| 摘要 |
<p>Trifocal eye-contactlens consisting of three, mainly concentric parts. - A central part correcting the course of lightrays in case of myopia, an outer circular part, correcting the rays in case of presbyopia and between these two parts a - circular - transitium-part, in which the focal distance changes gradually from the value of the central part, to that of the outer part.</p> |
