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Imaging and documentation of the human retina for clinical diagnostics are conventionally achieved by classical optical methods. We designed a digital laser scanning fundus camera. The optoelectronical instrument is based on scanning laser illumination of the retina and a modified video imaging procedure. It is coupled to a digital image buffer and a microcomputer for image storage and processing. Aside from its high sensitivity the LSF incorporates new ophthalmic imaging methods like polarization differential contrast. We give design considerations as well as a description of the instrument and its performance.

Background and Objective This study investigated the feasibility of 850 nm diode laser‐induced thermotherapy (LITT), a new procedure providing local hyperthermia and photocoagulation, a minimally invasive treatment of tumors, and other disorders such as benign prostate hyperplasia. Study Design/Material and Methods: An improved fiber optic diffuser inserted through a catheter was used to irradiate prostate, liver, and kidney tissue in‐vitro. Experimental results were compared with predictions from mathematical simulations based on measured optical tissue parameters. Results After 10 minutes of irradiation with 2–4.6 W CW laser power, sizable coagulation diameters had been achieved. In prostate and kidney tissue, temperature rises and coagulation diameters after laser irradiation were found to be smaller than in liver tissue. Those tissues also had a higher threshold for carbonization, thus reducing the risk of damage to the delivery system. Conclusion The data suggest that a low power diode laser can be recommended for use in LITT to treat prostate and kidney tissue. © 1996 Wiley‐Liss, Inc.

Safety standards such as American National Standards Institute Z-136.1 do not give clear light-level limitations for laser scanning ophthalmoscopes. To have more than a rough estimation the retinal temperature rise due to intraocular scanning laser illumination was calculated on the basis of a thermal model. The predicted temperature development with time was compared with the calculated effect of other retinal illumination patterns with well-known hazard risks. The similarity of the thermal effect of retinal scanning and extended-source pulsed illumination is discussed and used to give maximum permissible light-level recommendations for the safe use of laser scanning ophthalmoscopes.

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