Article Date: 9/1/2006

FACE OFF

Welcome to Face Off, a column that explores controversial topics in the diagnosis and management of retinal diseases. Several topics are covered in each issue, with one specialist writing in favor of the treatment or surgery and another writing in opposition, regardless of whether they personally believe in that position.  

In this column, we will explore the subject of dyes and staining material for internal limiting membrane (ILM) dissection during vitrectomy surgery.

While we are not recommending any particular treatment for patients, this will serve as an exercise in exploring pro and con aspects of treatment decisions that we face regularly. This column should be interpreted in the spirit of a debate society. I hope that you will find the column interesting, entertaining, and educational.

THE THREE TOPICS IN THIS ISSUE ARE:

1. Use of indocyanine green (ICG) for ILM dissection
2. Use of trypan blue for ILM dissection
3. Use of intravitreal triamcinolone for ILM dissection

ICG for ILM Dissection

IN FAVOR OF
Kent W. Small, MD:

Approximately 10 years ago, I was not using any ICG staining when performing macular hole surgery and my closure rate with gas was around 75%. I suspect that my attempts to peel the ILM were incomplete. Since I have started using diluted ICG for ILM peeling, I have only had one failure. One could make the argument that rather than improved visualization from ICG staining, this improvement was due to improved instrumentation.

In regard to concerns of toxicity with ICG, I have never seen evidence of this, perhaps because I wash out the ICG within a minute of injecting it. My high closure rate since using ICG and the Tano diamond-dusted retinal scratcher has allowed for more flexibility in the strict face-down positioning regimen after macular hole surgery.

OPPOSED
Stewart Daniels, MD:

Macular hole surgery has become one of our most successful and satisfying surgical procedures, with a high success rate whether we peel the ILM or whether we use ICG to better visualize the ILM.

Without a doubt, ICG is a useful tool to learn how to rapidly, reproducibly, and completely dissect the ILM. However, experimental studies have shown in vitro
toxicity, and possible clinical examples of ICG toxicity have been reported as retinal pigment epithelium (RPE) atrophy, potentiation of phototoxicity, visual field defects, alteration of the ILM-retinal cleavage plane, and optic neuropathy. A definitive guide to the risks and benefits of ICG-assisted ILM peeling will likely require a large multicenter, randomized clinical trial using a standardized protocol with matched controls. Until we have better answers, I will peel the ILM in patients who have failed macular hole surgery or those eyes with poor prognosis, but I no longer use ICG. In the vast majority of cases of macular hole, I do not to peel the ILM or use ICG. It takes only one poor outcome, such as phototoxicity with ICG, to remind us of the familiar phrase first written by English physician, Thomas Sydenham (not Hippocrates or Galen) in 1860: "Primum non nocere — Above all, do no harm"!

Use of Trypan Blue for ILM Dissection

IN FAVOR OF
J. Fernando Arevalo, MD, FACS:

Recently, trypan blue dye has been shown to be beneficial for staining the ILM, facilitating membrane identification and removal. Although not studied formally, it is our impression that the staining results in less iatrogenic surgical retinal damage and a shorter operating time compared with not staining, because of the ease of membrane identification. In our experience, ILM staining was fainter than the staining of epiretinal membranes (ERMs), but still provides a clear demarcation between peeled and unpeeled ILM, facilitating ILM identification and removal.

Furthermore, our technique has improved and is more careful now with clear visualization of the ILM. In addition, we have found no signs or symptoms of ocular toxicity attributable to trypan blue. Our visual and anatomic outcomes have been consistent with expectations for a group of patients undergoing ILM peeling during macular hole surgery and unresponsive diabetic macular edema. Because of the recent concerns regarding potential ICG toxicity, trypan blue may be a useful alternative stain in vitreoretinal surgery.

OPPOSED
Khaled A. Tawansy, MD:

I do not believe that you necessarily have to stain the ILM for dissection. It is an unnecessary step that can prolong the surgery and potentially add to complications. I am concerned about the potential for similar toxicity with trypan blue to the RPE or retina, as has been found with ICG. In the absence of animal studies to demonstrate safety and in the absence of human studies demonstrating the visual acuity benefits of using trypan blue for ILM dissection, I would tend to avoid using it.

The Use of Triamcinolone Acetonide for ILM Dissection

IN FAVOR OF
Gaurav Shah, MD:

The use of intravitreal staining agents has gained great popularity in removal of posterior hyaloid, cortical vitreous, and ILM. In contrast to other staining agents such as ICG and trypan blue, Kenalog is useful for all layers being removed. Kenalog, unlike ICG, does not become part of the tissue but highlights whatever tissue is present in the vitreous cavity. Triamcinolone has advantages over ICG for ILM peeling. Triamcinolone requires no preparation, can be reinjected once ILM peeling has begun, has no photosensitizing properties like ICG, is useful for patients with iodine allergy, and is significantly less expensive then ICG. Triamcinolone peeling does not affect hole-closure rates, and at least clinically, does not seem to be toxic. Given all the advantages of Kenalog, it has become the ideal adjunct that can stain posterior hyaloid, cortical vitreous, and the ILM.

OPPOSED
Clive H. Sell, MD:

The primary argument against the use of triamcinolone acetonide for ILM dissection involves its limited mechanical benefits combined with a small but significant risk of complications. Triamcinolone acetonide does not stain ILM, but rather sticks to any remnants of the cortical vitreous. These strands can be easily identified with the use of the soft-tipped canula. The risks of early cataract formation, glaucoma, and endopthalmitis are well known. These risks are combined with possible mechanical and toxic damage from a medication not approved for intraocular use applied directly onto the surface of the retina.

Abdhish R. Bhavsar, MD, is an attending retina surgeon at the Phillips Eye Institute, director of clinical research at the Retina Center, P.A., in Minneapolis, Minn, and adjunct assistant professor at the University of Minnesota. He also serves as state chair of the Minnesota Diabetes Eye Exam Initiative. E-mail him about Face Off at bhavs001@umn.edu.



Retinal Physician, Issue: September 2006