[Intraoperative optical coherence tomography in retinal detachment]

[Intraoperative OCT in retinal detachment with macular involvement]

Hintergrund

Seit wenigen Jahren ermöglicht die intraoperative optische Kohärenztomographie (iOCT) die Darstellung retinaler Strukturen im Operationsmikroskop.

Ziel

Das Ziel dieser Studie ist die Analyse des Verhaltens der Netzhaut und die morphologische Befundung während Operationen bei Ablatio retinae mit Makulabeteiligung.

Methoden

Retrospektive Analyse von 41 konsekutiven Augen mit Makula-off-Ablatio, welche mittels Pars-plana-Vitrektomie (ppV) unter Verwendung von iOCT behandelt wurden, durch qualitative Beurteilung der Netzhautmorphologie zu definierten Zeitpunkten im OP-Ablauf.

Ergebnisse

In 63 % der Fälle gelang die iOCT-Darstellung der abgehobenen Makula, in den anderen Fällen überstieg die Netzhautabhebung die maximale Scantiefe der iOCT. Unter Perfluorodecalin zeigten 53,7 % der Augen noch subretinale Flüssigkeit, und 22 % der Augen zeigten eine Falte der äußeren Netzhautschichten. In 61 % der Augen konnte persistierende subretinale Flüssigkeit unter der endgültigen Tamponade festgestellt werden. Die subretinale Flüssigkeit konnte intraoperativ in dieser Menge mit bloßem Auge nicht festgestellt werden. In einem Fall konnte intraoperativ ein Makulaformen neu erkannt werden, in 3 Fällen zeigte sich zum Operationszeitpunkt eine wieder anliegende Makula.

Diskussion

Die Informationen der iOCT führen eher selten zu einer Änderung oder Erweiterung des Eingriffs. Sie liefert jedoch in Echtzeit neue Informationen über intra- und subretinale Flüssigkeitsverteilung, die nicht immer der klinischen Einschätzung entsprechen. Die Bedeutung von persistierender subretinaler Flüssigkeit und die Falten der äußeren Netzhautschichten am Ende der Operation sind noch unklar. Sie könnten möglicherweise als prognostischer Faktor für das postoperative Outcome dienen.

Intraoperative Optical Coherence Tomography Guided Ocular Surgeries: Critical Analysis of Clinical Role and Future Perspectives

Intraoperative imaging of ocular tissues for diagnostic and therapeutic applications has gained immense admiration in recent years. The real time cross-sectional imaging, as well as three and four dimensional reconstruction abilities of intraoperative optical coherence tomography (iOCT), has enhanced our knowledge on many fronts in surgical maneuvers. In this review, we discuss the iOCT discovered constructive knowledge in the cornea, cataract, refractive, glaucoma, pediatric ocular, and various retinal conditions. The practical utility with decision modifying aspects along the specified ocular tissues and with respect to specific ocular entities have been narrated. Moreover, limitations and future directions have also been emphasized to make ophthalmic care more comprehensive in the future.

Live video rate volumetric OCT imaging of the retina with multi-MHz A-scan rates

Surgical microscopes are vital tools for ophthalmic surgeons. The recent development of an integrated OCT system for the first time allows to look at tissue features below the surface. Hence, these systems can drastically improve the quality and reduce the risk of surgical interventions. However, current commercial OCT-enhanced ophthalmic surgical microscopes provide only one additional cross sectional view to the standard microscope image and feature a low update rate. To present volumetric data at a high update rate, much faster OCT systems than the ones applied in today's surgical microscopes need to be developed. We demonstrate live volumetric retinal OCT imaging, which may provide a sufficiently large volume size (330x330x595 Voxel) and high update frequency (24.2 Hz) such that the surgeon may even purely rely on the OCT for certain surgical maneuvers. It represents a major technological step towards the possible application of OCT-only surgical microscopes in the future which would be much more compact thus enabling many additional minimal invasive applications. We show that multi-MHz A-scan rates are essential for such a device. Additionally, advanced phase-based OCT techniques require 3D OCT volumes to be detected with a stable optical phase. These techniques can provide additional functional information of the retina. Up to now, classical OCT was to slow for this, so our system can pave the way to holographic OCT with a traditional confocal flying spot approach. For the first time, we present point scanning volumetric OCT imaging of the posterior eye with up to 191.2 Hz volume rate. We show that this volume rate is high enough to enable a sufficiently stable optical phase to a level, where remaining phase errors can be corrected. Applying advanced post processing concepts for numerical refocusing or computational adaptive optics should be possible in future with such a system.

Live video rate volumetric OCT imaging of the retina with multi-MHz A-scan rates

Surgical microscopes are vital tools for ophthalmic surgeons. The recent development of an integrated OCT system for the first time allows to look at tissue features below the surface. Hence, these systems can drastically improve the quality and reduce the risk of surgical interventions. However, current commercial OCT-enhanced ophthalmic surgical microscopes provide only one additional cross sectional view to the standard microscope image and feature a low update rate. To present volumetric data at a high update rate, much faster OCT systems than the ones applied in today's surgical microscopes need to be developed. We demonstrate live volumetric retinal OCT imaging, which may provide a sufficiently large volume size (330x330x595 Voxel) and high update frequency (24.2 Hz) such that the surgeon may even purely rely on the OCT for certain surgical maneuvers. It represents a major technological step towards the possible application of OCT-only surgical microscopes in the future which would be much more compact thus enabling many additional minimal invasive applications. We show that multi-MHz A-scan rates are essential for such a device. Additionally, advanced phase-based OCT techniques require 3D OCT volumes to be detected with a stable optical phase. These techniques can provide additional functional information of the retina. Up to now, classical OCT was to slow for this, so our system can pave the way to holographic OCT with a traditional confocal flying spot approach. For the first time, we present point scanning volumetric OCT imaging of the posterior eye with up to 191.2 Hz volume rate. We show that this volume rate is high enough to enable a sufficiently stable optical phase to a level, where remaining phase errors can be corrected. Applying advanced post processing concepts for numerical refocusing or computational adaptive optics should be possible in future with such a system.

Intraoperative optical coherence tomography and ab interno trabecular meshwork surgery with the Trabectome

Importance

This study is the first description of the use of the intraoperative optical coherence tomography (iOCT) for trabecular meshwork surgery with the Trabectome in a regular clinical setting.

Background

The aim of this study is to evaluate intraoperatively the immediate success of ab interno trabeculotomy with the Trabectome defined as a removal of the trabecular meshwork.

Design

This is a retrospective clinical study performed in the University Eye Hospital, Medical School Hannover.

Participants

A total of nine consecutive Caucasian patients suffering from primary open angle glaucoma, pigment dispersion glaucoma, or pseudoexfoliation glaucoma took part in the study.

Methods

All patients underwent ab interno trabeculotomy surgery with the Trabectome using a commercially available iOCT to visualize the anterior chamber angle (ACA) before and after the procedure. The visualization was done using a modified Swan-Jacobs lens (all nine patients) or without lens (view from above, five patients).

Main outcome measures

The main outcome of this study is the success of visualization of the ACA on iOCT, especially the postprocedural visualization of the wound gap after removal of the trabecular meshwork.

Results

Using the view from above, the ACA could be visualized before and after the procedure in only two of the five cases. Using the modified Swan-Jacobs lens, the ACA could be visualized before the procedure and the trabecular meshwork opening after the procedure in all nine patients.

Conclusion

The iOCT can be used to objectify the immediate success of the surgical procedure, ie, the removal of the trabecular meshwork, of ab interno trabeculotomy with the Trabectome. The procedure itself cannot be captured sufficiently via iOCT.