Purkinje Images
When does a Purkinje image occur? What forms the brightest image? What forms the dimmer images? What determines the size and positions of the reflected images?
- A Purkinje image occurs when a light source or illuminated object is positioned in front of the eye, light is reflected from the cornea and the lens surfaces - The brightest image is formed by the first and most powerful surface, which is the anterior cornea, while other dimmer images are formed by the posterior cornea, anterior and posterior lens - Sizes and positions of the reflected images are determined by the radius of curvature of the surface, the size of the source, as well as the distance between the source and the surface
What causes catadioptric images(type of Purkinje Image)? What is involved in a catadioptric image?
- Catadioptric images are all the images from optical surfaces(posterior cornea, anterior lens, and posterior lens) viewed through the cornea, except for the anterior cornea - In a catadioptric image, reflection and transmission are involved since they are viewed through the cornea
What are the types of orders of Purkinje images? What causes each of them to form?
- First-order Purkinje images (I-IV) are formed by reflection at a single surface - Second-order Purkinje images (V-VI) are formed by reflection at 2 surfaces
What surface causes catoptric images(type of Purkinje Image)? Where are catoptric images formed?
- Images that are purely due to reflection cause catoptric images - Catoptric images are ONLY formed on the anterior cornea
What does the anterior cornea act as when forming a purkinje image? What are the equations that go along with this?(On picture, and in handout for lab)
- The Anterior cornea acts as a spherical mirror when forming a purkinje image
What can Purkinje images be used for in the clinic or for research?
Purkinje images can be used in the clinic or for research to: - Locate axes and their associated angles - Hirschberg Tests - Measure corneal curvature (keratometry) - Measure lens curvature and position - Measure lens changes in accommodation - Monitor very precise eye position (eye-tracking)
What are the types of purkinje images?
The types of Purkinje Images are catoptric and catadioptric images
