Vitrectomy: Removal of the gel (called the vitreous) from within the eyeball. This may be done because it has blood and scar tissue in it that blocks sight. The eye surgeon then replaces the clouded gel with a clear fluid. QUESTION What causes dry eyes? See Answer From Eye Health Resources Eye Care When You Have Graves' Eye DiseaseFinding the Care You Need for MS Featured Centers Good and Bad Foods for PsoriasisVideo: Getting Personal on Life With MS Health Solutions From Our Sponsors Shot-Free MS Treatment Your Child and COVID-19