Aimof the work demonstrate the affection of the allergic conjunctivitis on the corneal surface and topography.Study has been undertaken to determine corneal topographic characteristics of patients with allergic conjunctivitis and compare the change in corneal topographic indices in allergic conjunctivitis subjects with normal subjects. Case – control study was carried out in Bani Suif Ophthalmic hospital among 204 eyes divided into two groups 102 diseased eyes  with allergic conjunctivitis and 102 normal eyes  age and gender matched normal subjects from July 01, 2018 to November 30, 2019. Patients with disease other than allergic conjunctivitis, previous history of corneal scars, dry eye, eye infections ,uveitis , history of surgery and unwilling to participate in the study were excluded. Age and gender matched subject with normal ocular finding were considered as a normal comparable group. The purpose and procedure of study were clearly explained to verbal consent was received from all subjects. Uncorrected and corrected distance visual acuity of each eye was assessed. Detailed anterior segment examination was carried out with the help of a Slit lamp biomicroscopy.Diagnosis of allergic conjunctivitis was made on the basis of the typical clinical history of severe itching and burning sensation with characteristic signs, including giant papillae on the upper palpebral conjunctiva, limbal infiltrates, and eosinophilic concretions (Horner–Trantas'_dots).