One of the trickiest parts of an anterior vitrectomy is seeing the vitreous.
You can often see the nearly invisible vitreous strands pushing another structure aside or detect that the vitreous has occluded an I/A aspiration port. However directly seeing the vitreous is difficult. Scott Burk at Cincinatti Eye helped to solve this problem with his description of using Kenalog (off label) to stain vitreous that had prolapsed into the anterior chamber (ref below). As Kenalog is not approved by the FDA for this indication and as some retinal surgeons have had sterile and even infectious endophthalmitis from using Kenalog its use is controversial. However it is a very useful adjunct to anterior vitrectomy. For more detail on vitrectomy pls see: http://www.medrounds.org/cataract-surgery-greenhorns/2005/10/chapter-5-managing-surgical.html or the section in this blog.
You can often see the nearly invisible vitreous strands pushing another structure aside or detect that the vitreous has occluded an I/A aspiration port. However directly seeing the vitreous is difficult. Scott Burk at Cincinatti Eye helped to solve this problem with his description of using Kenalog (off label) to stain vitreous that had prolapsed into the anterior chamber (ref below). As Kenalog is not approved by the FDA for this indication and as some retinal surgeons have had sterile and even infectious endophthalmitis from using Kenalog its use is controversial. However it is a very useful adjunct to anterior vitrectomy. For more detail on vitrectomy pls see: http://www.medrounds.org/cataract-surgery-greenhorns/2005/10/chapter-5-managing-surgical.html or the section in this blog.
Dr Burk described a process to wash the preservative off of the Kenalog to use in the anterior chamber. His process dilutes the 40mg/ml Kenalog 10:1 and washes off the preservative with a filter. I have summarizied the steps of his technique below and show the technique in the video. Please keep in mind that this is not approved by the FDA for this technique and does carry some risk of TASS (sterile anterior chamber inflamation) and of endophthalmitis. you can also use the preservative free kenalog which is now available and dilute it 10:1 which although more expensive is easier and is approved for intraocular use.
Preparing the Kenalog Stain
- TB syringe to withdrawn 0.2 ml of well shaken Kenalog (40mg/ml)
- Remove the needle and replace with a 5 (or 22) micron syringe filter (Sherwood Medical)
- Force the suspension through the filter and discard the preservative filled vehicle
- The Kenalog will be trapped on the syringe side of the filter
- Transfer the filter to a 5 ml syringe filled with balanced salt solution (BSS)
- Gently force the BSS through the filter to further rinse out preservative
- Repeat rinsing a few times
- Place a 22 gauge needle on the distal end of the filter
- Draw 2 ml of BSS into the syringe through the filter to resuspend the Kenalog
- The Kenalog (now without preservative and dilute 10:1) will stain vitreous strands white
one of the nice things about the kenalog stain is that you can better understand the fluid dynamics of vitreous removal. you can see the vitreous streaming around the cutter with a leaking wound. you can see the vitreous heading better toward the cutter if you hold the cutter low and the irrigation cannula high. here is a video showing these principles.
References
Burk SE, Da Mata AP, Snyder ME, Schneider S, Osher RH, Cionni RJ. Visualizing vitreous using Kenalog suspension J Cataract Refract Surg. 2003 Apr;29(4):645-51
Burk, SE, Question 32: When and How Do I Stain the Vitreous With Intracameral Kenalog? from Chang DF, Oetting TA, Kim T, Curbside Consultations in Anterior Segment Surgery, Slack Inc, Thorofare NJ, 2007.
