Reproducibility study on the Scheimpflug Cataract Video Camera

The Zeiss Scheimpflug Cataract Video Camera was designed to photograph, store and analyze cataracts in a semi-automated fashion for cross-sectional and longitudinal studies. We conducted a reproducibility study of this system. Twenty-four normal and 61 cataractous eyes were photographed twice by each of two of the authors in the 90 degree meridian and microdensitometry was performed on each of the stored images. Reproducibility was then determined using the intraclass correlation coefficient to determine whether or not the differences encountered were due to variability in the system or due to actual differences among the images. The intraclass correlation in the lens nucleus was 0.995 with 95% confidence limits of .992-.996. Therefore, reproducibility was 99.5%. In the anterior cortex, intraclass correlation was .941 with 95% confidence limits of .919-.959. In the posterior cortex intraclass correlation was .905 with 95% confidence limits of .870-.932. Reproducibility with this instrument was therefore excellent and with certain limitations, this may be a useful instrument in monitoring lens changes in certain diseases and the effects of anti-cataract agents.

Cure for the AA battery blues. Six-volt battery pack from previously discarded Polaroid batteries

The Polaroid Polapulse batteries obtained from exhausted Polaroid 600 or Polaroid SX-70 film cassettes can be used to power a 6-V camera flash. A method for attaching these previously discarded batteries is described.

A further note on the photography of cataracts

Polarized light used in conjunction with a quarter-wave plate, as previously described, was further modified with colour filters in order to test whether blue-free light increased contrast by reducing fogging due to lenticular fluorescence. The reproducibility of photographic records over a period of at least six months was also tested with satisfactory results in both of these objectives.

[A method of intravital study of pulmonary microcirculation in closed-chest cats]

The methods of intravital study of the cat lungs have been updated. A device has been designed for the investigation of microvessels in extended lung areas of spontaneously breathing closed-chest cats. The principles for quantitative analysis of microcirculatory lung parameters have been elaborated. These new methods allow the study of important natural phenomena of the lung microvascular functions.

Use of circularly polarized light in fundus and optic disc photography

Circularly polarized light was used in fundus and optic disc photography to reduce reflected glare and photographic artifacts originating from the ocular media and the lenses of the fundus camera. A standard fundus camera was used, with circular polarizers placed in the illumination and observation paths. The quality of fundus photography was improved significantly in eyes with intraocular lenses, cataract, vitreous haze, or high myopia as well as in normal eyes, in fundus photography of the retinal periphery, and in optic disc photography.

Slit-lamp photography made easy by a spot metering system

The use of a standard 35 mm camera with a spot metering system to take slit-lamp photographs is described. This system is mounted on a standard Haag-Streit slit-lamp and can be used with good results even by inexperienced operators.

Monocular diplopia accompanying ordinary refractive errors

Monocular diplopia is commonly encountered in ophthalmic practice. We discovered that it could be induced in nine (82%) of 11 normal eyes with ordinary spherical or astigmatic defocus of the retinal image. Possible mechanisms responsible for this effect include retinal processing, diffraction effects, and spherical aberration. By employing geometric blur circle theory and using a simple optical model to photograph the effect, we concluded that monocular diplopia in the setting of ordinary refractive error is secondary to relatively minor optical irregularity such as spherical aberration. Contour enhancement properties of the retina probably accentuate this effect. Ordinary refractive error should therefore not be overlooked or discounted in patients with monocular diplopia.

Solid-state imagers for microscopy

Solid-state imagers offer a variety of options to the modern optical microscopist. Photodiode arrays, charge injection devices, and charge-coupled devices are the three basic types of solid-state imagers available for research imaging. The charge-coupled device (CCD) is the solid-state imager of choice, because of its superior characteristics and its widespread acceptance in the research environment. The performance characteristics of the CCD are well documented and understood, having been quantified by many experimenters, especially in the physical sciences. CCDs exhibit dynamic ranges up to 50,000:1, very high quantum efficiency, and ultralow noise. The camera system in which a device is used, however, dictates the overall performance which can be achieved. The CCD imaging system as it applies to cell biology is discussed in detail in Hiraoka et al. (1987). A video camera operating at 30 frames/second does not provide the resolution, low noise, dynamic range, and linearity of a slow scan, cooled camera operating at 1 frame/second. Conversely, a slow scan camera does not offer the user the facility to resolve rapidly changing events in real time. The analogy between an 8-mm movie camera (video camera) and a 35-mm snapshot camera (slow scan cooled camera) is a useful one to emphasize the different character of these two electronic imaging systems. These two basic camera systems both employ CCD imagers, and each has very different, but complementary, characteristics. No one camera system can address the wide variety of imaging problems which face the modern microscopist. The user of this new generation of instrumentation must decide which system best fits the problem at hand.

Instrumentation for small joints: the arthroscope

This first of three articles on arthroscopy of small joints is a brief overview of the current arthroscopes and the modifications that have made arthroscopy of small joint spaces possible. Those modifications include angulation at 25-30 degrees, improved low-light, high-resolution chip cameras, and use without a bulky camera adapter. The largest possible arthroscope should be used, but size is limited in diameter to 2.0 mm for the distal radioulnar and temporomandibular joints, 2.7 mm for the midcarpal joint, and 3.0 mm for the radiocarpal joint. The need to have high-quality repair service available is stressed.