Refractive Errors Flashcards
What is Myopia?
Myopia is when the eyeball is too long, or the cornea is too curved, which causes light to focus in from the retina
What is Hyperopia?
Hyperopia is when the eyeball is too short or the cornea is too flat, causing light to focus behind the retina
What is Astigmatism?
The cornea or lens has an irregular shape, which leads to multiple focal points instead of a single point.
As we age what happens to the lens?
The lens becomes less flexible which can lead to hyperopia because the lends struggles to focus on nearby objects
What contributes to developing myopia in the vision?
Prolonged screen time, reading without proper lighting, and not spending enough time outdoors
What type of lens helps with myopia(negative) sight and how do they help?
Concave lens: (thinner in the center) helps diverge light rays, allowing them to focus on the retina
What type of lens helps with hyperopia(positive) sight and how do they help?
Convex lenses:(thicker in the center) converge light rays, allowing them to focus on the retina.
What type of lens helps with astigmatism?
Cylindrical lenses are used to correct the irregular curvature of the cornea
Define Emmetropia.
An eye that focuses light precisely on the retina
What does OD stand for and what does it refer to?
Oculus Dexter: Refers to the right eye
What does OS stand for and what does it refer to?
Oculus spinster: left eye
What does SPH stand for and what does it do?
Sphere: indicates the degree of myopia or hyperopia
What does ClY stand for and what does it do?
Cylinder: indicates degree of Astigmatism
What does the axis do?
Ensures that the cylindrical correction is oriented correctly to address the specific shape of the eye
What does the ADD do for the spectacle prescription?
Add in additional magnifying power for reading (used for presbyopia)
