No abstract

A method for measuring the tilt and decentration of intraocular lenses (IOLs) in the static eye using the Purkinje image locations is presented. The patient fixates on a target that is coaxial with the camera or is at a predetermined angle with the camera axis. A telecentric stop is introduced in the camera so the positions of the Purkinje images on the film are independent of their distance from the camera. Measurements of the image locations on the film are used with anterior chamber depth and corneal curvature measurement to calculate the tilt and decentration of the IOL. In a group of 14 randomly selected patients with posterior chamber IOLs, 13 gave Purkinje images that could be measured. The average tilt was 7.8 degrees and the average decentration was 0.7 mm.

Fiber lasers of neodymium-doped glass have been used on a pulsed basis to amplify 1.06-1, radiation. To prevent oscillation, the ends are polished at an angle such that reflected light is lost from the cavity. With the high inversion which can then be obtained, gains as large as 5 X 104 have been observed in a 1-m long fiber. The gain was measured as a function of pumping energy and as a function of time during the pumping pulse at which the amplification was determined.

Optical sectioning is the simultaneous illumination and viewing of only a thin region of a specimen. An illuminated slit is imaged at the plane of interest and is swept laterally by the action of an oscillating mirror. The light returning from the specimen reflects from a second facet of the oscillating mirror and forms a stationary image of the illuminated slit. At this stationary image a second slit is placed, which passes light from the desired plane and rejects scattered light from other depths within the specimen. Light passing through the second slit is reflected from the third facet of the oscillating mirror and is focused to the final image plane. The image is reconstructed as the image of the second slit sweeps across the image plane. An important ophthalmological application is the examination of the endothelial cell layer of the cornea, either by contact or noncontact techniques. Optimization for image illuminance and resolution is discussed.