Retina Changes in Blood Flow on Optic Nerve Head After Vitrectomy for Rhegmatogenous Retinal Detachment Takeshi Iwase, Misato Kobayashi, Kentaro Yamamoto, Kosei Yanagida, Eimei Ra, and Hiroko Terasaki Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan Correspondence: Takeshi Iwase, De- PURPOSE. To determine the preoperative characteristics and the changes in retinal blood flow partment of Ophthalmology, Nagoya following vitrectomy in eyes with a rhegmatogenous retinal detachment (RRD). University Graduate School of Medi- cine, 65 Tsurumai-cho, Showa-ku, METHODS. Twenty-five–gauge vitrectomy without scleral bucking was performed on 31 eyes of Nagoya 466-8560, Japan; 31 patients with macula-on RRD. The retinal blood flow on the optic nerve head (ONH) was [email protected]. assessed by laser speckle flowgraphy (LSFG), and the mean blur rate (MBR) and pulse Submitted: August 21, 2016 waveform parameters before and at 10 days, 1, 2, 3, and 6 months after the surgery were Accepted: October 10, 2016 examined. Eyes treated by scleral buckling, and eyes with an epiretinal membrane and cataract that underwent surgery were used as controls. Citation: Iwase T, Kobayashi M, Ya- mamoto K, Yanagida K, Ra E, Terasaki RESULTS. The mean preoperative MBR-vessel on the ONH was significantly lower in eyes with H. Changes in blood flow on optic RRD than in the fellow unaffected eyes (P < 0.001), but it was not significantly different from nerve head after vitrectomy for rheg- the operated eye and the fellow eye in the control group. A significant increase in the mean matogenous retinal detachment. In- MBR-vessel on the ONH was observed following vitrectomy in eyes affected by RRD (P < vest Ophthalmol Vis Sci. 0.001), whereas no significant difference was observed in the fellow eye, the scleral 2016;57:6223–6233. DOI:10.1167/ buckling–treated eyes, and the control eyes. Of the eight pulse waveform parameters, only iovs.16-20577 the flow acceleration index was significantly lower in eyes with a RRD than in the fellow eyes preoperatively, but then it significantly increased with time following vitrectomy. The changes in the MBR-vessel were not correlated with that of other parameters (e.g., the ocular perfusion pressure). CONCLUSIONS. These results indicate that the retinal blood flow is reduced in eyes affected by RRD preoperatively, and can recover following successful RRD repair by vitrectomy. Keywords: retinal blood flow, rhegmatogenous retinal detachment, vitrectomy, laser speckle flowgraphy rhegmatogenous retinal detachment (RRD) is a separation incision instruments and wide-angle viewing systems.13 Be- A of the sensory retina from the RPE caused by tears in the cause PPV without concomitant scleral buckling does not entail retina and can lead to a permanent loss of vision if untreated.1 a compressional step, it is possible to evaluate the natural Rhegmatogenous retinal detachment is usually treated by either course of ocular blood flow before and after successful RRD scleral buckling alone or by pars plana vitrectomy (PPV) with repair. However, there have been only a few studies examining or without scleral buckling. The results of a randomized the effects of PPV on the ocular blood flow in eyes with RRD. controlled trial indicated that both of these surgical procedures Kimura et al.14 reported that the ocular microcirculation is led to successful reattachment in phakic, pseudophakic, and normal 6 months after PPV for RRD. It has been reported that a 2 aphakic patients with similar final reattachment rates. gas tamponade might have subclinical adverse effects on the Although scleral buckling is a well-established surgical circulation in the region of the neuroretinal disk rim.14 treatment for RRD, it has been reported that the procedure A variety of techniques have been developed for measuring can cause problems in the ocular circulation.3–10 Diddie and the retinal blood flow including fluorescein angiography,15 Ernest7 used the microsphere technique and found that the radioactive microspheres,16 hydrogen clearance,17 laser Dopp- encircling buckling method significantly decreased the retinal ler technique,4,5 color Doppler ultrasonography,18 and the and choroidal circulation in rabbit eyes. There have also been 9 several studies reporting that scleral buckling can reduce the pulsatile technique. Time intensiveness and problems with retinal5,6,8 and choroidal blood flow.9–11 Compressional mech- reproducibility have hampered the widespread use of many of anisms have been cited as the cause of the reduced choroidal these measurement techniques. More recently, a Doppler 19 blood flow following scleral buckling.7,12 Thus, the reduced optical coherence tomographic (OCT) technique, OCT ocular blood flow has been attributed to a direct obstruction of angiography,20 and optical microangiography (OMAG)21,22 have the choroidal venous drainage by the scleral buckling, and the been developed and used to measure the blood flow on the time course of the ocular blood flow following scleral buckling optic nerve head (ONH) and retina using high-resolution depth- is always affected by the procedures. resolved imaging with high reproducibility. However, these The safety and effectiveness of PPV has improved by the techniques still have inherent limitations for clinical use improvements in the surgical instruments including micro because of the time intensiveness of the procedures. iovs.arvojournals.org j ISSN: 1552-5783 6223 This work is licensed under a Creative Commons Attribution 4.0 International License. Downloaded from iovs.arvojournals.org on 09/27/2021 Changes in Blood Flow After Retinal Detachment IOVS j November 2016 j Vol. 57 j No. 14 j 6224 Laser speckle flowgraphy (LSFG) is a noninvasive, real-time All patients underwent a comprehensive ophthalmic method that has been used to measure the relative blood flow examination as standard examination in our hospital including on the ONH. The measurement duration is only 4 seconds and the measurements of the IOP and axial length, slit-lamp can be performed without the intravenous injection of any biomicroscopy, fundus photography with the Optomap camera contrast agents.23–25 A recent update of the software embed- (Optos plc., Dunfermline, Scotland), spectral-domain OCT (SD- ded in the most recent LSFG device (LSFG Analyzer, v. 3.1.62; OCT; Spectralis OCT, Heidelberg Engineering, Heidelberg, Softcare Co., Ltd., Fukutsu, Japan) enables the recording of Germany), and LSFG before, and 10 days, and 4, 8, 12, and images synchronized with each cardiac cycle, and can then 24 weeks after the surgery. determine the various blood flow parameters at each All patients were asked to abstain from alcoholic and heartbeat. Laser speckle flowgraphy can detect the speckle caffeinated beverages on the morning of the day of the contrast pattern produced by the interference of the illumi- examination because the intake of alcohol and caffeine can nating laser light that is scattered by the movement of influence the IOP28,29 and blood pressure.30,31 Thirty minutes erythrocytes in the blood vessels. This enables the device to before the LSFG examinations, 0.4% tropicamide/phenyleph- calculate the relative blood flow in the vessels of the ONH and rine (Mydrin P; Santen Pharmaceutical Co., Ltd., Osaka, Japan) retina, which is expressed as the mean blur rate (MBR).23–25 was used to dilate the pupil. The subjects rested for 10 to 15 The ‘‘vessel extraction’’ function of the software then identifies minutes in a quiet, dark room before the examination, and all the vessel and tissue areas on the ONH so that the MBR of each examinations were performed in the sitting position. The area can be assessed separately. The vessel area can be used to refractive error (spherical equivalent) was measured with an evaluate the blood flow in the retinal vessels excluding the autorefractometer (KR8900; Topcon, Tokyo, Japan), and the choroidal blood vessels.26 Aizawa et al.27 reported that the axial lengths were measured by partial optical coherence coefficient of variation (COV) for determining the MBR was 3.4 interferometry (IOLMaster; Carl Zeiss Meditec, La Jolla, CA, for the ONH. Therefore, LSFG is considered to be suitable for USA). The IOP was measured with a handheld tonometer measuring the blood flow rates on the ONH. (Icare; Tiolat Oy, Helsinki, Finland). The systolic and diastolic However, there have been only a few reports describing the blood pressures (SBP and DBP) were measured at the left ocular blood flow in eyes affected by RRD before surgery and brachial artery at the height of the heart in a sitting position that following PPV. It is not easy to estimate the preoperative with an automatic sphygmomanometer (CH-483C; Citizen, retinal blood flow in eyes affected by RRD because the retinal Tokyo, Japan). The mean arterial blood pressure (MAP), and vessels are tortuous and ascend vertically to the surface to the mean ocular perfusion pressure (MOPP) were calculated as RPE in the areas where the retina is detached. follows: MAP ¼ DBP þ 1/3 (SBP À DBP), MOPP ¼ 2/3MAP À 32 Thus, the aim of this study was to evaluate the blood flow IOP. on the ONH in the PPV-treated eyes with RRD by comparing The size of the retinal tear and the extent of the retinal the values with that of the fellow eyes and the scleral buckling– detachment were calculated as the ratio of retinal tear or treated eyes. Laser speckle flowgraphy was used to determine extent of detachment area to the area of the entire fundus the changes in the ONH blood flow before and after surgery. photograph taken with the Optomap camera. Laser Speckle Flowgraphy (LSFG) ETHODS M The LSFG-NAVI (Softcare Co., Ltd.) instrument was used to Ethics Statement determine the ONH blood flow. The principles of LSFG have been described in detail.33–36 Briefly, this instrument consists This was a retrospective, cross-sectional, single-center study, of a fundus camera equipped with an 830-nm diode laser as the and the procedures used were approved by the Ethics light source and a standard charge-coupled device sensor (750 Committee of the Nagoya University Hospital (Nagoya, Japan).