Vision

Blood supply of macula:

1. Posterior Cerebral Artery
2. Middle Cerebral Artery

Snell 8th- 473

Structure seen through opthalmoscope:
1.Optic Disc
2.Retina
3.Blood vessels
4.Macula

Snell 8th-349

Explanation :
Lesion of left optic nerve: Total blindness of left eye.
Lesion of right optic nerve: Total blindness of right eye.
Lesion of lateral fibers in left side of optic chiasma: Left nasal hemianopia.
Lesion of lateral fibers in right side of optic chiasma: Right nasal hemianopia C + D.
Lesion of lateral fibers in both sides of optic chiasma: Binasal hemianopia.
Lesion of medial fibers in optic chiasma: Bitemporal hemianopia.
Lesion of left optic radiation: Right homonymous hemianopia.
Lesion of right optic radiation: Left homonymous hemianopia.nknown.

Ref : Sembulingam 6th edition (Figure-168.5)

Explanation : Three areas are present in visual cortex:
i. Primary visual area (area 17), which is concerned with the perception of visual impulses.
ii. Secondary visual area or visual association area (area 18), which is concerned with the interpretation of visual impulses.
iii. Occipital eye field (area 19), which is concerned with the movement of eyes (Chapter 152). Pretectal nucleus is concerned with light reflexes.

Ref : Sembulingam 6th edition (Page- 991)

Explanation :

Ref : Sembulingam 6th edition (Table- 141.1)

Explanation : Optic tract is formed by uncrossed fibers of optic nerve on the same side and crossed fibers of optic nerve from the opposite side. Fibers from fovea do not enter superior colliculus. Supraoptic nucleus of hypothalamus: It is concerned with the retinal control of pituitary in animals. But in human, it does not play any important role. Fibers from lateral geniculate body pass through internal capsule and form optic radiation.
Ref : Sembulingam 6th edition (Page- 990,991)

There are two types of bipolar cells:
a) OFF-center bipolar cells and
b) ON-center bipolar cells.
These cells respond in opposite ways to the glutamate released by the photoreceptors because they express different types of glutamate receptors. Like photoreceptors, the bipolar cells do not fire action potential and only respond with graded postsynaptic potentials

Explanation : First order neurons (primary neurons) are bipolar cells in the retina. Axons from the bipolar cells synapse with dendrites of ganglionic cells. Second order neurons (secondary neurons) are the ganglionic cells in ganglionic cell layer of retina. Axons of the ganglionic cells form optic nerve. Optic nerve leaves the eye and terminates in lateral geniculate body. Third order neurons are in the lateral geniculate body. Fibers arising from here, reach the visual cortex.
Ref : Sembulingam 6th edition (Page- 989)

Explanation : Amplitude of accommodation varies with age. Amplitude of accommodation at different age groups is: 10 years = 11.0 D, 20 years = 9.5 D, 30 years = 7.5 D, 40 years = 5.5 D, 50 years = 2.0 D, 60 years = 1.2 D, 70 years = 1.0 D.
Ref : Sembulingam 6th edition (Page- 998)

Receptors are those in the rods and cones in the retina that respond to light are- photoreceptors

Argyll Robertson Pupil (ARP):
Hallmark of neurosyphilis
1. Light-near dissociation (no reaction to light but brisk response to near).
2. Both pupils usually involved, but the degree may be asymmetrical.
3. Pupils are small and frequently irregular in shape.
4. Pupils dilate poorly after instillation of mydriatics.
5. To make a diagnosis of ARP vision in the affected eye must be normal.

Explanation : Pupillary reflexes are classified into three types: 1. Light reflex 2. Ciliospinal reflex 3. Accommodation reflex.
Ref : Sembulingam 6th edition (Page- 994)

Explanation :

Ref : Sembulingam 6th edition (Figure- 169.1)