Settings, Techniques, and Technologies Oh H, Oshima Y (eds): Microincision Vitrectomy Surgery. Emerging Techniques and Technology. Dev Ophthalmol. Basel, Karger, 2014, vol 54, pp 147–149 (DOI: 10.1159/000360460)

Intraocular Optical Coherence Tomography Marco Mura a  · Francesco Barca b  

 

b

Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; U.O. Chirurgia Oftalmica, Azienda Ospedaliero Universitaria Pisana (AOUP), Pisa, Italy

 

Abstract Since its introduction as a diagnostic instrument, optical coherence tomography (OCT) has become an essential instrument for ophthalmologists as it offers accurate details on both the vitreoretinal interface and the retinal layers. Initially designed as a pre- and post-operative instrument, today we are attending to its introduction as an intraoperative tool. Inspired by the intravascular use of the OCT, we developed a prototype spectral domain OCT probe for intraocular use. It is therefore possible to make dynamic real-time scans from the vitreous and retina at the posterior pole and in the peripheral retina. This type of endo-OCT may therefore help surgeons during surgical procedures, making them safer and more accurate. © 2014 S. Karger AG, Basel

In the last decade, optical coherence tomography (OCT) has changed the way ophthalmologists diagnose and treat vitreoretinal diseases. Pre- and postoperative OCT examinations have led to a better understanding of the pathophysiology and prognosis in vitreoretinal diseases [1, 2]. Image resolution and scanning speed have substantially improved with the recent introduction of spectral domain OCT, providing structural details of the retina and vitreoretinal interface at an almost histological level [3]. The use of OCT during vitreo-

retinal surgery has been described before in the form of hand-held probes or microscope-mounted OCT systems [4, 5]. This intraoperative use of the OCT has proven to be useful in the decisionmaking process during surgery, resulting in improved technical performance and ultimately a better outcome for the patients [6]. In recent years, OCT has become an irreplaceable tool for the diagnosis, management, and prognosis of many vitreoretinal diseases [1–3]. However, the idea of having OCT as an adjuvant during surgery is relatively new [4, 5]. The first report describing the use of a hand-held OCT device was published in 2009 [7–9]. Recently, Binder et al. [5] reported the application of a standard OCT system mounted in the operating microscope. Due to its inherent technical limitations, microscope-mounted OCT has mainly been used to obtain scans of the central macular area, to assess the completeness of the macula peeling of epiretinal membrane and internal limiting membrane and to identify local iatrogenic damage after membrane peeling. This device can also be used to assess the presence of subretinal fluid in the macula area in cases of retinal detachment. Of course, static microscope-mounted standard OCT devices offer only limited possibilities in a dynamic surgical environment. The devices Downloaded by: University of Hong Kong 198.143.53.1 - 8/17/2015 5:51:28 AM

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Fig. 1. Schematic representation of a side-scanning OCT probe.

Fig. 2.Intraocular OCT image of the subretinal membrane (SRM).

patients without the use of any staining that could potentially be toxic, especially in a detached retina. Furthermore, identification of early proliferative vitreoretinopathy or the presence of remnants of a posterior hyaloid can be very difficult even with the use of staining a­ djuvants. The possibility of identifying and removing proliferative tissue from the subretinal space with the help of real-time OCT images reduces the need for larger retinotomies (fig. 2). This decreases unnecessary iatrogenic damage and leads to

Mura · Barca Oh H, Oshima Y (eds): Microincision Vitrectomy Surgery. Emerging Techniques and Technology. Dev Ophthalmol. Basel, Karger, 2014, vol 54, pp 147–149 (DOI: 10.1159/000360460)

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described by Binder et al. [5] and Ray et al. [4] do not have the possibility to examine more peripheral areas of the eye, which can be imaged very well with an intraocular probe. An intraocular probe can offer dynamic examination and real-time imaging during surgery without the need for a tracking system and an image stabilization system. We have used a prototype intraocular probe to assess several patients during retina surgery [10]. The device is a 23-gauge sidescanning spectral domain OCT probe in a 20-gauge catheter. The device works at wavelength of 1,300 nm, it has a 15-micron axial resolution, 6-mm field of view, and 4 mm of working distance (fig. 1). With the OCT prototype, the following was possible: (1) Detection of the presence of otherwise invisible membranes, e.g. epiretinal membrane proliferation (2) Identification of subretinal membranes otherwise not visible due to the presence of substantial retinal edema and thickened retina (3) Confirming the completeness of membrane removal in patients with epiretinal and subretinal membrane proliferation (4) Identification of small retinal breaks, especially in patients with very light colored fundi impossible to detect with a standard internal search (5) Identification and localization of a cleavage plane in patients with tractional retinal detachment and combined tractional retinal detachment-rhegmatogenous retinal detachment (6) Detection of residual subretinal fluid, perfluorocarbon, or silicone oil in the macula area and peripherally in an air-filled eye or an eye with hazy optical media An intraocular OCT probe offering dynamic scan capabilities could also be useful in various steps of the surgical procedure. The identification of epiretinal proliferation makes it possible to perform epiretinal membrane peeling in these

less exposed retinal pigment epithelium and diminished induction of inflammation through the use of a laser – all positive effects that may lead to a better outcome for the patient. The possibility of an intraocular OCT probe for scanning is also advantageous in cases of opacified media or in air-filled eyes where the visibility is poor. In those cases, visualization of the retina becomes challenging, and it becomes impossible to identify, for example, residual perfluorocarbon liquid or the presence of subretinal perfluorocarbon liquid/oil/fluid, which if not properly removed can lead to retinal folds and poor visual prognosis. The possibility to perform OCT-guided vitreous body removal provides certainty over the complete removal of all possible vitreous tractions. As a common procedure, vitreous shaving is performed in patients with the aid of triamcinolone, but following this procedure a significant amount of vitreous is seen to be left in place when checked with the intraocular OCT probe.

Small retinal breaks can sometimes be missed, especially in patients with very light pigmented fundi. In these patients a scan of the periphery with the intraocular OCT probe can highlight the presence of the breaks. In cases of fibrovascular proliferation, such as proliferative diabetic retinopathy, it can sometimes be challenging to find the correct cleavage plane, but intraoperative OCT can show a clear identification of such planes to guide the dissection. That means safer removal of fibrovascular tissue from the retinal surface, reducing the chance of iatrogenic damage. In conclusion, an intraocular endoprobe can provide the surgeon with extremely important information, helps him in the decision-making progress (especially in more complex retinal pathology), and allows him to perform OCT-guided surgical maneuvers with potential improvement of the precision and safety of the procedure that could lead to better surgical outcomes.

References   4 Ray R, Barañano DE, Fortun JA, Schwent BJ, Cribbs BE, Bergstrom CS, Hubbard GB 3rd, Srivastava SK: Intraoperative microscope-mounted spectral domain optical coherence tomography for evaluation of retinal anatomy during macular surgery. Ophthalmology 2011; 118:2212–2217.   5 Binder S, Falkner-Radler CI, Hauger C, Matz H, Glittenberg CG: Clinical applications of intrasurgical SD-optical coherence tomography. ARVO Meeting Abstracts 2010;51:268.   6 Huang LL, Hirose T: Portable optical coherence tomography in management of vitreoretinal diseases: current developments, indications, and implications. Semin Ophthalmol 2012;27:213–220.

Marco Mura Academic Medical Center, University of Amsterdam Meibergdreef 9 NL–1105AZ Amsterdam (The Netherlands) E-Mail [email protected]

  7 Scott AW, Farsiu S, Enyedi LB, Wallace DK, Toth CA: Imaging the infant retina with a hand-held spectral-domain optical coherence tomography device. Am J Ophthalmol 2009;147:364–373.   8 Muni RH, Kohly RP, Sohn EH, Lee TC: Hand-held spectral domain optical ­coherence tomography finding in ­shaken-baby syndrome. Retina 2010; 30(4 ­suppl):S45–S50.   9 Chong GT, Farsiu S, Freedman SF, et al: Abnormal foveal morphology in ocular albinism imaged with spectral-domain optical coherence tomography. Arch Ophthalmol 2009;127:37–44. 10 Mura M, Barca F, Chung R, Tan HS, Engelbrecht LA, de Bruin M, Verbraak F: Use of a new intra-ocular spectral domain OCT in vitreo-retinal surgery. Am J Ophthalmol 2013, submitted.

Intraocular OCT Oh H, Oshima Y (eds): Microincision Vitrectomy Surgery. Emerging Techniques and Technology. Dev Ophthalmol. Basel, Karger, 2014, vol 54, pp 147–149 (DOI: 10.1159/000360460)

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  1 Adhi M, Duker JS: Optical coherence tomography – current and future applications. Curr Opin Ophthalmol 2013;24: 213–221.   2 Sakata LM, Deleon-Ortega J, Sakata V, Girkin CA: Optical coherence tomography of the retina and optic nerve – a review. Clin Experiment Ophthalmol 2009;37:90–99.   3 Kiernan DF, Mieler WF, Hariprasad SM: Spectral-domain optical coherence tomography: a comparison of modern high-resolution retinal imaging systems. Am J Ophthalmol 2010;149:18–31.

Intraocular optical coherence tomography.

Since its introduction as a diagnostic instrument, optical coherence tomography (OCT) has become an essential instrument for ophthalmologists as it of...
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