Johnny’s mother takes him to the eye surgeon because she has noticed that when J
ID: 178517 • Letter: J
Question
Johnny’s mother takes him to the eye surgeon because she has noticed that when Johnny is tired – he goes “cross-eyed”. While holding Johnny’s head while he is facing him, the doctor asks Johnny to follow his penlight with his eyes. Johnny can follow the light in all positions except when the doctor covers his left eye and put the light in the lower lateral portion for his right eye. Instead of following the light with his right eye, his eye turns in and up. What muscle or muscles were affected? Which muscle, or muscles normally antagonize this movement?
Explanation / Answer
Strabismus or cross-eyed is caused due to the poor control over the eye muscle. Six muscles are used in controlling the direction and the focus of the lenses. The problem may also be caused due to the damage to the nerves that transmit information to the eye muscles. The muscles involved are:
medial rectus (MR), lateral rectus (LR), superior rectus (SR), inferior rectus (IR), superior oblique (SO), and inferior oblique
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