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This abstract is assigned to session AOB Free Papers 2

Presentation type	Oral presentation
Title	The use of optical coherence tomography angiography to observe changes in iris vasculature after strabismus surgery

Purpose	Currently, iris fluo-angiography is the only imaging technique to detect vascular filling defects prior to strabismus surgery in patients at risk for anterior segment ischemia. In this study, we investigate the use of non-invasive optical coherence tomography angiography (OCTA) in detecting not only these filling defects but also changes in vascularization after surgery. OCTA could help determine if and when staged surgery should take place.
Methods	Patients undergoing strabismus surgery of the rectus muscles were prospectively included from September until November 2021. OCTA images were taken pre- and postoperatively. The vascular density of the iris in the operated quadrant was calculated using Image J. Vascular densities were compared using a one-sided paired t-test. Filling defects were qualitatively assessed.
Results	18 patients were included. Only 6 had images with sufficient quality to calculate vascular density. In total, 8 eyes were analyzed. When only the best (hand-picked) image was used, we found a significant decrease in vascular density from a mean of 24,95% preoperatively to a mean of 22,71% postoperatively (p=0,03). We also calculated the means of the vascular density found in all images of the operated quadrants that were of sufficient quality. In this case, a decrease in vascular density from a mean of 24,24% to 22,40% was found. This difference was no longer significant (p=0,07). No vascular filling defects were found.
Conclusion	OCTA can be a useful non-invasive tool in the pre- and postoperative assessment for patients undergoing strabismus surgery. OCTA reliably detects changes in vasculature and vascular filling defects, but only when high-quality images are used.
Conflict of interest	No

Authors 1

Last name	VANLANGENAEKER
Initials	L
Department	UZ Leuven
City	Leuven

Authors 2

Last name	Putcuijps
Initials	K
Department	KU Leuven
City	Leuven

Authors 3

Last name	Van Aerschot
Initials	J
Department	UZ Leuven
City	Leuven

Authors 4

Last name	DIELTIËNS
Initials	M

Authors 5

Last name	Cassiman
Initials	C
Department	UZ Leuven
City	Leuven