Analysis of Peripapillary Atrophy Using Spectral Domain Optical Coherence Tomography

Objective To study retinal morphologic changes around the optic disc in patients with peripapillary atrophy (PPA) with high-resolution spectral domain optical coherence tomography (SD OCT). Design Cross-sectional, retrospective analysis. Participants A total of 103 eyes of 73 patients with PPA and 21 eyes of 12 normal patients seen at the New England Eye Center, Tufts Medical Center, between January 2007 and August 2009. Methods Spectral domain optical coherence tomography images taken through the region of PPA were quantitatively and qualitatively analyzed. Inclusion criteria included eyes with at least 300 μm of temporal PPA as detected on color fundus photographs. The study population was divided into subgroups according to the following clinical diagnoses: glaucoma (n=13), age-related macular degeneration (n=11), high myopia (n=11), glaucoma and high myopia (n=3), and optic neuropathy (n=11). Fifty-four patients were classified with other diagnoses. By using OCT software, retinal thickness and retinal nerve fiber layer (RNFL) thickness were both manually measured perpendicular to the internal limiting membrane and retinal pigment epithelium (RPE) 300 μm temporal to the optic disc, within the region of PPA. Qualitative analysis for morphologic changes in the atrophic area was also performed. Main Outcome Measures Qualitative assessment and quantitative measures of retinal and RNFL thickness in PPA. Results The study group was categorized by 6 characteristics demonstrated in the area of PPA by SD OCT: RPE loss with accompanying photoreceptor loss, RPE disruption, RNFL thickening with plaque-like formation, intraretinal cystic changes, inner and outer retinal thinning, and abnormal retinal sloping. Statistical analysis of measurements revealed a statistically significant difference in the total retinal thickness between normal eyes and eyes with PPA (P=0.0005), with normal eyes 15% thicker than the eyes with PPA; however, the RNFL thickness was not significantly different between the normal eyes and the eyes with PPA (P=0.05). Conclusions Eyes with PPA manifest characteristic retinal changes that can be described via SD OCT.National Institutes of Health (U.S.) (Contract R01-EY11289-24)National Institutes of Health (U.S.) (Contract R01-EY13178-10)National Institutes of Health (U.S.) (Contract R01-EY013516-07)United States. Air Force Office of Scientific Research (FA9550-07-1-0101)United States. Air Force Office of Scientific Research (FA9550-07-1-0014)Massachusetts Lions Eye Research Fund, Inc

Analysis of Choroidal Thickness in Age-Related Macular Degeneration Using Spectral-Domain Optical Coherence Tomography

Purpose To understand the relationship between choroidal thickness and various disease factors in patients with age-related macular degeneration (AMD) using spectral-domain optical coherence tomography. Design Cross-sectional, retrospective analysis. Methods Fifty-seven eyes of 47 patients with wet and dry AMD seen between November 2009 and January 2010 at the New England Eye Center, Boston, Massachusetts, were analyzed. Choroidal thickness was measured by 2 independent observers at 11 sites with high-definition horizontal 1-line raster scans through the foveal center. A retrospective chart review was performed to obtain data concerning duration of disease, number of intravitreal anti–vascular endothelial growth factor injections, visual acuity, lens status, and concomitant retinal pathologic features. The Pearson correlation and Student t test were used for statistical analysis for assessment of choroidal thickness changes in wet and dry AMD. Results The choroid in eyes with wet and dry AMD demonstrated a wide range of thicknesses above and below the normal mean (range, 77.5 to 399.5 μm; standard deviation [SD], 90.2). Nearly one third (33.3%) of the eyes with AMD measured less than 1 SD below the mean. Eyes with wet AMD demonstrated a mean subfoveal choroidal thickness of 194.6 μm (SD, 88.4; n = 40) compared with 213.4 μm (SD, 92.2; n = 17) in the dry AMD group. The choroidal thickness in eyes with dry AMD was correlated inversely with age (r = −0.703; P = .002); however, analysis of the number of intravitreal anti–vascular endothelial growth factor injections, number of years of disease, and visual acuity failed to demonstrate any significant correlations with choroidal thickness. Conclusions This study demonstrated that choroidal thickness can be measured by spectral-domain optical coherence tomography and that variable choroidal thickness exists among patients with the clinical diagnosis of wet and dry AMD. However, it is unclear at this time why in some eyes, choroidal thickness either increases or decreases with the disease. Further studies need to be carried out to understand the significance of choroidal thickness with respect to visual function and disease progression over time.Research to Prevent Blindness, Inc. (United States) (Challenge Grant)National Institutes of Health (U.S.) (Grant R01-EY11289-23)National Institutes of Health (U.S.) (Grant R01-EY13178-10)National Institutes of Health (U.S.) (Grant R01-EY013516-07)United States. Air Force Office of Scientific Research (Grant FA9550-07-1-0101)United States. Air Force Office of Scientific Research (Grant FA9550-07-1-0014)Massachusetts Lions Eye Research Fund, Inc

Ultra-High-Resolution Optical Coherence Tomographic Findings in Commotio Retinae

Commotio retinae is a self-limited opacification of the retina secondary to direct blunt ocular trauma. Histologic studies of monkeys and humans relate this clinical observation to damaged photoreceptor outer segments and receptor cell bodies.[superscript 1 - 3] Reports using time-domain optical coherence tomography (OCT) and spectral-domain OCT support the involvement of the photoreceptor layer, but these techniques lack the resolution necessary to confirm results of histologic analysis.[superscript 4 - 6] Prototype high-speed ultra–high-resolution OCT (hs-UHR-OCT) images demonstrate these anatomical changes in a patient with acute commotio retinae.National Institutes of Health (U.S.) (Contract Number RO1-EY11289-23)National Institutes of Health (U.S.) (Contract Number R01-EY13178-07)United States. Air Force Office of Scientific Research (Grant Number FA9550-07-1-0101)United States. Air Force Office of Scientific Research (Grant Number FA9550-07-1-0014

Effect of Intravitreous Anti–Vascular Endothelial Growth Factor Therapy on Choroidal Thickness in Neovascular Age-Related Macular Degeneration Using Spectral-Domain Optical Coherence Tomography

A critical method of monitoring patients with neovascular age-related macular degeneration (AMD) being treated with anti–vascular endothelial growth factor (anti-VEGF) is optical coherence tomography (OCT), which uses low-coherence interferometry of light to examine the retina in vivo on a micrometer scale.National Institutes of Health (U.S.) (Grant R01-EY11289-25)National Institutes of Health (U.S.) (Grant R01-EY13178-10)National Institutes of Health (U.S.) (Grant R01-EY013516-07)National Institutes of Health (U.S.) (Grant R01-EY019029-02)United States. Air Force Office of Scientific Research (Grant FA9550-10-1-0551)United States. Air Force Office of Scientific Research (Grant FA9550-10-1-0063)Massachusetts Lions Club

Choroidal Thickness in Normal Eyes Measured Using Cirrus HD Optical Coherence Tomography

Purpose: To examine choroidal thickness and area in healthy eyes using spectral-domain optical coherence tomography (SD-OCT). Design: Retrospective, observational case series. Methods: Thirty-four eyes (34 subjects), with no retinal or choroidal disease, underwent high-definition raster scanning using SD-OCT with frame enhancement software. Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid/sclera junction at 500-μm intervals up to 2500 μm temporal and nasal to the fovea. The central 1-mm area of the choroid was also measured, along with foveal thickness of the retina. All measurements were performed by 2 independent observers. Statistical analysis was used to correlate inter-observer findings, choroidal thickness and area measurements with age, and choroidal thickness with retinal foveal thickness. Results: The 34 subjects had a mean age of 51.1 years. Reliable measurements of choroidal thickness were obtainable in 74% of eyes examined. Choroidal thickness and area measurements had strong inter-observer correlation (r = 0.92, P < .0001 and r = 0.93, P < .0001 respectively). Area had a moderate negative correlation with age (r = −0.62, P < .0001) that was comparable to the correlation between mean subfoveal choroidal thickness and age (r = −0.61, P < .0001). Retinal and choroidal thickness were found to be poorly correlated (r = −0.23, P = .18). Mean choroidal thickness showed a pattern of thinnest choroid nasally, thickening in the subfoveal region, and then thinning again temporally. Mean subfoveal choroidal thickness was found to be 272 μm (SD, ± 81 μm). Conclusions: Choroidal thickness can be measured using SD-OCT high-definition raster scans in the majority of eyes. Choroidal thickness across the macula demonstrates a thin choroid nasally, thickest subfoveally, and again thinner temporally, and a trend toward decreasing choroidal thickness with age.National Institutes of Health (U.S.) (Contract R01-EY11289-23)National Institutes of Health (U.S.) (Contract R01-EY13178-10)National Institutes of Health (U.S.) (Contract R01-EY013516-07)United States. Air Force Office of Scientific Research (FA9550-07-1-0101)United States. Air Force Office of Scientific Research (FA9550-07-1-0014

A combined LIFOpriority scheme for overload control of e-Commerce web servers

E-commerce Web-servers often face overload conditions during which revenue-generating requests may be dropped or abandoned due to an increase in the browsing requests. In this paper we present a simple, yet effective, mechanism for overload control of E-commerce Web-servers. We develop an E-commerce workload model that separates the browsing requests from revenue-generating transaction requests. During overload, we apply LIFO discipline in the browsing queues and use a dynamic priority model to service them. The transaction queues are given absolute priority over the browsing queues. This is called the LIFO-Pri scheduling discipline. Experimental results show that LIFO-Pri dramatically improves the overall Web-server throughput while also increasing the completion rate of revenue-generating requests. The Web-server was able to operate at nearly 60 % of its maximum capacity even when offered load was 1.5 times its capacity. Further, when compared to a single queue FIFO system, there was a seven-fold increase in the number of completed revenue-generating requests during overload. Keywords: E-commerce, overload control, Web-servers, LIFO, priority. 1

Effect of Anti–Vascular Endothelial Growth Factor Therapy on Choroidal Thickness in Diabetic Macular Edema

PurposeTo determine the effect of anti-vascular endothelial growth factor (VEGF) therapy on choroidal thickness in eyes with diabetic macular edema (DME).DesignA retrospective, cohort analysis of 59 eyes from 59 patients with DME without prior anti-VEGF therapy.MethodsChoroidal thickness was measured using semiautomated segmentation of enhanced depth imaging optical coherence tomography images at 0.5-mm intervals from 2.5 mm nasal to 2.5 mm temporal to the fovea. Changes in choroidal thickness with and without anti-VEGF treatment over 6 months were compared. Best-corrected visual acuity and central foveal thickness were analyzed to evaluate the association of choroidal thickness with functional and anatomic outcomes.ResultsOf the 59 eyes with DME, 26 eyes were observed without treatment, whereas 33 underwent intravitreal anti-VEGF therapy (mean number of injections, 2.73) over 6 months. In untreated eyes, there was no significant change in best-corrected visual acuity (P = .098), central foveal thickness (P = .472), or choroidal thickness at all measurements along the macula (P = .057 at the fovea). In eyes treated with anti-VEGF injections, choroidal thickness decreased significantly at the fovea (246.6 to 224.8 μm; P &lt; .001) and at 0.5 mm nasal (240.9 to 221.9 μm; P = .002) and 0.5 mm temporal (249.3 to 224.8 μm; P = .011) to the fovea. The decrease in subfoveal choroidal thickness after anti-VEGF treatment was not associated with the cumulative number of anti-VEGF injections (R(2) = 0.031; P = .327) or to changes in best-corrected visual acuity (R(2) = 0.017; P = .470) or central foveal thickness (R(2) = 0.040; P = .263).ConclusionsCentral choroidal thickness decreases after anti-VEGF therapy for DME after 6 months, but may not be associated with functional or anatomic outcomes in eyes with DME

Analysis of Short-Term Change in Subfoveal Choroidal Thickness in Eyes With Age-Related Macular Degeneration Using Optical Coherence Tomography

BACKGROUND and OBJECTIVE: To measure the sub-foveal choroidal thickness in patients with age-related macular degeneration (AMD) over 6 months.PATIENTS and METHODS: A retrospective, observational study of patients with AMD followed up for 6 months at the New England Eye Center. Baseline and 6-month follow-up subfoveal choroidal thickness was measured using spectral-domain OCT and compared.RESULTS: for the entire cohort, there was statistically significant thinning of the subfoveal choroidal thickness at 6 months compared to baseline that was driven by the cohort of patients with neovascular AMD (181.2 +/- 75 mu m to 173.4 +/- 63 mu m; P=.049).CONCLUSION: There was a statistically significant decrease in subfoveal choroidal thickness observed in this cohort of patients with AMD over 6 months, but it was driven by the subgroup of patients with neovascular age-related macular degeneration.Research to Prevent BlindnessNIHAir Force Office of Scientific ResearchTufts Med Ctr, New England Eye Ctr, Boston, MA USAUniversidade Federal de São Paulo, São Paulo, BrazilMIT, Dept Elect Engn & Comp Sci, Elect Res Lab, Cambridge, MA 02139 USAUniversidade Federal de São Paulo, São Paulo, BrazilNIH: RO1-EY11289-25NIH: R01-EY13178-10NIH: R01-EY013516-07NIH: R01-EY019029-02Air Force Office of Scientific Research: FA9550-10-1-0551Air Force Office of Scientific Research: FA9550-10-1-0063Web of Scienc