1596-1650 accommodationandrefraction astronomical atmosphericturbulence conics conicsections diagnosis double earlyworksto1800 eye eyeglasses handbooks history icelandspar imagingsystemsinastronomy instrumentation knowledge lenses manuals methods ocular ocularrefraction opticalproperties optics opticsdescartes optometry refractionandaccommodation refractiveerrors rené retinoscopy science spherical telescopes ww300b73421998 ww300d877p1978