From Emory Eye Center (LBL), Emory University, Atlanta, Georgia; and Cole Eye Institute (SKS), Cleveland Clinic Foundation, Cleveland, Ohio.
Presented as a poster at the Association for Research in Vision and Ophthalmology annual meeting; May 2–6, 2010; Fort Lauderdale, Florida.
The authors have no financial or proprietary interest in the materials presented herein.
Address correspondence to Sunil K. Srivastava, MD, Cole Eye Institute, Cleveland Clinic Foundation, 9500 Euclid Ave., i32, Cleveland, OH 44195. E-mail: firstname.lastname@example.org
Perfluorocarbon liquids are used as adjunctive tools during vitrectomy surgery for complex retinal detachment repair. The high specific gravity and optical clarity of these materials allow their use intraoperatively for temporary tamponade and mechanical fixation of the retina. These substances facilitate flattening and unfolding of the retina by displacing subretinal fluid anteriorly.1–4 However, it is unclear what specific changes occur to the retinal ultrastructure immediately following placement of perfluorocarbon liquids in the eye.
Optical coherence tomography (OCT) is a non-invasive tool that allows assessment of retinal architecture by producing detailed in vivo imaging of the photoreceptors and retinal pigment epithelium.5,6 Compared with time-domain OCT, spectral-domain OCT (SD-OCT) provides enhanced imaging resolution and faster acquisition time, creating a more complete image of retinal microstructure.7–9
To understand the effects of perfluorocarbon liquids on the retinal anatomy during detachment repair, we present two patients who underwent intraoperative SD-OCT imaging during vitrectomy surgery using perfluoro-n-octane (PFO).
A 78-year-old woman with a history of age-related macular degeneration presented with a macula-off retinal detachment in her left eye. Visual acuity with correction measured 20/50 in the right eye and 20/400 in the left eye. She underwent surgical repair of her retina, including placement of a scleral buckle and pars plana vitrectomy. During the case, PFO was injected into the eye to flatten the retina. An air–fluid exchange was performed and silicone oil was then placed in the eye.
Figure 1 demonstrates the SD-OCT images obtained preoperatively, after PFO injection, and after injection of silicone oil. A large area of subretinal fluid was seen on the preoperative image. After PFO instillation, persistent subretinal hyporeflectance was seen (Fig. 1B, arrows), consistent with subretinal fluid. The subretinal fluid resolved by 1 month. After silicone oil removal, SD-OCT did not display any subretinal fluid, but there was disruption of the inner segment–outer segment junction. Final visual acuity in the left eye measured counting fingers at 3 feet.
Figure 1. Spectral-domain optical coherence tomography images obtained preoperatively, intraoperatively, and postoperatively from case 1. (A) Preoperative imaging confirms a macula-off retinal detachment (arrow). (B) Intraoperative image, after instillation of perfluoro-n-octane, shows incomplete flattening of the retina with residual subretinal fluid (arrows). (C) Postoperative image at 4 months shows resolution of subretinal fluid under silicone oil. (D) Postoperative image at 5 months following silicone oil removal demonstrates disruption of the inner segment–outer segment junction (arrowheads).
A 51-year-old woman presented with a recurrent macula-off rhegmatogenous retinal detachment in the left eye. Two months previously, she had undergone scleral buckling, pars plana vitrectomy, and C3F8 gas fill in the left eye. During her second surgery, a pars plana vitrectomy with lensectomy, membrane peeling, inferior retinectomy, endolaser, and silicone oil tamponade was performed.
Figure 2 demonstrates the SD-OCT images obtained preoperatively, after PFO injection, and after injection of silicone oil. A large area of subretinal fluid was seen on the preoperative image. After PFO injection, persistent subretinal hyporeflectance was seen (Fig. 2B, arrows), consistent with subretinal fluid. This hyporeflectance was present under silicone oil at 1-month follow-up (Fig. 2C), persisted mildly under oil after 4 months, and resolved by month 6. Disruption of the inner segment–outer segment junction was also noted. Visual acuity was hand motions by postoperative month 4 and remained the same at 6-month follow-up.
Figure 2. Spectral-domain optical coherence tomography images obtained preoperatively, intraoperatively, and postoperatively from case 2. (A) Preoperative imaging confirms a macula-off retinal detachment (arrow). (B) Intraoperative image following instillation of perfluoro-n-octane reveals residual subretinal fluid (arrows). (C) Postoperative image at 1 month shows subretinal fluid under silicone oil (arrowheads). (D) Postoperative image at 4 months shows a trace amount of subretinal fluid under silicone oil (arrowheads). (E) Postoperative image at 6 months shows resolution of subretinal fluid under silicone oil.
Perfluorocarbon liquids are used as adjunctive tools during repair of complex retinal detachments. To identify changes in retinal microstructure that occur during rhegmatogenous retinal detachment repair with perfluoro-n-octane in human eyes, we obtained images of patients undergoing pars plana vitrectomy for rhegmatogenous retinal detachment using intraoperative SD-OCT. Our results demonstrate the ability to obtain high-resolution, real-time images of retinal architecture intraoperatively through PFO and silicone oil. Furthermore, our study shows that residual subretinal fluid may be identified intraoperatively despite tamponade with PFO. This residual subretinal fluid may explain why some patients have more prolonged recovery following rhegmatogenous retinal detachment repair.
The OCT finding of residual subretinal fluid following repair of macula-involving retinal detachments has been described previously and is estimated to occur in 12% to 25% of cases.10–14 In our two cases, the amount of subretinal fluid on SD-OCT decreased significantly after PFO injection. Clinically there was no evidence of subretinal fluid following PFO instillation. Because the amount of fluid identified was small in both cases, no further manipulation was performed. In one of the two cases, this subretinal fluid resolved by month 1. In the other case (case 2), the amount of fluid present postoperatively persisted until 6 months but decreased with time. It is possible that the area of subretinal hyporeflectance in this second case represents changes in the outer retina rather than fluid. However, given the appearance of residual fluid during surgery, we believe this hyporeflectance represents subretinal fluid.
In both cases, visual outcomes were poor and more likely due to the damage from the detachment itself (and macular degeneration in case 1) than to the presence of persistent subretinal fluid. In both cases, we identified disruptions at the inner segment–outer segment junction in the postoperative SD-OCT images. In case 1, this finding may also be related to the patient’s underlying advanced macular degeneration. This disruption in the inner segment–outer segment junction may have relevance as an indication of damage to the photoreceptors.10–12
A hand-held SD-OCT probe (Bioptigen, Inc., Durham, NC) that is microscope-mounted was used to acquire images preoperatively, following tamponade with PFO, and after silicone oil instillation. Its use in the operating room via a handheld probe was previously described.15 However, a limitation of this probe is the need to hold the hand steady during image acquisition. The use of a custom-made microscope mount reduces the movement error generated from hand-held use.
Intraoperative OCT imaging during retinal detachment surgery has several potential benefits. It can provide additional information of the retinal architecture, including confirmation of macular involvement and the presence and location of preretinal and subretinal membranes. Additionally, after placement of PFO, intraoperative imaging may help identify previously unrecognized pockets of subretinal fluid. By having this information intraoperatively, the surgeon may decide to employ additional techniques, whether removal of clinically unidentified preretinal membranes or further manipulation to remove residual subretinal fluid, to ensure adequate repair.
Future applications of intraoperative imaging include correlating intraoperative findings with postoperative visual outcomes. This technique may improve patient outcomes by providing surgeons with additional information with which to make decisions regarding surgical management and by allowing more precision in surgical techniques.
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