Corneal Topography in Vernal Keratoconjunctivitis

Vernal keratoconjunctivitis (VKC) is a chronic allergic disease, with seasonal periods of exacerbation.VKC is characterized by itching, photophobia. white mucous discharge, lacrimation, foreign body sensation, and pain due to corneal involvement of shield ulcers. Corneal involvement in VKC involves injury to the superficial and basal epithelial layers and anterior stroma . Excessive eye rubbing and a slow release of matrix metalloproteinases penetrate the cornea in presence of chronic epithelial damage causing astigmatism and corneal ectasia . These changes may be undetected until advanced complications such as keratoconus(KC) with thinning and protrusion of cornea leading to myopia and astigmatism . These changes can be measured accurately by corneal topography, making it the gold standard in the screening of keratoconus and other corneal ectasias . Corneal topography is a method of computer-assisted examination of the cornea in which multiple concentric light rings are projected on cornea. Changes in corneal topography indices to be studied include changes in effective refeactivepower ,asphericity , corneal asymmetry index and visual performance . It is a non-invasive exploratory technique to analyse both qualitatively and quantitatively the morphology of the cornea . The Penta Cam is a cornea and anterior segment topography device, based on a rotating Scheimpflug camera. Its optical cross-sectional analysis that helps in imaging of anterior and posterior corneal surfaces which provides with fullpachymetric map and many other data such as corneal aberrometry and densitometry that allow early detection of ectasia.