Biomedical subjects

D U Bartsch

Publications and source records attributed to D U Bartsch.

25 records · Page 2Linked to original sources

PubMed1995

Confocal scanning infrared laser ophthalmoscopy for indocyanine green angiography.

PURPOSE: We used indocyanine green to study wavelength-optimized confocal scanning infrared laser angiography in patients with retinal and choroidal disease. METHODS: A confocal scanning laser ophthalmoscope with an excitation wavelength of 795 nm was operated both in tight and wide confocal imaging modes. We examined 77 subjects with and without retinal and choroidal disease (including diabetic retinopathy, age-related macular degeneration, and subretinal neovascularization). RESULTS: The scanning laser ophthalmoscope allowed acquisition of images, in the wide confocal imaging mode, of the retinal circulation and late leakage sites without late injections of dye to outline the retinal vasculature. In the tight confocal imaging mode, optical subtraction of the light contribution of the retinal circulation allowed examination of the choroidal circulation, and vice versa. The wide confocal mode appears equivalent to other scanning laser ophthalmoscopes in recording images from retinal and choroidal layers. CONCLUSIONS: There are three differences between the confocal scanning laser ophthalmoscope and conventional instruments. First, the late images allow excellent visualization of the retinal circulation without a landmark injection. Second, confocal imaging allows optical subtraction of retinal circulation when focusing on the choroid and vice versa. Third, the instrument acquires and processes all data digitally, is personal computer-based, is compact, operates with a mouse-driven graphical user interface, and allows easy data exchange with conventional software. With further modifications in software and hardware, this device offers the possibility of producing a three-dimensional map of the retinal and choroidal vasculature.

Adult↗

PubMed1994

Axial intensity distribution analysis of the human retina with a confocal scanning laser tomograph.

We have analysed the change of reflected light intensity along the optical axis or axial intensity distribution in images acquired with a confocal scanning laser tomographic system in human fundus examination. We hypothesized that confocal light detection units used in scanning laser tomographs register light originating from multiple layers within the human macula and that intraretinal structures might also be observable. To test this hypothesis we examined the axial intensity distribution in human maculas of normal volunteers, patients with cystic and other macular abnormalities and in an artificial retina in a plastic eye model. A total of over 140 patients and volunteers were examined. We analysed this distribution in 20 normal healthy volunteer eyes found the origin of the artifacts that cause retinal vessels to appear elevated. We examined four patients with cystic maculas and were able to detect the presence of two structures in axial direction contributing to the axial intensity distribution. A plastic eye model with a cellophane sheet covering a fluid pocket was developed to mimic the appearance of a large macular cyst. The axial intensity distribution analysis showed the presence of two distinct gaussian profiles. The results of this study show that confocal scanning laser tomographic imaging of the human fundus allows extraction of information regarding the axial position of intraretinal layers and that correction for the deeper retinal reflections may allow more precision in imaging of the retinal surface.

Adult↗

PubMed1993

Effect of repetitive imaging on topographic measurements of the optic nerve head.

OBJECTIVE: A confocal scanning diode laser ophthalmoscope was used to determine the number of examinations needed to obtain highly reproducible topographic measurements of the optic nerve head and peripapillary retina. DESIGN: Topographic images of the optic nerve head and peripapillary retina were obtained in one randomly selected eye on five separate visits. On each occasion the selected eye had five examinations. For each examination, one image was acquired (a total of 25 images per eye). Reproducibility was calculated as the average SD of all image elements (65,536 pixels). SETTING: Glaucoma referral center. SUBJECTS: Five normal subjects and five patients with glaucoma. INTERVENTION: Topographic imaging of the optic nerve head and peripapillary retina. MAIN OUTCOME MEASURE: Number of examinations needed to obtain highly reproducible topographic measurements. RESULTS: In healthy subjects, reproducibility with one examination per visit was 35.5 microns; this improved to 25.7 microns with three examinations and 22.5 microns with five examinations. In older patients with glaucoma, the reproducibility improved from 40.2 microns with one examination per visit to 28.5 and 24.1 microns with three and five examinations, respectively. CONCLUSION: We recommend a series of three examinations to provide high reproducibility with optimal efficiency in terms of time and materials used.

Adult↗

PubMed1993

Laser-tissue interaction and artifacts in confocal scanning laser ophthalmoscopy and tomography.

The goal of the present study was to analyze the interaction between incident laser light and retinal tissue in confocal scanning laser ophthalmoscopy and tomography. We examined the change in axial intensity distribution during evaluation of the retinal surface topography in macular and optic nerve head evaluation in normal volunteers and patients with different retinal diseases. Additionally, we examined a model eye with a model cyst and human globes in an eye mounting chamber. We found that confocal scanning laser tomographs record specular reflected light originating from intraocular surfaces as well as light scattering from deeper retinal structures. Concave and convex retinal surfaces and eye movements may influence accurate topographic detection. Knowledge of the exact mechanism of image formation in confocal tomography is of great importance for the understanding of validity of these measurements. Proper identification of observed artifacts and preventive measures will increase the utility, reproducibility, and validity of this technology.

Cysts↗

PubMed1993

New ophthalmic lasers for the evaluation and treatment of retinal disease.

Ophthalmic lasers are used as diagnostic as well as therapeutic modalities in patients with retinal diseases. Recent advances in laser technology have allowed more convenient selection of wavelength and a wide variety of delivery systems is available to deliver the laser energy to the retina. In addition, newer lasers that disrupt and cut tissue will become available for use in patients with retinal diseases. The use of imaging lasers and lasers in combination with dyes selectively to enhance their effects have become useful in diagnosis and understanding of pathophysiology of diseases. These lasers will also be therapeutically useful. This manuscript delineates the new types of diagnostic and therapeutic lasers, new imaging dyes and techniques as they apply to retinal diseases as well as the principles of laser-tissue interaction as applied to the retina. This should allow the ophthalmologist who treats patients with retinal diseases to make more intelligent decisions regarding the use and acquisition of laser systems.

Animals↗

PubMed1989

Confocal laser tomographic analysis of the retina in eyes with macular hole formation and other focal macular diseases.

To study the retinal surface in the human eye in normal and diseased states we used laser scanning tomography. The confocal arrangement of the laser tomographic scanner permits examination of retinal topography in the axis perpendicular to the retinal surface. The eyes examined with the laser tomographic scanner included normal eyes, eyes with macular holes, impending macular holes, radiation retinopathy, macular edema, photocoagulation scars, subfoveal scars, and serous detachment of the fovea associated with subretinal neovascularization. The laser tomographic scanner is a new method that allows measurements of the topography of the internal limiting membrane in the macular area and may improve our understanding of the pathophysiologic characteristics and treatment of a variety of disorders of the macula.

Adult↗

PubMedDate not supplied

A new objective digital computerized vision screening system.

PURPOSE: Fewer than 40% of children in the crucial younger-than-4 age group are evaluated for visual problems by pediatricians. This is due to impracticality from either a clinical or practice efficiency standpoint. Current photoscreening methods require trained readers and suffer from significant subjectivity and interobserver variability. We report a cross-sectional, double-masked study using new digital imaging with objective, automated, computerized image analysis. METHODS: Two-hundred six children aged 9 months to 16 years were prospectively studied in a University-based pediatric ophthalmology practice. Images were taken by volunteers with a modified digital camera which, when downloaded, were analyzed within 35 seconds by new image analysis software. The analysis was compared to a masked review of a complete pediatric ophthalmic exam. RESULTS: Overall agreement between physician and the objective computerized analysis was 86.9%. Positive predictive value was 91%, sensitivity was 89%, and specificity was 83%. CONCLUSIONS: This automated digital imaging screening system eliminates human bias and provides accurate and immediate results. The system requires no special expertise.

Adolescent↗