Constructing retinal fundus photomontages. A new computer-based method.

Purpose: To develop computer algorithms for reconstructing 24-bit color, wide-angle composite retinal fundus images from a set of adjacent 45 degrees fundus slides. The authors present the description, technical details, and results of the image reconstruction technique.

Methods: Patients with retinal degeneration underwent fundus photography with a 45 degrees field-of-view fundus camera.

Quantitative analysis of retroillumination images.

We have developed a semi-automated image processing system for analysis and evaluation of retroillumination images. This paper describes methods used to compensate for illumination variations in the images, separation of data into cataractous and non-cataractous portions, how quantitative measurements are made and how they assess the pathological condition. In addition to the traditional area measurement, this system computes the net integral of density and several measurements involving the location of the opacity in relation to the pupillary margin.

Reproducibility study of posterior subcapsular opacities on the NEI retroillumination image analysis system.

We developed a semi-automated retroillumination image analysis system which combines speed, ease of operation and interactive analysis. The system measures cataract area and integral of cataract density (ID). For system reproducibility evaluation, 20 eyes with posterior subcapsular opacities were captured twice by two photographers.

Cardiovascular flow velocity measurements by 2D Doppler imaging for assessment of vascular function.

Clinical two-dimensional (2D) Doppler ultrasound flow velocity measurement is important for determination of arterial wall shear stress, blood-tissue exchange, myocardial and valvular function. Such 2D Doppler flow velocity images are usually displayed in color, superimposed on the gray-scale, cross-section structural images of the tissue. There are several limitations to this technique of flow measurement, some due to the instrumentation and some to the way the measurement is made.

Development of a Scheimpflug slit lamp camera system for quantitative densitometric analysis.

We have developed a computerised video system for accurate quantification of lens opacities from Scheimpflug images. Using a modified Zeiss Scheimpflug camera and Macintosh computer, the system software can warn of improper exposure and can provide immediate results of cataract progression on individual patients. These results are obtained from a novel technique which automatically divides the lens into anatomical regions and computes regional densities in the standard optical density unit.