Repeated orbital decompression surgery
Reviewed by James Hsuan

This is a retrospective review of nine redo orbital decompressions in six patients. All operations were performed for dysthyroid optic neuropathy, both initially and when repeated. The interval between first and redo decompressions varied from one to 15 years and all patients were euthyroid at the time of further surgery although three were smokers. Three patients had a clinical activity score (CAS) of four or above. Eight out of nine eyes had decreased acuity, four had reduced colour vision and one had an afferent pupillary defect. All patients had field loss. Following repeat decompression, there was significant improvement in all these parameters in affected patients. Proptosis reduced on average by 3mm. The authors stress the importance of adequate apical decompression, in particular removing the posterior medial wall and the orbital plate of the palatine bone. They noted that scarring from previous surgery, loss of anatomical landmarks and bleeding made the redo operations technically more difficult. The aetiology of late dysthyroid optic neuropathy is discussed. Significant reactivation of inflammation seems to be doubtful given the low CAS scores in at least half the patients. The authors suggest that low grade smouldering disease possibly combined with an orbital apex syndrome with congestion may be the mechanism. The study is limited by having small numbers, but is a useful warning to be aware of late compressive optic neuropathy in these patients without a frank reactivation of their inflammatory thyroid eye disease. 

Compressive optic neuropathy and repeat orbital decompression: a case series.
Kauh CY, Gupta S, Douglas RS, et al.
OPHTALMIC PLASTIC AND RECONSTRUCTIVE SURGERY
2015;31:385-90.