The most common eye problem is a squint, which may need rectification with glasses, or in severe cases, an operation. Some children may have cortical vision defect. This means that the part of the brain that is responsible for understanding the images the child sees is not functioning properly. When examined the eyes may appear healthy, but he or she will not be able to see properly. The difficulty is in unscrambling the messages received from the brain, when learning to read for example.