AUG 24, 2012
Retina/Vitreous
This retrospective study found that the artificial iris diaphragm often retained silicone oil from the anterior chamber in severely damaged eyes and was also useful for preventing phthisis and preserving vision.
The authors reviewed the charts of 94 consecutive patients (94 eyes) with hypotony or iris defects who received an artificial iris diaphragm and silicone oil tamponade. The mean follow-up was 586 days.
At the last follow-up visit, 61.7 percent of patients showed no silicone oil in the anterior chamber. Kaplan–Meier survival analysis showed a mean survival time for a functional diaphragm of 1227 days.
Keratopathy improved at least temporarily in 55.3 percent of cases, and vision improved or remained stable in 38.2 percent. The diaphragm was more successful when the underlying disease was trauma or congenital malformation. No influence on diaphragm survival from baseline IOP or mean postoperative IOP was observed. Only one eye had to be enucleated.
The authors note that the reason for failure of the diaphragm was not clear in most cases. They speculate that sometimes silicone oil gets into the anterior chamber through small gaps between the implant and the eye. The creep behavior of silicone oil may facilitate this. The gaps may be due to an imperfect location of the diaphragm in the ciliary sulcus, the stretching of the diaphragm by fixating sutures or scar formation.
However, permanent removal of silicone oil was successful in 13 patients, in some patients even after multiple attempts. So if silicone oil has entered the anterior chamber, a revision should be attempted to remove the silicone oil by paracentesis.