The tracer also simultaneously served as a capsular stain to facilitate the phacoemulsification, explained Dr. Huang, assistant professor of ophthalmology, Doheny Eye Center of Pasadena, Doheny and Stein Eye Institutes, David Geffen School of Medicine, University of California, Los Angeles.
In a report published in Ophthalmology (2017;Apr 28. pii: S0161-6420(17)30949-1. doi: 10.1016/j.ophtha.2017.03.058. [Epub ahead of print]), Dr. Huang explained that a 1-mm side port paracentesis was created in right eyes in a superotemporal position and in left eyes inferotemporally, and an anterior chamber maintainer was inserted through the paracentesis.
A syringe was used to evacuate aqueous humor and a tracer was added. After imaging was completed, the anterior chamber maintainer was removed, the tracer was irrigated, and lidocaine and viscoelastic were used before the phacoemulsification procedure began.
The creation of additional wounds beyond that of standard phacoemulsification was avoided because tracer exchange occurred through the anterior chamber maintainer, which was converted into the second instrument port.
An imaging device platform (Spectralis HRA + OCT Flex module, Heidelberg Engineering) was used to image the tracer movement.
The camera head of the instrument was positioned over the eye, and a 55-degree lens was used to obtain confocal scanning laser ophthalmoscopic infrared (cSLO-IR) or angiographic images and an anterior segment lens used if optical coherence tomography (OCT) imaging was simultaneously done, he noted.
The surgeons obtained fluorescent images in the ICG capture mode to establish the preinjection background. After the ICG was injected, fluorescent images, cSLO-IR images, or videos were obtained with the patients instructed to look in different directions.
“Similar to postmortem eyes and living eyes from non-human primates, aqueous angiography in living human subjects undergoing phacoemulsification showed segmental patterns,” Dr. Huang reported. “The initial angiographic signal was seen by 40.5 ± 9.4 seconds with a range from 18 to 70 seconds in the eight subjects. In all cases, the nasal signal was the strongest.”