PubMed · 6579372
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S D McPherson. 1983. The continuous vision lens.. https://pubmed.ncbi.nlm.nih.gov/6579372/
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In this article product developments for ophthalmic lenses are discussed: new materials, designs and coatings. High-index plastic substrates allow to offer corrections which are simultaneously light and thin and for the first time there are high performant plastic photochromic lenses. Head and eye movements with latest generation's progressives are very similar to natural vision behaviour. Special aspheric designs have been developed for comfortable vision for near and intermediate distances. Finally there are new coatings which protect the high quality surfaces of plastic lenses distinctly longer than before.
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A method published elsewhere for estimating dioptric power from meridional measurements is generalized here to allow for measurements of sagitta, lens thickness, and prismatic effect as well. Measurements may be of only one type or of combinations of types. Any number of measurements may be used. Within the usual limitations of first-order optics the method always works and gives all solutions when solutions exist. When no solutions exist it gives approximate solutions called least-squares estimates. At least one least-squares estimate always exists. A wide class of ostensibly distinct problems reduces to a single standard routine that is easy to execute with matrix-handling software. If there is reason to believe that the dioptric power is of some particular form then constrained estimation may be applied to find that form.