PubMed · 15435526
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H SCHROEDER. 1950. Contact lens problems.. https://pubmed.ncbi.nlm.nih.gov/15435526/
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PURPOSE: To describe a dual-purpose lens that can be used both as a planoconcave direct-image lens and wide-angle lens. This lens provides good resolution, is autoclavable and self-stabilizing. DESIGN: New instrument design. METHOD: This lens has two components (lenses): the inferior element is a modification of the standard, self-stabilizing planoconcave, one-piece acrylic lens with 4 footplates and is used in a similar manner; the superior part is a biconvex glass lens in a high-temperature-resistant plastic casing. The superior plastic casing is screwed on the inferior lens to convert it into a wide-angle lens. The lens is used as a self-stabilizing, planoconcave or wide-angle lens and is sterilized by autoclaving. RESULT: The planoconcave direct-image inferior lens gives a high-resolution image with a field of view of 20 degrees. The wide-angle lens on assembly of the inferior and superior parts gives a static field of view of 80 degrees and a dynamic field of view of 98 degrees. CONCLUSION: The two-piece dual-purpose contact lens is an inexpensive substitute for both planoconcave and traditional wide-angle lens without compromising the stability and quality of the fundus image.
After outlining what is meant by wavefront aberration, the history of the field of wavefront technology is sketched and methods for measuring ocular wavefront aberration are briefly described. The variations in aberration of the normal eye with the individual and their pupil size, accommodation and age are summarised. Potential contact lens applications are outlined, including the design and on-eye performance of single-vision lenses, lenses for presbyopes and keratoconics, orthokeratology, tear film studies, and the design and performance of customised contact lenses intended to minimise residual lens-eye wavefront error.