There is a new solution form Walter RX Eyepiece for rangefinder cameras users who suffer from astigmatism:
This is an ingenious little device that solves two big problems. Your optical deficiency, and astigmatism. Now, using this device, you are able to put your eye up close to the eyepiece, allowing you to see the full frames in the finder and in the case of the Leica M9 or M8, you can clearly also see the illumination arrows indicating the exposure. Obviously this is crucial for perfect ergonomics and correct photography. The eyepiece is hand made from solid brass with a matt black coating to match the Leica cameras. The eyepiece contains your personal lens matching your prescription of the eye you use to take pictures with. The real ingenious part of this accessory is that the Walter RX eyepiece ® is engineered to always stay in a horizontally aligned position. Mounted on a high quality, German engineered, freely rotating ball bearing, the eyepiece will always fall back to the same horizontal position with ease, no matter what angle you hold the camera.
