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New Orleans—The dermis fat graft is an overlooked procedure that merits consideration as a primary or secondary ocular implant and for complex socket reconstruction, suggested James Katowitz, MD.
"In many respects, and in certain patients in particular, it approaches the ideal for an ocular implant. It's readily accessible, provides adequate volume as well as increased lining for the socket, we have no exposure or extrusion problems, and in children in particular it will increase in size as the child grows," he continued. Dr. Katowitz is professor of ophthalmology, University of Pennsylvania Health System's Scheie Eye Institute and The Children's Hospital of Philadelphia.
To avoid an implant that would require multiple exchanges, Dr. Katowitz used a 12-mm dermis fat graft. Eighteen years later, the graft had doubled in size to 24 mm, and no exchanges had been necessary. The bony orbit had also become much more symmetric over the years in the presence of the combined graft and a conformer.
While advocating their use in certain surgical situations, Dr. Katowitz pointed out that dermis fat grafts do have several disadvantages: they require harvesting from a second site, may atrophy in adults, and may require debulking in children, especially if the child gains a lot of weight. However, these problems are generally surmountable, he added.
Providing more details about each category of use for a dermis fat graft, Dr. Katowitz noted that, in addition to its potential as a primary ocular implant, the dermis fat graft can be used for contracted sockets and for congenital microphthalmia.
"Our preference at the Children's Hospital has been to try progressive conformer expansion first for congenital microphthalmia, since the critical thing is to develop enough space in the orbit before trying a dermis fat graft or else one can get a cicatrizing process," he said.
"Some orbits may not have a response to traditional approaches and require orbital expanders such as hydrogel or inflatable materials. In addition, sometimes craniofacial bony expansion is necessary because the bony orbit has no response at all, thus limiting development of an adequate socket," Dr. Katowitz continued.
The graft can be used as a primary implant following enucleation in very young children, as in the case described earlier, and in certain situations where there is socket contraction. In such cases, it can be used to provide additional lining for socket problems, which limit the use of a conformer.
As a secondary implant, a dermis fat graft is useful as a means of covering exposure in a primary implant, Dr. Katowitz said. The grafts also can be used to address cicatricial entropion or contraction, if not too severe, as mentioned above.
Complex socket problems resulting from serious infections, secondary necrosis, burns, or post-radiation issues may also benefit from a dermis fat graft.
The use of radiation to treat retinoblastoma or other orbital tumors can lead to eventual extrusion of a primary implant. In such cases, Dr. Katowitz recommends assisting blood supply to the graft with a temporalis muscle flap.
He also described use of a microvascular free flap harvested from the radial forearm. "This is basically a dermis fat graft, which can be placed in the socket and connected to the facial vessels for an adequate blood supply. With additional periorbital soft tissue surgery, a relatively acceptable result can often be achieved," he explained.