In order to provide comfortable viewing for extended periods, one can use a "BinoViewer" - or binocular viewer. This is a device which allows the single image coming from the scope to be viewed by both eyes. If using a binoviewer, it is necessary to have pairs of eyepieces (preferably "matched") - one for each eye.

The Stellarvue binoviewer is one of the less expensive binoviewers, but actually offers very respectable performance for the price (under $200, compared to Denkmeiers, which are close to $1000 for the top-end model). This binoviewer has a 1.25" nosepiece which can be inserted where the eyepiece normally fits at the back of the telescope; it then provides two slots for a pair of eyepieces to look through. I have not used the Stellarvue binoviewers except to initially try them, so I cannot make detailed comments on performance. However I can definitely say that looking through a binoviewer can be much more comfortable than looking through a single eyepiece, and squinting with the other eye (or using an eye patch).