The requirements for air-to-air, air-to-water, and water-to-water vision, except for minor complications, are relatively easily attained by the normal human eye. Because of the internal reflection and because the human eye is primarily adapted to air vision, therefore, the novel requirements demanded in water-to-air vision present an interesting challenge. One method of accomplishing this task and the means employed is the subject of this report.
Water-to-air vision can be attained in a number of ways, but the following limitations were placed upon the designs of any lens system which we were to develop:
It was necessary for water (index of refraction, n = 1.33) to be in direct contact with the globe: This eliminated from consideration contact lenses, ordinary underwater goggles, helmets, periscopes, and the like.
The eye was assumed to have an over-all index of refraction of 1.33.
The apex of the cornea was to be approximately 7.8
DUANE TD, EMRICH RJ, SHEPLER HG. Lens System Designed for Water-to-Air Vision in the Submerged Human Eye. AMA Arch Ophthalmol. 1959;61(4):561-564. doi:10.1001/archopht.1959.00940090563010