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

Step 1: Understanding the Clinical Finding.
The patient has complete loss of vision in the left eyeThis condition is known as monocular blindnessIt indicates damage to the visual pathway before the fibers from both eyes partially cross
Step 2: Anatomy of the Visual Pathway.
Visual signals travel from the retina → optic nerve → optic chiasma → optic tract → lateral geniculate body → visual cortexThe optic nerve carries all visual information from one eye before reaching the chiasma
Step 3: Correlating Lesion with Symptoms.
(A) Optic nerve: Damage to the left optic nerve causes complete loss of vision in the left eye (monocular blindness)Correct
(B) Optic chiasma: Lesion produces bitemporal hemianopia (loss of peripheral vision in both eyes)
(C) Optic tract: Lesion causes contralateral homonymous hemianopia
(D) Ciliary body: Involved in accommodation and aqueous humor production, not complete vision loss
Step 4: Conclusion.
Therefore, complete vision loss in the left eye indicates injury to the left optic nerve