Contrast-enhanced intraoperative optical coherencetomographyJustis P Ehlers, Stephen A McNutt, Peter K Kaiser, Sunil K Srivastava

Vitreoretinal Service, Cole EyeInstitute, Ophthalmic ImagingCenter, Cleveland ClinicFoundation, Cleveland, Ohio,USA

Correspondence toDr Justis P Ehlers, VitreoretinalService, Cole Eye Institute,Ophthalmic Imaging Center,Cleveland Clinic Foundation,9500 Euclid Avenue/i32,Cleveland, OH 44195, USA;ehlersj@ccf.org

Received 28 December 2012Revised 6 March 2013Accepted 20 March 2013Published Online First23 April 2013

To cite: Ehlers JP,McNutt SA, Kaiser PK, et al.Br J Ophthalmol2013;97:1384–1386.

ABSTRACTOptical coherence tomography (OCT) has revolutionisedclinical ophthalmology. The translation of OCT into theoperating room is a natural next step given its high-resolution anatomic information. Contrast agents andenhancement have significantly improved the diagnosticcapabilities of numerous imaging modalities (such as CTand MRI). The use of OCT contrast agents inophthalmology has been generally lacking. In this report,we describe the novel application of triamcinolone as anOCT contrast agent for intraoperative OCT to improvevisibility of tissue interfaces and planes (eg, posteriorhyaloid insertion points). The application of thistechnology may have wide-ranging implications forenhanced image-guided surgery, intraoperative OCT anddynamic or functional applications of OCT technology.

INTRODUCTIONSince the initial descriptions of optical coherencetomography (OCT), the ability to visualise ana-tomic features and pathology in the eye hasimproved tremendously.1 The advent of spectraldomain-optical coherence tomography (SD-OCT)improved the resolution and visualisation, whiledecreasing acquisition time.2 Although the qualityof in vivo imaging has improved, widespread devel-opment of contrast-enhanced OCT has beenlimited. We have previously described the ex vivouse of prednisolone, lipid-based artificial tears andtriamcinolone for contrast-enhanced OCT in theanterior segment.3 In addition, we described peri-operative contrast-enhanced OCT to provide func-tional assessment of corneal wound integrity ineyes undergoing cataract surgery.4

The enhanced visualisation achieved with con-trast agents facilitates improved identification oftissue layers and allows for a more dynamic orfunctional OCT.3 4 Intraoperative optical coherencetomography (iOCT) is an emerging field that usesthe high-resolution cross-sectional informationafforded by OCT to improve visualisation of surgi-cal ophthalmic pathology. iOCT provides thesurgeon with a rapid feedback on microarchitec-tural changes and reveals the underlying impact ofsurgical manoeuvres on ophthalmic tissues.5–10

Transparent and translucent tissues are visualised enface in real time during a surgical procedure with astandard operating microscope. Efforts at seamlessintegration of iOCT into surgical practice includemicroscope integration, software advances,dynamic motion imaging, enhanced visualisationand development of surgical instruments.6 7 9

Using contrast-enhanced iOCT may provideimproved visualisation of tissue interfaces. In thisreport, we provide a novel description of

contrast-enhanced iOCT using preservative-freetriamcinolone (Triesence, Alcon, Fort Worth, Texas,USA) as a contrast agent for posterior segmentsurgery.

METHODSA retrospective consecutive case series of four eyeswith iOCT imaging following placement ofpreservative-free triamcinolone was performed.Institutional review board approval was obtainedand the study adhered to the tenets of theDeclaration of Helsinki. Informed consent wasobtained from all participants for surgical interven-tion and iOCT.Intraoperative imaging was performed using a

custom microscope-mounted iOCT system, using aportable SD-OCT probe (SDOIS; Bioptigen; ResearchTriangle Park, North Carolina, USA). A standardisedimaging protocol was used with iOCT imaging per-formed at various surgical milestones as well as priorto the initial incision (eg, pre-incision). Volume scan-ning was performed with 10×10 m area with 100B-scans per area at both 0 and 90°. Pre-incision iOCTscans were performed once the patient was positionedand prepped for surgery. All patients underwent corepars plana vitrectomy. Prior to elevating the posteriorhyaloid, intravitreal triamcinolone (Triesence) wasused to stain the posterior hyaloid. Following instilla-tion of the triamcinolone, iOCT scanning wasrepeated.Qualitative analysis of the changes in reflectivity

in the pre-injection and post-injection scans wasperformed with particular attention to the poster-ior hyaloid as well as at the level of the retina.Three-dimensional reconstruction was performedto evaluate the contrast enhancement of the poster-ior hyaloid anatomy.

RESULTSiOCT image analysis following instillation of triam-cinolone revealed increased hyper-reflectivity at theposterior hyaloid. This provided improved visual-isation of the posterior hyaloid anatomy and itsfocal insertion points (eg, fovea and optic nerve)and pre-macular bursa (figure 1A–D). Contrastenhancement was noted to have a granular hyper-reflectivity with increased shadowing noted poster-ior to the triamcinolone ‘granules’ (figure 1B,D).Triamcinolone contrast-enhanced iOCT also pro-vided evidence for the presence of a subclinical,inner retinal defect and possible full-thickness holein a vitreomacular traction case. Following removalof the hyaloid, the signal strength of the iOCT scanwas suboptimal with limited resolution of theretinal architecture. However, with the presence ofthe contrast agent, this subclinical abnormality

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could be visualised, as there appeared to be triamcinolone particleswithin the retinal substance suggesting a retinal defect (figure 2).Given these iOCT findings, the surgeon was able to address theabnormality (eg, gas tamponade, positioning) appropriately withan optimal surgical result. Three-dimensional reconstruction ofcontrast-enhanced iOCT scans highlighted the increased reflectiv-ity of the stained hyaloid intraoperatively and provided an out-standing view of the hyaloidal anatomy (figure 3).

DISCUSSIONThe in vivo use of contrast-enhanced OCT has been limited.3 4

In this report, we highlight the translation of this method to theoperating room through the use of contrast-enhanced iOCT.The increased reflectivity profile of triamcinolone, as visualisedduring iOCT, allowed for improved visualisation of posteriorstructures during vitreoretinal surgery, particularly related toposterior hyaloidal anatomy. The improved visualisation of pos-terior tissues has many implications for vitreoretinal surgery andiOCT. In one case of vitreomacular traction syndrome, iOCTfollowing hyaloid removal was of limited quality. However,

contrast enhancement within the retinal substance at the foveaprovided evidence of an inner retinal defect allowing thesurgeon to make appropriate changes in surgical management.Due to the limited scan quality, the enhanced contrast providedimproved visibility of the area of interest. Based on thesefinding, contrast-enhanced iOCT may facilitate the identificationof surgical planes and optimise surgical manoeuvres given theimprovement in anatomic visualisation. This is an area of activeresearch that we are pursuing.

The limitations of this study include the small sample size andretrospective nature. The qualitative analysis limits statisticaltesting of the data. However, the image differences are strikingand clearly represent changes in the reflectivity profile of thescans due to the presence of the agent. The novel nature of theuse of contrast enhancement for iOCT provides strength forthis study.

The advent of contrast agents has greatly improved the diag-nostic and therapeutic capacity of imaging modalities through-out medicine, such as CT and MRI. The development ofcontrast enhancement for OCT may expand its application and

Figure 1 (A) Pre-contrast intraoperative optical coherence tomography (iOCT) B-scan showing a faintly visible hyaloid and its insertion (arrow)at the macular hole shown above. (B) Post-contrast iOCT B-scan showing contrast enhancement of hyaloid insertion at a macular hole (arrow).(C) Pre-contrast iOCT B-scan showing a faint posterior hyaloid (arrow). (D) Post-contrast iOCT B-scan showing the hyaloidal insertion at the opticnerve (arrow) and shadowing posterior to IVT ‘granules’ (arrowhead).

Ehlers JP, et al. Br J Ophthalmol 2013;97:1384–1386. doi:10.1136/bjophthalmol-2012-303048 1385

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utility, resulting in a more dynamic or functional assessmenttool.3 4 11

The definitive role for contrast agents in OCTremains unknownand further research is needed to better understand the role forcontrast agents in iOCT. Additional testing of various agents isalso warranted to identify those agents with optimal properties(eg, increased reflectivity with minimal shadowing). Targeted con-trast is also important, such as for the internal limiting membraneor posterior hyaloid. Additionally, applications for anteriorsegment surgery need to be explored. Prospective analysis of theutility of contrast agents for iOCT is important. We have initiateda prospective study on the utility of iOCT that includes analysis ofthe reflectivity properties of adjuvant dyes (eg, indocyanine green)and other agents (eg, triamcinolone). Along with the microscopeintegration of OCT systems and OCT-compatible microsurgicaltools, OCT contrast agents may help to change the approach toophthalmic surgery.

Acknowledgements The authors thank Amit Vasanji, PhD of ImageIQ for hisassistance with three-dimensional reconstruction.

Competing interests The following competing interests may be relevant to thispublication: JPE-Bioptigen (P); PKK-Carl Zeiss Meditec (C), Alcon (C); SKS-Bauschand Lomb (C); Bioptigen (P).

Ethics approval Cleveland Clinic’s IRB.

Provenance and peer review Not commissioned; externally peer reviewed.

Data sharing statement Additional images of contrast-enhanced OCT imagesfrom the eyes included in this study are available if needed.

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Figure 2 Intraoperative optical coherence tomography B-scanfollowing hyaloid removal revealing contrast enhancement within theretinal substance (arrow) secondary to triamcinolone. Scan is of limitedquality and was unable to be improved at the time of imaging, makingthe resolution of retinal architecture difficult. Increased contrast andhyper-reflectivity within the retina allows the surgeon to identify theabnormality and strongly suggests the presence of an inner retinaldefect with partial or full-thickness retinal hole. Note triamcinolonegranules located at the optic nerve (arrowhead).

Figure 3 Three-dimensional reconstruction showing pre-contrast andpost-contrast-enhanced images improving visibility of the posteriorhyaloid and the hyaloidal anatomy. Prior to contrast application, theposterior hyaloid is minimally visible on optical coherence tomography(upper). Following instillation of contrast agent (triamcinolone), thehyaloid is visualised clearly (lower).

1386 Ehlers JP, et al. Br J Ophthalmol 2013;97:1384–1386. doi:10.1136/bjophthalmol-2012-303048

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doi: 10.1136/bjophthalmol-2012-30304823, 2013

2013 97: 1384-1386 originally published online AprilBr J Ophthalmol Justis P Ehlers, Stephen A McNutt, Peter K Kaiser, et al. coherence tomographyContrast-enhanced intraoperative optical

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