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Three-pronged approach reduces diabetic retinal detachment risk
KOLOA, Hawaii — Three tools reduce risk and increase surgical efficacy in cases of complex diabetic traction retinal detachment, according to a presentation here.
“My surgical approach has evolved to include a combination of wide-angle viewing, viscoelastic delamination; and illuminated diamond knife delineation. With these tools, I have improved my efficiency and reduced my chances of iatrogenic retinal break formation or unexpected hemorrhage,” said Allen C. Ho, MD, here at Retina 2001, presented with Hawaii 2001, the Royal Hawaiian Eye Meeting, sponsored by Ocular Surgery News in conjunction with the New England Eye Center.
Delamination of adherent tissue to underlying retina is one of the greatest surgical challenges that vitreoretinal surgeons face.
“A typical scenario is the attachment of complex diabetic fibrovascular membranes. While some of these proliferative diabetic membranes are easily delaminated with lifting techniques, other broad-based tight attachments or ‘plaques’ of adherent membranes are difficult to segment or delaminate,” he said.
Surgical goals
Generally there are three goals in cases of complex diabetic traction retinal detachment, according to Dr. Ho.
“One is to clear the media; two is to relieve traction forces on the macula, which tend to be the more complicated cases where we have fibrovascular proliferation and mechanical forces distorting the macula; and three is to minimize complications such as hemorrhage, retinal breaks and recurrent vitreous hemorrhage, which we now know is often related to vascularization of sclerotomy sites,” he said.
Challenges during the time of surgery include surface bleeding, field of view, tight membranes and adherent membranes to underlying retina, ischemic retina and delamination.
Dr. Ho performs a modified en-bloc dissection after initial vitrectomy, applying most attention on areas of fibrovascular proliferation around the optic disc.
“Prior to dissection, it is important to acknowledge particularly thin and ischemic areas as well as possible to avoid retinal breaks from direct tissue trauma or from traction on attached fibrovascular tissue,” he said.
Tools and technique
Wide-angle viewing helps because it enables the surgeon to see the effects of local surgical maneuvers on more distant tissue simultaneously.
“At Wills Eye Hospital in Philadelphia, we have both contact and non-contact wide-angle viewing systems. These provide an excellent field of view when approaching complex diabetic traction retinal detachments. This field of view or perspective is important prior to membrane dissection as it helps the surgeon develop a plan of delamination,” Dr. Ho said.
Viscoelastic membrane dissection is an important tool, he said, because it markedly improves the efficiency and safety of the delamination process.
“I think the Healon itself has a tamponading effect and can also push blood out of the way.
Prior to the viscoelastic injection, Dr. Ho creates a plane by making a small incision in the diabetic fibrovascular membrane.
“It is important to make the incision small, so that the injected viscoelastic will dissect membrane from retina and not simply reflux back into the vitreous cavity,” he said
His initial incision and injection often occurs adjacent to the optic disc where the underlying retina is thickest and where there is commonly a good tissue plane between the diabetic membrane and peripapillary retina.
“It is important to inject slowly, directing the bent cannula in the direction of the dissection, as opposed to straight down into the retina. Viscoelastic dissection will transmit equal forces upward on the diabetic membrane and downward on detached retina, safely separating the two tissue planes,” he said.
Use of an illuminated diamond knife completes the procedure.
“Using this with the Alcon Accurus light source was very good. The fiberoptic ‘lights up’ the entire diamond cutting end and allows it to be well visualized even under more opaque fibrovascular membranes. With the DORC Hexon light source, the effect was spectacular. There was simply no need for any other lighting. One can see where one needs to be and what one needs to do” he said.
He uses gripping forceps to elevate the membrane, and then once the membrane is separated from the underlying retina he uses an intuitive back-and-forth sewing motion to delaminate the membranes.
“There is a good safety margin, which reduces the possibility of iatrogenic breaks,” he said.
Dr. Ho recommends paying particular attention to diathermy.
“Incomplete diathermy is the cause of many immediate postoperative vitreous hemorrhages,” he said.
For Your Information:
- Allen Ho, MD, can be reached at Wills Eye Hospital, Retina Services, 900 Walnut St., Philadelphia, PA 19107; (215) 928-3300; fax: (215) 238-0804; e-mail: acho@att.net.