12 - Opth - Refractive Error - Hypermetropia, Astigmatism, Presbyopia Flashcards Preview

CP2 > 12 - Opth - Refractive Error - Hypermetropia, Astigmatism, Presbyopia > Flashcards

Flashcards in 12 - Opth - Refractive Error - Hypermetropia, Astigmatism, Presbyopia Deck (10):
1

What is hypermetropia

long sightedness

2

what happens in hypermetropia + why

light focused behind retina due to
-refractive power too weak (<60) - cornea/lens too flat)
- axial hypermetropia (eye too short <22.22m)

3

possible cause + associated ocular conditions - hypermetropia

usually genetic component
-Acute angle closure glaucoma
-squint
-amblyopia

4

What may compensate hypermetropia - what can this lead to

partial compensation with accommodation - tiredness of gaze, headaches and convergent squint in children

5

how to correct hypermetropia

corrected by convergent (convex) lens (+ve prescription)

6

Astigmatism - cause + effect

by cornea or lens lacking regular curvature in all directions - light rays lack a single point of focus

7

How to correct Astigmatism

with cylindrical lens - along with correcting main refractive error

8

Presbyopia - when? what happens? reduces what?

in old age - starts at 40y and ends by 60y
- progressive sclerosis of lens - reduces accommodative ability

9

define presbyopia

age related impaired accommodation and near vision

10

how to correct presbyopia

correct with convex lens (+ve prescription)

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