract Surg 2008;34(5)835-41.