Optical coherence tomography (OCT) has revolutionized the evaluation of vitreoretinal disease1 and has informed surgical decision-making.2 Intraoperative OCT (iOCT) has been described using a variety of systems in a variety of pathological conditions.3,4 Handheld devices have been shown to be useful during examination under anesthesia (EUA) in children with vitreoretinal disease, such as retinopathy of prematurity.5 Handheld iOCT has also been described in macular surgery6,7 and retinal detachment repair.8 Microscope-mounted systems have been used in macular hole surgery,9 idiopathic epiretinal membrane (ERM) peeling,10,11 and repair of retinal detachment.12
The purpose of this investigation is to report the experience of one clinical center with the commercially available, handheld iVue (Optovue, Fremont, CA) spectral-domain (SD) iOCT system. The use of this iOCT system has been reported during EUA in a case of Coat's disease associated with facioscapulohumeral muscular dystrophy.13 To our knowledge, this is the first description of this system in a variety of vitreoretinal surgical scenarios.
Patients and Methods
This is a retrospective, observational case series examining the role of iVue iOCT system in vitreoretinal surgery. This study was approved by the institutional review board of Tufts Medical Center and was conducted in adherence to the tenets of the Declaration of Helsinki. Patients undergoing clinically indicated vitreoretinal surgical procedures that were imaged with the iVue system between February 2011 and March 2012 at the New England Eye Center, Tufts Medical Center, Boston, were identified. iVue is an SD-OCT system with an incident wavelength of 840 nm ± 10 nm imaging at 26,000 A-scan/second with a transverse resolution of 15 µm.
For intraoperative use, the handheld iVue was mounted onto a stabilizing arm, which was sterilely draped (Figure 1). The system was maneuvered to the appropriate focusing depth by the surgeon with the aid of a pupil camera. The system automatically focused on the retina within the range of −15D to +12D. Fine focus was then achieved manually. The area of interest in the retina was brought into view by maneuvering the patient's eye using a sterile, cotton-tipped applicator. Repeated scanning was often necessary before an image through the retinal area of interest was obtained. A 6 mm × 6 mm retinal thickness map and a 7-line high-resolution raster were displayed on a workstation connected to the handheld imaging system. Intraoperative images were taken before the use of sulfur hexafluoride (SF6) gas and after the removal of vitreous hemorrhage or silicone oil. Imaging used approximately 3 minutes of operative time. Images were qualitatively assessed and compared to fundus photography and perioperative OCT done in an outpatient clinical setting when available using Cirrus SD-OCT (Carl Zeiss Meditec, Dublin, CA). Review of patient medical records was also performed.
Photograph of the iVue handheld spectral-domain intraoperative optical coherence tomography system sterilely draped in an operative setting.
Five patients were identified (Table).
Data From the Five Cases Analyzed
In 2009, a 6-month-old girl presented with unilateral sporadic retinoblastoma in the right eye. On genetic testing, she was found not to have deletion of the retinoblastoma-1 gene. She underwent plaque radiotherapy, which resulted in regression of her tumor, and had been followed with serial EUAs. In 2011, at age 2, she underwent EUA, which confirmed that there was no subclinical recurrence of her disease and no evidence for radiation retinopathy. Intraretinal calcification found on fundus photography was identified in iOCT (Figure 2). There was no evidence of any lesions in her contralateral eye. She was able to fixate on and follow objects both before and after EUA.
Case 1: Examination under anesthesia. (A) Intraoperative optical coherence tomography (iOCT) macular thickness map. Red line indicates the retinal location of the (B) iOCT high-definition raster scan. (C) Intraoperative fundus photograph.
A 68-year-old woman with a history of an ERM in the left eye, which had been successfully treated with membrane peeling in 2010, presented with an ERM in the right eye in 2011. Preoperative best-corrected visual acuity (BCVA) was 20/50. She underwent 23-gauge pars plana vitrectomy (PPV) with membrane peeling in the right eye. iOCT images were obtained after the peel and demonstrated inner retinal changes (Figure 3). These changes could also be seen in the SD-OCT taken postoperatively as an outpatient. Postoperative BCVA was 20/25.
Case 2: Epiretinal membrane. (A) Intraoperative optical coherence tomography (iOCT) macular thickness map. Red line indicates the retinal location of the (B) iOCT high-definition raster scan. Note the residual inner retinal band of tissue. (C) iOCT macular thickness map. Red line indicates the retinal location of the (B) iOCT high-definition raster scan. Note the inner retinal changes. (E) Outpatient OCT taken before surgery. (F) Outpatient OCT taken postoperatively.
A 63-year-old man presented with a full-thickness macular hole in his right eye. His preoperative BCVA was 20/60. The patient underwent 23-gauge PPV with membrane peeling in the right eye. Indocyanine green dye was used to visualize the internal limiting membrane, which was also peeled. Images were taken with iOCT both before and after peeling. There was difficulty obtaining a scan centered over the fovea after membrane peel (Figure 4). Injection of SF6 to a level of 30% fill was then performed. Images were unable to be obtained through gas. Postoperative BCVA was 20/30.
Case 3: Macular hole. (A) Intraoperative optical coherence tomography (iOCT) macular thickness map. Red line indicates the retinal location of (B) iOCT high-definition raster scan taken before macular hole repair. (C) iOCT macular thickness map. Red line indicates the retinal location of the (B) iOCT high-definition raster scan taken after macular hole repair. (E) Outpatient OCT taken before surgery. (F) Outpatient OCT taken postoperatively.
A 71-year-old pseudophakic woman with a past ocular history of no light perception vision in the left eye due to a chronic total retinal detachment presented in 2008 with a new retinal detachment in the right eye. At that time, she underwent 20-gauge PPV with retinal detachment repair. Intraoperatively, proliferative vitreoretinopathy was noted and silicone oil was used. Her retina remained attached under oil with a BCVA of counting fingers at 4 feet. In 2012, she underwent 23-gauge PPV with removal of silicone oil. Intraoperatively, indirect biomicroscopy found the retina to be attached. iOCT demonstrated preretinal membranes and retinal thickening (Figure 5). The retinal location of the high-resolution raster scans was difficult to know because the map program was not functioning adequately. Images were unable to be obtained through oil. The patient's postoperative BCVA was 20/100.
Case 4: History of retinal detachment repair with silicone oil. (A) Intraoperative optical coherence tomography (iOCT) macular thickness map. Red line indicates the retinal location of the (B) iOCT high-definition raster scan taken after silicone oil removal. Case 5: Diabetic retinopathy with non-clearing vitreous hemorrhage. (C) iOCT macular thickness map. Red line indicates the retinal location of the (B) iOCT high-definition raster scan taken after removal of hemorrhage.
A 72-year-old man with a past medical history of poorly controlled diabetes and hypertension was being followed for diabetic retinopathy. He had a history of central retinal vein occlusion and cystoid macular edema in both eyes. The patient had undergone intravitreal injection of triamcinolone in both eyes, grid laser in the left eye, and intravitreal bevacizumab (Avastin; Genentech, South San Francisco, CA) in the right eye. He developed proliferative diabetic retinopathy in both eyes, which was treated with panretinal photocoagulation and complicated by vitreous hemorrhage. This necessitated a 23-gauge PPV with endolaser in the right eye in 2010. In 2011, the patient underwent 23-gauge PPV with endolaser in the left eye for non-clearing vitreous hemorrhage. His preoperative BCVA was counting fingers at 6 ft. Intraoperative images taken after removal of vitreous hemorrhage showed an atrophic macula without cystoid macular edema (Figure 5). His postoperative BCVA returned to his pre-hemorrhage baseline of 20/300.
Various iOCT systems have been used intraoperatively in a vitreoretinal surgical setting.3 Our investigation reports the use of a commercially available, portable, handheld SD-iOCT system in a variety of cases, including EUA, ERM, full-thickness macular hole, retinal detachment, and non-clearing vitreous hemorrhage in the setting of proliferative diabetic retinopathy.
The images obtained were clinically useful in all cases. In case 1 of an EUA in the setting of a treated, regressed retinoblastoma, iOCT confirmed that the lesion had no subclinical depth. In case 2 of ERM peel, iOCT demonstrated changes in the inner retinal architecture after membrane peeling. This phenomenon has been observed and is postulated to be convoluted internal limiting membrane.8 Similar changes were identified on out-patient OCT. In case 3 of a full-thickness macular hole, closure of the hole was demonstrated after repair on unregistered scans. By contrast, Ehlers et al. have reported increases in macular hole volume just after surgical repair with outer retinal changes.14 This underscores the need for further investigation. Postoperative outpatient OCT demonstrated closure of the hole, as well. In case 4 of silicone oil removal after retinal detachment repair, the retina was confirmed to be attached after oil removal with evidence of preretinal tractional bands. In case 5 of removal of vitreous hemorrhage in the setting of proliferative diabetic retinopathy, the macula was found to be flat after the hemorrhage was removed without cystoid macular edema.
This is the first description of the iVue in a variety of vitreoretinal surgical scenarios. The extent to which iOCT influences surgical decision-making warrants further investigation in more subjects. Advantages of this system are its relatively low cost and clinical versatility, and its ability to be attached to a slit lamp mount and used in a seated position. Images obtained intraoperatively were able to identify retinal features similar to those seen in an outpatient setting. However, the resolution of the iVue high-definition raster is not as good as that of the Cirrus high-definition 1-line raster.
Among the disadvantages of this system is that it is difficult to center the scan on the area of interest in the retina. Improved design of the stabilizing arm (iStand) to allow for movement of the iOCT system in multiple planes would be useful. Currently, the stabilizing arm is only able to be adjusted in the axial direction. Active registration software would also be helpful in image acquisition and improving comparability of images from the pre- and postoperative clinical setting. Further, it is unable to image through vitreous hemorrhage, SF6 gas, or silicone oil.
The use of the sterile draping technique in conjunction with the stabilizing arm improved image quality by minimizing movement issues reported with the hand-held technique6 with minimal addition to operative time. Future directions of investigation aimed at addressing the shortcomings of the handheld design include use of microscope integrated heads-up display.15,16
- Puliafito CA, Hee MR, Lin CP, et al. Imaging of macular diseases with optical coherence tomography. Ophthalmology. 1995;102(2):217–229. doi:10.1016/S0161-6420(95)31032-9 [CrossRef]
- Duker JS, Kaiser PK, Binder S, et al. The International Vitreomacular Traction Study Group classification of vitreomacular adhesion, traction, and macular hole. Ophthalmology. 2013;120(12):2611–2619. doi:10.1016/j.ophtha.2013.07.042 [CrossRef]
- Ehlers JP, Tao YK, Srivastava SK. The value of intraoperative optical coherence tomography imaging in vitreoretinal surgery. Curr Opin Ophthalmol. 2014;25(3):221–227. doi:10.1097/ICU.0000000000000044 [CrossRef]
- Hahn P, Migacz J, O'Connell R, Maldonado RS, Izatt JA, Toth CA. The use of optical coherence tomography in intraoperative ophthalmic imaging. Ophthalmic Surg Lasers Imaging. 2011;42Suppl:S85–94. doi:10.3928/15428877-20110627-08 [CrossRef]
- Chavala SH, Farsiu S, Maldonado R, Wallace DK, Freedman SF, Toth CA. Insights into advanced retinopathy of prematurity using handheld spectral domain optical coherence tomography imaging. Ophthalmology. 2009;116(12):2448–2456. doi:10.1016/j.ophtha.2009.06.003 [CrossRef]
- Dayani PN, Maldonado R, Farsiu S, Toth CA. Intraoperative use of hand-held spectral domain optical coherence tomography imaging in macular surgery. Retina. 2009;29(10):1457–1468. doi:10.1097/IAE.0b013e3181b266bc [CrossRef]
- Pichi F, Alkabes M, Nucci P, Ciardella AP. Intraoperative SD-OCT in macular surgery. Ophthalmic Surg Lasers Imaging. 2012;43(6 Suppl):S54–60. doi:10.3928/15428877-20121001-08 [CrossRef]
- Lee LB, Srivastava SK. Intraoperative spectral-domain optical coherence tomography during complex retinal detachment repair. Ophthalmic Surg Lasers Imaging. 2011;42 Online: e71–74.
- Hayashi A, Yagou T, Nakamura T, Fujita K, Oka M, Fuchizawa C. Intraoperative changes in idiopathic macular holes by spectral-domain optical coherence tomography. Case Rep Ophthalmol. 2011;2(2):149–154. doi:10.1159/000328752 [CrossRef]
- Nam DH, Desouza PJ, Hahn P, et al. Intraoperative spectral domain optical coherence tomography imaging after internal limiting membrane peeling in idiopathic epiretinal membrane with connecting strands. Retina. 2015;35(8):1622–1630. doi:10.1097/IAE.0000000000000534 [CrossRef]
- Ray R, Baranano DE, Fortun JA, et al. Intraoperative microscope-mounted spectral domain optical coherence tomography for evaluation of retinal anatomy during macular surgery. Ophthalmology. 2011;118(11):2212–2217. doi:10.1016/j.ophtha.2011.04.012 [CrossRef]
- Ehlers JP, Ohr MP, Kaiser PK, Srivastava SK. Novel microarchitectural dynamics in rhegmatogenous retinal detachments identified with intraoperative optical coherence tomography. Retina. 2013;33(7):1428–1434. doi:10.1097/IAE.0b013e31828396b7 [CrossRef]
- Lee GD, Chen VM, Barnes AC, Goldman DR, Duker JS. Retinal telangiectasis detected during a vision screening examination in a child with hearing loss led to the diagnosis of facioscapulohumeral muscular dystrophy. J AAPOS. 2014;18(3):303–305. doi:10.1016/j.jaapos.2014.02.009 [CrossRef]
- Ehlers JP, Xu D, Kaiser PK, Singh RP, Srivastava SK. Intrasurgical dynamics of macular hole surgery: an assessment of surgery-induced ultrastructural alterations with intraoperative optical coherence tomography. Retina. 2014;34(2):213–221. doi:10.1097/IAE.0b013e318297daf3 [CrossRef]
- Ehlers JP, Srivastava SK, Feiler D, Noonan AI, Rollins AM, Tao YK. Integrative advances for OCT-guided ophthalmic surgery and intraoperative OCT: microscope integration, surgical instrumentation, and heads-up display surgeon feedback. PLoS One. 2014;9(8):e105224. doi:10.1371/journal.pone.0105224 [CrossRef]
- Tao YK, Srivastava SK, Ehlers JP. Microscope-integrated intraoperative OCT with electrically tunable focus and heads-up display for imaging of ophthalmic surgical maneuvers. Biomed Opt Express. 2014;5(6):1877–1885. doi:10.1364/BOE.5.001877 [CrossRef]
Data From the Five Cases Analyzed
|Case||Age||BCVA Preoperatively||BCVA Postoperatively||Diagnosis||Procedure|
|1||2||Fixate and follow||Fixate and follow||Retinoblastoma||Examination under anesthesia|
|2||68||20/50||20/25||Epiretinal membrane||PPV with membrane peel|
|3||63||20/60||20/30||Macular Hole||PPV with repair of macular hole and SF6 gas|
|4||75||CF 4 ft||20/100||History of retinal detachment repair with silicone oil||PPV with silicone oil removal|
|5||72||CF 6 ft||20/400||Diabetic retinopathy vitreous hemorrhage||PPV with removal hemorrhage|