A recent prospective study tested whether optical coherence tomography angiography (OCT-A) was useful in appraising anterior segment ischemia (ASI), a rare but potentially vision-threatening complication of strabismus surgery.1

Researchers believe the invasive and time-consuming nature and potential adverse effects limit the utility of indocyanine green angiography and fluorescein angiography, the current standard for assessing anterior segment circulation.

The study prospectively recruited nine adults undergoing strabismus surgery on at least one vertical muscle and evaluated images of 10 eyes. Indocyanine green angiography and OCT-A of the iris were taken preoperatively and one day post-op.  

The researchers found a 2% reduction in iris vessel density after strabismus surgery with OCT-A. The new diagnostic tool also detected filling defects in the quadrant adjacent to the operated muscle in one patient.

Researchers concluded that the clinical relevance of the small differences is not yet known and that further research is needed to determine OCT-A’s use in clinical practice because of the study’s small sample size.

In a commentary accompanying the study, David G. Hunter, MD, PhD, noted the observation that iris vessel density is transiently reduced after strabismus surgery is not unexpected.2 OCT-A uses vessel density as a surrogate for perfusion, and it does not characterize vascular leakage, perfusion delay or filling speed, which are all notable features of ASI, he said.

1. Velez FG, Davila JP, Diaz A, et al. Association of change in iris vessel density in optical coherence tomography angiography with anterior segment ischemia after strabismus surgery. JAMA Ophthalmol. July 12, 2018. [Epub ahead of print].

2. Hunter DG. Improving access—but not outcomes—with iris optical coherence tomography angiography. JAMA Ophthalmol. July 12, 2018. [Epub ahead of print].