High power lens with a measurement water cell.
A simple water cell can be used to increase the range of an ordinary lensometer by about three times by using an application of Snell's law. This technique can be very useful in low vision applications where other methods of measuring high plus ophthalmic lenses are always cumbersome and time consuming and sometimes inaccurate or inconclusive.
D005139:Eyeglasses; D007909:Lenses; D008722:Methods; D009907:Optometry / Q000295:instrumentation*; D012030:Refractive Errors / Q000534:rehabilitation*; D014481:United States