The registration of retinal images is required to facilitate the study of the optic nerve head and the retina. The method we propose combines the use of mutual information as the similarity measure and simulated annealing as the search technique. It is robust toward large transformations between the images and significant changes in light intensity. By using a pyramid sampling approach combined with simulated reannealing we find that registration can be achieved to predetermined precision, subject to choice of interpolation and the constraint of time. The algorithm was tested on 49 pairs of stereo images and 48 pairs of temporal images with success.

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To determine absorption coefficients for sodium chloride solution (saline) and balanced salt solution at the 193-and 213-nm laser wavelengths. Methods: Absorption coefficients were obtained for each of the component species found in balanced salt solution. This was achieved by measuring laser pulse transmission through solutions of varying concentration. The experiments were repeated using the 193-nm excimer and 213-nm solid-state laser wavelengths. Results for each species were then used to obtain an overall absorption coefficient and penetration depth for balanced salt solution and 0.9% sodium chloride solution. Results: Absorption coefficients in balanced salt solution for the 193-and 213-nm wavelengths were found to be 140 and 6.9 cm −1 , respectively. In 0.9% sodium chloride solution, the absorption coefficient was 81 cm −1 at 193 nm and 0.05 cm −1 at 213 nm. At 193 nm, absorption in balanced salt solution was dominated by sodium chloride. Sodium citrate emerged as the dominant species of absorption at 213 nm.

Transmission time was reduced from 15-20min to 20-30s and the image size was reduced from 1.3 MB to 20-30 kB by compressing the images before transmission. Image quality is still excellent.