I'm gonna try this one. I just graduated from NS last month, but prior to NS I worked for many years in ophthalmology. I quite often saw geriatric patients with what you have described, although it can happen to quite young folks also. Pterygiums and pingueculas are protien/fatty like substances that are sitting on the conjunctiva of the eyeball. Usually at the nasal aspect of the eye or the temporal and are honey yellowish in color from years of prior sunlight exposure or chronic dry eyes. Another possiblility is conjunctival edema right at the area where an older person may not have been able to completely close one of their eyes completely the night before and the conjuntival sac dries out and fluid tries to come to the aid of the exposed area. Again, others may offer some different possibilities, but I have seen this occur in the elderly before. Just my first impression and I could be completely off the mark!