Physiological Optics Flashcards
What is the Refractive Index of the Cornea?
1.37
What is the Refractive Index of the Aqueous?
1.33
What is the Refractive Index of Lens?
1.43
What is the Refractive Index of Vitreous?
1.33
What is the Total Refractive Power of the Eye?
60 D
What is the Corneal Power?
43 D
What is the Lens Power?
+15 D to +20 D
What occurs as the light travel through the eye? and what is the image?
Refraction
Inverted
What is Emmetropia?
The focal point parallel light rays coming into the eye is on the retina
“perfect vision”
What is Ametropia?
Refractive error is present
What is Myopia?
Nearsightedness
What is the shape of a myopic eye?
Eyeball is too long
Where does the focal point land for myopic eye?
Within the vitreous
In front of the retina
What lens can correct myopia?
Diverging or Minus lens
Concave
What is Hyperopia?
Farsightedness
What is the shape of a hyperopic eye?
Eyeball is too short
Where does the focal point land for hyperopic eye?
Behind the retina
What lens can correct hyperopia?
Converging or Plus Lens
Convex
What is Astigmatism?
Refractive Error is not equal in all meridians
One meridian is curvier than the other
What is the shape of the cornea for an Astigmatism eye
Football
Where does the focal point land for astigmatism?
There is 2 focuses in the eye
No focal point
What lens can correct astigmatism?
Sphero-cylindrical Lenses
What are examples of Amplitude of Accomodation?
Gradually decreases with age
Lens becomes less flexible
What is the Conoid of Sturm?
How rays are refracted through two different power meridians
Optical Condition refractive power of cornea and lens is not the same in all meridians
What is the Unequal image sizes called?
Aniseikonia
What is the Unequal Refractive Errors called?
Anisometropia
What is the Amplitude of Accomodation?
Measured in Dioptres
Gradually Decreases in age
Lens becomes less flexible
What are Accommodative Conditions?
Presbyopia
Latent Hyperopia
What is the Accommodative Condition for loss of accommodation associated with aging?
Presbyopia
What is the Accommodative Condition for amount of hyperopia that can be overcome with accomodation?
Latent Hyperopia
What is the Refractive of the Eye?
63 D
What is the Reduced or Simplified Eye?
Gullstrand is 58.60 D
Eye is 22.6m in length
Anterior focal point is 17mm in front of the cornea
Nodal point is 5.6mm behind the cornea