Biomedical subjects

J K Ijspeert

Publications and source records attributed to J K Ijspeert.

3 recordsLinked to original sources

PubMed1995

Light scattering in donor lenses.

Light scattering for normal and cataractous lenses from 21-86 yr old donors was measured in vitro. As expected, scattering increased with severity of cataract. Scattering decreased with angle according to a power law. This corresponded to the power law finding for functional straylight measurements in early-cataract patients using white light (power around -2). In vitro, straylight increased monotonically from 700 nm (power around -2.3) towards 400 nm (power around -2.0). For extreme cataracts the angular dependence flattened at small angles. The present results suggest that the structures dominating in light scattering differ not by scattering type but by number, and that they are not very small compared to wavelength. The present results were used to specify the separate effects of light absorption and light scattering on lenticular light transmission.

Adult↗

PubMed1991

Retinal contrast loss with non-monofocal IOLs.

Non-monofocal IOLs are designed to give simultaneously sharp images of distant and near objects. This is achieved by means of different focal distances for various portions of the light reaching the eye. As a result, for any given object, one part of the light will be properly focused, while another part is out of focus. This results in a sharp image superposed on a blurred image, causing contrast loss. The retinal contrast loss as a function of spatial frequency is derived in this paper.

Contrast Sensitivity↗

PubMed1990

Functional quantification of diaphany.

Intraocular straylight can be measured, in clinical as well as normal cases, by the direct compensation technique. Intraocular straylight is known to originate from the cornea, lens and fundus. We have studied a fourth source: the translucency of the iris and surrounding ocular wall. For lightly-pigmented normal eyes this source proved to be important. In the present paper results are reported from a patient with X-linked megalocornea. He had diaphany of the iris, as is common in these patients, and photophobic complaints. Quantitative measurements showed that the translucency was much increased so that the intraocular straylight was far above the normal level.

Adult↗