This book represents a substantial revision of the excellent monograph written in 1974 by Charles Windsor, M.D. and Jane Hurtt, R.N., A.A., Eye Muscle Problems in Childhood: a Manual for Parents — second edition. Although their booklet is now about 40 years old, it has remained the best guide available for informing parents, patients and primary care physicians about the complex subject of eye muscle problems. Both authors have generously given me permission to update and modify their publication. I would also like to thank the tens of thousands of patients who have entrusted me with their care over the past 40 years. Their questions inspired this book. There are no “dumb questions” when it comes to medical matters. If a question exists in a patient’s mind, it should be addressed. If that question remains unasked or unanswered, or if the answer is not understood, not only the doctor-patient relationship may suffer, but adverse medical consequences may follow.