Refractive Error Flashcards
What percent of the adult population in the USA are myopic?
42%
By _____, it is expected that ______ of the world’s population will be myopic.
2050, 50%
_____ of the world’s population over ____ years of age have presbyopia.
100%, 50
Are convex plus or minus? Concave?
Convex: plus
Concave: minus
What is the far point of the eye?
The point conjugate with the retina of the unaccommodated eye
In front of the eye for myopes
Behind the eye for hyperopes
At optical infinity for emmetropes
How can we correct refractive error?
With lens whose second focal point coincides with patient’s far point
Describe the location of the object/image when wither is at optical infinity.
When object is at optical infinity, image lies at second focal point of lens
When image is at infinity, object lies at the first focal point of the lens
When should we specify bvd?
When prescribing a spec Rx great than -6 or +6
What occurs during accommodation? Who can accommodate?
Increase refractive power of the crystalline lens
Ciliary muscle contracts
Zonules relax
What happens when you overcorrect a hyperope? (Fogging)
You turn them into a myope
How do we stop a hyperope from accommodating?
Cycloplegic drugs
Fogging
Describe total hyperopia.
Get rid of all the accommodation with a cyclopegic drug you measure total hyperopia
Describe manifest hyperopia.
Max plus to best V/A measure manifest hyperopia
Describe latent hyperopia. How do you calculate it?
Hyperopia masked by accommodation
Total-manifest
Describe facultative hyperopia.
The difference between the result found under fog and the max plus to best V/A
Hyperopia under fog - hyperopia before fogging
