In an electronic endoscope apparatus according to the present invention, a micromirror device reflects light from a light source to allow it to enter a light guide. The etch process comprises a sequence of at least three steps, wherein the sequence is repeated at least once. The first compensation device comprises a thyristor-controlled reactor for each of the phases of the ac network. This Abstract is provided for the sole purpose of complying with the Abstract requirement rules that allow a reader to quickly ascertain the subject matter of the disclosure contained herein. The novel finding is that it is possible to carry out the oxidation of 1,2:5,6-di-O-isopropylidene–D-glucofuranose with DMSOacetic anhydride and a reduction reaction in one pot obtaining high yields of recrystallised and analytical pure 1,2:5,6-di-O-isopropylidene–D-allofuranose. Also provided are ophthalmic components useful in ophthalmic imaging applications, as well as methods of assessing intracranial pressure that are based, at least in part, on the degree of papilledema, if any, present in the subject.