Windows 10 bootable USB using USB/DVD Download Tool. IMP: If you get âThe selected file is not a valid ISO fileâ error, please follow the instructions mentioned in our how to fix the selected file is not a valid ISO file error guide.
However, in some cases it can cause troublesome vision distortion. Here are the most common signs and symptoms of astigmatism: 1  Blurring or distortion of images at all distances. 2  Headache. 3  Fatigue. 4  Squinting. 5  Eye discomfort or irritation. 6  Difficulty seeing at night.
What is Astigmatism? Astigmatism usually occurs when the front surface of your eye, the cornea, has an irregular curvature. Astigmatism is one of a group of eye conditions known as refractive errors and these errors cause a disturbance in the way that light rays are focused within your eye. Astigmatism often occurs with nearsightedness and farsightedness, conditions also resulting from refractive errors.