Keratoconus can be difficult to detect, because it comes on slowly. Nearsightedness and astigmatism also accompany this disease, so you may have distorted and blurred vision. You might also notice glare and light sensitivity. Keratoconic patients often have prescription changes each time they visit their eyecare practitioner. It?s not unusual to have a delayed diagnosis of keratoconus, if the practitioner is not familiar with the early-stage symptoms of the disease.