Note, how when there is a little too much exposed platform to the upper lid, the eye is drawn to the lid, rather than the pupil. Hollowness, whether through ageing, or post blepharoplasty complication also lends a 'roundness' to the eye. In the after pictures you can see how orbital fillers are used to address this problem.
(The image below, though not the best quality, is an excellent example of this)
The reports on longevity of filler, are from 9 months to 24 months. Latest reports are very positive, for the procedure lasting between 18-24 months. This area is not as mobile as others and this factor contributes to the longer lasting result.