1. Blakiston’s Pocket Medical Dictionary;Osol,1973
2. Acquired ptosis in the young and middle-aged adult population;Kersten;Ophthalmology,1995
3. Extended wear of hard gas permeable contact lenses can induce ptosis;Fonn;CLAO J,1986
4. Rigid gas-permeable vs. hydrogel contact lenses for extended wear;Fonn;Am J Optom Physiol Opt,1988
5. Palpebral aperture sizes of rigid and soft contact lens wearers compared with nonwearers;Fonn;Optom Vis Sci,1996