Lecture 6.1: Special Senses – The Eye and the Ear Flashcards
1
Q
How many fibres does the Optic nerve have?
A
> 1million
2
Q
How many fibres does the Auditory nerve have?
A
30,000
3
Q
What percentage of blindness is preventable?
A
50%
4
Q
Name 4 preventable causes of blindness (4)
A
- ARMD
- Glaucoma
- Cataracts
- Diabetic Retinopathy
5
Q
What is Phototransduction?
A
Process by which light energy is translated into electrical
energy
6
Q
What are the 2 Photoreceptors found in the Eye?
A
Rods and Cones
7
Q
What are Rods sensitive to? Where are they found?
A
- Sensitive to low level light – night vision
- All areas of retina except fovea
8
Q
What are Cones sensitive to? Where are they found?
A
- 3 different photopigments – red, green and blue
- Daytime vision
- Highest density at fovea
9
Q
What is Myopia?
A
- Short-sightedness is a very common eye condition
where you cannot see objects far away clearly - Eyeball too long or lens too curved
- Image formed in front of the retina
10
Q
What is Hypermetropia?
A
- Long-sightedness is where you find it hard to see
things nearby, but you can see things far away clearly - Eyeball too short or lens too flat
- Image formed behind the retina
11
Q
What is Visual Acuity?
A
- How well we can resolve fine detail
- Snellen chart
12
Q
What is the Ishihara Test?
A
- Test of colour vision
13
Q
What do you check when assessing vision? (8)
A
- Visual acuity
- Ishihara test
- Pupillary reflexes
- Blind spot
- Ophthalmoscopy (retina, optic nerve)
- Visual fields
- Eye movements
- Ocular alignment
14
Q
Why is an Ophthalmoscopy done?
A
- Visualisation of the vitreous and retina
- Can use pupillary dilatation
15
Q
What does Black blobs in the Vitreous mean?
A
Vitreous haemorrhage