2.3 - Application to the human eye Flashcards
What is optical axis
Hypothetical line passing through centre of curvature of all surfaces in system
What does light fall on when you look at an object
Your fovea centralis - best VA
What is direction of angle between visual and optical axis
It is 5 degrees nasal and 2 degrees upward on average
How can you approximate cornea by one surface
By combining anterior and posterior cornea surface
How can you approximate cornea by one lens with a homogeneous n
Not just one refractive index - changes throughout but as 1st level approximation, can use single refractive index for crystalline lens
What are the refracting surfaces of light in the eye
Front and back surfaces of cornea and lens
What is fovea centralis
- Highest level/best of VA
- Highest number of photoreceptors and megapixels
- Doesn’t lie on OA = slightly off OA
- When we carry out task, e.g. what’s bottom line of letters read - image placed on fovea centralis
What is the visual axis
Passes through centre of pupil, hits retina at most sensitive point - fovea centralis
How many surfaces does lens have in eye
4
What is power in reduced eye
+60D
What is n and n’ in reduced eye
n = 1 n' = 4/3
What is emmetropic reduced eye
No refractive error
reduced eye - take more complicated system and reduce it to single thin lens
