Hydrogel bandage minimizes risks of microincision vitrectomy surgery

The ocular bandage enables a sutureless procedure with a decreased risk of endophthalmitis.

Issue: September 10, 2010

BySeenu M. Hariprasad, MD

Seenu M. Hariprasad

Microincision vitrectomy surgery was first performed in 2002 by Fujii and colleagues, and in the last 8 years it has revolutionized the way surgery is performed. There are numerous advantages for the patient that outweigh the few existing risks. However, data presented at the Association for Research in Vision and Ophthalmology meeting in May demonstrates that new technologies may decrease the few remaining risks, further elevating the status of microincision vitrectomy surgery.

There are a number of benefits to 23- or 25-gauge microincisional surgery over traditional 20-gauge surgery, starting with the elimination of the sutures. Without sutures, the entry and exit from the eye is so rapid that more time can be spent working on the back of the eye; patient comfort is measurably increased by not having bothersome sutures present after surgery; and postsurgical astigmatism concerns are essentially a non-issue. In addition, the reduced trauma to the conjunctiva leaves the eye with less scarring and speeds recovery.

Although there are many benefits with microincision vitrectomy surgery, there have been reports of increased risk of endophthalmitis after surgery. Wound gape during blinking may provide an entry, and early hypotony after surgery may be the suction force that pulls the bacteria from the surface of the eye into the anterior or posterior chamber. Incarcerated vitreous may also provide an entry for bacteria into the posterior chamber. While studies show that changes to perioperative anti-infection protocol may make a difference with 25-gauge microincision vitrectomy surgery, there are additional options that address a variety of risks associated with vitrectomy surgery.

Experimental human cadaveric eye demonstrating ReSure Ocular Bandage sealing two 23-gauge MIVS sutureless vitrectomy ports. Infusion line below demonstrates burst pressure of 140 mm Hg without evidence of leakage.

Image: Hariprasad SM

Currently awaiting U.S. Food and Drug Administration approval and already approved in Europe is an in situ forming hydrogel bandage (ReSure Adherent Ocular Bandage, Ocular Therapeutix) that creates a temporary, soft and lubricious surface barrier to protect clear corneal incisions from the external environment. The ocular bandage is a two-part synthetic liquid system that gels on the ocular surface in 30 seconds to form a hydrogel that is soft and flexible. The bandage typically resides on the de-epithelialized tissue for 3 to 4 days, after which it is gradually replaced by new epithelium as the gel sloughs off in the patient’s tears due to biodegradation and the mechanical action of the eyelid. The hydrogel is composed substantially of water and polyethylene glycol, widely considered an inert and biocompatible material. Thus, it is 100% synthetic and carries no risk of viral transmission. The hydrogel bandage protects the patient by covering the de-epithelialized incisions during healing, and provides immediate patient comfort without compromising the patient’s vision or the physician’s clinical observation.

Ocular Therapeutix has stressed that the ReSure Ocular Bandage is currently only an investigational device undergoing clinical evaluations in the U.S. for clear corneal surgery following intraocular lens placement. It is not indicated for use as a sealant or for use in vitreoretinal surgery.

Recent studies of the ReSure Bandage to secure sutureless 23- and 20-gauge vitrectomy incisions in fresh human cadaveric eyes may provide a solution to the current risks associated with microincision vitrectomy surgery. It should be noted, however, that this was a research study only and should not be construed as clinical practice guidance. Further clinical evaluations would be necessary to fully evaluate the ReSure Bandage's utility in vitreoretinal surgery.

In one part of the study, two beveled 23-gauge incisions were made in each eye; one was left bare (no sutures or hydrogel) and the other was covered with hydrogel. India ink was placed over the wounds, then the IOP was cycled through between 0 to 30 mm Hg ten times and manual pressure was applied around the incision site. After all the ink was removed from the surface, the incisions were histologically processed and light microscopy was used to visualize ink particle ingression into the incisions. The results demonstrated that applying the gel to 23-gauge sutureless incisions decreased the ink ingress rate from 66% in the bare wound to 0% in the wound covered with hydrogel.

In the second part of the study, two straight 20-gauge vitrectomy incisions were made with a microvitreoretinal blade in each eye, of which one was sutured with 7-0 Vicryl and one was covered with hydrogel. The same process of ink and pressure as described above was completed, and the results showed that the hydrogel worked at least as well as the sutures. Both groups demonstrated an ink ingression rate of 0%, and burst pressure demonstrated that hydrogel might actually be stronger than sutures.

Ocular bandages may help with a variety of issues that can occur after vitrectomy surgery. Perhaps most important, they may decrease the rate of bacterial influx into a freshly created vitrectomy wound. This would be a significant advance that may assuage any remaining fears physicians may have with performing microincision vitrectomy surgery. Ocular bandages may also help increase the burst pressure, thereby increasing the integrity of the wound. This is useful not only with microincision vitrectomy surgery, but also with traditional 20-gauge pars plana vitrectomy. In some very rare circumstances, 20-gauge sutures can break and lead to abrupt hypotony in the eye. In cases of reoperation, it can be challenging to close the sclerotomy and sutures can be difficult to use. In both of these cases an ocular bandage would be extremely helpful. In the cataract surgery landscape, an ocular bandage would theoretically reduce rates of endophthalmitis in clear corneal incisions by offering greater corneal wound integrity when sutures are not used.

For the majority of surgeons, the advantages of the microincision surgical platform compared to first-generation 20-gauge vitrectomy incredibly outweigh the small fears of an increase in endophthalmitis risk. When we combine microincision vitrectomy surgery with hydrogel ocular bandages, we are potentially decreasing endophthalmitis risk and getting the best of both worlds.

Reference:

Singh A, Hosseini M, Hariprasad SM. Polyethylene glycol hydrogel polymer sealant for closure of sutureless sclerotomies: A histologic study [published online ahead of print June 24, 2010]. Am J Ophthalmol. doi:10.1016/j.ajo.2010.04.002.

Seenu M. Hariprasad, MD, is an associate professor of surgery, director of the clinical research section of Ophthalmology and Visual Science and chief of Vitreoretinal Service at University of Chicago. He can be reached at the Department of Ophthalmology and Visual Science, University of Chicago, 5841 S. Maryland Ave., MC 2114, Chicago, IL 60637; 773-795-1326; e-mail: retina@uchicago.edu. Dr. Hariprasad is a consultant for Ocular Therapeutix.