Macular Degeneration is the issue that creates loss in vision which is supposed to be non-curable or low curable disease.It occurs due to issue in retina's central part which is known as macula. This can result in an individual's vision getting effected while reading or viewing something.
According to the question, Roberta might be experiencing macular degeneration disease in which the she is not able to properly see some words or letter that fall between the sentences.
