To present a case of sensory strabismus due to keratoconus with an ipsilateral nodular lesion of the bulbar con-junctiva.The patient is a 17 year-old-boy. The fixing eye was the right eye and keratoconus in this eye was late onset. Vision in the left eye was poor and keratoconus was advanced in this eye. Due to longstanding of keratoconus and occurrence in the sensitive period, sensory exotropia had developed in the left eye. A nodular lesion of the bulbar conjunctiva was also present in the ipsilateral eye.Sensory exotropia is not unusual but to be due to longstanding keratoconus is not a usual strabismus. If keratoconus develops before 7 years of age, sensory strabismus can develop. We reported and reviewed literature that keratoconus seldom begins in the sensitive period where abnormal visual experience affects visual development and may induce sensory exotropia.