Bubble cascade may form not only in stout beers.

In a glass of stout beer, a very large number of small dispersed bubbles form a texture motion of a bubble swarm moving downwards. Such a cascading motion is caused by a gravity-driven hydrodynamic instability and depends on the interbubble distance. To estimate these two corresponding indicators, an experimentally measured velocity profile is required and, thus, is obtained a posteriori. However, it is unknown why the bubble cascade is observed only in stout beer with nitrogen, such as Guinness beer. To address this question via a priori estimation, here, we develop a mathematical continuum model of film flow in bubbly liquid, uncovering the essential dynamics among many physical processes occurring simultaneously in a glass. To validate the proposed model, we perform a numerical simulation of the distribution of massless Lagrangian particles in an inclined container. We investigate the effects of particle concentration, inclination angle, particle diameter, and container size on the cascading film flow. The results reveal that the motion and waviness of clear-fluid film can be successfully estimated a priori to experiments or simulations. Moreover, it is found that the continuum behavior of particles in the film flow is analogous to the continuum description of rarefied gas dynamics. These findings explain how the cascading bubbles in a pint glass of stout beer satisfy the continuum assumption and suggest a general condition for the onset of the cascade, for instance, a 200-l drum for carbonated water.

Long-term outcomes of intravitreal activated protein C injection for ischemic central retinal vein occlusion: an extension trial.

PURPOSE: Our previous 1-year pilot study evaluated the efficacy of intravitreally injected activated protein C (APC) in 10 eyes with ischemic central retinal vein occlusion (CRVO). The reperfusion of the areas of retinal nonperfusion (RNP) exceeded 50% of the baseline in five (50%) eyes 1 year after the APC injection. The current study evaluated the long-term efficacy and safety of intravitreal APC. METHODS: The 10 eyes in the pilot study were included in this study. Other treatments were administered at the physicians' discretion after the pilot study. We evaluated visual acuity (VA), central retinal thickness (CRT) and perfusion status, and adverse events and severity over the long term. RESULTS: The median follow-up was 60 months (range, 48-68 months). Compared with baseline, the post-treatment VA improved significantly (P < 0.001) from 1.39 to 1.06 logarithm of the minimum angle of resolution. The CRT improved significantly (P < 0.001) from 1090 to 195 µm at the last visit. The RNP areas decreased from an average 29.7 disc areas (DAs) at baseline to an average 16.5 DAs at the last examination (mean, 40 ± 6.5 months after the first APC treatment). No adverse events were related to intravitreal APC. CONCLUSION: No complications were associated with intravitreal APC, the clinical course improved, and improved RNP was maintained for the long term, suggesting that intravitreal APC may be an alternative treatment for CRVO.

Activated Protein C for Ischemic Central Retinal Vein Occlusion: One-Year Results.

Intravitreally administered activated protein C in 10 eyes with ischemic central retinal vein occlusion significantly improved macular edema; in 5 eyes, the reperfusion of the retinal nonperfused areas exceeded 50% of baseline.

VOLUME-RENDERED ANGIOGRAPHIC AND STRUCTURAL OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY OF MACULAR TELANGIECTASIA TYPE 2.

PURPOSE: To evaluate multimodal imaging including volume-rendered angiographic and structural optical coherence tomography of macular telangiectasia Type 2 (MacTel2) for right-angle vein complexes, macular cavitations, and signs of deeper retinal vascular invasion. METHODS: Retrospective review of imaging performed in a community-based retinal referral center. The eyes were scanned using optical coherence tomography using split-spectrum amplitude-decorrelation techniques to derive flow information. These data were extracted and used to create volume-rendered images of the retinal vasculature with integrated structural information derived from the component optical coherence tomographic images. RESULTS: There were 24 eyes of 16 patients who had a mean age of 61.8 years. Right-angle veins seemed in association with vascular proliferation external to the deep vascular plexus. The origin of a right-angle vein was surrounded by a stellate arrangement of radiating retinal vessels apparently caused by contraction of surrounding tissue in the temporal macula. Cavitations were found in the fovea and varied in size and configuration from one examination to the next. Many smaller cavitations, called microcavitations, were seen in the surrounding macula. Vascular invasion occurred into the subretinal space. CONCLUSION: There are contractile features of the tissue in the temporal macula and the number, size, and temporal variations in the cavitations have not been in not mentioned in previous published descriptions of MacTel2. Vascular invasion of deeper layers occurred in the temporal macula through the outer nuclear layer. Volume-rendered angiographic and structural optical coherence tomography offers unprecedented ability to examine the vascular interrelationships their associations with cavitations in the macula.

A Comparison Between Optical Coherence Tomography Angiography and Fluorescein Angiography for the Imaging of Type 1 Neovascularization.

PURPOSE: To determine the sensitivity of the combination of optical coherence tomography angiography (OCTA) and structural optical coherence tomography (OCT) for detecting type 1 neovascularization (NV) and to determine significant factors that preclude visualization of type 1 NV using OCTA. METHODS: Multicenter, retrospective cohort study of 115 eyes from 100 patients with type 1 NV. A retrospective review of fluorescein (FA), OCT, and OCTA imaging was performed on a consecutive series of eyes with type 1 NV from five institutions. Unmasked graders utilized FA and structural OCT data to determine the diagnosis of type 1 NV. Masked graders evaluated FA data alone, en face OCTA data alone and combined en face OCTA and structural OCT data to determine the presence of type 1 NV. Sensitivity analyses were performed using combined FA and OCT data as the reference standard. RESULTS: A total of 105 eyes were diagnosed with type 1 NV using the reference. Of these, 90 (85.7%) could be detected using en face OCTA and structural OCT. The sensitivities of FA data alone and en face OCTA data alone for visualizing type 1 NV were the same (66.7%). Significant factors that precluded visualization of NV using en face OCTA included the height of pigment epithelial detachment, low signal strength, and treatment-naïve disease (P < 0.05, respectively). CONCLUSIONS: En face OCTA and structural OCT showed better detection of type 1 NV than either FA alone or en face OCTA alone. Combining en face OCTA and structural OCT information may therefore be a useful way to noninvasively diagnose and monitor the treatment of type 1 NV.

Fecal Lipid Excretion after Consumption of a Black Tea Polyphenol Containing Beverage-Randomized, Placebo-Controlled, Double-Blind, Crossover Study.

Obesity is a serious medical condition worldwide. Inhibition of lipid absorption is very important in preventing obesity. In a previous study, we found that postprandial elevation of triacylglycerol was suppressed by the intake of black tea polyphenol (BTP). We also reported that BTP caused lipid excretion into feces in an animal study. The present study is a clinical trial that examined lipid excretion. In this randomized, placebo-controlled, double-blind, crossover study, in the first test period participants were asked to drink either a beverage containing 55 mg BTP or a control beverage without BTP 3 times a day for 10 d. After an 11-d interval, for the second test period, they then drank the alternate test beverage 3 times a day for 10 d. During the test periods, the participants were asked to eat meals standardized according to calorie and fat content. Stool samples were obtained during the last 3 d of each test period for fecal lipid measurements. Total lipid excretion increased from 5.51±1.73 to 6.87±1.91 g/3 d after BTP intake in comparison with intake of the control beverage. These results indicated that BTP increased lipid excretion.

The Spatial Profile of Macular Pigments Is Related to the Topological Characteristics of the Foveal Avascular Zone.

PURPOSE: Macular pigments are preferentially concentrated in the central fovea, an area devoid of vasculature. We hypothesized that there may be a link between the macular pigment profile and the size and structural characteristics of the foveal avascular zone (FAZ). METHODS: Two-wavelength autofluorescence method was used to quantify macular pigment optical density (MPOD) and the radius at half peak of MPOD, which was defined as the retinal eccentricity where the MPOD value was 50% of the peak value. Volumetric spectral-domain optical coherence tomography (OCT) images of the macula were obtained from 32 subjects. The equivalent radius of the FAZ was determined using data generated from OCT angiography. Generalized estimating equations were used to test the hypothesis that there are interrelationships among the central foveal thickness, peak MPOD, the radius at half peak of MPOD and the equivalent radius of the FAZ. RESULTS: The equivalent radius of the FAZ was highly correlated with the radius at half peak of MPOD (P < .001). The equivalent radius of the FAZ was a significant predictor for central foveal thickness (P < .001). The significant predictor for peak MPOD was central foveal thickness (P = .004). Eyes with larger FAZs were more likely to have a secondary peak in their MPOD spatial profile in a zone ranging from 0.5 to 1.0 degrees from the foveal center. CONCLUSIONS: The spatial distribution of macular pigment is related to the size of the FAZ, in addition to the central foveal thickness. It is possible that xanthophyll pigment accumulation in the macula serves functions, such as attenuation of shorter wavelengths of light, that would have been provided by the light-filtering characteristics of blood vessels.

Panuveitis With Exudative Retinal Detachments After Vaccination Against Human Papilloma Virus.

A 20-year-old white woman presented with bilateral acute visual loss (visual acuity: 20/60), panuveitis, and exudative retinal detachments 3 weeks after a second dose of quadrivalent human papillomavirus (HPV4) vaccine. She was treated with oral prednisolone for 6 weeks and responded rapidly. By week 4, vision had normalized and clinical signs resolved. Uveitis after HPV4 vaccination has been reported in two cases. Although the differential diagnosis includes Harada disease, temporal correlation with HPV4 and definitive response to a short course of treatment implicate the vaccine in this case. Vaccine-induced uveitis is rare and difficult to distinguish from coincidental autoimmune disease.

Volume-Rendering Optical Coherence Tomography Angiography of Macular Telangiectasia Type 2.

PURPOSE: To evaluate the vascular structure of eyes with macular telangiectasia type 2 (MacTel2) using volume-rendered optical coherence tomography angiography (OCTA). DESIGN: Retrospective cross-sectional study. PARTICIPANTS: A total of 14 consecutive patients (20 eyes) with MacTel2 who had a signal strength score ≥55 and could maintain fixation during the scan process. METHODS: The eyes were scanned using optical coherence tomography with split-spectrum amplitude decorrelation techniques to derive flow information. Data were extracted and used to create volume-rendered images of the retinal vasculature that could be rotated about 3 different axes for evaluation. MAIN OUTCOME MEASURES: Descriptive appraisal of the vascular abnormalities associated with MacTel2. RESULTS: Vessels posterior to the outer boundary of the deep retinal plexus were secondary to retinal thinning, vascular invasion, or a combination of both. These vessels had the same shape and distribution as the late staining seen during conventional fluorescein angiography. Lateral contraction in the temporal macula in 5 eyes created an appearance of vessels radiating from a central locus, which was the site of a right angle vein. Loss of macular tissue as part of the disease process led to a central amalgamation of the inner vascular plexus and the deep vascular plexus, which appeared to be in a state of decline. Subretinal neovascularization originated from the retinal circulation but involved not only the subretinal space but also could infiltrate the remaining, thinned, retina. CONCLUSIONS: Volume rendering of OCTA information preserves the 3-dimensional relationships among retinal vascular layers and provides opportunities to visualize retinal vascular abnormalities in unprecedented detail. The retinal vascular leakage and invasion in MacTel2 may arise as a consequence of loss of control with depletion of Müller cells and exposure of the remaining retinal vessels to the more hypoxic environment near the inner segments of the photoreceptors.

Clinical Course of Vitreomacular Traction Managed Initially by Observation.

BACKGROUND AND OBJECTIVE: To investigate the clinical course and outcomes of patients with vitreomacular traction (VMT) managed initially by observation. PATIENTS AND METHODS: This noncomparative case series included patients with a diagnosis of VMT based on clinical symptoms and findings on spectral-domain optical coherence tomography (SD-OCT) between 2005 and 2014. VMT was documented using a standardized grading system based on the degree of distortion of the foveal contour. Data were collected at five retina clinics using standardized collection forms. Visual acuity, changes in SD-OCT findings, and timing of the release of VMT as seen on SD-OCT were recorded. RESULTS: The study included 230 eyes of 185 patients. Mean age was 72.5 years, and mean follow-up was 32 months. At baseline, VMT grading was grade 1 in 92 eyes (40%), grade 2 in 118 eyes (51.3%), and grade 3 in 20 eyes (8.7%). By last follow-up, spontaneous release of VMT occurred in 73 eyes (31.7%). Spontaneous release of VMT occurred at a mean of 18 months (median: 10.9 months) after initial visit. Mean logMAR best corrected visual acuity (BCVA) was 0.28 (20/55) (range: 20/20 to 20/400) at baseline and 0.25 (20/51) (range: 20/20 to 20/400) at last follow-up. Pars plana vitrectomy was performed in 10 eyes (4.1%) for macular hole (six eyes) and increased VMT (four eyes); BCVA was at least 20/40 in eight of the 10 eyes at last follow-up. CONCLUSION: Patients with VMT generally had a favorable clinical course when managed initially by observation. Spontaneous release of VMT occurred in approximately one-third of patients. At last follow-up, pars plana vitrectomy was performed in fewer than 5% of patients.

MULTIMODAL VISUAL FUNCTION TESTING IN EYES WITH NONEXUDATIVE AGE-RELATED MACULAR DEGENERATION.

PURPOSE: To investigate the interactions among drusen type and multimodal vision testing in eyes with nonexudative age-related macular degeneration. METHODS: Fifty-one eyes of 39 patients with nonexudative age-related macular degeneration underwent fundus imaging including spectral domain optical coherence tomography, color fundus photograph, and autofluorescence imaging, each of which was graded by 2 masked readers. Multimodal vision testing included visual acuity using the Early Treatment Diabetic Retinopathy Study protocol refraction, contrast sensitivity, and microperimetry. RESULTS: Generalized estimating equation modeling showed that the significant predictors of contrast sensitivity was the presence of pseudodrusen (P = 0.012) and refractive error (P = 0.028). The presence of pseudodrusen inversely correlated with contrast sensitivity. The significant predictors of parafoveal microperimetry score were area of confluent hypoautofluorescence (P = 0.026) and the presence of pseudodrusen (P = 0.027). Both of them showed an inverse correlation with microperimetry score. The only significant predictor of macular microperimetry score was the presence of pseudodrusen (P = 0.004), which showed an inverse correlation with microperimetry score. CONCLUSION: The analysis of predictors of the visual function highlights the importance of pseudodrusen. Pseudodrusen are not only the risk factor of late age-related macular degeneration but also affect visual function. Recognition of this problem is important for low-vision rehabilitation and therapeutic strategies for late age-related macular degeneration.

MULTIMODAL IMAGING FINDINGS AND MULTIMODAL VISION TESTING IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION.

PURPOSE: To investigate the interactions among multimodal imaging findings and multimodal vision testing in neovascular age-related macular degeneration. METHODS: Patients enrolled in a prospective study of neovascular age-related macular degeneration with at least 3 previous intravitreal anti-vascular endothelial growth factor injections. Each patient underwent multimodal fundus imaging including spectral domain optical coherence tomography and fundus autofluorescence, and multimodal vision testing, including visual acuity, contrast sensitivity, reading speed, and microperimetry. RESULTS: There were 73 eyes of 49 consecutive patients enrolled. Generalized estimating equations' modelling showed that the significant independent predictors of visual acuity were the area of confluent hypoautofluorescence and involvement of the foveal center with either granular or confluent hypoautofluorescence (P < 0.001). Contrast sensitivity was negatively correlated with the area of confluent hypoautofluorescence (P < 0.001), involvement of the foveal center with granular hypoautofluorescence (P = 0.017), and subfoveal choroidal thickness (P = 0.042). The only significant predictor of reading speed was the size of confluent hypoautofluorescence (P < 0.001). The size of the defect in the ellipsoid zone (P < 0.001) and the presence of intraretinal fluid (P = 0.045) were correlated with microperimetry score. CONCLUSION: Confluent absence of autofluorescence was a highly significant predictor of vision testing and serves as an easy parameter to obtain in patients with neovascular age-related macular degeneration.

Colocalization error between the scanning laser ophthalmoscope infrared reflectance and optical coherence tomography images of the heidelberg spectralis.

PURPOSE: To examine the colocalization error between the infrared reflectance (IR) scanning laser ophthalmoscope (SLO) and spectral domain optical coherence tomography (SD-OCT) images of the Heidelberg Spectralis. METHODS: The IR and corresponding horizontal raster SD-OCT images were compared in 10 healthy volunteers examined with 3 Heidelberg Spectralis + OCT instruments. The center points of retinal vessels selected by random uniform sampling in scanning laser ophthalmoscope-IR images were compared with colocalizing points in corresponding SD-OCT images by two masked readers. The error of colocalization was measured in the SD-OCT image. The point positions were recorded using Cartesian coordinates measured in microns. The error of colocalization was evaluated using a fixed-effects generalized least squares regression model with location and instrument as predictor variables. RESULTS: A total of 1,617 points in the IR and SD-OCT images were analyzed, and the mean error of colocalization was 42.2 ± 32.4 µm. The Heidelberg Spectralis instrument used was not a significant predictor of colocalization error (P = 0.15). The colocalization errors were negatively correlated with x-coordinate position (P < 0.001). CONCLUSION: There is a mean colocalization error between the IR and SD-OCT images produced by the Heidelberg Spectralis that is on the scale of many features being evaluated in the fundus. The variability in these measurements means the confidence interval for the exact colocalization is much larger. Because of the magnitude and variability of the error, the colocalization feature of the Heidelberg Spectralis should be used as a rough guide, not an absolute determinant.

REFRACTILE DRUSEN: Clinical Imaging and Candidate Histology.

PURPOSE: To evaluate eyes with refractile drusen using clinical imaging and to identify candidate histologic correlates of refractile drusen. METHODS: Refractile drusen were defined as drusenoid material containing small refractile spherules. Retrospective analysis of color, autofluorescence, and spectral domain optical coherence tomography images of eyes with refractile drusen was performed to characterize the morphology and topography of these lesions. Macular sections from donor eyes were processed with a von Kossa stain for calcium phosphate and viewed by light microscopy. Punches of retinal pigment epithelium-choroid from donors with geographic atrophy were prepared for transmission electron microscopy. RESULTS: Fundus findings of 14 eyes of 10 patients with age-related macular degeneration (age, 82.9 ± 5.6 years) were evaluated. A generalized loss of autofluorescence signal over refractile drusen appeared to spread over a larger area than each druse, for drusen located centrally. By color fundus photography, refractile drusen showed corresponding depigmentation around drusen that were located in the center of the macula. Optical coherence tomography imaging of refractile drusen showed hyperreflective dots. In the histologic specimens, drusen contained many small spherules rich in calcium phosphate. Ultrastructural examination of the spherules showed complex assemblies consisting of concentric shells containing thin layers of calcium. CONCLUSION: Refractile drusen appear to be a stage of drusen regression marked by loss of retinal pigment epithelium, thus contributing to the development of geographic atrophy. Calcium-containing spherules appear to account for the glistening appearance.

Retinal pigment epithelial tear after intravitreal aflibercept for neovascular age-related macular degeneration.

Two eyes with neovascular age-related macular degeneration and a suboptimal response to intravitreal ranibizumab and bevacizumab developed tears after being switched to intravitreal aflibercept, a drug with enhanced binding characteristics to vascular endothelial growth factor. Both eyes had sub-retinal pigment epithelium (RPE) choroidal neovascularization adherent to the back surface of the RPE in the fibrovascular RPE detachment that showed increased contracture of the fibrovascular tissue following the use of aflibercept. The driving force to develop the tears may be related to the recently described angiofibrotic switch, which is governed by the ration of connective tissue growth factor to vascular endothelial growth factor.

Direct photocoagulation to leakage points to treat chronic macular edema associated with branch retinal vein occlusion: a pilot study.

SUMMARY STATEMENT: Direct photocoagulation reduces the central foveal thickness (CFT) in cases with chronic branch retinal vein occlusion (BRVO) of longer than 12 months duration. Photo-coagulation might be effective for chronic macular edema due to branch retinal vein occlusion. BACKGROUND: The aim was to investigate the effect of direct photocoagulation for treating chronic macular edema associated with BRVO. METHODS: This study was a noncomparative, pilot interventional case series. We examined the CFT and best-corrected visual acuity over 6 months in patients with BRVO treated with direct photocoagulation. RESULTS: Sixteen eyes of 16 patients had been treated with direct photocoagulation (mean follow-up period, 20.5 months). The mean CFT decreased significantly (P<0.001) between the baseline (465 µm) and the final visit (304 µm). The mean (logarithm of the minimum angle of resolution equivalent) best-corrected visual acuity at the baseline was 0.39 and improved significantly (P<0.001) to 0.20 at the final visit. CONCLUSION: Direct photocoagulation to leakage points is beneficial for treating chronic macular edema associated with chronic BRVO of longer than 12 months duration.

The lack of concordance between subretinal drusenoid deposits and large choroidal blood vessels.

PURPOSE: To evaluate the concordance between pseudodrusen as manifested by subretinal drusenoid deposits and large choroidal blood vessels using stereological analysis of spectral-domain optical coherence tomography (SD OCT) images. DESIGN: Retrospective, observational case series. METHODS: The SD OCT images of 31 consecutive patients with the clinical appearance of pseudodrusen from a private-referral retinal clinic were retrospectively reviewed. A grid of 19 evenly spaced vertical lines was randomly superimposed on each SD OCT image using ImageJ to perform systematic uniform random sampling. The main outcome measure was the likelihood of association between subretinal drusenoid deposits and large choroidal vessels. RESULTS: Uniform random systematic sampling of 589 samples found the proportion of geometric probes intersecting subretinal drusenoid deposits to be 0.28, large choroidal vessel 0.65, and both 0.19. This value was nearly identical to the product of the joint probabilities and was within the 95% confidence interval (0.15-0.21) of the point estimate as calculated by the binomial theorem, indicating mutual independence. The subretinal drusenoid deposits were associated with neither large choroidal vessels nor the intervals in between. CONCLUSIONS: Our results demonstrate that there is no concordance between subretinal drusenoid deposits and large choroidal vessels or the stroma in between. As a consequence, hypotheses postulating that subretinal drusenoid deposits are associated with large choroidal vessels or the choroidal stromal spaces should be abandoned. Stereological techniques are powerful methods used in image evaluation in other fields of study and appear to have utility in analyzing OCT findings of the retina and choroid.

Outer retinal corrugations in age-related macular degeneration.

IMPORTANCE: Optical coherence tomography (OCT) abnormalities of age-related macular degeneration (AMD) have not been fully characterized because of the complex morphology and a lack of correlative histologic studies. Expansion of our ability to interpret increasing attributes brings us closer to the goal of in vivo histologic analysis of the eye by OCT. OBJECTIVE: To describe a new outer retinal finding of AMD using spectral-domain (SD) OCT and suggest histopathologic correlates. DESIGN, SETTING, AND PARTICIPANTS: Twenty-five eyes of 16 patients with AMD with severe atrophy due to either choroidal neovascularization (CNV) or geographic atrophy (GA) and 53 donor eyes of 53 patients with late AMD were included. Imaging studies were conducted at a referral retinal practice and histopathology was done at a university research laboratory. EXPOSURES: Findings in the outer retina were evaluated in SD-OCT images in eyes with atrophy of the retinal pigment epithelium (RPE) and compared with histopathologic findings in eyes with GA or CNV that also showed loss of the RPE. MAIN OUTCOMES AND MEASURES: Spectral-domain OCT and histologic characteristics of the outer retina. RESULTS: The mean (SD) age of the 16 patients was 82.7 (7.9) years. Twenty eyes had CNV and 5 eyes had GA. The mean best-corrected visual acuity was 0.800 logMAR (interquartile range, 0.350-1.000 logMAR), a Snellen equivalent of 20/126. A curvilinear hyperreflective density was identified above the Bruch membrane line within the atrophic area in the SD-OCT images. At the internal border, the material was contiguous with the outer portion of the RPE band. Below the material was a relatively hyporeflective space. The material was thrown into folds in cases with atrophy following CNV or was seen as a sheet with numerous bumps in eyes with GA. Review of histopathologic findings of eyes with advanced GA and CNV revealed a rippled layer of basal laminar deposits in an area of RPE atrophy that was located in the same level as the curvilinear line seen in the OCT images. CONCLUSIONS AND RELEVANCE: We have described a new entity, termed outer retinal corrugations, which may correspond to histological findings of basal laminar deposits, extracellular deposits that persist in eyes with late AMD. Observation of this undulating band does not necessarily mean there is exudation or leakage; as a consequence, these patients do not need treatment based on this solitary finding.

Matched control study of visual outcomes after arteriovenous sheathotomy for branch retinal vein occlusion.

BACKGROUND: The purpose of this study was to evaluate visual outcomes of arteriovenous sheathotomy for macular edema due to branch retinal vein occlusion (BRVO). METHODS: The medical records of 45 eyes from 45 patients who had undergone vitrectomy surgery with arteriovenous sheathotomy for BRVO were studied. Forty-five eyes of 45 patients with a BRVO but without intervention were studied as the control group. The best-corrected visual acuity and central macular thickness were compared between the two groups at baseline and at 1, 3, 6, and 12 months postoperatively. RESULTS: Improvement of best-corrected visual acuity was 0.42 logarithm of the minimum angle of resolution (logMAR) units in the sheathotomy group and 0.22 logMAR units in the control group (P=0.007). The mean postoperative central macular thickness was significantly thinner in the sheathotomy group at 1 month (P=0.01), but not at 3, 6, and 12 months (P=0.75, P=0.81, and P=0.46, respectively). Improvement of best-corrected visual acuity at 12 months was significantly correlated with baseline best-corrected visual acuity, age, duration of symptoms, and sheathotomy (P<0.05). CONCLUSION: Arteriovenous sheathotomy for BRVO improves best-corrected visual acuity significantly more than the natural course of the BRVO disease process.