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G Wollstein

Publications and source records attributed to G Wollstein.

9 recordsLinked to original sources
PubMed2006

A new quality assessment parameter for optical coherence tomography.

AIM: To create a new, automated method of evaluating the quality of optical coherence tomography (OCT) images and to compare its image quality discriminating ability with the quality assessment parameters signal to noise ratio (SNR) and signal strength (SS). METHODS: A new OCT image quality assessment parameter, quality index (QI), was created. OCT images (linear macular scan, peripapillary circular scan, and optic nerve head scan) were analysed using the latest StratusOCT system. SNR and SS were collected for each image. QI was calculated based on image histogram information using a software program of our own design. To evaluate the performance of these parameters, the results were compared with subjective three level grading (excellent, acceptable, and poor) performed by three OCT experts. RESULTS: 63 images of 21 subjects (seven each for normal, early/moderate, and advanced glaucoma) were enrolled in this study. Subjects were selected in a consecutive and retrospective fashion from our OCT imaging database. There were significant differences in SNR, SS, and QI between excellent and poor images (p = 0.04, p = 0.002, and p<0.001, respectively, Wilcoxon test) and between acceptable and poor images (p = 0.02, p<0.001, and p<0.001, respectively). Only QI showed significant difference between excellent and acceptable images (p = 0.001). Areas under the receiver operating characteristics (ROC) curve for discrimination of poor from excellent/acceptable images were 0.68 (SNR), 0.89 (IQP), and 0.99 (QI). CONCLUSION: A quality index such as QI may permit automated objective and quantitative assessment of OCT image quality that performs similarly to an expert human observer.

Aged↗
PubMed2000

Glaucomatous optic disc changes in the contralateral eye of unilateral normal pressure glaucoma patients.

OBJECTIVE: To evaluate the optic disc for structural abnormalities in the contralateral eye of unilateral normal pressure glaucoma patients. DESIGN: Cross-sectional study. PARTICIPANTS: Fifty-three unilateral normal pressure glaucoma patients. TESTING: Optic disc imaging with the Heidelberg Retina Tomograph (HRT). MAIN OUTCOME MEASURES: Optic disc structural parameters. RESULTS: Of the contralateral (normal visual field) eyes, 79.2% were found to have an abnormal optic disc by HRT analysis. Of the glaucomatous (abnormal visual field) eyes, 94.3% were found to have an abnormal disc. The patterns of disc abnormality were defined as marked or moderate diffuse thinning of the neuroretinal rim (NRR) or broad or narrow focal thinning of the NRR. The most common pattern in the contralateral eyes was moderate diffuse thinning of the NRR (45.2%). The most frequently abnormal segments were the nasal superior (73. 8%) followed by the nasal inferior and the global NRR parameter (both 54.8%). CONCLUSIONS: A high frequency of NRR thinning was found in the contralateral (normal visual field) eyes of unilateral normal pressure glaucoma patients by HRT analysis. Knowing whether these abnormalities predict future progression to the development of visual field abnormality must wait until longitudinal studies are completed. If a disc abnormality is shown to predict future field loss, then early identification will allow early treatment.

Aged↗
PubMed2000

Identifying early glaucomatous changes. Comparison between expert clinical assessment of optic disc photographs and confocal scanning ophthalmoscopy.

OBJECTIVE: To compare the ability of expert clinicians, using qualitative assessment of stereoscopic optic disc photographs, and confocal scanning laser ophthalmoscope imaging to discriminate between healthy persons and patients with early glaucoma. DESIGN: Comparative instrument validation study. PARTICIPANTS: Seventy-two healthy persons and 51 patients with early glaucoma (average visual field mean deviation, -3.6 dB). Early glaucoma was defined as a history of ocular hypertension and a reproducible visual field defect scoring 5 or less in the Advanced Glaucoma Intervention Study classification, regardless of optic disc appearance. INTERVENTION: Stereoscopic optic nerve head (ONH) photography and Heidelberg Retina Tomograph (HRT) imaging, (Heidelberg Engineering GmbH, Dossenheim, Germany). MAIN OUTCOME MEASURES: Ability of clinical assessment of stereoscopic ONH photographs and analysis of HRT parameters, taking into account the optic disc size, to detect early glaucomatous optic disc changes. RESULTS: The specificity of the majority opinion of five observers to detect early glaucomatous optic disc changes was 94.4%, with a sensitivity of 70.6%. Using the HRT analysis, the specificity was 95.8% and the sensitivity was 84. 3%. CONCLUSIONS: Heidelberg Retina Tomograph image analysis that takes into account the optic disc size is more sensitive than clinical assessment of stereoscopic optic disc photographs in distinguishing between healthy persons and patients with early glaucoma.

Aged↗
PubMed1999

Inter- and intraobserver variation in the analysis of optic disc images: comparison of the Heidelberg retina tomograph and computer assisted planimetry.

AIMS: The development of imaging and measurement techniques has brought the prospect of greater objectivity in the measurement of optic disc features, and therefore better agreement between observers. The purpose of this study was to quantify and compare the variation between observers using two measurement devices. METHODS: Optic disc photographs and images from the Heidelberg retina tomograph (HRT) of 30 eyes of 30 subjects were presented to six observers for analysis, and to one observer on five separate occasions. Agreement between observers was studied by comparing the analysis of each observer with the median result of the other five, and expressed as the mean difference and standard deviation of differences between the observer and the median. Inter- and intraobserver variation was calculated as a coefficient of variation (mean SD/mean x 100). RESULTS: For planimetry, agreement between observers was dependent on observer experience, for the HRT it was independent. Agreement between observers (SD of differences as a percentage of the median) for optic disc area was 4.0% to 7.2% (planimetry) and 3.3% to 6.0% (HRT), for neuroretinal rim area it was 10.8% to 21.0% (planimetry) and 5.2% to 9.6% (HRT). The mean interobserver coefficient of variation for optic disc area was 8.1% (planimetry) and 4.4% (HRT), for neuroretinal rim area it was 16.3% (planimetry) and 8.1% (HRT), and (HRT only) for rim volume was 16.3%, and reference height 9.1%. HRT variability was greater for the software version 1.11 reference plane than for version 1.10. The intraobserver coefficient of variation for optic disc area was 1.5% (planimetry) and 2.4% (HRT), for neuroretinal rim area it was 4.0% (planimetry) and 4.5% (HRT). CONCLUSIONS: Variation between observers is greatly reduced by the HRT when compared with planimetry. However, levels of variation, which may be clinically significant, remain for variables that depend on the subjective drawing of the disc margin.

Glaucoma↗
PubMed1998

Identification of early glaucoma cases with the scanning laser ophthalmoscope.

PURPOSE: This study aimed to define the confocal laser scanning ophthalmoscope (Heidelberg Retina Tomograph [HRT]) parameters that best separate patients with early glaucoma from normal subjects. STUDY DESIGN: A cross-sectional study. PARTICIPANTS: A total of 80 normal subjects and 51 patients with early glaucoma participated (average visual field mean deviation = -3.6 dB). INTERVENTION: Imaging of the optic nerve head with the HRT and analysis using software version 1.11 were performed. MAIN OUTCOME MEASURES: The relation between neuroretinal rim area and optic disc area, and cup-disc area ratio and optic disc area, was defined by linear regression of data derived from the normal subjects. The normal ranges for these two parameters were defined by the 99% prediction intervals of the linear regression between the parameter and optic disc area, for the whole disc, and for each of the predefined segments. Normal subjects and patients were labeled as abnormal if the parameter for either the whole disc or any of the predefined segments was outside the normal range. The sensitivity and specificity values of the method were calculated. RESULTS: The highest specificity (96.3%) and sensitivity (84.3%) values to separate normal subjects and those patients with early glaucoma were obtained using the 99% prediction interval from the linear regression between the optic disc area and the log of the neuroretinal rim area. Similar specificity (97.5%) and lower sensitivity (74.5%) values were obtained with the 99% prediction interval derived from regression between the disc area and cup-disc area ratios. Poor separation between groups was obtained with the other parameters. CONCLUSIONS: The HRT, using the technique of linear regression to account for the relationship between optic disc size and rim area or cup-disc area ratio, provides good separation between control subjects and patients with early glaucoma in this population.

Aged↗
PubMed1997

Aging changes of the optic nerve head in relation to open angle glaucoma.

AIMS: To determine the age related changes in optic nerve head structure in a group of normal subjects and assess the significance of any changes in relation to those found in open angle glaucoma. METHODS: A group of 88 white volunteers and friends and spouses of patients with a normal visual field and normal intraocular pressure was studied. Two different imaging and measurement devices were used (computer assisted planimetry and scanning laser ophthalmoscopy), and the results from each were compared. Measurements were made of the optic disc, optic cup, and neuroretinal rim areas, and the vertical optic disc diameter and cup/disc diameter ratio. RESULTS: Neuroretinal rim area declined at the rate of between 0.28% and 0.39% per year. Vertical optic cup diameter and optic cup area increased with age. The mean cup/disc diameter ratio increased by about 0.1 between the ages of 30 and 70 years. CONCLUSIONS: Age related changes are significant and measurable, and should be taken into account when assessing the glaucoma suspect, and when estimating the rate of progression of glaucomatous optic neuropathy in patients with established disease.

Adult↗
PubMedDate not supplied

Macular changes in type I Gaucher's disease.

The authors illustrate the spectrum of Gaucher's disease involving the eye in the case of a 51-year-old man suffering from Type I Gaucher's disease who presented with unusual macular changes. This is the first report of chronic adult non-neuronopathic disease (Type I) with a plaque-like mass at the fovea. Our hypothesis is that the lesion at the fovea is probably an aggregation of Gaucher's cells.

Fluorescein Angiography↗