All content on Eyewiki is protected by copyright law and the Terms of Service. This content may not be reproduced, copied, or put into any artificial intelligence program, including large language and generative AI models, without permission from the Academy. Introduction In humans, prolonged contraction of the ciliary and medial rectus muscles during close reading will result in eye strain. On the other hand, eye strain will not occur if the ciliary and medial rectus muscles do not contract dur...