Question

A patient fell from bed. On examination there is loss of complete vision from left eye. Which of the following structure is injured in this case?

• A. Optic nerve
• B. Optic chiasma
• C. Optic tract
• D. Ciliary body

Hint:

Monocular blindness = lesion of optic nerve before the optic chiasma.

Answer 1

The Correct Option is A

To determine which structure is injured causing complete vision loss from the left eye, we need to understand the anatomy and function of the visual pathway. Here's a breakdown of the relevant structures:

1. The optic nerve is responsible for transmitting visual information from the retina to the brain. Damage to the optic nerve can lead to loss of vision in the affected eye.
2. The optic chiasma is where the optic nerves partially cross. Injury here typically causes bitemporal hemianopia, affecting the peripheral vision of both eyes, not complete vision loss in a single eye.
3. The optic tract carries visual information from the optic chiasma to the brain. An injury here would cause contralateral homonymous hemianopia, affecting the same side of the visual field in both eyes, not complete vision loss in a single eye.
4. The ciliary body is part of the eye involved in focusing and producing aqueous humor. Its injury does not cause complete vision loss.

Given these options, the correct answer is "Optic nerve". An injury to the optic nerve in the left eye would result in the complete loss of vision in that eye, aligning with the symptoms described in the question.

Conclusion:

The structure most likely injured to cause complete vision loss from the left eye is the optic nerve. The other structures listed affect vision differently, either impacting both eyes or not causing complete vision loss.