Neuro Opthalmology

Question 1

Pitutary adenoma which vision will be lost

Answer 1

B/l temporal vision
As b/l nasal fibres cross at optic chiasma — pitutary adenoma would compress these fibres and the loss of vision would be temporal coz nasal fibres are responsible for temporal vision

Question 2

Earliest optic nerve fibres affected in optic nerve lesion

Answer 2

Macular fibres → central visual field affected → central scotoma
Causes of central scotoma all optic nerve diseases, earliest manifestation- optic neuritis (mcc multiple sclerosis)
Hereditary Optic neuropathy
Toxic optic neuropathy( due to toxic agents like ethambutol)
Nutritional optic neuropathy
Cone dystrophy( stargard disease)

Question 3

Cause of bitemporal hemianopia

Answer 3

Buy ( bi) 3 PC AC
3- 3rd ventricular glioma
p- pitutary ademoma ( macroadenoma >10 mm)
C-craniopharyngioma ( tumour of rathkes pouch)
A- anterior communicating artery aneurysm
C-cavernous sinus thrombosis

All are relations of chiasma ( superior - rathkes pouch, inferior- pitutary)

Question 4

Wernickes pupil

Answer 4

Abnormal dilation of pupil in optic tract lesion ( used to differentiate between LGB lesion and optic tract lesion as visual field lost in all these cases is same and cannot be used for diagnosis)

Question 5

Nerve supply of ocular muscles

Answer 5

OAT
Oculomotor —medial rectus ,inferior rectus, superior rectus and inferior oblique

Abducens—lateral rectus

Trochlear—superior oblique

All extraocular muscles (like levator palpebri are supplied by occulomotor)

Question 6

Order of neurons in visual path

Answer 6

First order—photoreceptors
Second— bipolar cells
Third order—ganglion cell(optic nerve)
Fourth order—from LGB (optic radiations)