<prompt> Fleischer ring is characteristic of -MegalocorneaDiabetesChalcosisKeratoconus  <response>: In keratoconus slit lamp examination may show thinning and ectasia of central cornea, opacity at the apex and Fleischers ring at the base of cone, folds in Descemets and Bowmans membranes. Very fine, veical, deep stromal striae Vogt lines which disappear with external pressure on the globe are peculiar feature.Reference:Comprehensive ophthalmology,AK Khurana,4th edition,page no.119 