Optics: Lens Effectivity Flashcards
What is the vertex distance?
The distance between the cornea and the ocular (back) surface of the spectacle lens
Where is the far point of the myopic eye?
At a fixed distance from the eye
Where must the secondary focal point be in order to correct the refractive error?
Must be coincident with the far point
The power of a correcting lens depends on…
Where its located
What is the purpose of optical correction?
To transfer the object from infinity to the far point
When we replace a myopic patients contact lens with a spectacle lens, what must we do to the power?
Increase the power in the spectacle lenses
Does a hyperope have a higher script in their contacts or glasses?
Higher in their contacts
Does a myopic patient have a higher script for contacts or glasses?
Glasses script higher
Moving a spectacle lens away from a myopic eye make lens effectively ______.
Weaker
To increase the effective power of spectacles for hyperopes, you need to move them..
Away from the eye
Moving the spectacle lens closer to a hyperopic eye makes them effectively ______.
Weaker
Effective power of spectacle lens used to correct myopia is increased by moving the lens…
Towards the eye
