Neuro - Visual system Flashcards
What are all of the different parts that make up the eye?
Lateral:
- Upper eyelid
- Palpebral fissure
- Lateral canthus
- Lower eyelid
Medial:
- Pupil
- Iris
- Sclera
- Medial canthus
- Caruncle
- Limbus
What structures make up the lacrimal system?
- Lacrimal gland
- Punctum
- Canaliculus
- Tear duct
- Tear sac
What are the 4 layers of the tear film?
- Lipid
- Water
- Mucin
- Epethelial
What is the function of the tear film?
- Maintains smooth cornea-air surface to supply the cornea with oxygen
- Removal of Debris
- Bactericide
What is conjunctiva?
Thin, transparent tissue that covers the outer surface of the eye
What is sclera?
The tough, opaque tissue that serves as the eyes protective outer coat
‘The white of the eye’
What is the cornea?
The transparent dome covering the front of the ye used to refract light and focus light
What is the uvea?
The vascular coat of the eyeball which lies between the sclera and retina
What is categorised as central vision?
- Detail day vision
- Colour vision
What is categorised as peripheral vision?
- Shape
- Movement
- Night vision
- Navigation vision
What is Emmetropia?
The refractive statem of the eye which parallel rays of light are focused on the retina to produce a clear image
What is Ametropia?
A mismatch between axial length and refractive power so parallel rays of light do not fall onto the retina
What is myopia?
Parallel rays coverge before they reach the retina
What are the symptoms of myopia?
- Blurred vision
- Headaches due to trying to focus
What are the treatment options for myopia?
- Correction with diverging lens (negative lenses)
- Correction with contact lens
- Correction by removing the lens to reduce refractive power of the eye
What is hyperopia?
Parallel rays of light converge past the retina
What are the symptoms of hyperopia?
- Unable to see close objects/fine print
- Asthenopic symptoms:
- Eyepain
- Headache in frontal region
- Burning sensation in eyes
- Blepharoconjunctivitis
What are the treatment options for hyperopia?
- Correction with converging lens (positive lenses)
- Correction with positive lens and cataract removal
- Correction with contact lens
- Correction with intraocular lens
What is astigmatism?
Parallel rays come to focus 2 focal lines rather than a single focal point
What can cause an astigmatism?
The refractive media is not spherical
What are the symptoms of astigmatism?
- Asthenopic symptoms (headaches, eyepain)
- Blurred vision
- Distortion of vision
- Head tilting and turning
What are the treatment options for astigmaitsm?
- Regular astigmatism - cylinder lenses with or without spherical lens
- Irregular astigmatism - rigid cylinder lenses, surgery
What is presbyopia?
Naturally occurring loss of nearsightedness due to increased rigidity of the lends and increased stiffness the ciliary muscle
What are the treatment options for presbyopia?
Convex lenses
Why do both eyes get visual field affects if there is a lesion to the optic nerve posterior to the optic chiasma?
This is because 53% of nerve fibres cross over at the optic chiasma and go the go to the opposite eye, so a lesion will affect the opposite eye also
What type of nerve causes pupil constriction?
Parasympathetic nerve of CN III
What type of nerve causes pupil dilation?
Sympathetic nerve of CN III
What is the difference between a direct light reflex and a consensual light reflex?
A direct light reflex if the constriction of the the pupil of the light stimulated eye
A consensual light reflex is the constriction of the pupil of the opposite eye to the one being stimulated
What are the 6 ectraocular muscles and the 3 cranial nerves that innervate them?
6 extraocular: - Lateral rectus - Medial rectus - Superior rectus - Inferior rectus - Superior oblique - Lateral oblique 3 cranial nerves: - Cranial nerve III - Cranial nerve IV - Cranial nerve VI
What is duction
Eye movement in one eye
What is version?
Simultaneous movement of both eyes in the same direction
What is vergence?
Simultaneous movement of both eyes in the opposite direction
What is convergence?
Simultaneous adduction movement in both eyes when viewing a near object
What is saccade?
Short fast burst eye movement
What is smooth pursuit?
Sustained slow eye movement
What is a nystagmus?
Oscillatory eye movement
Optokinetic nystagmus - oscillatory eye movement + fast phase reset saccade
