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Is intraoperative optical coherence tomography a useful guide for surgery?
Real-time information supports decision-making process
 Susanne Binder |
There are several advantages in combining an OCT system with the surgical microscope. By providing real-time information on the surgical procedure and on the behavior of vitreoretinal tissue, it facilitates surgery and supports the surgeon’s decision-making process, thus improving surgical outcome. It also allows us to examine patients who are unable to sit upright, such as infants with ROP and elderly patients, in a lying position, directly on the operating table. OCT examinations can be repeated during surgery, without losing sterility.
Intraoperative imaging is a common practice in other areas, such as neurosurgery, in which different technologies are used for real-time evaluation of structure and function and to guide surgical decisions. We started this new adventure in 2008 and now use OCT routinely for vitreoretinal surgery. In cataract surgery, we have a study ongoing in which intraoperative OCT is used to measure foveal thickness and evaluate optic nerve behavior.
I think that the disadvantage of using OCT for only postoperative examination is that you can no longer change what has been done without reopening the eye and doing repeat surgery. If there are residual membranes, you can certainly diagnose them postoperatively, but only intraoperative imaging allows you to peel them off in the same session. If you have a patient with opaque media, such as a dense cataract, you cannot do OCT before surgery, but can remove the cataract and do OCT on the table immediately after. This is even more important in patients with a history of AMD because you can evaluate the condition of the fovea, and if there is some fluid, you can treat the eye immediately with anti-VEGF at the end of surgery. Thanks to OCT, you can also see the impact of cataract surgery in patients with dry AMD. In patients with retinal detachment, you can differentiate between a macula-on and macula-off detachment with higher certainty.
Susanne Binder, MD, is an OSN Europe Edition Editorial Board Member and can be reached at Rudolph Foundation Clinic, Vienna, Austria. Disclosure: Dr. Binder has no relevant financial disclosures.
Current technology not ready for intraoperative use
 Daniele Veritti |
Intraoperative OCT, despite being a very promising technology, is still in its infancy. Available devices have significant limitations regarding real-time imaging, microscope integration, time efficiency and analysis software. Moreover, the importance of this imaging modality in improving surgical outcomes has not yet been demonstrated.
Most intraoperative OCT systems are derived from diagnostic OCTs adapted to be integrated in the operating room instrumentation. Some of them require the procedure to be stopped in order to acquire images. This results in a non-real-time imaging of surgical maneuvers, with significant time delays and with the need of additional operators to control the instrument.
In addition, most of the surgical instruments that are in use today are metallic. This causes critical shadowing of the OCT image and affects the real-time visualization of ocular tissues.
Software analysis packages are still lacking in the fields of real-time analysis of OCT data and in the identification of critical feedback to the vitreoretinal surgeon. Moreover, we need to develop imaging protocols specifically designed for intraoperative use that can provide the surgeon with a simultaneous display of the surgical field and fast real-time OCT imaging.
In conclusion, it is uncertain how intraoperative OCT will change vitreoretinal surgery and what will be its impact on surgical outcomes and visual results. Extensive research is still needed to fix the inadequate areas of this technology. Nevertheless, real-time intraoperative OCT promises to be a useful adjunctive tool in surgical decision making, and it has also shown to be an ideal imaging technique to provide a real-time dosimetry of subthreshold laser retinal photocoagulation, in which fast scanning and proper aiming are much easier to obtain.
Daniele Veritti, MD, can be reached at Department of Ophthalmology, University of Udine, Udine, Italy. Disclosure: Dr. Veritti has no relevant financial disclosures.