Impact of segmentation density on spectral domain optical coherence tomography assessment in Stargardt disease.

PURPOSE: Automated spectral domain optical coherence tomography (SD-OCT) segmentation algorithms currently do not perform well in segmenting individual intraretinal layers in eyes with Stargardt disease (STGD). We compared selective B-scan segmentation strategies for generating mean retinal layer thickness and preserved area data from SD-OCT scans in patients with STGD1. METHODS: Forty-five eyes from 40 Stargardt patients were randomly selected from the ongoing Natural History of the Progression of Atrophy Secondary to Stargardt Disease (ProgStar) study. All eyes underwent SD-OCT using a standard macular volume consisting of 1024 × 49 equally spaced B-scans within a 20 × 20 degree field centered on the fovea. All 49 B-scans were segmented manually to quantify total retina, outer nuclear layer (ONL), photoreceptor inner segments, photoreceptor outer segments (OS), and retinal pigment epithelial layer (RPE). Mean thickness and total area were generated using all 49 B-scans (spaced 122 µm apart), 25 B-scans (every other B-scan, spaced 240 µm apart), 17 B-scans (every third scan, 353 µm apart), and 13 B-scans (every fourth scan, 462 µm apart), as well as by using an "adaptive" method where a subset (minimum 25 B-scans) of B-scans that the grader deemed as significantly different from adjacent B-scans were utilized. Mean absolute and percentage errors were calculated for macular thickness and area of different retinal layers for the different B-scan subset selection strategies relative to using all 49 B-scans, which was considered the reference or ground truth. RESULTS: Mean thickness and area measurements were significantly different for any regularly spaced reduction in B-scan density relative to the ground truth. When an adaptive approach was applied using a minimum of half the scans, the differences relative to ground truth were no longer significantly different. The mean percent differences for the area and thicknesses of the various layers ranged from 0.02 to 33.66 (p < 0.05 for all comparisons) and 0.44 to 7.24 (p > 0.05) respectively. CONCLUSION: Manual segmentation of a subset of B-scans using an adaptive strategy can yield thickness and area measurements of retinal sublayers comparable to the reference ground truth derived from using all B-scans in the volume. These results may have implications for increasing the efficiency of SD-OCT grading strategies in clinical trials for STGD and other related macular degenerative disorders.

[Static retinal vessel analysis in acute blood pressure increase]. / Statische retinale Gefäßanalyse bei akutem Blutdruckanstieg.

BACKGROUND: The aim of this study was to examine the changes in static analysis of the retinal vasculature during an acute rise of blood pressure in young normal subjects. MATERIAL AND METHODS: An increase of blood pressure was induced in 30 young normal subjects (age 18 - 30 years) by physiological stress. Retinal fundus photographs were taken before and immediately after the stress. The central retinal artery equivalent (CRAE), the central retinal vein equivalent (CRVE) and the arterio-venous ratio (AVR) were calculated by automated vessel analysis software (Talia Technology, Lod, Israel). The same vessel segments were measured before and after the rise of blood pressure. RESULTS: At rest, mean CRAE was 97.3 ± 9.6 micrometer, CRVE 114.5 ± 12.5 micrometer and AVR 0.85 ± 0.08. The mean systemic perfusion pressure was elevated by physiological stress from a mean of 90.7 ± 7 mmHg by 18.0 ± 7.8 mmHg. The static retinal vessel analysis showed a constriction of the arteries by a mean of -1.3 ± 3.9 microns and a venous dilatation of 0.6 ± 7.2 microns. The retinal AVR was diminished significantly (p = 0.02) by -0.015 ± 0.032. The degree of arterial constriction - but not the change of AVR - correlated significantly (r = -0.39; p = 0.048) with the degree of rise of blood pressure. CONCLUSION: Retinal autoregulation during acute increase of blood pressure in young normal subjects can be measured by static retinal vessel analysis.

[Detection of amlyogenic risk factors with the vision screener S 04]. / Detektion amblyogener Risikofaktoren mit dem Vision Screener S 04.

INTRODUCTION: The Vision Screener® (Plusoptix) was developed for the recognition of amblyogenic refractive errors without cycloplegia. The aim of this study was to evaluate the sensitivity and specitifity for the detection of amblygenic refractive errors in preschool children. Furthermore it was investigated whether small angle strabismus as another cause for amblyopia could be detected by manual evaluation of corneal reflex images on printouts. PATIENTS AND METHODS: 83 children aged between 0.5 and 6 years without strabismus had undergone 3 measurements without cycloplegia with the Vision Screener before cyclplegic retinoscopy was performed. In a second group of 72 children with orthotropia or a manifest strabismus < 10° the position of the eyes without correction was evaluated in a complete orthoptic and ophthalmological examination. Three measurements with the Vision Screener were performed in non-cycloplegic status. The centre of the "cloud of viewing directions" was determined on print-outs and the distance to the points of origin (middle of pupil) measured for each eye. The sum of distances of right and left eyes was taken for determination of total deviation and the assymetry was calculated by the difference of distances of the right and left eyes. RESULTS: There was a total sensitivity of 75% (specifity 91%) for amblyogenic refractive error (prevalence: astigmatism 22%, hyperopia 6%, anisometropia 6%). A change of threshold criteria increased the total sensitivity to 86% and 93%, whereas specifity was lowered to 80% and 76%, respectively. Eight children showed a manifest strabismus. In 75% of these cases the determined deviation of corneal reflex images in the horizontal direction was outside of the normal range; analysis of asymmetry showed an abnormal result in 37.5% of the cases. CONCLUSION: The examination using the Vision Screener may detect refractive errors and partially small angle strabismus as amblyogenic risk factors; however, additional tests should be added for screening examinations. An ophthalmological examination including cycloplegic retinoscopy cannot be replaced. Despite acceptable sensitivity and specifity the major portion of positively screened children will be without pathological findings at cycloplegic controls, because the amount of "false-positive" results exceeds the amount of "true-positive" results based on a prevalence of 5% for amblyopia.

The expanded role of the barium enema in the evaluation of patients presenting with acute abdominal pain.

The role of the barium enema in the evaluation of patients with acute abdominal pain is well established. It is utilized in the diagnosis and treatment of several suspected clinical entities, including appendicitis, diverticulitis, intussusception, and volvulus. There is another group of patients in whom a vague clinical presentation and an indeterminate bowel gas pattern fail to clarify the diagnosis. The role of the barium enema has been expanded as an early diagnostic aid in the evaluation of these patients. Based on abdominal film findings, three patient categories are presented, in whom the early use of a "judicious" barium enema may safely and quickly contribute to the preoperative definition of the underlying disease process, allowing for the correct mode of therapy to be undertaken.

[Topographic, 3D and Quantitative analysis of autofluorescence in dry, age-related macular degeneration]. / Topografische, 3D- und quantitative Darstellung der Autofluoreszenz bei trockener altersabhängiger Makuladegeneration.

OBJECTIVE: Autofluorescence of the retina allows one to quantify and follow the extent and progression of dry, age-related macular degeneration (ARMD) changes. The objective of this study was to compare different analysis methods for displaying autofluorescence images. METHODS: In a consecutive series of 15 patients with mild dry AMD and 15 patients without retinal pathologies, one 30 degrees autofluorescence image was obtained with the Heidelberg retina angiograph (HRA). Evaluation was performed by observers masked to the clinical group for each of the three analysis displays: topographic map in false colours (similar to height lines in maps), 3D display of optical density and quantitative, standardised evaluation of optical density values. RESULTS: For the 30 eyes included, grading of ARMD versus normal yielded a sensitivity of 83 -92 % for the topographic map, 58 - 83 % for the 3D and 75 - 83 % for quantitative optical density display. The corresponding specificity was 87 - 93 % for the topographic map, 53 - 60 % for the 3D and 67 - 80 % for the quantitative optical density display. CONCLUSIONS: Analysis by topographic mapping is suitable to supply quantitative information of optical density for evaluating autofluorescence images. In spite of being illustrative, a 3D display of optical density does not offer sufficient properties for analysis.

Fluorescein angiography compared to three-dimensional measurements by the retinal thickness analyzer in classic choroidal neovascularization.

PURPOSE: To compare and correlate imaging of classic subfoveal choroidal neovascularization (CNV) with noninvasive 3-dimensional imaging by the retinal thickness analyzer (RTA) to conventional fluorescein angiography (FA). METHODS: A total of 29 eyes of 29 consecutive patients with predominantly classic CNV eligible for photodynamic therapy underwent FA and RTA imaging. The FA dimensions of the CNV were measured independently by two graders. With the RTA, masked to FA the size of the CNV itself as imaged in 3-dimensional reconstruction, the size of significantly thickened retina overlying the CNV and the maximum retinal thickness were measured. RESULTS: The mean diameter of the CNV determined from 3-dimensional RTA reconstructions showed an excellent correlation with measurements from FA (r = 0.91, p < 0.001). The area of retinal thickening was by a mean of 0.7 mm in diameter larger and correlated moderately well with the size of the CNV on FA (r = 0.65, p < 0.001). In contrast, there was no correlation between the absolute retinal thickness and the CNV size on FA. CONCLUSIONS: Noninvasive quantitative mapping of predominantly classic CNV by RTA is feasible and also allows 3-dimensional measurement of the lesion itself. The results correlate well with FA assessment but visualize different properties of the disease.

[Artifacts in optical coherence tomography (OCT) imaging of the retina]. / Artefakte bei der Bildgebung der Netzhaut mittels optischer Kohärenz-Tomographie (OCT).

PURPOSE: The purpose of this study was to investigate artifacts of OCT scans and of software analysis for retinal cross-section scans in a specialised retina clinic setting. METHODS: A total of 205 vertical cross-hair OCT scans of retinal Stratus OCTs were randomly chosen from the database. All scans had been performed by one experienced technician. There were 75 (37%) normal findings, the remaining scans showed various types of retinal pathology: All scanning artifacts were analysed. Retinal thickness of all scans was measured automatically at the centre of the macula using two different software algorithms: the instrument's built-in "Stratus OCT Viewer V 4.01" and the stand-alone application "Datamedical OCTview V 3.5" (Datamedical Consulting, Hamburg). Errors of the software to correctly identify the retinal surface and the outer highly reflective layer were assigned into three categories: none, minor error (no influence on measurements) and major error. RESULTS: A total of 7.3% of all OCT scans showed scanning artifacts: 5 motion artifacts, 9 scans with low signal intensity and 1 decentred scan. Scanning artifacts significantly increased the frequency of software errors (p = 0.012). The presence of retinal pathology also increased the number of errors (p = 0.004). Software analysis yielded a total of 20 major and 2 minor errors for the Stratus OCT (overall 10.7%) and 32 major and 64 minor errors for the Datamedical Viewer (p < 0.001). Measurements by Datamedical OCTview were a mean of 57 micron higher due to a different definition of the outer retinal border. Retinal pathologies significantly increased the likelihood of software errors for both algorithms (both p < 0.01), most critical were macular holes and changes in age-related macular degeneration. CONCLUSION: Scanning artifacts were associated with a significantly higher frequency of software errors. As artifacts of scans and software occur frequently, the interpretation of OCT scans requires special attention to artifacts.

Acute childhood hemiplegia.

A 10-year-old child presented to the emergency department with a sudden onset of right hemiparesis and dysphasia. A thorough evaluation, including CT scan of the brain and cerebral angiography, resulted in a diagnosis of acute childhood hemiplegia. The diagnosis of acute childhood hemiplegia depends on characteristic cerebral angiographic findings. The treatment of this particular entity is supportive, often with incomplete recovery.

Angiopoietin 2 expression in the retina: upregulation during physiologic and pathologic neovascularization.

Vascular development in the embryo requires coordinated signaling through several endothelial cell-specific receptors; however, it is not known whether this is also required later during retinal vascular development or as part of retinal neovascularization in adults. The Tie2 receptor has been implicated in stabilization and maturation of vessels through action of an agonist ligand, angiopoietin 1 (Ang1) and an antagonistic ligand, Ang2. In this study, we have demonstrated that ang2 mRNA levels are increased in the retina during development of the deep retinal capillaries by angiogenesis and during pathologic angiogenesis in a model of ischemic retinopathy. Mice with hemizygous disruption of the ang2 gene by insertion of a promoterless beta-galactosidase (beta gal) gene behind the ang2 promoter, show constitutive beta gal staining primarily in cells along the outer border of the inner nuclear layer identified as horizontal cells by colocalization of calbindin. During development of the deep capillary bed or retinal neovascularization, other cells in the inner nuclear layer and ganglion cell layer, in regions of neovascularization, stain for beta gal. Thus, there is temporal and spatial correlation of Ang2 expression with developmental and pathologic angiogenesis in the retina, suggesting that it may play a role.