The effect of relative spectacle magnification on aniseikonia.

PURPOSE: The purpose of this article is to study the effects of modifying relative spectacle magnification to determine what effect this has on aniseikonia, binocularity, and visual comfort. METHODS: A prospective analysis of 34 aniseikonic patients was undertaken. The etiology of aniseikonia varied from physiologically occurring to induced. Aniseikonic screening included manifest refraction, keratometry, axial length, Randot stereoacuity, associated phoria, and Keystone space eikonometry. A modified pair of spectacles was fabricated on the basis of magnification principles for iseikonic lenses. Each patient was also given a control pair of conventional spectacles. A 4-week trial period was allowed for each pair of spectacles, pertinent examination measurements were repeated, and a patient survey was administered. Data were analyzed by t-test and chi-square. RESULTS: Modifying relative spectacle magnification reduced mean aniseikonic error by 1.06% (P < 0.0001). A difference was found between the control and modified spectacles for subjective reports of visual comfort, performance, and eye-strain (P < 0.05). There was no difference between the two groups for stereoacuity or cosmetic appearance of lenses. At the conclusion of the study, 93% of patients preferred the modified lenses in direct comparison. CONCLUSIONS: Our results confirm that modification of lens designs to equalize relative spectacle magnification reduces aniseikonia and improves subjective comfort and performance of anisometropic spectacles.

Development of a fiber-optic sensor for trace metal detection in aqueous environments.

The availability and speciation of a number of metals widely dispersed in the aquatic environment intimately affect the biogeochemistry of the ocean and its inhabitants. Much research has been focused on the development of analytical methodologies to elucidate better the background concentrations, variability, and contaminant effects of metal species. The purpose of this research is to investigate the viability of a fiber-optic sensor that will be a sensitive and selective probe for trace metals in natural waters.