Laser-tissue interactions.

Current ophthalmic laser treatment can be described on the basis of its effect on tissue. Laser variables such as wavelength, spot size, power, and mode of delivery are all controllable, but are dependent on the transparency, pigmentation, and water content of the tissue involved. This discussion introduces the clinician to these variables, while describing specific laser-tissue interactions.

Complications of anterior segment laser procedures.

The majority of complications associated with laser procedures can be minimized or avoided through proper technique. The astute clinician is aware of all potential complications and is prepared to manage any undesired effects promptly and correctly. This review discusses how to minimize the risk of significant complications and describes the appropriate treatment protocols for complications associated with specific anterior segment laser procedures.

CO(2) laser-based differential absorption lidar system for range-resolved and long-range detection of chemical vapor plumes.

A dual CO(2) laser-based differential absorption lidar (DIAL) system has been constructed and demonstrated for range-resolved mapping of chemical vapor plumes. The system acquires high range resolution through the use of plasma-shutter pulse clippers that extinguish the nitrogen tail of the CO(2)-laser output. Aprogrammable servomotor-driven scanner allows full hemispherical coverage of the interrogated field. A high-speed direct-detection receiver subsystem is used to gather, process, and display vapor-concentration data in near real time. Data demonstrating range-resolved detection of low concentrations of chemical plumes from ranges of 1 to 2 km are presented. In the column-content detection mode, trace levels of secondary vapors from various organophosphate liquids were monitored. Detection of an SF(6) vapor plume released 16 km from the DIAL system is also adduced.

Design of an open path near-infrared diode laser sensor: application to oxygen, water, and carbon dioxide vapor detection.

An open path diode laser sensor was constructed with near-infrared diode lasers and two-tone frequency-modulation spectroscopy. The sensor incorporates several novel features (such as digital signal-processing algorithms, a computerized line-locking routine, and discontinuous wavelength scanning) that are important in a field instrument. The sensor was used to monitor oxygen, water, and carbon dioxide in the near-infrared spectral range. For oxygen, an absorbance detection sensitivity of 2 × 10(-6) in a 10-Hz bandwidth was demonstrated with a GaALAs laser at 760.56 nm. The stability of the sensor was 0.1% over a period of 10 h when an absorbance of 6 × 10(-3) was monitored.

A case of monocular triplopia of lenticular origin.

A 70-year-old male experienced unilateral monocular triplopia of lenticular origin. The images formed a nearly equilateral triangle and were equally clear. It was noted that the images were formed by sections of the crystalline lens whose borders were parallel to the orientation of the anterior Y-sutures.

Fusion lock diameter and the forced vergence fixation disparity curve.

The effect of the diameter of the fusion lock on the forced vergence fixation disparity (FD) curve was investigated because of ambiguity in the results of previous investigations. Data gathered from 20 asymptomatic subjects with normal binocularity showed that the fusion lock diameter had no noticeable effect on the shape of the curve. Further investigations using symptomatic subjects showing large FDs or steep forced vergence FD curves showed that fusion lock diameter did have an effect on the curves of these subjects. The results are interpreted for their clinical implications through a control systems model of the accommodation-vergence interaction.