Question

Injury to the Right Optic Nerve can result in ___% loss of vision in the ____ Eye.

A. 100% ; Right

B. 50% ; Right

C. 25% ; Right

D. 0% ; Right

E. 100% ; Left

Answer 1

Option A-100%,Right

Optic Nerve is the 2nd Cranial nerve which is present in the back of Eye,which carry Visual Information from the Retina to the Brain(In to Occipital Cortex in Occipital Lobe of Your Brain)

Injury to Optic Nerve in Right Eye cause 100 % Blindness in the Right Eye becuase,without proper functioning of Optic nerve,No Visual Information from the Right Retina Passes in to Visual Cortex..So there is Blindness of Right Eye.

Similarly,If left Optic Nerve is Injured there will be Loss of Vision in your Left Eye.

Crossing Of Nasal Fibres of Optic Nerve occur in the Optic Chiasma.So Injury To Part of Visual pathway After Optic Chiasm(For Example Optic Tract, Lateral geniculate Body) There will be Loss of Temporal Field of Vision in Your Opposite eye & loss of Nasal Vision in the Same Eye.

This is Because Nasal Fibres of Right eye carry Vision from the Temporal Field of Eye.This Crosses to Opposite side in Optic Chiasm.Where as Temporal Fibres which carry visual information from nasal field of eye donot cross to ooposite side.

So Injury to Right Lateral Geniculate Body causes

1.Injury to Temporal Fibres of Right Eye that causes Loss of Nasal Field of Vision in Right Eye.

2.Injury to Nasal Fibres of Left Eye that causes Loss of Temporal field of Vision in Left Eye.

Visual Pathway--

Retina--Optic Nerve--Optic Chiasm--Optic tract --Lateral geniculate Body--Optic radiation--Visual Cortex.

Crossing of Nasal Fibres occur at Optic Chiasm Only.

So Injury in Optic Nerve affect vision in Same Side of Eye.