Vision

Question 1

in myopia the eye is too long/short

Answer 1

too long

Question 2

what eye condition is caused by a lens that is too thin or an eye that is too short

Answer 2

hyperopia

Question 3

people with myopia have difficulty seeing things that are close/far

Answer 3

far

Question 4

what special type of glasses does astigmatism require

Answer 4

cylindrical glasses that are only curved in one plane

Question 5

what is amblyopia

Answer 5

a lazy eye

Question 6

pathology of old age myopia

Answer 6

lens gets stiffer and less able to stretch and thin out to focus on close things

Question 7

what is diplopia

Answer 7

double vision, usually from nerve palsies

Question 8

what are the intrinsic eye muscles

Answer 8

ciliaris muscle, constrictor and dilator pupillae

Question 9

afferent pathway of light on eye

Answer 9

falls on retina –> optic nerve –> III nucleus in midbrain

Question 10

efferent light reflex

Answer 10

III nucleus in midbrain –> preganglionic parasympathetic fibres of III –> ciliary ganglion in orbit –> postganglionic fibres –> contrictor pupillae

Question 11

what is Horner’s syndrome

Answer 11

pupils of different sizes (aniscoria)

Question 12

would a III palsy usually have pupillary reflex

Answer 12

yes they would. Conditions that cause this palsy don’t usually affect parasympathetic fibres. If the reflex is absent then there may be a cerebral artery aneurysm

Question 13

how do postganglionic sympathetic fibres travel in head and neck

Answer 13

along with blood vessels

Question 14

what is phototransduction

Answer 14

conversion of light wave energy into an electrochemical response in rods and cones

Question 15

how do rods and cones activate the optic nerve

Answer 15

by producing an action potential

Question 16

what part of the rods and cones turns the light into electrochemical response

Answer 16

outer segment of stacked lamellae

Question 17

visual pigment of outer segments of rods

Answer 17

rhodospin

Question 18

visual pigment of outer segments of cones

Answer 18

opsins

Question 19

process of action potential production from light

Answer 19

light energy on pigment –> cis to trans –> bleaches –> cascade of processes –> Na+ channels close –> hyperpolarisation

Question 20

how do visual pigments regenerate

Answer 20

vitamin A takes it back to cis from trans

Question 21

signs of vit A deficiency in eye

Answer 21

bitot’s spots on conjunctiva
corneal ulceration
opacification of cornea

Question 22

visual defect caused by damage to optic chiasm

Answer 22

bitemporal hemianopia

Question 23

where is the primary visual cortex

Answer 23

occipital lobe area 17

Question 24

what does the optic tract contain

Answer 24

fibres from the same one half of vision in both eyes (i.e. the left half of the field)

Question 25

where does the optic tract fibres synapse

Answer 25

in the lateral geniculate body of the thalamus