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.
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
Kent W. Small, MD:
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.
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:
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.
Khaled A. Tawansy, MD:
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.
Use of Triamcinolone Acetonide for ILM Dissection
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.
Clive H. Sell, MD:
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.
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
Retinal Physician, Issue: September 2006