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Questions and Answers

  Is the motility/support peg necessary?
The vast majority of surgeons prefer to use the motility/support peg. A recent survey found that surgeons prefer to use a peg for both primary and secondary implants at rates of 73% and 53%, respectively. The peg allows direct coupling to the artificial eye, thus improving motility, while also reducing the weight on the lower lid, thus decreasing lower lid sag. However, some surgeons judge motility to be adequate without the use of the peg, although the data are not clear in this regard.

Can children be fit with a Bio-eye implant?
Yes, a Bio-eye hydroxyapatite implant can and should be used where indicated in children, except as outlined below. By age 3, the volume of the eye is 85% of that of the adult. The infant eye is 17 to 18 mm in diameter; the adult eye is 22 to 24 mm. Choose the largest implant that can enter the orbit without causing undue pressure on the overlying tissues. The size of the anterior orbit opening often limits the size of implant used, because the brow prevents entry of an implant that could otherwise be accommodated. Thus, if a 16-mm or larger Bio-eye implant can be inserted, it should be used. A Bio-eye implant can remain in place for life. If the opening will not allow at least a 16-mm implant, then a smaller, simple silicone sphere wrapped in sclera should be inserted, and the muscles should be attached. As the child develops and can accommodate a larger implant, the silicone sphere can be removed and replaced with a Bio-eye implant. In any case, some type of implant should be used, since the facial bones will not grow properly without an implant in the orbit to retain shape and stimulate growth.

What special concerns are there when fitting diabetics?
There are no additional concerns or technique modifications required to place a Bio-eye implant in a diabetic patient. However, a bone scan is always recommended in order to assess vascular ingrowth prior to drilling the implant.

What is the best way to manage exposures?
Fortunately, the two most comprehensive studies to date show very low rates of exposure for the Bio-eye HA implant.4 The means for treating an exposure varies as a function of its size and postoperative duration. Most small exposures (<= 3 mm) heal spontaneously. If there is no infection, small exposures occurring within 6 months postoperatively should be monitored without surgical intervention. If the exposure widens, a graft should be considered; but conjunctival flaps should not be used. If the exposure does not widen and remains stable, continue to observe it, unless the patient wants a graft or unless there is increased discharge. If the exposure occurs later than 6 months postoperatively, and vascularization of the implant is confirmed, the exposure should be observed, unless the patient wants a graft or unless there is increased discharge. However, most large exposures (>3 or 4 mm) are accompanied by some discharge and should be grafted.

Is it necessary to wrap the Bio-eye HA implant?
No, but it is advisable. The rough surface of natural hydroxyapatite snags against the soft tissues of the orbit. An unwrapped implant is difficult to place deep into Tenon's capsule, which is important in allowing the use of a large, volume-filling implant. Also, the wrapping serves as an additional barrier protecting the overlying tissues from abrasion due to this highly motile implant. I only use an unwrapped implant in cases having compromised orbital vascularity, such as in cases of prior irradiation treatment, to minimize barriers to fibrovascular invasion into the implant. But, even in such cases, I use a small cap of sclera over the anterior aspect of the implant.